This study evaluates suspended sediment concentration (SSC) in two estuaries in New Brunswick, Canada (Bouctouche and Cocagne). A linear relationship was first established between turbidity and SSC ((Formula presented.) = 0.97 and 0.94). Water-leaving reflectance was retrieved from Sentinel-2A and 2B imagery using the ACOLITE atmospheric correction. Turbidity was then estimated from satellite images using in situ turbidity data and a semi-empirical algorithm applied to the red-edge band (704 nm), selected based on a combined evaluation of statistical performance and physical consistency of retrieval patterns. This model yielded (Formula presented.) values of 0.40 in Bouctouche and 0.63 in Cocagne. Based on imagery from 2016 to 2024, seasonal patterns were detected in both estuaries, with higher SSC observed in April and May, likely due to increased river flow and snowmelt. The analysis also indicates that Bouctouche exhibits higher SSC values than Cocagne. A generalized linear model (GLM) was fitted using images from 2016 to 2023 where top-of-atmosphere SWIR (1600 nm) reflectance is below 0.02, minimizing sun glint and adjacency effects. The GLM predicts median SSC in each estuary using wind data, tidal levels and freshwater inflow, achieving (Formula presented.) values of 0.55 in Bouctouche and 0.54 in Cocagne in fivefold cross-validation. In both estuaries, higher SSC was associated with increased river discharge, stronger winds and ebb tides. Additionally, in Cocagne, lower tidal levels were also linked to elevated SSC. Finally, the study investigates longitudinal SSC variations along the estuarine channels. A decreasing gradient in SSC from upstream to downstream was observed in 67% of Bouctouche images and 82% of Cocagne images. These results suggest that sediment inputs originate both from the watershed and upstream river flow.

The development and implementation of environmental DNA (eDNA) assays have revolutionized aquatic species monitoring, yet progress is impeded by inconsistent standards in assay design, validation, and reporting. When insufficiently validated quantitative PCR (qPCR) assays are used for management and conservation, false positives or false negatives can have significant ecological and policy consequences. Drawing on existing standardized workflows, we present an integrated, multi-stage decision-oriented framework for eDNA assay development and validation that spans conceptual design through to in situ testing. The first stage includes a decision checklist for in silico assay validation, adapted from the empirical Thalinger validation scale, which enables users to critically assess the risk of false positives and false negatives before entering the laboratory. This early-stage evaluation informs and strengthens subsequent in vitro (i.e., specificity, sensitivity, and interference) and in situ testing, the key principles of which are presented here in a streamlined and accessible manner to support both expert and non-expert users. We illustrate the flexibility and scalability of these guidelines through three diverse case studies, from regional validation of a published assay to design and validation of novel genus-specific and species-specific assays for application to water samples and dietary analysis, respectively. Our trainee-led initiative reflects interdisciplinary partnerships across academic institutions, government agencies, and conservation organizations, and demonstrates how co-produced molecular tools can generate actionable results for fisheries management. The resulting decision support tool offers a reproducible, transparent, and adaptable pipeline for assay development, with broad applicability across freshwater fish monitoring programs in Canada and beyond.

Fine sediment infiltration is widely discussed as a stressor to wild salmonids’ spawning success, but its mechanisms and severity in wild salmonid redds are difficult to measure. This study examined wild Atlantic salmon (Salmo salar) redd survival using emergence traps in two small coastal streams with differing agricultural land-use intensities on Prince Edward Island, Canada. Measured environmental parameters included stream and hyporheic dissolved oxygen, water velocity, water level, redd temperature, redd substrate composition, and stream suspended solids. Wild Atlantic salmon redds were equipped with emergence traps during May to June in two study years to evaluate survival. No single environmental factor was strongly associated with the success of individual redd emergence. However, the West River exhibited approximately two-fold-higher portions of silt and clay in redd substrates. Despite this, only modest reductions in hyporheic dissolved oxygen were observed and appeared to be related to high discharge events rather than sediment accumulation. Mortality rates were highly variable across all study sites on both rivers, which may be attributed to fertilization success rather than environmental conditions, as natural mortality was at least 50%. Entombment of alevin from accumulated fine sediments was noted in several redds on the West River, suggesting this mechanism may contribute to mortality even when oxygen levels are adequate. Overall, the study highlights the resilience of salmon embryos with moderate hypoxic episodes and the challenges of linking sediment metrics to mortality in wild Atlantic salmon redds.

CRI-affiliated publications

Entries are sorted alphabetically and by year

Bergbusch N.T., Lo M., St-Hilaire A., Gibson R.B., Jardine T.D., Leonard K., Courtenay S.C. (2025). Centring Water in Impact Assessment: Reconsidering Environmental and Cultural Flows in Development Decision-Making in Canada. Environmental Management, 75(8) 2010-2030.

Considering regional impacts on downstream communities and ecosystems is challenging in impact assessments. We suggest that environmental and cultural flows have the potential to be applied to protect water more comprehensively in assessment but are currently underutilized. Environmental and cultural flows refer to adequate water quantity and quality for the environment and Indigenous rights. Through interviews and a scoping review of legislation and assessments, we address how these concepts are and could be embedded within Canadian impact assessments. To date, environmental flows have been considered in assessments involving dams, oil and gas, and mining, and the focus has been on fish and habitat, rather than Indigenous rights and cumulative withdrawals. We propose Regional Readiness through water councils, change, and consensus (three Cs) to prepare watershed actors to protect environment and cultural flows in impact assessments. The three Cs are: (1) Advisory councils dedicated to creating regional objectives and rules for ecosystem and rights-based needs, (2) Assessing hydrologic and water quality change with regional data and relationships to water, and (3) Building consensus on the cultural and ecological significance and sensitivity of water bodies. Development of this framework follows examples from Canadian water-related assessments and initiatives: Wolastoq Ecological Limits of Hydrological Alteration, Athabasca Chipewyan and Mikisew Cree assessments, Yinka Dene Water Management Policy, Grand Council Treaty #3 Nibi Declaration, Slave Watershed Environmental Effects Program, and Strategic Assessment of Wood Buffalo National Park. These cases demonstrate how the inclusion of environmental and cultural flows processes in assessment could enable greater water protection.
Bergbusch N.T., Saunders M.D., Leonard K., St-Hilaire A., Gibson R.B., Jardine T.D., Courtenay S.C. (2025). A systematic scoping review of the collaborative governance of environmental and cultural flows. Environmental Reviews, 33 1-28.

This study systematically reviews English-language papers about the collaborative governance of environmental and cultural flows. With mixed-methods analyses, we illustrate that the determination of environmental flow needs is common, with authors in 42 countries across 112 watersheds describing their management. In contrast, cultural flows (characterized by attention to both ecological and non-ecological needs, decision-making authority of Indigenous Nations, and Indigenous rights) were reported only in papers by authors in commonwealth, colonial countries: Australia, Canada, and New Zealand. Evaluated against the Organisation for Economic Co-operation and Development’s Water Governance Principles, we found that the literature reported efforts that considered appropriate local and regional scales, information and data, regulatory frameworks, and capacity building of communities and authorities engaged in environmental and cultural flow initiatives. However, there was limited consideration of the roles of communities in policymaking, which was more common in jurisdictions with decentralized governance. In jurisdictions with democratic community-based initiatives, environmental and cultural flows have not been approached in merely technical processes to communicate hydro-social-ecological information to decision-makers. Instead, the initiatives have created the context for evaluating new developments at the watershed level in light of communities’ social and ecological water goals, collaborating during unique drought and flooding conditions, working to rebalance power in decision-making through water justice, creating ecological and Indigenous reserved water rights, granting legal personhood for rivers, and protecting water for the environment and dependent people in water markets. Going forward, we identify a need for greater attention to community roles in environmental and cultural flows protection in water governance, including policy creation and evaluation, regulatory initiatives, strategic planning, and impact assessments.
Bowser E.E., Tunney T.D., Breau C., Hayden B. (2025). Resource use, niche width, and trophic position reveal diverse trophic structure in a tidal freshwater zone fish community. Journal of Fish Biology, 106(6) 1876-1888.

The tidal freshwater zone is an aquatic transition zone that links a river to its estuary and provides an important habitat used in the life cycle of resident and migratory fishes. Yet, information on the trophic structure of fishes in this habitat is scarce. To address this gap, we characterize the trophic structure of a fish community in the tidal freshwater zone of the Northwest Miramichi River (New Brunswick, Canada). Stable isotope analyses (δ13C, δ15N, and δ34S) of 17 fish species revealed diverse feeding strategies. Resource use varied across species; some fish relied on either marine or freshwater resources, whereas others integrated resources from both habitats. Fishes varied in their trophic position (range 3.1–4.2) which increased with reliance on marine-derived resources. Species isotopic niche widths varied widely (range 20.4 to 1015.3). Species with intermediate marine resource use (~0.50) had a mix of wide and narrow isotopic niche widths, contrary to wide niches predicted by current literature. Our findings indicate that these narrow-niched species may either act as a sort of tidal freshwater transition zone specialist or assimilate equal proportions of marine and freshwater resources on average. Trophic information from the tidal freshwater zone improves the understanding of fish communities and food web structure where freshwater rivers and marine ecosystems meet.
Brown C.J.M., Arciszewski T.J., Curry R.A., Smith D.S., Munkittrick K.R. (2025). The Utility of Fish Population Monitoring and Forecast Trigger Development for Designing Adaptive Aquatic Monitoring Plans for Large Industrial Developments. Environmental Management, 75(9) 2183-2197.

Most Environmental Impact Assessments (EIAs) fail to generate effective monitoring and forecast triggers because there is a lack of appropriate baseline data and forecasting, especially for biotic endpoints. Herein, we provide an example of how to develop monitoring and forecast triggers with biotic data, specifically fish populations, to assess impacts of a planned refurbishment of the Mactaquac Hydroelectric Generating Station, a large hydroelectric facility. We recommend strategies for developing interim monitoring triggers until sufficient biological data is collected, including default critical effect sizes or data percentiles when there are only a few years of data. When there is sufficient data the monitoring trigger can be based on the predicted normal range, i.e., 2x standard deviation of the means. We generated forecast triggers with the general linear model, partial least squares regression, and elastic net regression. We demonstrate that interannual variability of fish population characteristics sampled consecutively for 4 years was insufficient for meaningful monitoring and forecast trigger development. Collecting sufficient baseline data for new projects in an undeveloped area will be challenging due to costs and regulatory and economic time frames as current practice is generally 1 or 2 years. Changes to existing projects, such as in this study, or new projects near existing development should have existing baseline data – if forethought is given as to effective endpoints. The alignment of monitoring requirements between developments within a watershed will improve monitoring, modelling, and prediction over the long term and for consideration of future developments.
Corey E., Linnansaari T., O’sullivan A.M., Curry R.A., Cunjak R.A. (2025). Wild juvenile Atlantic salmon (Salmo salar) offer insights into movement patterns of territorial freshwater fishes in relation to high temperature and proximity to thermal refuges. Canadian Journal of Fisheries and Aquatic Sciences, 82.

When exposed to increased water temperatures, salmonids abandon territories and relocate to areas of cool water (thermal refuges). Using juvenile Atlantic salmon (Salmo salar) as a model species, our study, conducted over two seasons (2009 and 2010) with 636 salmon parr tagged by Passive Integrated Transponder (PIT) across 9 km of the Little Southwest Miramichi river, investigated the effects of high temperature stress on their movement. We aimed to determine the extent of their travel to thermal refuges, primary direction, duration within these refuges, and post-event redistribution. In 2009, despite temperatures peaking at 26.1◦ C, no significant parr aggregations were noted. However, 2010 experienced notable changes: temperatures exceeding 27.3◦ C for 4 days prompted 32.7% of the parr to form aggregations, with movements significantly greater than in 2009 (p < 0.001), peaking at 7.4 km. Most migrations were localized within specific river reaches. By late fall, 92.3% of parr returned to or near their original tagging locations. These observations underscore the importance of thermal refuges and the adaptive strategies juvenile salmon employ during extreme temperature events.
Crossley L.M., MacQuarrie K.T.B., Danielescu S. (2025). Agricultural nitrate attenuation in a small groundwater-influenced wetland system. Frontiers in Environmental Science, 13.

Nitrate contamination of freshwater systems is common in agricultural watersheds, leading to human and environmental health concerns. The Bells Creek watershed, located in central Prince Edward Island (PEI), Canada, is dominated by agricultural land use and has elevated nitrate concentrations in groundwater and surface water. Beneficial Management Practices (BMPs), such as constructed wetlands, may provide a means of mitigating such contamination; however, the significance of small wetlands in regulating or attenuating nitrate in PEI has yet to be investigated. In this year-long (August 2023 – July 2024) study, the nitrate loads delivered to a small (1.2 ha) groundwater-influenced, stream-wetland system were quantified using high-frequency monitoring techniques. Results indicate that discharge variability is the primary control on the observed variability of surface and subsurface nitrate loads. The total annual nitrate load to the wetland was approximately 30,000 kg NO<inf>3</inf>-N/yr. Groundwater discharge, which bypasses the wetland riparian zone, contributed approximately 67% of the total load to the wetland. Weekly flux calculations revealed that the wetland behaved as a nitrate sink for 49 out of 52 weeks of the year. Overall, the wetland attenuated 39% of the imported annual nitrate load which, on a wetland catchment area basis, is equivalent to 21.1 kg NO<inf>3</inf>-N/ha catchment/yr. A positive, non-linear trend between the imported nitrate load and the percent change in nitrate load revealed that the wetland attenuated disproportionately more nitrate during periods of high imported loads. These findings indicate that small, constructed wetlands may be an effective component of BMPs aimed at reducing nitrate loads in agriculturally dominated watersheds like those in Prince Edward Island.
Culberson A.E., Nakamoto B., Lento J., Curry R.A., Harrison P.M. (2025). New bass on the block: Trophic interactions among invasive largemouth bass Micropterus salmoides and local sportfish. Journal of Fish Biology, 106(3) 784-796.

Novel introductions of largemouth bass, Micropterus salmoides, often cause negative impacts on endemic populations of prey fishes and interspecific competitors. Although many studies have investigated trophic interactions between M. salmoides and smallmouth bass, Micropterus dolomieu, few have included chain pickerel, Esox niger, as a competitor despite similarities in their habitat use. We used stable isotope analysis to investigate the trophic ecology of a recently introduced population of M. salmoides in the Wolastoq|Saint John River. Specifically, we measured carbon (δ13C) and nitrogen (δ15N) isotopes to describe isotopic niches and infer resource use of introduced M. salmoides, M. dolomieu, E. niger, and native yellow perch, Perca flavescens, at various life stages. Our results showed that isotopic niche overlap occurred between M. salmoides and other study species, indicative of resource competition. However, resource use plasticity, as demonstrated by a wide variety of resources (marine, terrestrial, littoral, and pelagic) used by all study species, could potentially reduce interspecific competition. Our findings indicate that competition is highest between adult M. salmoides and E. niger, but the presence of a seasonal marine resource can provide important contributions to diets and potentially reduce competition. Further research should focus on monitoring of long-term trends to identify the dynamics of all study species as M. salmoides populations become further established and dispersed.
Deb S., Guyondet T., Coffin M.R.S., Barrell J., van den Heuvel M. (2025). Effect of ecosystem stressors on biogeochemical processes and bivalve-mediated bioremediation approaches for estuary resilience. Estuarine Coastal and Shelf Science, 323.

Nutrient loading, derived from human-induced land-based activities, poses a significant risk of anthropogenic eutrophication in most estuaries worldwide and is considered a high-priority ecosystem stressor. Similarly, estuaries in the southern Gulf of Saint-Lawrence, Canada, are facing threats from this ecosystem stressor leading to potential nutrient over-enrichment, which not only affect primary production timing and abundance but can also alter the entire ecosystem dynamics. Determining the trophic condition of such estuaries becomes more critical when 58 % of the system is covered with natural populations of bivalve species. Therefore, we developed for the first time, a high-resolution 3-D coupled physical-biogeochemical model for the Bouctouche Estuary, Canada, based on Finite Volume Coastal Ocean Model and Integrated Compartment Model (FVCOM-ICM) whose water quality kinetics are further integrated with a benthic filter-feeder Dynamic Energy Budget (DEB) ecophysiological submodule to examine the present physical-biogeochemical condition, predict the responses of pelagic-benthic activity to different stages of nutrient loading and promote bivalve-mediated bioremediation approach. Results revealed that nutrient loading areas are characterized by low dissolved oxygen and biogeochemically distinct waters. Further, heterogeneity in estuarine biogeochemical processes is responding to water renewal time. Concomitantly, bivalves can bioextract about 11 % of riverine nitrogen inputs seasonally showing that both components can affect the net primary production distribution. Overall, this modeling framework will allow an ecosystem-based bioremediation approach for effective nutrient management to enhance estuary resilience.
Dibike Y.B., Broadbent J., Musetta-Lambert J., Reid T., Spoelstra J., Monk W.A., Nicholls E.M., Shrestha R.R., Beltaos S., Peters D.L., Zeng C., Bonsal B., Spence C. (2025). Toward a Canadian national river water quality modeling system: state of science and future prospects. Environmental Reviews, 33.

Water quality is of significant concern and ultimately critical to every Canadian’s quality of life and security. Canada has diverse and vast landscapes and stressors that impact various waterbodies differentially, with influencing factors including contaminant and nutrient loads from human activity (mining effluent, wastewater, agricultural runoff, plastics), landscape change (wetland drainage, urbanization), and climate change (warming water temperatures, longer open water seasons, extreme hydrological events, intensifying wildfires). Canadian rivers are especially important to the overall biogeochemistry, hydrology, biodiversity, and ultimate health of aquatic and terrestrial ecosystems. While each of Canada’s provinces and territories has extensive river water quality (physical, chemical, biotic) data and monitoring programs; Environment and Climate Change Canada coordinates various national programs that contribute to the collection and consolidation of these data and conducts extensive research into the study and modeling of key river water quality processes. Despite program-specific efforts, there remains poor capacity to predict current and future conditions in monitored and unmonitored Canadian rivers, particularly remote or northern rivers, due to a myriad of factors including lack of coordination among groups and examination of areas in which modeling efforts might be integrated. Herein, we review and analyze the current state of data availability, process studies, and modeling systems for Canadian river water quality. Our synthesis reveals that specific physical processes (water temperature, ice formation, permafrost thaw, sediment dynamics), biogeochemical processes (dissolved oxygen, dissolved organic matter, nutrient cycling, metals/contaminants), and ecological/biological features (biota mass, functional indicators) are well understood, though complex, and are amenable to empirical or mechanistic modeling. Review of this information assists us in identifying opportunities and challenges for developing a national water quality modeling system, that would eventually include similar modeling activities for parallel processes in lakes and integrated watersheds. We identify needs for stronger coordination of monitoring programs in remote areas, recommend use of novel remote sensing technologies, and development of a flexible, iterative “process” for integrated modeling to which stakeholders beyond government can contribute. Such a platform would support short-and long-term predictive models of Canadian water quality and ecosystem health, inform effluent concentration limits, and be an early warning system for source waters.
Eissenhauer F., Linnansaari T., Pratt T.C., Curry R.A., Harrison P.M. (2025). Upstream Migration Dynamics of Juvenile American Eels (Anguilla rostrata) Towards a Hydropower Dam in a Large River. Ecology of Freshwater Fish, 34(2).

Young American eels (Anguilla rostrata) undergo a remarkable migration from oceanic spawning grounds to continental growth habitats. Impaired river connectivity can prevent facultatively catadromous eels from completing their upstream migration. The effects of barriers on the upstream migration dynamics of this endangered species remain poorly understood. This study evaluated the timing of juvenile eel migration and the spatial distribution and size/age structure of migrating eels within the tidal and hydropower-regulated Wolastoq | Saint John River in Canada. Upstream eel migration in this river is restricted by the Mactaquac Dam and Generating Station, located 150 km upstream of the sea. Approximately 36,000 eels were caught with fyke nets at various locations between the river mouth and the Mactaquac Dam, measured for length, and a subsample (n = 401) was aged via sagittal otolith readings. While glass eels (not fully pigmented juvenile eels) were observed up to 90 km upstream, approximately 20 km beyond the point of saltwater intrusion, eels arriving at the Mactaquac Dam were exclusively fully pigmented, with 80% being continental age 1+ or 2+. The mean length of juvenile eels increased with distance upstream. These results indicate that upstream eel migration in the Wolastoq | Saint John River can take multiple years and involves phases of juvenile residency. Our study provides important insights into juvenile eel migration in large rivers and implications for effective management of passage success at barriers such as hydropower dams.
Fakhari M., St-Hilaire A., Martel R. (2025). Thermal refuge modeling: a short review. Environmental Reviews, 33.

Thermal refuges in river systems play a vital role in safeguarding aquatic organisms, particularly cold-water poikilotherms, during extreme temperature events. These refuges are characterized by localized temperature anomalies under the influence of different natural meteorological, hydrological, and geomorphological factors or human activities. The identification, prediction, and protection of thermal refuges have gained importance due to the rising impact of climate change and anthropogenic activities on river temperatures. Models have become increasingly used for addressing related concerns and applied questions in river science. This review examines various modeling approaches of thermal refuges, focusing on deterministic and statistical/stochastic models applicable in river environments. Deterministic models provide a process-based understanding of thermal dynamics, while statistical/stochastic models offer insights into spatial and temporal patterns by correlating thermal refuges/plumes to different controlling parameters. By analyzing the strengths and limitations of these methodologies, this review highlights their complementary roles in advancing thermal refuge research and management. Emerging opportunities, such as integrating thermal infrared imagery and machine-learning algorithms, underscore the potential for enhancing predictive capabilities in this critical field.
Ferchichi H., St-Hilaire A., Bujold J.N., Kassatly A., Vajou J. (2025). Compound thermal indices for two species of salmonids. Water Quality Research Journal, 60(2) 348-365.

Water temperature is a determinant variable for the overall health of the river ecosystem and aquatic biota, particularly for cold-water fish. Therefore, the characterization of river temperature is essential for the management of thermal habitats. However, currently, river thermal regime characterization is often achieved by calculating numerous thermal indices that are not often related to cold-water fish physiological requirements and thermal preferences. In this study, we developed a compound thermal index (CTI) based on a methodology used to calculate the water quality index (WQI) in Canada. CTI is composed of specific indicators related to the thermal tolerance thresholds for different life stages for two cold-water species (Atlantic salmon and brook trout), providing a simplified measure of the quality of the thermal habitat for these species. CTI was determined in two salmon/trout rivers in Québec, Canada (Ouelle and Ste-Marguerite). The results showed that (i) CTI allowed the characterization and classification of thermal habitat quality; (ii) the thermal habitat degradation was primarily influenced by climate conditions, particularly during warm and dry years with high temperatures and low precipitations; (iii) the improved thermal habitat quality was associated with air temperature and precipitation values close to seasonal normals; (iv) cold tributaries provided excellent thermal habitats.
Graves S., Chen S.M., McNamee R., Rodrigues T.H., Hayden B., Rochman C.M., Provencher J.F., Rennie M.D., Layton-Matthews D., Leybourne M., Sherwood O.A., Orihel D.M. (2025). Investigating the potential uptake of microplastic-derived carbon into a boreal lake food web using carbon-13 labelled plastic. Facets, 10.

Microplastics degrade slowly over time, leaching carbon (C) that could be subsequently incorporated into aquatic food webs. Current estimates of microplastic degradation vary, and little is known about microplastic-derived C fate under natural environmental conditions. To investigate whether microplastics leach C that is subsequently incorporated into aquatic food webs, we added isotopically enriched microplastics to Lake 378 at the Experimental Lakes Area in Ontario, Canada. In an ∼1100 L limnocorral (in situ open-bottom enclosure), we added 99%13 C-labelled polystyrene (8–216 μm in longest dimension) at a nominal concentration of 3268 particles/L. A second limnocorral without microplastics served as a negative control. Monthly measurements of δ13 C-DIC and δ13 C-DOC in filtered water revealed no detectable leaching of13 C from the plastic. Compound-specific isotope analysis of δ13 C in amino acids of bulk plankton and periphyton revealed a slight (0.5) enrichment in13C, within the range of natural variability for these organisms. Under the natural conditions of temperate oligotrophic lakes, degradation of microplastics is likely a very slow process that was not possible to detect in this 4-month experiment. Future studies should focus on assessing degradation of microplastics under realistic field scenarios to improve estimates of degradation pathways and associated time scales.
Grove C.M., Roloson S.D., Knysh K.M., Pavey S.A., Cairns D.K., Gilmour R.F., van den Heuvel M.R. (2025). Population Genetics of Atlantic Salmon (Salmo salar) in Prince Edward Island, Canada. Ecology and Evolution, 15(5).

Atlantic salmon (Salmo salar) have experienced population declines across their native range. Widespread stocking has been a population recovery strategy, but there is a growing awareness that stocking may put genetic integrity at risk. In Prince Edward Island, Canada, over 37 million salmon have been stocked since 1880. This study used a panel of six microsatellites and next-generation sequencing to evaluate the genetic composition of 884 individuals from 20 rivers. Bayesian clustering methods inferred groupings that were generally consistent with the spatial distribution of rivers. A cluster in northeastern PEI was the most distinct, clustering separately across all methods. Distance between rivers accounted for 25.8% of the variations, whereas stocking intensity did not predict genetic variation. The genetic composition of the most heavily stocked river changed over a few years, suggesting that wild free-ranging fish could outcompete stocked fish. Currently, PEI has multiple genetic stocks that are consistent with the post-glacial biogeography rather than stocking history. Clarification of these adaptations is required to guide the incorporation of genetics into management strategies for the benefit of Atlantic salmon conservation.
Hani I., Ouarda T.B.M.J., St-Hilaire A. (2025). Compound hydrological and thermal extremes: A nonstationary risk modeling approach for riverine ecosystems. Journal of Environmental Management, 394.

The increasing frequency and severity of compound hydro-climatic extremes pose a growing threat to cold-water aquatic ecosystems. This study develops a nonstationary multivariate risk modeling framework to assess the joint behavior of extreme summer river water temperature (Tw) and concurrent low flow (Q) in six unregulated Atlantic salmon rivers in eastern Canada. A dynamic additive copula approach is employed to model both the structure dependence and nonstationarity, with time-varying effects modeled via large-scale climate oscillation indices (teleconnections) and a temporal trend representing climate change. The proposed joint nonstationary model (J<inf>NS</inf>) is benchmarked against a joint stationary model (J<inf>S</inf>) and a univariate nonstationary model (U<inf>NS</inf>). Results show that J<inf>NS</inf> systematically outperforms both alternatives across all study sites. Temporal trends significantly increased Tw extremes at most rivers, while teleconnections emerged as dominant drivers of variability. Negative phases of the Southern Oscillation Index (SOI, El Niño conditions) and the North Atlantic Oscillation Index (NAO) increase the variability of Tw and low-flow events, respectively, while positive phases of the SOI (La Niña conditions) and NAO are associated with elevated joint and conditional exceedance probabilities, rising by up to 66 % in the Restigouche River and 45 % in the Highland River. By linking joint extremes to both long-term warming and oscillatory climate patterns, the study provides a predictive framework for anticipating compound risks and protecting thermally sensitive aquatic habitats under ongoing climate change and variability.
Hani I., St-Hilaire A., Ouarda T.B.M.J. (2025). Regional stream temperature modeling in pristine Atlantic salmon rivers: A hybrid deterministic–Machine Learning approach. Journal of Hydrology Regional Studies, 59.

Study region: Pristine Atlantic salmon rivers located across northeastern Canada and the U.S. Study focus: To simulate water temperature in ungauged rivers, we explore the regionalization of thermal parameters within the CEQUEAU model—a deterministic, semi-distributed hydrological and water temperature model. Additionally, a global sensitivity analysis is conducted to identify the most sensitive thermal parameters within the study region. We employed the support vector regression algorithm (SVR), to map the dependence of these parameters with climatic and watershed characteristics. New hydrological insights for the region: Parameters controlling radiative and sensible heat fluxes are the most critical for CEQUEAU water temperature modeling within the study region. Key explanatory variables include low cloud coverage, high wind speed quantiles, upstream land cover areal coverage, distance to the coast, watershed orientation, and topographical features describing surface curvature and elevation. The machine learning-based regionalization approach provides a robust approach for deriving water temperature model parameters from watershed attributes, provided flow measurements are available. Using leave-one-out cross-validation, support vector regression (SVR) significantly outperformed the traditionally used multiple linear regression (MLR), achieving a mean regional RMSE of 1.89 °C.
Hani I., St-Hilaire A., Ouarda T.B.M.J. (2025). Trends, teleconnections and nonstationary frequency modeling of riverine heatwaves in North American Atlantic salmon rivers (1979–2100). Science of the Total Environment, 989.

Freshwater ecosystems play a vital role in supporting cold-water species like Atlantic salmon, providing the essential conditions to complete critical life stages. However, climate change is increasingly disrupting these habitats, driving shifts in river hydrology and rising water temperatures that threaten their survival. This study quantifies the past (1979–2020) and assesses potential future changes (2030−2100) in the hydrological and thermal regimes of 35 Atlantic salmon rivers across northeastern North America. According to the selected climate change scenarios, the results reveal a significant potential rise in water temperature (Tw > 20 °C), drought conditions, and an increasing trend in heatwave frequency, duration, and intensity by the end of the century. Under the most pessimistic SSP5–8.5 scenario, the total duration of summer riverine heatwave (RH) averaged from 2061 to the end of the century is projected to rise 12-fold (98.0 days) compared to the average of 8.5 days, calculated from 1979 to 2020. Consequently, nearly half of the studied rivers are projected to enter a permanent state of summer heatwaves. We also propose a nonstationary riverine heatwave frequency (RHF) modeling framework, integrating both climate change through a temporal trend and climate variability through large-scale atmospheric-ocean oscillations (teleconnection indices) as covariates. Models incorporating climate-related covariates outperform stationary models without covariates, with the North Atlantic Oscillation and the Arctic Oscillation indices emerging as the most influential predictors. However, with the small sample sizes used in this study, the uncertainty can increase especially for extreme non-exceedance probabilities and for the most extreme values of the climate indices.
Hill C.R., O'Sullivan A.M., Hogan J.D., Curry R.A., Linnansaari T., Harrison P.M. (2025). Limitations of Non-Volitional Upstream Passage for Alewife (Alosa pseudoharengus) and Blueback Herring (Alosa aestivalis). River Research and Applications, 41(2) 480-498.

We used PIT telemetry (n = 10,292 fish tagged) to evaluate upstream passage at a non-volitional fishway (trap, lift, and truck) that passed approximately 10-million river herring (alewife Alosa pseudoharengus and blueback herring A. aestivalis) around the lowermost dam in the Wolastoq/Saint John River, NB between 2020 and 2023. Between 26% and 62% of tagged fish reached the fishway crowding pool, while less than 14% were detected passing upstream. River herring experienced considerable passage delays (median = 3 days) after reaching the crowder entrance. The probability of passing on the date of first detection was only 10%, and it was positively correlated with the rate of fishway operation (i.e., fish lifts/unit time). The rate and probability of passage were greater for alewife than blueback herring and increased with total length for both species. Collectively, our results suggest that passage efficiency and duration were limited by the movement capacity and operation frequency of the fishway, and potentially the (high) number of fish attempting to pass at a given time. Ultimately, if the design and operation of non-volitional fishways do not accommodate the size and behavior (i.e., schooling density and migration time) of target populations, our results indicate that potential consequences may include passage delays, reductions in passage efficiency, and selective pressures (e.g., size and species) on target populations.
Hill C.R., O'Sullivan A.M., Hogan J.D., Curry R.A., Linnansaari T., Harrison P.M. (2025). Poor Upstream Passage for Endangered Atlantic Salmon (Salmo salar) at a Trap-and-Transport Fishway in the Wolastoq/Saint John River, New Brunswick. River Research and Applications, 41(8) 1701-1711.

Declines of Atlantic salmon (Salmo salar) in the Wolastoq/Saint John River have largely coincided with hydropower development, and there is an urgent need to understand the status of bidirectional passage at existing barriers. We evaluated upstream passage efficiency and duration at the lowermost hydroelectric dam (Mactaquac Generating Station), which targets salmon for upstream passage with a manually operated fish lift and transport system. In a 2-year study, we captured, tagged, and released upstream adult migrants within 500 m of the fishway and monitored their movements using PIT, radio, and acoustic telemetry. Overall, a low proportion (19%) of individuals that approached the dam passed upstream, and successful individuals experienced considerable passage delays (mean = 58 days) despite visiting the fishway on multiple occasions prior to passage (mean = 8 visits). Salmon were approximately 41 times more likely to visit the fishway entrance during daylight hours (92% of total fishway detections occurred during daylight), likely reflecting elevated power generation and flow conditions during daylight. Further, salmon were approximately five times more likely to visit the fishway entrance while the fishway was not operational (70% of fishway detections while not operating). Accordingly, provided that the current daily flow regime at Mactaquac is not changed, we recommend increased fishway operation efforts during daylight hours to increase opportunities for salmon to pass upstream. However, we also found that salmon rarely reached the fishway crowding pool during fishway visits (regardless of fishway operation status), which suggests that issues of attraction and guidance within the lower fishway should be addressed in synchrony with increased fishway operation efforts. Ultimately, our observations suggest that poor fishway attraction, guidance, and operation schedules have been key factors limiting successful upstream passage for salmon in the river and highlight the importance of evaluating fishway performance post-construction.
Hill C.R., O’Sullivan A.M., Curry R.A., Linnansaari T., Harrison P.M. (2025). The performance of 76 kHz positional acoustic telemetry is challenged by acoustic conditions in the tailrace of a hydroelectric dam. Animal Biotelemetry, 13(1).

Background: Positional acoustic telemetry permits high-resolution (2D and 3D) tracking of tagged fish based on the speed of sound and time at which acoustic signals are detected at independent receivers. Such positional data has important implications for understanding fish behavior in hydropower tailraces, where movement and fishway passage may be influenced by complex hydraulic conditions. However, environmental features common to these settings—such as rocks, vegetation, bubbles, and suspended particles—can reflect, scatter, or absorb acoustic signals, contributing to spatial and temporal variation in positioning error. Therefore, validating system performance in tailrace environments is important for study design and interpretation. We evaluated the performance of a 76 kHz positional acoustic telemetry system (LOTEK MAP) in the tailrace (0–500 m downstream) of a large (672 MW generating capacity) hydroelectric dam, an environment characterized by reflective surfaces, complex hydraulics, and ambient noise from power generation. Methods: We quantified positional accuracy (i.e., Euclidean distance from measured deployment positions) and position efficiency (i.e., position estimates/total transmissions) for six stationary transmitters centered within two hydrophone arrays installed 0–150 m and 200–500 m downstream from the power station. Further, we used generalized linear models to explore how accuracy and position efficiency varied as a function of transmitter location, power station discharge (which represented variation in the acoustic environment at each hydrophone), and the number of receivers that contributed to position estimates. Results: The array nearest the power station (i.e., 0–150 m downstream) yielded no positional data. Performance improved marginally for the second array (i.e., 200–500 m downstream), but position efficiency was ultimately low (1%), variable across transmitter locations, and negatively correlated with discharge. When position estimates were obtained, positional accuracy was moderate (overall mean = 3 ± 3 m) and increased with the number of contributing receivers, but also varied in direction and magnitude as a function of transmitter location and discharge conditions. Conclusions: Performance of the telemetry system was limited by environmental conditions that influenced signal propagation at complex spatial and temporal scales and would ultimately challenge the interpretation of positional data for free-swimming fish in the tailrace. The telemetry system is likely not suitable for studies that require frequent and reliable positions in hydropower dam tailrace environments.
Kalvani Z., Tetteh P., Kamunde C., Stevens D., van den Heuvel M.R. (2025). Naphthenic Acid-Induced ROS Emissions by Rainbow Trout Mitochondria. Toxics, 13(12).

Naphthenic acid fraction compounds (NAFC) are prevalent in petrochemical wastewater, including from oil sands processing, and induce reactive oxygen species (ROS) emissions in isolated mitochondria. The purpose of this study was to verify if a primary carboxylic acid, the moderately hydrophobic NAFC 3,5-dimethyladamantane-1-acetic acid, would cause the mitochondrial ROS (hydrogen peroxide; H<inf>2</inf>O<inf>2</inf>) production and affect its consumption by mitochondria in multiple bioenergetic states. Intact mitochondria isolated from rainbow trout (Oncorhynchus mykiss) liver were exposed to commercially available 3,5-dimethyladamantane-1-acetic acid. The emission of ROS during States 3 and 4 respiration was quantified using fluorometry with an Oroboros fluorespirometer. Subsequently, select ROS emission sites in the mitochondrial complexes were isolated using inhibitors, and the ROS emission of each site was measured using the Amplex UltraRed-horseradish peroxidase (AUR-HRP) system. The compound 3,5-dimethyladamantane-1-acetic acid was equally potent in causing ROS emission in State 3 and State 4 ROS sites. The baseline (no NAFC) proportion of ROS emission by site was II<inf>F</inf> > I<inf>Q</inf> > III<inf>Qo</inf> > I<inf>F</inf>. The 3,5-dimethyladamantane-1-acetic acid compound increased ROS emission in a dose-dependent manner at II<inf>F</inf> with an EC<inf>50</inf> of 0.2 mM, which was not significantly different than the State 3 and 4 Oroboros response. In contrast, there was no consistent concentration-effect response at the other three ROS sites (I<inf>Q</inf>, III<inf>Qo</inf>, and I<inf>F</inf>). Malonate, an inhibitor of succinate dehydrogenase, eliminated ROS production in Oroboros experiments. These findings identify site II<inf>F</inf> as the predominant source of NAFC-stimulated ROS and provide mechanistic insight into how adamantane-type NAFCs impair mitochondrial redox balance in fishes.
Kelly M.G., Free G., Simaika J.P., Warner S., Bruder A., Correa-Bedoya A., de Oliveira Roque F., Eriksen T.E., Lento J., Macadam C.R., Meissner K., Moretti M.S., Penrose D., Stribling J., Poikane S. (2025). The global role of bioassessment in policy delivery and decision-making for inland waters. Journal of Environmental Management, 393.

Bioassessment is necessary to guide the management of freshwater ecosystems and promote sustainable water use. However, many countries either do not have nationally-approved bioassessment systems, or their bioassessment results are not used in water policy decision-making. Despite the importance and urgency of the topic, a global overview of bioassessment and its use in decision-making is missing. In this study, we analyzed survey responses from 341 bioassessment practitioners from 109 countries to examine the role bioassessment plays in freshwater governance. Two thirds of respondents reported that bioassessment was used in their country, with the strength of the link to legislation increasing with per capita Gross Domestic Product (GDP). Bioassessment data generally fulfilled several roles, including following trends over time and developing catchment plans, both significantly linked to increased per capita GDP. Strong relationships with stressors were cited as a strength of bioassessment over other forms of evidence gathering, whilst costs and shortage of trained staff were the most common weaknesses. Governance is key, being the main factor explaining why some countries don't have bioassessment and enabling its enaction through legislation in others. Initiatives therefore need to focus on creating an “enabling environment” as well as financial and technical aspects. We found synergies between having international agreements and using bioassessment for communication when delivering nationally important roles for bioassessment. By identifying key drivers for using bioassessment in decision making, our study provides recommendations to inform future research, policy and practice.
Kidd J., Bergbusch N.T., Epstein G., Gunn G., Swanson H., Courtenay S.C. (2025). A Fresh Perspective on Freshwater Data Management and Sharing: Exploring Insights from the Technology Sector. Water Switzerland, 17(14).

It is well established that effective management and restoration of freshwater ecosystems is often limited by the availability of reusable data. Although numerous public, private, and nonprofit organizations collect data from freshwater ecosystems, much of what is collected remains inaccessible or unusable by Rights holders and end users (including researchers, practitioners, community members, and decision-makers). In Canada, the federal government plans to improve freshwater data sharing practices through the newly formed Canada Water Agency, which is currently drafting a National Freshwater Data Strategy. Our study aimed to support these efforts by synthesizing insights from the technology sector, where data management and sharing practices are more mature. We interviewed 12 experts from the technology sector, asking them for advice on how to improve data sharing practices in the freshwater science sector. Using a Reflexive Thematic Analysis of participants’ responses to semi-structured interview questions, we identified nine broad recommendations. Recommendations centred on motivating open data sharing, promoting data reuse through data licences, training and skill building, and developing standards and digital solutions that enable data discovery, accessibility, interoperability, and reuse. These recommendations can support the numerous initiatives that are working to improve access to high-quality freshwater data and help address the pressing crisis of global freshwater ecosystem degradation.
Kuntyj O., Lister A., MacLatchy D. (2025). Limited feed, ammonia, 17α-ethinylestradiol and temperature cause variable effects on growth and gene expression in the growth hormone-insulin-like growth factor-1 pathway in juvenile mummichog (Fundulus heteroclitus). Comparative Biochemistry and Physiology Part C Toxicology and Pharmacology, 297.

Fish may be exposed to multiple environmental stressors that are known to impact growth, including environmental changes or contaminants. This study aimed to examine the effects of limited food availability and elevated total ammonia or 17α-ethinylestradiol (EE<inf>2</inf>) exposure under two temperatures (20 and 25 °C) on the growth of juvenile mummichog (Fundulus heteroclitus). Key genes in the growth hormone (GH)-insulin-like growth factor-1 (IGF-1) pathway were examined in muscle and liver tissues to explore their potential role in mediating growth. We conducted a 21-day experiment in which, compared to excess-fed fish, limited-fed fish exhibited decreased growth concomitant with reduced liver igf1 and muscle ghra expression. In two separate experiments of 21 and 33 days using NH<inf>4</inf>Cl treatment to elevate total ammonia levels, expression of GH-IGF-1 pathway genes (igf1, igf1ra, igf1rb, ghra, ghrb) in liver and muscle was not affected similarly between exposures, despite significant reductions in growth compared with control fish. Growth (body weight, specific growth rate) of fish held at 25 °C was greater than 20 °C, with NH<inf>4</inf>Cl inhibition of growth observed at both temperatures; however, the higher temperature attenuated the response. The temperature-induced increase in the growth of control fish did not affect the expression of GH-IGF-1 pathway genes after 21 days. The increased temperature resulted in lower actual EE<inf>2</inf> exposure concentrations, but EE<inf>2</inf> did not affect growth at either temperature. Overall, further studies are required to characterize the role of the GH-IGF-1 pathway in mummichog and the mechanism by which temperature and contaminants such as ammonia alter juvenile fish growth.
Leblanc N.M., Gahagan B.I., Anderson E.C., Whiteley A.R., Pavey S.A. (2025). Development of a high-throughput single nucleotide polymorphism panel for genetic stock identification of Striped Bass. Transactions of the American Fisheries Society, 154(3) 291-302.

Objective The Striped Bass Morone saxatilis is an anadromous fish that has experienced population declines and recoveries throughout its range from the 1960s to the present day. While many United States fisheries have reopened since the most recent declines, ongoing monitoring is required to ensure that numbers remain stable in the long term. Central to this is the need to determine the extent to which major spawning locations contribute to coastal stocks. While next-generation genomic sequencing can discriminate among closely related breeding aggregations within the Striped Bass native range, the cost per sample of next-generation sequencing methods currently used is too high to be applied to large-scale and long-term projects moving forward. Methods We developed, optimized, and evaluated a GT-Seq panel - a small panel of highly informative single nucleotide polymorphisms - capable of assigning large numbers of Striped Bass to six genetically distinct regions across the Striped Bass spawning range at much lower cost than the previous next-generation sequencing methods. Results The final panel of 233 loci was able to assign 95% of reference individuals to region of origin and had <5% error across all simulations when estimating the mixing proportion of any stock. Conclusions This panel is being used in ongoing characterizations of Striped Bass along the Massachusetts coast and the eastern coast of Nova Scotia. For researchers tracking the migration of Striped Bass throughout their native range, this panel provides a low-cost method of genetically characterizing stocks at specific locations and times that can be easily modified or updated as additional, new genetic data become available.
Lonati G.L., Durette-Morin D., Klymentieva H., Roehl L., Pavey S.A., Baumgartner M.F., Davies K.T.A. (2025). Groups of foraging North Atlantic right whales occur under diverse prey field conditions in the southwestern Gulf of St. Lawrence, Canada. Marine Ecology Progress Series, 772 21-42.

The southwestern Gulf of St. Lawrence (swGSL), Canada, is a foraging habitat for endangered North Atlantic right whales Eubalaena glacialis (NARWs). Late-stage copepods of the genus Calanus are NARW prey, and 3 Calanus species are present in the swGSL. We aimed to characterize spatiotemporal patterns in Calanus and environmental conditions associated with groups of foraging NARWs in 2 valleys of the swGSL, and to evaluate correlations between conditions and whale sighting rates. Over 3 years, we conducted day/night oceanographic profiling and whale surveys at 17 stations during July and August. C. finmarchicus and C. hyperboreus dominated the prey field in proportions that varied among stations, with less contribution from C. glacialis. Calanus layers typically occurred between 18 and 40 m subsurface and/or within 12 m of the seafloor. Three general vertical distributional patterns of Calanus were observed: a single subsurface layer, a single deep layer, or both subsurface and deep layers. Patterns corresponded with prey species composition and activity state (i.e. active or diapausing) within a station. Environmental conditions did not explain variation in whale sighting rates among stations. These results imply that NARWs regularly adjust their dive depth to exploit Calanus layers throughout the water column in the swGSL, except very close to the surface where prey concentrations are generally low. No single environmental context observed in our study can fully explain the diet, behavior, or distribution of NARWs in the swGSL, where multiple prey species likely increase the breadth of possible foraging conditions relative to more southerly, warmer habitats where C. finmarchicus alone dominates.
McKenzie M., Wood P., Durkota J., Monk W., Wilkes M., Mathers K. (2025). Incorporating the Interaction of Flow Into Invertebrate Responses to Fine Sediment Deposition in Temperate Rivers. Ecohydrology, 18(5).

Fine sediment (particles < 2 mm) is a natural and important component of riverine systems. However, excessive loads are one of the leading causes of ecological degradation globally. The flow regime is intrinsically linked to fine sediment dynamics (erosion, transport and deposition) and is further considered a ‘master’ variable in structuring the invertebrate community of lotic systems. To date, limited research has examined how the interaction of these variables affects the response of the ecological community, and how this varies temporally. Paired invertebrate, fine sediment and daily flow discharge data were acquired for 28 sites across England. Mixed effects models were used to determine the influence of fine sediment and flow, both individually and in interaction, on invertebrate indices and by season (spring and autumn). Our results indicate that some flow metrics were more influential in structuring the invertebrate community than others (including low pulse count and maximum annual monthly discharge), and flow metrics were more likely to have a significant effect on invertebrate indices in autumn than in spring. Flow was found to mitigate the negative effect of deposited fine sediment on invertebrate communities in some instances. This was particularly the case for high antecedent flow metrics (e.g., high flows in the seven days prior to sampling). However, overall, there was little evidence of an interaction between flow and fine sediment detected. Our study highlights the nuanced relationships between flow dynamics and deposited fine sediment, in influencing the composition of macroinvertebrate communities in lotic environments. Effective catchment management could integrate this knowledge, emphasising seasonality and site-specific hydrological characteristics to maximise ecological benefits.
Molot L.A., Schiff S.L., Baulch H.M., Curry R.A., Depew D.C., Dove A., Higgins S.N., Kidd K.A., Korosi J.B., Paterson A.M., Pick F.R., Venkiteswaran J.J., Walters D., Watson S.B., Zastepa A. (2025). Survey of metabolically essential trace metals in inland lakes and reservoirs across Canada: what constitutes a low metal system? Canadian Journal of Fisheries and Aquatic Sciences, 82.

Many proteins depend on metals for proper functioning, yet there is little information on the distribution of low metal concentrations in freshwaters nor what constitutes “low”. Eight dissolved metals were surveyed in 2017 in 39 lakes and reservoirs across Canada. RDA analysis revealed Co, Cu, Ni, and V in one group with higher concentrations on the Prairies, and Fe and Mn in a second group with higher concentrations on the Prairies and the Boreal Shield in Ontario. Zn and Mo lacked geographic patterns. Concentrations ranged several fold. Monod growth kinetic parameters were explored for their potential to infer growth limitation. Metal concentrations at or below growth thresholds (T<inf>m</inf> ≤ 1nmolL−1 ) should severely limit growth, while concentrations between T<inf>m</inf> and twice the half-saturation constant (2K<inf>m</inf>) will limit growth when other nutrients are in excess. Published and inferred T<inf>m</inf> suggest that Co, Mo, and Ni could have been low enough to occasionally limit growth in several Canadian oligotrophic lakes. There are too few published K<inf>m</inf> values to infer limitation above T<inf>m</inf>.
Monk W.A., Lento J., Demma M., Mackinnon R.L., Kerr G., Curry R.A. (2025). Balancing water needs and well-being: bringing social-cultural values into environmental flows using a DPSIR framework. Ecology and Society, 30(4).

Bringing social and cultural dimensions into environmental flows (eflows) is critical for sustainable river management, yet structured methods for this process are lacking. We tested the efficacy of a Driver-Pressure-State-Impact-Response (DPSIR) framework, quantified with Fuzzy Cognitive Mapping (FCM), to bridge ecological processes and social-cultural-spiritual values for the regulated Wolastoq | Saint John River | fleuve Saint-Jean, a large transboundary watershed in Maritime Canada. We integrated data from expert-led workshops, which produced 69 refined flow-ecology hypotheses, and a public survey on social-cultural-spiritual connections to the river. The resulting semi-quantitative model revealed a complex network of 39 social-ecological nodes with 941 positive and negative connections and provided a visual map of these connections. Network analysis identified flow variability (an environmental stressor) and peace + tranquility (a social-cultural-spiritual state) as the most significant nodes within the map, acting as critical bridges between the environmental and human domains. The framework explicitly linked physical processes and flow management actions, like hydropeaking, to tangible impacts on ecosystem health (e.g., water quality and biodiversity), recreational access, and community well-being, while also highlighting a potential feedback loop where a sense of peace also promotes environmental stewardship. Our findings demonstrate that the DPSIR-FCM approach is a powerful tool for creating a holistic, transparent, and socially defensible foundation for eflows management. It translates complex social-ecological interactions into an actionable decision-support tool that prioritizes management decisions that promote inclusive, evidence-based water governance.
Oyinlola M.A., Khorsandi M., Penman R., Earhart M.L., Arsenault R., McAdam S., Brauner C.J., St-Hilaire A. (2025). Assessing the impact of climate change and a water management programme on white sturgeon physiology in the Nechako River, British Columbia. Conservation Physiology, 13(1).

Climate change is impacting river ecosystems, underlining the need for water management strategies to protect native species within these ecosystems. Here, we evaluate the impact of climate change and water management on the physiology of white sturgeon (Acipenser transmontanus) in the Nechako River, British Columbia (Canada). Using the CEQUEAU hydrological–thermal model, we simulated daily water temperatures from 1980 to 2099 under two climate scenarios (SSP2-4.5 and SSP5-8.5). We assessed thermal exposure risk (T<inf>e</inf>) for different developmental stages of white sturgeon, focusing on the warmest 6-month period. Our findings show that embryos and yolk-sac larvae exhibit resilience, with T<inf>e</inf> values consistently <1 under both scenarios, signifying low thermal stress. In contrast, feeding larvae and juveniles experience elevated T<inf>e</inf> values, indicating significant future thermal stress. For feeding larvae, T<inf>e</inf> values exceeded 1 under both scenarios, reaching up to 1.5 by the mid-century (2050s) and up to 1.8 by the end of the century (2090s) under SSP5-8.5. Juvenile white sturgeon also faced increased thermal risks, with T<inf>e</inf> values rising >1 during July and August, reaching 1.4 and 1.8 by the 2050s and 1.8 and 2.0 by the 2090s under SSP5-8.5, compared to the 1980s. These results underscore the need to evaluate the existing water management programme to better accommodate the projected changes in thermal conditions associated with climate change. Additionally, regulated river discharge, which can both increase and decrease downstream temperatures, offers a strategic opportunity to mitigate some climate impacts through strategic dam discharge management.
Poulin P., St-Hilaire A., Boyer C., Bergeron N.E. (2025). Assessing the potential for Atlantic salmon (Salmo salar) colonization of Nunavik’s Arctic and subarctic rivers by 2070–2100. Arctic Science, 11.

In Nunavik, Québec, Canada, Atlantic salmon (Salmo salar) populations reach their northern limit in four rivers of southern Ungava Bay. With projected river warming from climate change, this study assesses the potential for Atlantic salmon to colonize new rivers in Nunavik by modelling water temperatures and evaluating river accessibility. Migration barriers were identified with a literature review, topographic data, and satellite imagery. Water temperatures were modelled with a generalized additive model using ERA5-Land air temperature, observed daily mean temperatures, and water surface temperature estimated from Landsat imagery. Our projections indicate an average increase of the rivers mean summer temperatures of 1.2–2.7◦Cbythe end of the century, enhancing thermal conditions in current salmon rivers with more days with optimal growth temperatures (16–20◦C) while still having limited days with thermal stress (>22◦C). By 2100, other Ungava Bay rivers may be colonized, as most are accessible and expected to reach more suitable temperatures. However, Nunavik’s northernmost rivers would remain too cold and colonization of the Hudson Bay watershed appears less likely due to the inaccessibility of most rivers and their distance from established anadromous populations.
Reed T.E., Wynne R., Coughlan J., Gargan P., Kaufmann J., Phillips K.P., Rinaldo A., Poole R., McGinnity P. (2025). A common garden experiment in the wild reveals heritable differences in migration tendencies among brown trout populations. Journal of Fish Biology, 106(6) 1816-1830.

We undertook a common garden experiment in the Burrishoole catchment, western Ireland, to test for heritable life-history differences among neighboring brown trout (Salmo trutta L.) populations that exhibit neutral genetic divergence. Experimental crosses were made using either local females (obtained from a below-waterfalls section of the Rough River within the Burrishoole) or females from the Erriff River—a neighboring catchment that currently produces a stronger run of anadromous migrants than the Burrishoole. Each female was mated to three different types of males: Rough Below-Falls, Rough Above-Falls (resident males obtained from above the waterfalls), and Erriff. Offspring from the resulting six crosses were introduced as unfed fry into a stretch of the Rough River bounded upstream by the waterfalls and downstream by a Wolf-type fish trap (Rough River Downstream Trap, RRDT). Genetic parentage analysis (16 microsatellite markers) was then used to assign offspring sampled at various time points and locations back to cross type. No differences in parr survival rates (electrofishing in the Rough River) were found among the crosses, but parr moving downstream (intercepted at the RRDT) were skewed toward the Erriff female × Erriff male cross, with a deficit assigning to the Rough Below-Falls female × Rough Above-Falls male cross. Smolts leaving fresh water (sampled at two sea-entry traps) were assigned disproportionately to crosses involving one or two Erriff parents. Offspring from pure Burrishoole crosses were more likely to become putative spawners than those from crosses involving one or two Erriff parents, pointing toward possible local adaptation. These results are consistent with heritable variation in migratory tendencies—a key aspect of intraspecific biodiversity that warrants protection—and with previous suggestions that the Burrishoole system may have evolved recently toward reduced anadromy following a novel and catastrophic anthropogenic change.
Roth D.H., Wellband K., Phillips K.P., Linnansaari T. (2025). Reproductive success of smolt-to-adult supplementation and wild Atlantic Salmon in an experimental stream under allopatric and sympatric conditions. North American Journal of Fisheries Management, 45(5) 835-850.

Objective: The reproduction success of Atlantic Salmon Salmo salar from a smolt-to-adult supplementation (SAS) program relative to that of wild Atlantic Salmon was assessed. Methods: Atlantic Salmon from for smolt-to-adult supplementation were released into a fenced-off natural stream on the Miramichi River, New Brunswick, Canada, for 4 years either in sympatry with wild Atlantic Salmon or under allopatry. Reproduction success was assessed via parentage analysis of young-of-the-year progeny. Results: At maiden spawning, SAS adults were significantly smaller in both length (by 13.2% for females, 16.5% for males) and weight (by 22.5% for females, 28.9% for males) than maiden-spawning wild fish of the same age. Under sympatric conditions, the number of successful SAS female spawners and their number of spawning partners were significantly lower than those for wild females. However, when SAS females were in allopatry, no differences from wild salmon under sympatric conditions were found with respect to the number of successfully spawning females or number of reproductive partners. The number of progeny per SAS female was significantly lower in both sympatric and allopatric release years than the number of progeny from wild females. The number of successful SAS male spawners was significantly lower than that of their wild counterparts in one of the two studied sympatric years. Also, the number of successful SAS males in allopatry was lower in an overall comparison with wild male salmon in sympatry, although success of males in allopatric years is not independent of the success of SAS females, restricting the comparability of males in sympatry and allopatry. For successfully spawning SAS males, no significant difference in the number of progeny was found relative to wild fish. Conclusion: Our findings indicate that differences in reproduction success occur between SAS and wild Atlantic Salmon, which most likely stem from the captive-rearing environment. Theoretically, the increased survival rate of smolts that are reared to maturity in captivity could compensate for the reduced SAS offspring numbers. In an effort to continue assessing the benefits and risks of SAS programs as a salmonid population recovery tool, future work should focus on (1) better understanding how to improve the captive-rearing environment to augment the spawning success and reduce genetics risks of SAS Atlantic Salmon, (2) assessing repeat-spawning rates and success for SAS fish, and (3) remaining vigilant for unanticipated negative population effects.
Rubio-Ríos J., Hayden B., Nakamoto B.J., Casas J.J. (2025). Black alder may enhance riparian buffer mitigation of pine-plantation effects on macroinvertebrate food webs in headwater streams. Ecological Indicators, 176.

Over the past century, drylands have undergone significant landscape transformations. Abandonment of traditional crops and pastures led to development of extensive afforestation programs with conifers, which often lacked an ecologically sound orientation, raising concerns on their potential consequences on recipient ecosystems. Forest streams heavily rely on inputs of terrestrial organic carbon and thus are particularly vulnerable to human-driven changes in catchment and riparian forests. One point of uncertainty is whether existing stands of deciduous trees in the riparian zone may buffer headwater stream food webs from the impacts of afforestation on the surrounding landscape. We used stable isotopes of carbon and nitrogen to investigate whether the presence of the nitrogen-fixing black alder in the riparian zone alters the impacts of pine plantations on macroinvertebrate food webs of headwater streams. We observed a consistent consumption of leaf litter by shredders, but a higher importance of autochthonous support to all macroinvertebrate functional feeding groups than initially expected, especially in absence of alder. In addition, we discerned a potential trend toward a food chain lengthening at streams holding riparian alder in winter. Overall, our results indicate that riparian alder can enhance the buffer effect exerted by other broadleaf species through a reduction of the usual wide nutritional imbalance existing between benthic consumers and resources, which may translate into longer food chains. These findings highlight the critical role of riparian vegetation, particularly deciduous species like black alder, in maintaining headwater stream ecosystem integrity within afforested landscapes. Incorporating riparian vegetation management into afforestation planning can enhance stream food-web stability and support more balanced aquatic ecosystems.
Samways K.M. (2025). Supplementation of adult Atlantic salmon (Salmo salar) restores biofilm biomass and benthic metabolism. Fisheries Research, 291.

Restoration of adult Atlantic salmon (Salmo salar) populations can restore key ecological functions in nutrient-limited freshwater ecosystems. This study assessed the effects of marine-derived nutrients (MDNs) from spawning salmon on biofilm biomass and benthic metabolism in two adjacent watersheds, the Upper Salmon River (USR) and Point Wolfe River (PWR), located in and around Fundy National Park, New Brunswick, Canada. Using a Before-After-Control-Impact (BACI) design, between 2015–2017 we monitored changes in biofilm growth, metabolism, and stable isotope signatures across upstream (reference) and downstream (treatment) sites in both rivers. Significant increases in biofilm biomass (up to 0.099 μg chlorophyll m−2) and net daily metabolism (up to 13.1 mg O₂ m⁻² d⁻¹) were observed at treatment sites in the USR where adult salmon were released. In contrast, no such increases occurred in reference sites, or the non-supplemented PWR. Stable isotope analysis confirmed MDN assimilation in biofilm and linked enriched δ¹ ³C and δ¹ ⁵N values to the presence of adult salmon. A mass balance nutrient model demonstrated that adult salmon, unlike juvenile stocking, deliver net nutrient gains to streams. This study provides the first empirical evidence for functional ecosystem recovery in Atlantic salmon rivers via adult supplementation, emphasizing the role of salmon as a keystone species and supporting their use in both demographic and ecological restoration efforts in the endangered inner Bay of Fundy population range.
Saunders M.D., Bergbusch N., Knysh K.M., MacIntyre L.P., Pater C.C., Coffin M.R.S., Boudreau M., van den Heuvel M.R., Courtenay S.C. (2025). Using Nearshore Fish Communities to Evaluate Eutrophication Impact in Temperate Estuaries. Fishes, 10(2).

Using fishes as indicators of estuarine degradation is informative in long-term monitoring programs. Beach seine hauls were used in four estuaries that differed in their trophic and tidal status. The study found that inner, middle, and outer estuarine nearshore fish communities differed significantly at from all estuaries, for all sampling times. To reduce the effects of within-estuary variability, between-estuary differences were examined separately for inner, middle, and outer estuarine areas. These analyses revealed differences in north-south and trophic status in communities between estuaries. The north-south differences were characterized by more benthic fishes, such as mummichogs and fourspine stickleback in the microtidal northern estuaries and proportionally more pelagic fishes, such as Atlantic silversides and river herring in the mesotidal estuaries. In both multivariate and univariate analyses, mummichogs were also featured as being most abundant in the more eutrophic estuaries. The distance-based redundancy analysis showed that bare sediment coverage was the strongest correlate of the north-south differences, while the Ulva to Zostera plant gradient was more influential in predicting eutrophication impacts on communities in the inner and middle estuary.
Sugden S., White A.B., Lento J., Kurek J., Dimitrovas I., Emry S., Hua X., Ijzerman M.M., Kidd K.A., Morrow K.L., Ollinik J.E., Schnell L., Thormeyer M., Edge C.B. (2025). Legacy effects of four decades of insecticide applications on contemporary riverine benthic macroinvertebrates. Environmental Pollution, 376.

Insecticides have known effects on riverine benthic macroinvertebrate (BMI) assemblages. However, there is limited understanding of the legacy effects of insecticides, particularly in watersheds that received decades of historical applications. From 1952 to 1993, over 6.2 million ha in the province of New Brunswick (Canada) was treated with one to twelve different insecticides including dichlorodiphenyltrichloroethane (DDT), aminocarb, fenitrothion, and phosphamidon. Using a contemporary BMI dataset that included 274 sites within watersheds that cover 50 % of New Brunswick, we evaluated the relative importance of historical insecticide applications and contemporary environmental variables in explaining variability in BMI assemblages. We found that historical insecticides explained a significant, but small, amount of variation in contemporary assemblages. The number of insecticide applications showed a stronger association with BMI metrics than the total amount of insecticide(s) applied, though contemporary environmental measures such as urban land use, substrate size, geology, and climate all had more explanatory power than insecticide metrics. Our results suggested that while contemporary environmental variables and historical insecticide applications both affect BMI assemblage composition, the former often had a stronger role in structuring assemblages. Recognizing the influence of legacy stressors provides important context for understanding contemporary bioindicator responses to environmental change.
Wegscheider B., Rideout N.K., Monk W.A., Gray M.A., Steeves R., Baird D.J. (2025). Modeling nature-based restoration potential across aquatic–terrestrial boundaries. Conservation Biology, 39(5).

Today, few watersheds remain untouched by global change processes arising from climate warming, impoundments, channelization, water extraction, pollution, and urbanization. The need for restoration has resulted in a myriad of interventions, generally performed at small scales, which have limited measurable impact in restoring biodiversity and ecosystem functions. We propose bringing nature-based restoration (also referred to as rewilding) principles to rivers and their watersheds to allow freshwater ecosystems to heal themselves and present a case study example for the Wolastoq, a transboundary watershed on North America's east coast. We aimed to identify key areas for the provision of the ecosystem function secondary productivity in the watershed and explored how the existing network of protected lands contributes to its conservation. We first developed species distribution models for 94 aquatic insects and 5 aerial insectivores and then considered human footprint and existing protected areas when employing spatial prioritization to meet 2 area-based targets (17% and 30% [i.e., Aichi Biodiversity Target 11 and Canada's 30×30, respectively]) for conservation or restoration of freshwater secondary production. Current conservation protection in the watershed was predicted to be insufficient to protect either ecosystem function providers or receivers of secondary production. By considering integrated conservation strategies, restoration and conservation actions can be better allocated throughout habitat patches to ensure sustained provision of ecosystem functions across the watershed. Nature-based restoration and conservation can help inform Canada's area-based targets, providing a framework for incorporating ecosystem functions into conservation planning and offering practical insights for policy and restoration efforts aimed at safeguarding biodiversity.
West D.W., Hicks B.J., Ling N., van den Heuvel M.R., Tremblay L.A. (2025). Effects of point-source discharges on shortfin eels (Anguilla australis) along the Waikato River, New Zealand. New Zealand Journal of Marine and Freshwater Research, 59(2) 319-338.

The Waikato River is the longest river in New Zealand and is exposed to range of anthropogenic stressors. This study investigated the effects of three major point-source discharges on resident shortfin eels Anguilla australis along the river. Shortfin eels were caught from sites upstream and downstream of discharges of bleached kraft mill effluent (BKME) from pulp and paper manufacture, sewage, and a thermal power plant. At each site, population parameters (relative abundance and age structure) and individual metrics of health such as condition factor and organ (gonad, liver, and spleen) to somatic weight ratios were measured. Blood, biochemical (hepatic 7-ethoxyresorufin-O-deethylase or EROD) and chemical markers (bile chemistry and trace elements in flesh) were also measured. Measures of exposure and response to discharges confirmed that the shortfin eels were resident at the sites sampled. The discharges had few negative impacts on individual eel health and positive responses were seen to warm water discharge. However, resident shortfin eels were immature so reproductive responses could not be determined. In conclusion, shortfin eels in this study showed few responses to the effects of the discharges except for increased resin acids, bile polycyclic aromatic hydrocarbons, and EROD at the BKME site.
Yates A.G., Brua R.B., Culp J.M., Aguiar F.C., Ajayan A.P., Aspin T., Bundschuh M., Calderón M.R., Csabai Z., Dallas H., Datry T., Silva K.D., Dzavi J., England J., Erős T., Gebler D., Goedkoop W., González-Ferreras A.M., Hamilton D.P., Hughes R.M., Juen L., Kefford B.J., Koroiva R., Krynak E.M., Lavoie I., Lento J., Ligeiro R., Martins R.T., Masese F.O., de Assis Montag L.F., Musetta-Lambert J., Painter K.J., Poikane S., Rico A., Ruaro R., Sabater S., Michelan T.S., Schoelynck J., Smucker N.J., Stanković I., Stubbington R., van Deventer H., van Niekerk L., Van den Brink P.J., Várbíró G., Wanderi E.W. (2025). Charting a course for freshwater biomonitoring: The grand challenges identified by the global scientific community. Ecological Indicators, 176.

The past 50 years have seen biomonitoring emerge as an essential means of generating the knowledge needed to inform protection and restoration of freshwater ecosystems. Despite the successes of biomonitoring, most freshwater ecosystems remain unmonitored. Moreover, degradation of freshwaters continues at a rapid rate with new threats and novel stressors emerging that are difficult to assess using existing techniques. New technologies and techniques have been developed to improve biomonitoring, but application has been slow and integration with existing approaches is often problematic. Clearly, freshwater biomonitoring faces many important challenges that must be addressed to meet management needs of the coming decades. We identify Grand Challenges facing freshwater biomonitoring with the aim of encouraging research and practice to address these challenges. We asked 256 biomonitoring scientists from around the globe to identify what they considered the most important challenges. From their submissions we established five Grand Challenges and 18 associated subchallenges. For each Grand Challenge, we outline the current state of biomonitoring practice and suggest promising pathways and approaches to address them. By identifying and describing these challenges, we strive to position freshwater biomonitoring to take advantage of emerging opportunities and enhance its capacity to meet current and future management needs.
Andrew S., Swart S., McKenna S., Morissette J., Gillis C.A., Linnansaari T., Currie S., Morash A.J. (2024). The impacts of diel thermal variability on growth, development and performance of wild Atlantic salmon (Salmo salar) from two thermally distinct rivers. Conservation Physiology, 12(1).

Temperature in many natural aquatic environments follows a diel cycle, but to date, we know little on how diel thermal cycles affect fish biology. The current study investigates the growth, development and physiological performance of wild Atlantic salmon collected from the Miramichi and Restigouche rivers (NB, Canada). Fish were collected as parr and acclimated to either 16–21 or 19–24◦C diel thermal cycles throughout the parr and smolt life stages. Both Miramichi and Restigouche Atlantic salmon parr grew at similar rates during 16–21 or 19–24◦C acclimations. However, as smolts, the growth rates of the Miramichi (−8% body mass day−1) and Restigouche (−38% body mass day−1) fish were significantly slower at 19–24◦C, and were in fact negative, indicating loss of mass in this group. Acclimation to 19–24◦C also increased Atlantic salmon CT<inf>max</inf>. Our findings suggest that both life stage and river origin impact Atlantic salmon growth and performance in the thermal range used herein. These findings provide evidence for local adaptation of Atlantic salmon, increased vulnerability to warming temperatures, and highlight the differential impacts of these ecologically relevant diel thermal cycles on the juvenile life stages in this species.
Arthington A.H., Tickner D., McClain M.E., Acreman M.C., Anderson E.P., Babu S., Dickens C.W.S., Horne A.C., Kaushal N., Monk W.A., O’brien G.C., Olden J.D., Opperman J.J., Owusu A.G., Poff N.L., Richter B.D., Salinas-Rodríguez S.A., Mbale B.S., Tharme R.E., Yarnell S.M. (2024). Accelerating environmental flow implementation to bend the curve of global freshwater biodiversity loss. Environmental Reviews, 32(3) 387-413.

Environmental flows (e-flows) aim to mitigate the threat of altered hydrological regimes in river systems and connected waterbodies and are an important component of integrated strategies to address multiple threats to freshwater biodiversity. Expanding and accelerating implementation of e-flows can support river conservation and help to restore the biodiversity and resilience of hydrologically altered and water-stressed rivers and connected freshwater ecosystems. While there have been significant developments in e-flow science, assessment, and societal acceptance, implementation of e-flows within water resource management has been slower than required and geographically uneven. This review explores critical factors that enable successful e-flow implementation and biodiversity outcomes in particular, drawing on 13 case studies and the literature. It presents e-flow implementation as an adaptive management cycle enabled by 10 factors: legislation and governance, financial and human resourcing, stakeholder engagement and co-production of knowledge, collaborative monitoring of ecological and social-economic outcomes, capacity training and research, exploration of trade-offs among water users, removing or retrofitting water infrastructure to facilitate e-flows and connectivity, and adaptation to climate change. Recognising that there may be barriers and limitations to the full and effective enablement of each factor, the authors have identified corresponding options and generalizable recommendations for actions to overcome prominent constraints, drawing on the case studies and wider literature. The urgency of addressing flow-related freshwater biodiversity loss demands collaborative networks to train and empower a new generation of e-flow practitioners equipped with the latest tools and insights to lead adaptive environmental water management globally. Mainstreaming e-flows within conservation planning, integrated water resource management, river restoration strategies, and adaptations to climate change is imperative. The policy drivers and associated funding commitments of the Kunming–Montreal Global Biodiversity Framework offer crucial opportunities to achieve the human benefits contributed by e-flows as nature-based solutions, such as flood risk management, floodplain fisheries restoration, and increased river resilience to climate change.
Brown C.J.M., Noble B.F., Munkittrick K.R. (2024). Examination of recent hydroelectric dam projects in Canada for alignment of baseline studies, predictive modeling, and postdevelopment monitoring phases of aquatic environmental impact assessments. Integrated Environmental Assessment and Management, 20(3) 616-644.

Environmental impact assessment (EIA) has been widely criticized by the aquatic science community for poorly aligned approaches when selecting endpoints and collecting data during the baseline, predictive modeling, and postdevelopment monitoring phases. If these critical phases of the EIA process are not aligned properly, it can be difficult to evaluate the presence of postdevelopment effects. Examples of the misalignment of these phases include baseline studies failing to measure indicators that are monitored postdevelopment; predictive assessments that do not quantitatively predict conditions or potential impacts postdevelopment; and the failure to identify relevant indicators that may detect effects postdevelopment. For aquatic assessments, understanding how to protect critical ecosystem attributes to satisfy regulatory concerns could help to better align aquatic science monitoring activities across EIA phases. In this article we investigate recent Canadian hydroelectric dam EIAs to evaluate how well recent assessment approaches are meeting these necessary conditions of good aquatic EIA practice through the lens of ecosystem services from a fish's perspective. We found that larger facilities generally had baseline studies and modeling that better supported postdevelopment monitoring, but improvements in structure, linkages, and expectations would better align EIA phases in a manner that would improve assessments and environmental protection. Integr Environ Assess Manag 2024;20:616–644. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
Bée S., St-Hilaire A., van den Heuvel M. (2024). Modeling sediment concentrations and loads for two small agricultural watersheds in Prince-Edward-Island (Canada): present conditions and a future scenario. Frontiers in Water, 6.

The degradation of soils and its detrimental consequences on aquatic environments is an important research topic in agricultural regions such as Prince Edward Island (PEI, Canada). Enhanced information related to suspended sediments in watercourses can serve as an effective decision-making tool in agricultural land management. This study aims to compare flow, suspended sediment concentrations (SSC), and loads using the Soil and Water Assessment Tool (SWAT) in two watersheds in Prince Edward Island (PEI). The final investigations will focus on the potential variations in hydrological and sedimentary values in the future using a relatively pessimistic climate change scenario. Finally, the projected sediment concentrations and loads will be analyzed, considering their potential impacts on ecosystems. Water level and turbidity were recorded using two water level loggers and two optical backscatter sensors (OBS) deployed in the Tuplin Creek and Spring Valley watersheds. These instruments continuously recorded suspended sediments and flow data from June 2021 to September 2022. The data were used to manually calibrate the hydrological and suspended sediment models. The understanding of sediment loads and the benefits of proposed changes to agricultural practices can be tested with the SWAT model, as it incorporates a land use index that varies spatially and temporally. Calibration and validation of both the hydrological and sediment models were satisfactory, with Kling-Gupta Efficiency coefficients varying between 0.51 and 0.73 and Nash-Sutcliffe coefficients varying between 0.61 and 0.73 respectively, indicating successful simulation of both variables in an agricultural context in spite of relatively short calibration and validation periods. Under the selected climate change scenario (RCP 8.5), daily flows and suspended sediment concentrations were simulated until 2,100, showing a slight increase in the average suspended sediment concentration (CSS). For Tuplin Creek, extremely high sediment peaks (>1,500 mg/L) could become significantly more frequent, potentially causing more frequent and severe ecosystem disturbances according to the simulations.
Cantonati M., Armanini D.G., Demartini D., Papatheodoulou A., Bilous O.P., Colombo F., Angeli N., Stancheva R., Dörflinger G., Manoylov K.M. (2024). Has climate change over the last ten years caused a banalisation of diatom communities in Cypriot streams? Science of the Total Environment, 947.

To unveil possible changes in diatom communities in Cypriot streams over the last ten years or so, we selected samples from the years 2020, 2021, and 2022 for the “recent” dataset (N = 119) and samples from the years 2010 and 2011 for the “historical” dataset (N = 108). Biotic homogenization has become a truly global phenomenon. Here we show that, over the last ten years, in response to increased water temperature, conductivity, and discharge variability due to climate-change, Cypriot stream diatom communities include a higher number of trivial (= widespread, tolerant, and opportunistic), aerial, and thermophilic species, have reduced β-diversity and increased nestedness. Moreover, IndVal analysis shows that indicator species from the historical dataset were characteristic, often relatively rare species, while the indicators of the recent dataset were a group of typical trivial, eutraphentic, and thermophilic species. As is almost always the case, the diatom communities we studied were subjected to multiple stressors, often affecting them in opposite ways. Besides the increase in trivial species, the reduction in β-diversity, and the rise in nestedness mentioned above, the diatom assemblages we studied also showed an increase in α-diversity that could be due to a moderate reduction in nutrients in several sites. High-ecological-integrity ecosystems, such as springs, waterfalls, and dripping rock-walls, in particular springs that were shown to be excellent hydrologic refugia in climates heavily affected by climate change, and the stream sites close to them should be carefully protected, as they can be refugia for sensitive and characteristic species that can recolonize the adjacent streams after adverse climatic events.
Carvey Q.B., Pavey S.A., Diamond A.W., Davoren G.K., Lavoie R.A., LeBlanc N.M., Legard M.J., Robertson G.J., Runnells E.S., Petalas C., Major H.L. (2024). Genetic structure of Atlantic Puffins (Fratercula arctica) breeding in Atlantic Canada. Conservation Genetics, 25(6) 1159-1174.

The Atlantic Puffin (Fratercula arctica; hereafter ‘puffin’) breeds at the southern limit of its range in the Gulf of Maine, where waters are warming faster than most of the world’s oceans. Puffin productivity and survival have decreased in the Gulf of Maine with warming, but population-level declines have not been detected. Understanding the connectivity between Gulf of Maine breeding colonies and colonies to the north has become a priority to determine the demographic importance of immigration, but mark-recapture and tracking studies have yet to resolve this question. In this study, we used double digest restriction-site associated DNA sequencing (ddRADseq) to quantify neutral genetic differentiation among five breeding colonies in Atlantic Canada, identify outlier single nucleotide polymorphisms (SNPs), and determine if puffins can be reliably assigned to their breeding colony. We identified a new genetic cluster of puffins, represented by Machias Seal Island, and recommend that this colony be considered separately from Newfoundland and Québec for management. We found three outlier SNPs, with the rare alleles predominantly present in Machias Seal Island puffins, and recommend further research to determine the extent that selection may be contributing to the differentiation of Machias Seal Island. Puffins could be reliably assigned to the Machias Seal Island or the northern-colony genetic cluster, including with a subset of the 200 highest-F<inf>ST</inf> SNPs. Finally, we did not identify evidence of inbreeding at any colony, suggesting that effective population sizes are large enough to buffer against these negative effects.
Danielescu S., MacQuarrie K.T.B., Nyiraneza J., Zebarth B., Sharifi-Mood N., Grimmett M., Main T., Levesque M. (2024). Development and Validation of a Crop and Nitrate Leaching Model for Potato Cropping Systems in a Temperate–Humid Region. Water Switzerland, 16(3).

The Root Zone Water Quality Model (RZWQM) is a one-dimensional process-based model used for simulating major physical, chemical, and biological processes in agricultural systems. To date, the model has not been applied to potato production systems for simulating nitrate leaching. In this study, 35 datasets collected between 2009 and 2016 at a field under a three-year potato (potato–barley–red clover) rotation in Prince Edward Island (PEI), Canada, have been employed for calibrating and validating the water, nitrogen (N) cycling, and plant growth routines of RZWQM and for subsequently estimating nitrate leaching. The model fitness, evaluated using univariate and bivariate indicators, was rated as high for most of the parameters tested. As a result of the combined influence of higher infiltration and reduced plant uptake, the model showed that the highest leaching at the rotation level occurred between September and December. A secondary leaching period occurred in spring, when residual soil nitrate was mobilized by increased percolation due to snowmelt. Most of the nitrate leaching occurred during the potato year (89.9 kg NO<inf>3</inf>–N ha−1 y−1), while leaching for barley and red clover years had comparable values (28.6 and 29.7 kg NO<inf>3</inf>–N ha−1 y−1, respectively). The low N use efficiency of the entire rotation (i.e., 30.2%), combined with the high NO<inf>3</inf>–N concentration in leachate (i.e., 34.9 mg NO<inf>3</inf>–N L−1 for potato and 16.3 mg NO<inf>3</inf>–N L−1 for the complete rotation), suggest that significant efforts are required for adapting management practices to ensure sustainability of potato production systems.
Dobbs K.D.R., Lynn T.J., Bruce M.R., Reyes-Prieto A., Samways K.M., Curry R.A., Duffy M.S. (2024). Freshwater mussel glochidia infesting anadromous Gaspereau below a hydroelectric generating station: implications for mussel conservation. Hydrobiologia, 851(3) 617-632.

The Wolastoq | Saint John River (W|SJR) in New Brunswick, Canada, is regulated by hydroelectric dams with the largest and furthest downstream being the Mactaquac Generating Station (MQGS). River regulation can disrupt ecosystem connectivity by restricting access to upstream habitat for fishes and parasitic mussel larvae dependent on fishes for dispersal. Following installation of the MQGS, the number of Gaspereau (Alewife, Alosa pseudoharengus [Wilson, 1811]) and Blueback herring, Alosa aestivalis [Mitchill, 1814]) that spawn in that region of theW|SJR has increased dramatically. We assessed ectoparasitic freshwater mussel glochidia on Gaspereau captured at the MQGS and found 100% infested with an average of 43.2 glochidia per fish. Glochidia infested gill rakers, with increasing intensities from the first to fourth gill arch (P < 0.001). At least one million Gaspereau are passed above the MQGS annually, suggesting that millions of glochidia are simultaneously passed upstream each year with their hosts. We sequenced mitochondrial markers (ND1, COI) to ascertain mussel species and confirm both Alewife and Blueback herring as hosts for Alewife Floater (Utterbackiana implicata [Say, 1829]). This study provides critical baseline data on symbiotic interactions tightly interwoven in this river ecosystem and demonstrate that river regulation and fish passage considerations are more complex than most management plans account for currently.
Dubos V., St-Hilaire A., Laurion I., Bergeron N.E. (2024). Characterization of anadromous Arctic char winter habitat and egg incubation areas in collaboration with Inuit fishers. Arctic Science, 10(1) 215-224.

In Nunavik, anadromous Arctic char spend more than 6 months under ice-covered habitats, mainly in lakes. Their winter habitats in this region have been scarcely studied due to the challenging logistics in the Arctic. In this study, we worked with Inuit fishers to characterize the winter habitat and incubation areas used by Arctic chars in five overwintering lakes and one lentic river reach. The collaborating fishers determined char occupancy of certain areas related to fishing sites (presence, ab-sence, and spawning) and conducted measurements to characterize the sites while performing their fishing activities. The data showed that incubation areas were associated with significantly shallower depths and warmer (albeit not statistically signifi-cant) lake bottom temperatures than sites where no spawning occurs, which is beneficial for egg maturation. The productivity of these areas is also beneficial for fry that hatch during winter. Adult and post-smolt habitats tended to be associated with cold littoral zone, but their habitat did not show any other distinct characteristics. This exploratory study adds insights into the cryptic characteristics of the Arctic char winter habitat use, thanks to the Inuit fishers’ knowledge of fish habitats and movements, and the experience and expertise they have acquired working in the local environment.
Eerola E.S., Megyeri E., Piro A.J., Hayden B., Kahilainen K.K. (2024). Year-round sampling of the fish community in a boreal lake: differences between summer and winter influence estimates of species composition, catch, and fish size. Journal of Fish Biology, 105(4) 1163-1177.

Boreal lakes experience pronounced seasonal variation in abiotic factors, especially light, temperature, and oxygen. A deep boreal humic lake was sampled year-round to test putative changes in total fish catch, species composition, catch-per-unit-effort (CPUE), habitat use, fish size, and condition. Monthly sampling was conducted in Lake Pääjärvi, southern Finland, during one full year in 2020–2021 as well as in March and August 2021 and 2022. The fish community was dominated by cyprinid species in all months, but the percentage of percid fish caught increased during the warm summer period. Most fish were caught in littoral habitats and the highest catches occurred in summer, but some species (e.g., ruffe, Gymnocephalus cernua, and pikeperch, Sander lucioperca) remained abundant in the winter catch. The body size of fish was larger in the winter catch, while condition factor was higher in summer for most species. Fish species proportions in total catch, CPUE, and average size of fish were closest to the annual mean values in September, which may be used as the optimal period to monitor fish communities of similar deep boreal lakes. Our findings highlight the need for year-round research to reveal the impacts of rising temperatures and diminishing ice-covered periods in fish communities and lake food webs.
Eissenhauer F., Martin M., Adesola J., Curry R.A., Linnansaari T., Harrison P.M. (2024). Short-term survival and growth of American Eel elvers marked with visible implant elastomer tags. North American Journal of Fisheries Management, 44(4) 826-834.

Objective: Visible implant elastomer (VIE) tags are commonly used as a cost-effective tool for marking small fish, making them valuable in mark–recapture studies. It is crucial to quantify the impact of tagging procedures on fish survival to address inferential bias in mark–recapture studies. We assessed marking-related mortality and growth in American Eel Anguilla rostrata elvers in a 40-day laboratory experiment, following VIE tag application. Methods: There were 500 elvers (80–149 mm) that were divided into four treatment groups and one control group. Treatment groups were tagged with two tags in three body locations (anterior, central, posterior on left bilateral side) or with two tags in all three locations, while the control group remained untagged. Eels were retained in experimental tanks, and mortality rates were compared. Result: The VIE tagging did not significantly affect survival, which was 90.9% across all treatment groups and 92% for the untagged control group; nor did it affect growth. Conclusion: The application of VIE tags on various body parts should be a safe and effective method for marking American Eel elvers.
Gaczorek T., Dudek K., Fritz U., Bahri-Sfar L., Baird S.J.E., Bonhomme F., Dufresnes C., Gvoždík V., Irwin D., Kotlík P., Marková S., Mcginnity P., Migalska M., Moravec J., Natola L., Pabijan M., Phillips K.P., Schöneberg Y., Souissi A., Radwan J., Babik W. (2024). Widespread Adaptive Introgression of Major Histocompatibility ComplexGenes across Vertebrate Hybrid Zones. Molecular Biology and Evolution, 41(10).

Interspecific introgression is a potentially important source of novel variation of adaptive significance. Although multiple cases of adaptive introgression are well documented, broader generalizations about its targets and mechanisms are lacking. Multiallelic balancing selection, particularly when acting through rare allele advantage, is an evolutionary mechanism expected to favor adaptive introgression. This is because introgressed alleles are likely to confer an immediate selective advantage, facilitating their establishment in the recipient species even in the face of strong genomic barriers to introgression. Vertebrate major histocompatibility complex genes are well-established targets of long-term multiallelic balancing selection, so widespread adaptive major histocompatibility complex introgression is expected. Here, we evaluate this hypothesis using data from 29 hybrid zones formed by fish, amphibians, squamates, turtles, birds, and mammals at advanced stages of speciation. The key prediction of more extensive major histocompatibility complex introgression compared to genome-wide introgression was tested with three complementary statistical approaches. We found evidence for widespread adaptive introgression of major histocompatibility complex genes, providing a link between the process of adaptive introgression and an underlying mechanism. Our work identifies major histocompatibility complex introgression as a general mechanism by which species can acquire novel, and possibly regain previously lost, variation that may enhance defense against pathogens and increase adaptive potential.
Hayden B., Kovačić M., Kirinčić M., Marčić Z. (2024). Comparative trophic ecology of microhabitat-associated guilds of reef fishes in the Adriatic Sea. Journal of Fish Biology, 105(5) 1421-1431.

Reef ecosystems are characterized by highly heterogenous habitats and functionally diverse fish communities. Few studies have examined how functional diversity differs among habitats within these communities, i.e., species associated with a specific habitat may have similar trophic ecologies meaning that the functional diversity within the community is driven by habitat diversity or, conversely, high functional diversity within each habitat would indicate that resource segregation also occurs at the habitat level. We used stable isotope ratios of carbon and nitrogen to estimate trophic position, resource use and ontogenetic niche shifts of 15 reef fishes associated with four distinct habitat types (cryptobenthic, epibenthic sand, epibenthic rock and hyperbenthic) on the Croatian coast of the Adriatic Sea. Trophic ecology was quite similar across fish assemblages, but there was strong evidence of niche segregation among fish species within each assemblage showing high functional diversity within each microhabitat. The sampled fish community contained benthic and pelagic resource users, along with multiple intermediate generalists. Consumer stable isotope ratios revealed considerable interspecific variation in resource use among fishes within each habitat type. The cryptobenthic fishes were a notable exception to this trend with the narrow range of resource use values, indicating reliance of these species on a single resource. The greatest diversity of trophic positions within a guild was observed in cryptobenthic and rock-associated epibenthic fishes. The majority of observed ontogenetic variation in studied fish species reflected an increase in benthic resource use and trophic position. However, the degree of ontogenetic variation in trophic ecology of studied species, if present, was generally low, showing no dramatic change in the ecology of any species. The size structuring among guilds was considerable, with cryptobenthic fishes the smallest on average and hyperbenthic fishes the largest, despite guilds having similar ranges of trophic positions.
Hill C.R., Culberson A., O'Sullivan A.M., Adesola J., Curry R.A., Linnansaari T., Harrison P.M. (2024). A controlled experimental assessment of intraperitoneal PIT tag injection on survival of Blueback Herring. North American Journal of Fisheries Management, 44(1) 93-100.

Objective: Passive integrated transponder (PIT) telemetry is commonly used to monitor fish movements and behavior. To reduce inferential bias in PIT telemetry studies, it is important to quantify the effects of tagging procedures on fish survival. To this end, we conducted a controlled experiment to test the hypothesis that intraperitoneal injection of 23-mm PIT tags would have no effect on the survival of adult Blueback Herring Alosa aestivalis. Methods: We compared mortality rates of tagged and untagged Blueback Herring (n = 174; size range 202–277 cm) that were retained in experimental tanks for 14 days. Result: We observed no difference in the probability of survival between tagged (50% survival) and untagged (42%) groups. Conclusion: These results suggest that intraperitoneal tag injection is a safe and effective method of PIT tagging adult Blueback Herring and supports the use of this technique in field telemetry studies.
Johnston L.H., Huang Y., Bermarija T.D., Rafuse C., Zamlynny L., Bruce M.R., Graham C., Comeau A.M., Valadez-Cano C., Lawrence J.E., Beach D.G., Jamieson R.C. (2024). Proliferation and anatoxin production of benthic cyanobacteria associated with canine mortalities along a stream-lake continuum. Science of the Total Environment, 917.

Proliferations of benthic cyanobacteria are increasingly in the public eye, with rising animal deaths associated with benthic rather than planktonic blooms. In early June 2021, two dogs died after consuming material on the shore of Shubenacadie Grand Lake, Nova Scotia. Preliminary investigations indicated anatoxins produced by benthic cyanobacterial mats were responsible for the deaths. In this study, we monitored the growth of a toxic benthic cyanobacterial species (Microcoleus sp.) along a stream-lake continuum where the canine poisonings occurred. We found that the species was able to proliferate in both lentic and lotic environments, but temporal growth dynamics and the predominant sub-species were influenced by habitat type, and differed with hydrodynamic setting, nutrient and sunlight availability. Toxin concentration was greatest in cyanobacterial mats growing in the oligotrophic lakeshore environment (maximum measured total anatoxins (ATXs) >20 mg·kg−1 wet weight). This corresponded with a shift in the profile of ATX analogues, which also indicated changing sub-species dominance along the stream-lake transition.
Kalvani Z., Kamunde C., Stevens D., van den Heuvel M.R. (2024). A model naphthenic acid decouples oxidative phosphorylation through selective inhibition of mitochondrial complex activity. Environmental Toxicology and Pharmacology, 107.

The naphthenic acid fraction compound (NAFC), 3,5-dimethyladamantane-1-acetic acid, was tested for its ability to uncouple mitochondrial oxidative phosphorylation. Mitochondria isolated from rainbow trout (Oncorhynchus mykiss) liver were exposed to 3,5-dimethyladamantane-1-acetic acid in state 3 and 4 respiration, and mitochondrial membrane potential were quantified. Electron transport chain (ETC) protein complexes were isolated using pharmacological agents and inhibitors, and their activities measured. The NAFC compound completely inhibited states 3 and 4 respiration with an IC50 of 0.77 and 1.01 mM, respectively. The NAFC compound partially uncoupled mitochondrial membrane potential in state 3 and 4 respiration with an IC50 of 2.19 and 1.73 mM, respectively. The NAFC impaired the activities of ETC protein complexes with a 9.5-fold range in sensitivity. The relative inhibitory effect of the ETC protein complexes to NAFC was CIV≥CI>CIII>CII. The impairment of mitochondrial oxidative phosphorylation by adamantane 3,5-dimethyladamantane-1-acetic acid is mediated via its inhibition of ETC protein complexes.
Kidd J., Brammer J., Courtenay S., Swanson H., Avery-Gomm S. (2024). Pan-Canadian review of community-based monitoring projects and their capacity to enhance environmental monitoring programs for cumulative effects assessments. Facets, 9 1-19.

While community-based monitoring (CBM) can support meaningful participation of the public in environmental decisionmaking, it remains unclear if and how CBM can support western science approaches to biophysical studies within cumulative effects assessment (CEA). We scored 40 Canadian CBM projects on their ability to enhance CEA’s western science approaches to environmental monitoring. We used multivariate analyses to determine if the highest-scoring projects shared characteristics that could inform the design of CBMs to support CEA. Cluster analysis and non-metric multi-dimensional scaling ordination revealed that highest-scoring projects were distinct from lower scoring projects, and the Similarity Percentages Routine identified characteristics that differentiated these projects. The highest-scoring projects involved non-profit organizations as bridging organizations that coordinated community participation and received funding and in-kind support from provincial/territorial government agencies. Participants in these projects collected measurements and samples using standardized protocols described in training manuals. Their data were publicly accessible in georeferenced databases and were used for baseline studies and resource management. There are existing CBM projects in Canada that thus appear well positioned to enhance western science approaches to CEA. Further study is required to identify how CBM projects can be designed to braid Indigenous and western science approaches to mutually enhance CEA methods.
Latif S., B.M.J. Ouarda T., St-Hilaire A., Souaissi Z., Rehana S. (2024). A new nonparametric copula framework for the joint analysis of river water temperature and low flow characteristics for aquatic habitat risk assessment. Journal of Hydrology, 634.

This study proposed a nonparametric copula hazard framework in the joint risk of river water temperature (RWT) and low flow (LF) events for aquatic ecosystems, specifically ectotherm fish. This nonparametric copula density can adapt to any mutual dependence structure, providing greater flexibility. This can reduce the risk of misspecification if the underlying assumption is violated compared to conventional parametric or semiparametric copula settings. The analysis uses nonparametric copulas densities like Beta kernel copula estimator (BKCE), Bernstein copula estimator (BCE), and Transformation kernel estimator (TKE), conjoined with Gaussian Kernel density estimations (GKDEs) and parametric marginals for joint annual maximum RWT (AMRWT) and LF. The study compares different models for analyzing five Swiss river basins: parametric copulas with best-fitted GKDE and parametric margins, versus nonparametric copula. Six bandwidth selectors are estimated to fit GKDE. BKCE with GKDE margins outperformed most stations, while TKE and BCE density with GKDE margins work best for only one station. However, at one station, BKCE with best-fitted parametric margins is outperformed. All stations except Station 2473 are characterized by temperature and low flows that may be conducive to stress of a number of aquatic species, causing high AMRWT (exceeding 19 °C) and minimum LF or specific discharge, SD) quantiles at low AND-joint return periods (RP). AND (i.e. low flow AND high temperature) hazard events are less likely to occur together than OR hazard events, while univariate RPs happen more often than OR-joint RPs. In addition, the joint RP of AMRWT, given LF at different percentiles, significantly affected AMRWT for various LF conditions. Higher AMRWT with low flow conditions results in lower joint RP (except station 2473), and this stress level would be reduced when conditioned with high LF events at the same AMRWT. Station 2473 has high LF even at low percentiles, and with low AMRWT makes it very less stressful than other station under different LF conditions. Summer river flow maintenance can improve aquatic environments with high RWT. Analyzing joint statistics is crucial to understanding mutual risk in freshwater ecosystems.
Leader S., Kettridge N., Hannah D., Mendoza C., Devito K.J. (2024). Diverse response of shallow lake water levels to decadal weather patterns in a heterogeneous glacial Boreal Plains landscape. Hydrological Processes, 38(4).

To examine the relative controls of landscape and climate on spatial variability, we measured water level dynamics of shallow lakes over two decades that represent both the heterogeneity of surficial geology classifications, and thus the potential range in surface and groundwater connectivity, and the long-term weather patterns of the Boreal Plain hydrogeoclimatic setting. Large ranges in shallow lakes water levels (between 0.25 and 2 m) were observed corresponding to extremes in precipitation relative to the long-term mean precipitation over the study period. We found low concurrence in water level dynamics among four detailed study lakes that received the same meteorological weather signal, but were located in different surficial geology texture classifications that incorporated important landscape parameters associated with lake water balance and storage. Surficial geology classification alone did not, however, distinguish between different ranges in lake water level measured in a broader synoptic survey of 26 lakes across the region. Thus, simple surficial geology classifications cannot alone be applied to classify Boreal Plain lake water level dynamics and other controls, notably landscape position, must also be considered. We further show that inter-annual variability in lake water levels was significantly greater than seasonal variability in this hydrogeoclimatic setting. This emphasizes the need for studies of sufficient length to capture weather extremes that include periods of wetting and drying, and demonstrates how observed magnitudes of water level variability, and lake function, can be an artefact of study length and initiation date. These findings provide a foundation to test and calibrate conceptual understanding of the wider controls of lake water levels to form holistic frameworks to mitigate ecological and societal impacts due to hydrological changes under climate and anthropogenic disturbance within and between hydrogeoclimatic settings.
Leader S., Kettridge N., Hannah D.M., Mendoza C., Devito K.J. (2024). Multi-year climate memory in shallow lake water levels. Journal of Hydrology, 642.

Landscape hydrologic memory of meteorological cycles can have an important impact on catchment hydrological responses by propagating clustering of wet or dry conditions into extreme events. The non-linear and hysteretic hydrologic response functions driven by memory are often only studied at shorter temporal scales (event, season) despite larger interannual hydrologic responses evident in some systems. Within the Canadian Boreal, lakes and lake water levels provide an important indicator that can be used to assess the role of landscape memory on catchment hydrological function. Landscape memory has also been hypothesised to control the hydrological dynamics of shallow lake ecosystems that are also important biogeochemically and ecologically. Here we combine measurements of lake water levels in 26 lakes of varying type at varying temporal frequencies within the glaciated sub-humid Boreal Plain, to examine the impact and variability of interdecadal, decadal, multi-year, and intra-annual memory on lake water levels. We show multi-annual hysteresis of precipitation-lake water levels with varied characteristics in space and time. These spatial variations in landscape memory are driven by differences in storage capacities controlled by heterogeneity in glacial landforms, wetland-forest landcover and lake properties. Thus, the propensity for drought years or wet years to persist or accumulate into extreme landscape drying or wetting varies significantly between different lake-landscape characteristics. We show how landscape memory is crucial to project lake water levels by defining spatial variability of the impact of periods of meteorological drought and deluge vital for understanding system sensitivity, duration of recovery and in turn infer resilience on Boreal Plain hydrology.
Leavitt J., Haralampides K. (2024). Investigating the Downstream Effects of River Regulation and Sediment Transport on the Grand Lake Meadows Complex, New Brunswick, Canada. Lecture Notes in Civil Engineering, 503 LNCE 205-213.

Sediment in a fluvial system impacts biological and physical processes such as fish, macrophytes and insect health, habitat suitability, fluid mechanics, and floods. Alterations to natural sediment transport such as those caused by hydropower dams and associated reservoirs must be understood since the entire ecosystem will be affected. The purpose of this research is to quantify the downstream effects that the Mactaquac Generating Station (MQGS) has on the sediment dynamics in the Wolastoq|Saint John River (W|SJR) in New Brunswick, Canada; we are specifically investigating how the downstream Grand Lake Meadows Complex (GLM Complex) has been affected by the changes in suspended sediment load. In order to understand implications of changes in sediment, we must first estimate how much sediment enters the reservoir, and the relationship between inflowing sediment and depositing sediment. Hydraulic parameters such as total suspended solids (TSS), turbidity and trap efficiency (TE) were used in this research to quantify the amount of suspended sediment entering the reservoir since the construction of the MQGS in 1968. Field data were collected during the summer and fall months to estimate suspended sediment concentrations, and a linear relationship between turbidity and TSS was developed during ice cover months to complete a year-round dataset. The relationships were generated for four different reaches in the lower Wolastoq|Saint John River and were used as a passive method for estimating TSS concentrations. The relationships had R2 values of 0.85, 0.88, 0.95 and 0.98 for the Meductic, Longs Creek, MQGS and Bill Thorpe Walking Bridge sites, respectively. In the study region, sediment transport peaks with the high flows during the spring freshet and fall rain storms and reduces with the low flows during the summer and winter months. The results of this research will further the understanding of sediment dynamics locally, and the impacts on the development and formation of the GLM Complex, while also advancing our understanding of sediment dynamics and regulated rivers in general.
LeRoux N.K., Pavlovskii I., O'Sullivan A.M., Mulligan R.P., Bonnington A.C., Kurylyk B.L. (2024). Morphodynamics of a composite sand-cobble beach in response to extratropical cyclone Fiona and seasonal wave variability. Science of the Total Environment, 916.

Climate change is driving higher coastal water levels, and models project accelerated future sea-level rise and coastal storm intensification. These dynamics paired with anthropogenic coastal alterations will drive drastic coastal change worldwide. Composite beaches with mixed sediment sizes warrant detailed study as these exhibit complex morphodynamics in response to changing hydrodynamics due to the distinct transport thresholds of different sediment types. This study uses a novel multi-method approach to investigate a composite sand-cobble beach in Atlantic Canada experiencing a shortening seasonal sand-covered period. Hydrodynamic forcing and associated beach changes were monitored over a focused eight-month period, while satellite-based visual imagery and reconstructed wave data were analyzed over longer periods. Results show that intra-annual wave energy changes drive sand dynamics, with reduced summer wave energy facilitating short-term deposition. Long-term positive trends were identified in late spring wave heights, which likely contribute to the shortening sand-covered period. Seasonal dynamics were overwhelmed by extratropical cyclone Fiona, which made landfall on September 24, 2022, generating significant wave heights up to 6.8 m in the bay, mobilizing sediment, and steepening cobble berms. A new index approach based on visual imagery facilitated the investigation of beach sand appearance/disappearance using the relative redness of sand compared to cobble. Finally, the UAV-based surveys yielded high-resolution orthomosaics and LiDAR-based elevation mapping, and highlighted pronounced longshore variability in erosion and deposition during Fiona. The beach mostly recovered to pre-storm conditions in <4 months, which indicates that proposed beach nourishment activities may only experience temporary success. The longer-term results showing a conversion of sand to cobble suggest that loss of sandy beach habitat is likely to increase, even without shoreline migration or coastal squeeze driven by sea-level rise.
Maclean D.A., Baglole T., Bourgouin M., Chiasson B., Deb J.C., Erdozain M., James R.J., Negrazis L., Tousignant L., Wiebe P., Adams G., Bennett J.R., Emilson E.J.S., Fenton N.J., Forbes G.J., Gray M.A., Kidd K.A., McCartney A., Moreau G., Porter K.B., Valeria O., Venier L.A. (2024). Predicting present and future habitats using LiDAR to integrate research and monitoring with landscape analyses. Forestry Chronicle, 100(2) 194-207.

Managed forests contribute to both economic and non-timber values, but the ecological role of managed, including planted, forests to biodiversity objectives at the landscape scale needs to be better understood. In this project in collaboration with J.D. Irving, Limited, we: 1) used airborne LiDAR and field data to identify terrestrial habitats; 2) monitored selected taxa by 18 stand type/seral stage habitat types in intensively and extensively managed forests and reserves; 3) assessed effects of management intensity on water quality and aquatic habitat; and 4) projected forest and wildlife habitat under planned management and natural disturbance scenarios. Taxa studied included songbirds, bryophytes and beetle species associated with mature-overmature forests, and several listed ground vegetation species. LiDAR-based enhanced forest inventory provided forest structure variables that improved bird habitat models and spatial predictions of bird habitat, metrics explaining bryophyte composition and richness, and variability in beetle abundance and richness. There was no evidence of negative landscape-level effects of increasing management intensity on bird communities in mature forest stands, suggesting that managed spruce-fir-tolerant hardwood landscapes provide habitat for bird species that need old forest. Richness, diversity, and composition of bryophyte guilds in reference stands in Mount Carleton Provincial Park unmanaged reserve did not differ from stands in the intensively managed District. The landscape focus and stratification into stand type/seral stages were important to understand habitat requirements. Catchments with greater forest management did not show any consistent signs of biological impairment from smaller to larger scales, and all sites had good or very good biological water quality based on the aquatic insect communities. This study helped to evaluate forest management effects on habitat areas, detected with airborne LiDAR data, that need to be addressed to enhance decision making processes.
McAlpine D.F., Huynh H.M., Pavey S.A. (2024). The extinct sea mink, Neogale macrodon: a putative specimen in the New Brunswick Museum, Canada, confirmed as American mink, Neogale vison. Archives of Natural History, 51(1) 171-188.
McKenzie M., Brooks A., Callisto M., Collins A.L., Durkota J.M., Death R.G., Jones J.I., Linares M.S., Matthaei C.D., Monk W.A., Murphy J.F., Wagenhoff A., Wilkes M., Wood P.J., Mathers K.L. (2024). Freshwater invertebrate responses to fine sediment stress: A multi-continent perspective. Global Change Biology, 30(1).

Excessive fine sediment (particles <2 mm) deposition in freshwater systems is a pervasive stressor worldwide. However, understanding of ecological response to excess fine sediment in river systems at the global scale is limited. Here, we aim to address whether there is a consistent response to increasing levels of deposited fine sediment by freshwater invertebrates across multiple geographic regions (Australia, Brazil, New Zealand and the UK). Results indicate ecological responses are not globally consistent and are instead dependent on both the region and the facet of invertebrate diversity considered, that is, taxonomic or functional trait structure. Invertebrate communities of Australia were most sensitive to deposited fine sediment, with the greatest rate of change in communities occurring when fine sediment cover was low (below 25% of the reach). Communities in the UK displayed a greater tolerance with most compositional change occurring between 30% and 60% cover. In both New Zealand and Brazil, which included the most heavily sedimented sampled streams, the communities were more tolerant or demonstrated ambiguous responses, likely due to historic environmental filtering of invertebrate communities. We conclude that ecological responses to fine sediment are not generalisable globally and are dependent on landscape filters with regional context and historic land management playing important roles.
Millar W., Monk W.A., Gray M.A. (2024). Effects of winter water quality conditions on Atlantic Salmon embryo mortality and deformity rates in the Serpentine River (New Brunswick, Canada). Canadian Water Resources Journal, 49(3) 269-281.

In-stream incubation of Atlantic Salmon (Salmo salar) embryos within artificial redds using Jordan/Scotty fish egg incubator boxes is an alternative to traditional hatchery-based incubation methods. Winter water quality conditions, such as temperature and dissolved oxygen vary within natural redds and influence wild embryo development and survival. The differences in landscape characteristics and in-stream habitat features at catchment-, reach-, and site spatial scales were investigated to determine how they influenced water quality conditions within the Serpentine River, New Brunswick. A total of 14,400 hatchery-fertilized salmon embryos were incubated within river substrates from November 2020 to January 2021. The proportion of embryo mortalities within our experiment was high (44.9%), but still within the range observed in the literature from other incubation experiments, and the proportion of embryo deformities between our sites was very low (2.7%). Despite variations in average water temperature, cumulative degree days, and coefficient of variation in dissolved oxygen (DO) concentration, none were statistically significant for explaining embryo mortalities or deformities. Patterns were, however, evident across sites showing trends towards a decrease in mortality with cumulative degree days, and an increase in deformities with greater variation in DO. Improving our knowledge on Atlantic Salmon incubation habitat supports future research and restoration opportunities for adaptation under a changing climate.
Moran P.A., Colgan T.J., Phillips K.P., Coughlan J., McGinnity P., Reed T.E. (2024). Whole-Genome Resequencing Reveals Polygenic Signatures of Directional and Balancing Selection on Alternative Migratory Life Histories. Molecular Ecology, 33(23).

Migration in animals and associated adaptations to contrasting environments are underpinned by complex genetic architecture. Here, we explore the genomic basis of facultative anadromy in brown trout (Salmo trutta), wherein some individuals migrate to sea while others remain resident in natal rivers, to better understand how alternative migratory tactics (AMTs) are maintained evolutionarily. To identify genomic variants associated with AMTs, we sequenced whole genomes for 194 individual trout from five anadromous–resident population pairs, situated above and below waterfalls, in five different Irish rivers. These waterfalls act as natural barriers to upstream migration and hence we predicted that loci underpinning AMTs should be under similar divergent selection across these replicate pairs. A sliding windows based analysis revealed a highly polygenic adaptive divergence between anadromous and resident populations, encompassing 329 differentiated genomic regions. These regions were associated with 292 genes involved in various processes crucial for AMTs, including energy homeostasis, reproduction, osmoregulation, immunity, circadian rhythm and neural function. Furthermore, examining patterns of diversity we were able to link specific genes and biological processes to putative AMT trait classes: migratory-propensity, migratory-lifestyle and residency. Importantly, AMT outlier regions possessed higher genetic diversity than the background genome, particularly in the anadromous group, suggesting balancing selection may play a role in maintaining genetic variation. Overall, the results from this study provide important insights into the genetic architecture of migration and the evolutionary mechanisms shaping genomic diversity within and across populations.
Nakamoto B.J., Forbes G., Bursey C., Cormier J., O’sullivan A., Hayden B. (2024). Niche partitioning of bobcat and Canada lynx near their distribution contact zone. Facets, 9 1-11.

Canada lynx (Lynx canadensis) are keystone predators. However, contact with congenerics, like the bobcat (Lynx rufus), could alter lynx trophic ecology and destabilize boreal food webs. We set out to describe the trophic niches of these species in allopatry and sympatry to assess how resources are partitioned among them and project whether the northward expansion of the bobcats’ range will lead to the displacement of lynx. To quantify the trophic niche, we measured stable isotopes of carbon and nitrogen in muscle and liver samples of bobcat and lynx. Our results indicate that both bobcat and lynx consumed snowshoe hare as their primary prey. However, lynx specialized on hare throughout our study, whereas bobcats foraged as generalists in sympatry with lynx and hare-specialists in allopatry. Our results highlight the contrasting ecological strategies of two congeneric felids and underscore the potential relevance of foraging efficiency in shaping the trophic niche of consumers in competitive environments.
O'Sullivan A.M., Alex K.I. (2024). Establishing present-day Sockeye Salmon (Oncorhynchus nerka|sćwin) spawning capacity in the highly impacted sq,awsitkʷ|Okanagan River to guide population conservation and restoration. River Research and Applications, 40(7) 1195-1204.

The presence of dams on the Columbia River (CR) has reduced Sockeye Salmon (Oncorhynchus nerka|sćwin) numbers to a fraction of their historic numbers. The Syilx Okanagan Nation Alliance (SONA) has led voices of concern regarding the impacts of diminishing Sockeye Salmon numbers on the ecosystem health of the s (Formula presented.) awsitkʷ|Okanagan River (s|OR), a tributary of the CR. In the early 2000s efforts commenced to rehabilitate the s|OR Sockeye population. These efforts have seen the population rise from a running average of 40,000 to 200,000. However, the contemporary spawning capacity of the s|OR is unknown, and this metric is critical to guide the conservation and restoration of this keystone species. We employed a spawning capacity model relating fish length and gravel size to spawning potential. We collected substrate data at 49 sites throughout our 37-km study area, and used fish length and egg numbers from n = 269 Sockeye Salmon to establish s|OR specific fecundity metrics. The model estimated the s|OR has the capacity to support 147,687 (±33,346) Sockeye spawners, in its current condition. Whilst our model has limitations, we suggest a minimum escapement of 147,687 Sockeye spawners ought to be passed to the s|OR per annum. These fish will have broad ecosystem benefits and will be culturally beneficial to SONA peoples. Finally, continued restoration of s|OR habitat should enhance opportunities for Sockeye Salmon to continue their remarkable recovery.
Oyinlola M.A., Khorsandi M., Mayer N.B., Butler N., Van Wert J.C., Eliason E.J., Arsenault R., Brauner C.J., Hinch S.G., St-Hilaire A. (2024). Thermal exposure risk in different life stages of Chinook salmon in the Nechako River system, British Columbia. Climatic Change, 177(12).

Climate change is affecting freshwater systems, leading to increased water temperatures, which is posing a threat to freshwater ecological communities. In the Nechako River, British Columbia, a water management program has been in place since the 1980s to maintain water temperatures at 20 °C during the migration of adult Sockeye salmon. However, the program's effectiveness in mitigating the impacts of climate change on resident species like Chinook salmon's thermal exposure is uncertain. In this study, we utilised the CEQUEAU hydrological model and life stage-specific physiological data to evaluate the consequences of the current program on Chinook salmon's thermal exposure under two contrasting climate change and socio-economic scenarios (SSP2-4.5 and SSP5-8.5). The results indicate that the thermal exposure risk is projected to be above the optimal threshold for parr (intermediate juvenile) and adult life stages under both scenarios relative to the 1980s. Under the SSP5-8.5 scenario, these life stages could experience an increase in thermal exposure ranging from two to five times higher by the 2090s compared to the 1980s. This exposure is projected to occur during the months in which these life stages emerge, including the period when the program is active (July 20th to August 20th). Additionally, our study shows that climate change will result in a substantial rise in cumulative heat degree days, ranging from 1.9 to 5.8 times (2050s) and 2.9 to 12.9 times (2090s) in comparison to the 1980s under SSP5-8.5. Our study highlights the need for a holistic approach to reviewing the current Nechako management plan, ensuring that all species in the Nechako River system are considered especially in the face of climate change.
Rahmati N., St-Hilaire A., Curry A., Rincón E. (2024). Hydro-thermal modelling of the potential impacts of reservoirs on water temperature and incubation time of Atlantic salmon and brook trout in the Tobique River, Canada. River Research and Applications, 40(8) 1484-1496.

Water temperature is recognised as a crucial variable in lotic ecosystems affecting the metabolism of aquatic organisms, with extremely high-temperature events increasing the risk of mortality of various species. Impounding rivers to regulate flow and generate electricity is one of the causes of altered thermal regimes in river systems. This paper presents the results of a study to simulate the impact of reservoirs on downstream temperatures of the Tobique River, New Brunswick, Canada. CEQUEAU, a hydrological and water temperature model, was used to simulate and assess the flow and water temperature of the Tobique River from 1997 to 2020. It was coupled to a statistical model to generate water temperature at different depths in the reservoir. Results show that the CEQUEAU model was successfully calibrated for water temperature with an overall root mean square error of 1.7°C. Based on the results, when water is drawn from the lower parts of the reservoir, the mean water temperature downstream of the dam increases in winter and spring by ~1°C. The results of this paper provide insight into how dams can affect the incubation time of cold-water species in eastern Canada. We calculated the hatching degree days of Atlantic salmon and Brook trout to evaluate the impact of dams on fry emergence. Results indicated that the hatching period of Atlantic salmon and Brook trout downstream of reservoirs may shorten under the influence of dams.
Rideout N.K., Alavi N., Lapen D.R., Hajibabaei M., Mitchell G.W., Monk W.A., Warren M., Wilson S., Wright M.T.G., Baird D.J. (2024). Quality versus quantity: response of riparian bird communities to aquatic insect emergence in agro-ecosystems. Frontiers in Sustainable Food Systems, 8.

In many agricultural landscapes where field drainage is required to enhance crop production, agricultural drainage ditches, and their associated banks and hedgerows can support riparian biodiversity, including bird communities. Against a global background of farmland bird and terrestrial insect decline due to agricultural intensification and extensification, emerging aquatic insects in these aquatic corridors can provide a pulse of energy-rich, nutritionally-important food for birds and other wildlife. In this paper, we quantify the value of drainage ditch habitats in terms of aquatic insect production as a potential food source for riparian foraging birds in a river basin in eastern Canada. Despite being highly managed, agricultural drainage ditches remained extremely productive in terms of emerging biomass of aquatic insects (high quantity), but large-bodied aquatic insects such as mayflies, stoneflies and caddisflies, which are rich in fatty acids, were more common in natural, forested streams and less common in agricultural streams and ditches. The proportion of riparian insectivorous birds was lowest along straight ditches running through agricultural fields and highest among meandering (sinuous) streams in more forested areas, suggesting that agricultural drainage systems may not be able to fully support resource use for foraging predators that rely on emerging aquatic insects. Agricultural producers can improve habitat provisioning for birds on their farms by supporting mosaicked farmscapes through careful conservation and management of ditches and ditch bank vegetation. Establishing larger forest blocks with natural or unmanaged streams between areas of more intense land use can ensure the provisioning of more high quality prey to riparian insectivorous birds, helping to find the balance between agricultural productivity and protection of declining bird populations.
Semeniuk C.A.D., Church K.D.W., Eissenhauer F., Grimm J., Hechler R.M., Howell B.E., Ivanova S.V., Klemet-N'guessan S., Madliger C.L., Reid J., Thompson-Kumar K.A., Arismendi I., Penaluna B.E., Kirkwood A.E., Febria C.M. (2024). On increasing equity and inclusion of early-career professionals for conferences and conference networking in canadian fisheries and aquatic science societies. Canadian Journal of Fisheries and Aquatic Sciences, 81(11) 1606-1620.

As early-career professionals (ECPs) navigate their education and professional development in the aquatic sciences, many seek to build a network to help guide their entrance into the field. As influential organizations, scientific societies play a vital role through hosted conferences, where ECPs can meet and share ideas with others, and find mentors to facilitate their colleagues' journey within the profession. However, not all ECPs are the same, and those from marginalized backgrounds face unique challenges. Here, we provide a perspective on ways scientific societies can ensure all members are provided with equitable opportunity to discover, access, and build career-defining networks at conference events, including the critical role of mentors in navigating obstacles to success. Our recommendations originate from an early-career networking workshop in 2022 at a Canadian fisheries and aquatic sciences conference. The day-long hybrid event comprised interactive activities and discussions on how societies and their conferences can foster and promote inclusive networking for all, including suggestions on maximizing inclusivity for online attendees. This perspective serves as a call to action for scientific societies and senior-career professionals to meaningfully engage with ECPs and marginalized members to promote transformative science.
Shipley O.N., Dabrowski A.J., Bowen G.J., Hayden B., Pauli J.N., Jordan C., Anderson L., Bailey A., Bataille C.P., Cicero C., Close H.G., Cook C., Cook J.A., Desai A.R., Evaristo J., Filley T.R., France C.A.M., Jackson A.L., Kim S.L., Kopf S., Loisel J., Manlick P.J., McFarlin J.M., McMeans B.C., Connell T.C.O., Pilaar Birch S.E., Putman A.L., Semmens B.X., Stantis C., Stricker C.A., Szejner P., Trammell T.L.E., Uhen M.D., Weintraub-Leff S., Wooller M.J., Williams J.W., Yarnes C.T., Vander Zanden H.B., Newsome S.D. (2024). Design, development, and implementation of IsoBank: A centralized repository for isotopic data. Plos One, 19(9 September).

Stable isotope data have made pivotal contributions to nearly every discipline of the physical and natural sciences. As the generation and application of stable isotope data continues to grow exponentially, so does the need for a unifying data repository to improve accessibility and promote collaborative engagement. This paper provides an overview of the design, development, and implementation of IsoBank (www.isobank.org), a community-driven initiative to create an open-access repository for stable isotope data implemented online in 2021. A central goal of IsoBank is to provide a web-accessible database supporting interdisciplinary stable isotope research and educational opportunities. To achieve this goal, we convened a multi-disciplinary group of over 40 analytical experts, stable isotope researchers, database managers, and web developers to collaboratively design the database. This paper outlines the main features of IsoBank and provides a focused description of the core metadata structure. We present plans for future database and tool development and engagement across the scientific community. These efforts will help facilitate interdisciplinary collaboration among the many users of stable isotopic data while also offering useful data resources and standardization of metadata reporting across eco-geoinformatics landscapes.
Simaika J.P., Stribling J., Lento J., Bruder A., Poikane S., Moretti M.S., Rivers-Moore N., Meissner K., Macadam C.R. (2024). Towards harmonized standards for freshwater biodiversity monitoring and biological assessment using benthic macroinvertebrates. Science of the Total Environment, 918.

Monitoring programs at sub-national and national scales lack coordination, harmonization, and systematic review and analysis at continental and global scales, and thus fail to adequately assess and evaluate drivers of biodiversity and ecosystem degradation and loss at large spatial scales. Here we review the state of the art, gaps and challenges in the freshwater assessment programs for both the biological condition (bioassessment) and biodiversity monitoring of freshwater ecosystems using the benthic macroinvertebrate community. To assess the existence of nationally- and regionally- (sub-nationally-) accepted freshwater benthic macroinvertebrate protocols that are put in practice/used in each country, we conducted a survey from November 2022 to May 2023. Responses from 110 respondents based in 67 countries were received. Although the responses varied in their consistency, the responses clearly demonstrated a lack of biodiversity monitoring being done at both national and sub-national levels for lakes, rivers and artificial waterbodies. Programs for bioassessment were more widespread, and in some cases even harmonized among several countries. We identified 20 gaps and challenges, which we classed into five major categories, these being (a) field sampling, (b) sample processing and identification, (c) metrics and indices, (d) assessment, and (e) other gaps and challenges. Above all, we identify the lack of harmonization as one of the most important gaps, hindering efficient collaboration and communication. We identify the IUCN SSC Global Freshwater Macroinvertebrate Sampling Protocols Task Force (GLOSAM) as a means to address the lack of globally-harmonized biodiversity monitoring and biological assessment protocols.
Smith C., Phillips K., Roth D., Comeau A., Byrne T., L'Orsa S., Van Der Meer J., Linnansaari T., Jonsen I., Webber D., Fraser T., Smedbol S., Whoriskey F., Quirion J. (2024). Improving Fish Tracking Over Large Scale Oceans with Autonomous Marine Vehicles and a New Directional Acoustic Telemetry Receiver. Oceans Conference Record IEEE.

The use of autonomous marine vehicles equipped with onboard acoustic telemetry receivers has become increasingly popular for tracking aquatic animals over large scale oceans [1]. In this paper we present the results from at-sea trials of Innovasea's prototype advanced mobile receiver installed on both a Wave Glider and a Slocum glider and deployed in the Gulf of St. Lawrence. In at-sea range testing performed with both glider types, the redesigned receiver improved detection range by an average of 2.5 times that of a conventional receiver deployed in tandem as a baseline and made an average of 6.9 times more detections than the conventional receiver. Furthermore, during the at-sea mission deployment on the Wave Glider, the mobile receiver received 7.2 times more detections than the co-deployed conventional receiver. We demonstrated that the new mobile receiver enabled a significant increase in range relative to previous state-of-the-art acoustic telemetry technology, which ultimately resulted in an increased probability of detecting tagged animals at ocean-scale. The receiver should greatly increase the capability of autonomous vehicles carrying it to detect acoustically tagged animals in the vehicle's operation area.
Soto D.X., Dadswell M.J., Samways K.M., Cunjak R.A., Mcdermott T. (2024). Climate-Driven Oceanic Range Shift of Saint John River Atlantic Salmon Revealed by Multidecadal Stable Isotope Trends. Northeastern Naturalist, 30(4) 521-539.

Marine migration patterns of unique or regional stocks of Salmo salar (Atlantic Salmon) are poorly known. Atlantic Salmon (AS) utilizing the North Atlantic Subpolar Gyre (NASpG) for foraging and growth consist of stocks from the United States (41°N) to Greenland (64°N) in the western Atlantic and from Spain (41°N) to Norway (70°N) in the eastern Atlantic. Wide latitudinal range and unique riverine characteristics probably result in stocks selecting differing suites of marine sea-surface temperatures (SST) within the species' known selection range (i.e., their Grinnellian niche). We analyzed trends in stable carbon isotope (δ13C) composition from archived scale tissues in relation to long-term variation of SST for the North Atlantic Ocean to identify marine feeding regions used by adult AS successfully returning to the Saint John River, Canada, during the period 1982-2011. Marine foraging regions were determined for individuals that spent 1 winter (1SW) or multiple winters (MSW) at sea. During 1982-1991 and 1992-2001, AS which successfully returned, exploited more southern regions of the NASpG, while returning adults from 2002-2011 exploited more northern regions. Historically presumed marine feeding regions, which were identified by the isotopic model as probable during 1982-2001, have experienced a warming trend, and data suggests that AS returning to the Saint John River have been migrating further north in the NASpG in response to recent global climate change. The northward range shift as the North Atlantic warmed is consistent with recent biogeographical changes found among other marine species also following their Grinnellian niche.
Waddell J.M., Pater C.C., Coffin M.R.S., Gilmour R.F., Courtenay S.C., van den Heuvel M.R. (2024). Spatial and Temporal Variation of C, N, and S Stable Isotopes and Seagrass Coverage Related to Eutrophication Stress in Zostera marina. Coasts, 4(2) 419-436.

Zostera marina is an ecologically valuable species that has been declining due to anthropogenic environmental stressors. In this study, spatial and temporal indicators of eelgrass stress, such as coverage and biomass, were compared with the isotopic composition of C, N, and S to understand the mechanism(s) of plant stress. Eelgrass samples were collected in June, July, and August of 2020 at five stations along an estuary spatial gradient in the southern Gulf of St. Lawrence to measure above- and below-ground biomass and tissue isotopes in eelgrass leaves and roots/rhizomes. Eelgrass biomass was lowest at the innermost sampling station, which coincided with eutrophication-induced hypoxia relative to outer sampling stations. δ13C levels at the upstream station were depleted compared to downstream stations. Comparatively, δ15N and δ34S findings were not correlated with plant biomass. Thus, sulfide intrusion was not a major stressor for eelgrass in this estuary. Between the years 2014 and 2020, eelgrass coverage was found to have increased, which coincided with high and low recorded external nutrient loads from the Wheatley River, respectively. Ultimately, these findings indicate that isotopic composition and biomass can be useful in assessing the health of eelgrass in temperate estuaries.
Wegscheider B., Linnansaari T., Ndong M., Haralampides K., St-Hilaire A., Schneider M., Curry R.A. (2024). Fish habitat modelling in large rivers: combining expert opinion and hydrodynamic modelling to inform river management. Journal of Ecohydraulics, 9(1) 68-86.

Physical habitat models represent a widely used tool in river management, yet, there is a growing consensus—particularly for large rivers—that fundamental principles have limits, and it is evident that improved methodologies for assessment and design are needed. Here, we suggest a framework that takes steps towards resolving some of these issues, using changes of fish habitat in a large, regulated river as a case study. First, we propose using hydrodynamic modelling in combination with a fuzzy rule-based classification as a tool to delineate and quantify meso-scale fish habitat. Variability in spatial and temporal extent of mesohabitats can be modelled across a range of flows and under non-wadable conditions when standard mesohabitat surveys become largely unfeasible. Second, research effort and empirical data on habitat use and preference of fishes is typically focused on a small group of species and limited for many imperilled or elusive taxa; we suggest using expert knowledge to expand beyond one or a few species to build the biological models for a community-level assessment until empirical data becomes available. Third, sources of uncertainty that are linked to both fundamental elements of habitat models, namely the biological and hydrodynamic components, need to be quantified and reported in modelling outcomes. The steps described in our modelling framework represent key tools for river managers charged with developing environmental flows guidelines in large, regulated rivers.
Andrews S.N., Roth D.H., Kidd K.A., Pavey S.A., Reinhart B., Hayden B., Dadswell M.J., Linnansaari T., Curry R.A. (2023). Updated Data on Mercury and DDE in Striped Bass (Morone saxatilis) in Relation to Consumption Advisories for the Saint John River, New Brunswick, Canada. Northeastern Naturalist, 30(2) 226-243.

The Morone saxatilis (Striped Bass) population in Saint John River (SJR), NB, Canada, collapsed in the 1970s concurrent with dam construction, overfishing, and chemical pollution that may have impeded reproduction. To assess whether a chemical threat to Striped Bass or a health threat to fish consumers persists, we examined DDT and total mercury (THg) levels from 29 Striped Bass captured in the SJR including 16 genomically typed as SJR natives. DDT and DDD in female gonads were below detectable levels, and DDE averaged 0.08 ± 0.09 mg/kg wet weight (ww) but was considered too low to threaten reproduction. Total mercury in muscle and liver varied from 0.68 to 2.10 mg/kg and 0.35 to 3.27 mg/kg ww, respectively and exceeded Health Canada guidelines in all samples. We suggest regulators should update advisories for consumption including actively informing the public of the risk.
Arsenault M., O’Sullivan A.M., Ogilvie J., Gillis C.A., Linnansaari T., Curry R.A. (2023). Remote sensing framework details riverscape connectivity fragmentation and fish passability in a forested landscape. Journal of Ecohydraulics, 8(2) 121-132.

Fragmentation of stream networks from anthropogenic structures such as road culverts can affect the health of a catchment by negatively affecting the ecosystem’s biota, their movements, abundance, and species richness. We present a framework using publicly available LiDAR and orthophotography to locate and identify road crossings, i.e. the most prolific of barriers in forested landscapes, and evaluate fragmentation and passability at the landscape scale. Coupling the LiDAR stream network and private road network in the 3,223km2 study area, we identified 1,052 stream crossings of which, 32% were culverts and 12% of the total stream network was potentially inaccessible due to these culverts. We correctly identified the type of stream-road crossings at >90% of any stream order and at 100% at Orders >2. The 10 culverts restricting the most stream kilometers, restricted >34% of the potential stream habitats for four species of fish, a result that provides the resource management with a first assessment for effective improvement of connectivity across this landscape. With this framework, managers equipped with appropriate imagery can create a stream crossing database with minimal funding, create an inventory of instream barriers, and prioritize removals at a landscape-scale, thus providing an effective assessment and decision-making tool for their habitat restoration efforts.
Barry T., Christensen T., Behe C., Coon C., Culp J.M., Fletcher S., Gill M., Goedkoop W., Hindrum R., Jacobson C., Jones T., Lárusson K.F., Lento J., Marissink M., McLennan D., Price C., Rönkä M., Svoboda M., Thaulow I., Taylor J., Wegeberg S., Schmidt N.M., Smith R. (2023). Development of a multi-scale monitoring programme: approaches for the Arctic and lessons learned from the Circumpolar Biodiversity Monitoring Programme 2002-2022. Frontiers in Conservation Science, 4.

The Arctic Council working group, the Conservation of Arctic Flora and Fauna (CAFF) established the Circumpolar Biodiversity Monitoring Programme (CBMP), an international network of scientists, governments, Indigenous organizations, and conservation groups working to harmonize and integrate efforts to extend and develop monitoring and assessment of the Arctic’s biodiversity. Its relevance stretches beyond the Arctic to a broad range of regional and global initiatives and agreements. This paper describes the process and approach taken in the last two decades to develop and implement the CBMP. It documents challenges encountered, lessons learnt, and solutions, and considers how it has been a model for national, regional, and global monitoring programmes; explores how it has impacted Arctic biodiversity monitoring, assessment, and policy and concludes with observations on key issues and next steps. The following are overarching prerequisites identified in the implementation of the CBMP: effective coordination, sufficient and sustained funding, improved standards and protocols, co-production of knowledge and equitable involvement of IK approaches, data management to facilitating regional analysis and comparisons, communication and outreach to raising awareness and engagement in the programme, ensuring resources to engage in international fora to ensuring programme implementation.
Barry T., Christensen T., Behe C., Coon C., Culp J.M., Vongraven D., Fletcher S., Gill M., Goedkoop W., Hindrum R., Jacobson C., Jones T., Lárusson K.F., Lento J., Marissink M., McLennan D., Price C., Rönkä M., Svoboda M., Thaulow I., Taylor J., Wegeberg S., Schmidt N.M., Smith R., Petersen Æ. (2023). Corrigendum: Development of a multi-scale monitoring programme: approaches for the Arctic and lessons learned from the Circumpolar Biodiversity Monitoring Programme 2002-2022 (Frontiers in Conservation Science, (2023), 4, (1220521), 10.3389/fcosc.2023.1220521). Frontiers in Conservation Science, 4.

In the published article, there was an error in the author list, and authors Dag Vongraven and Ævar Petersen were erroneously excluded. The corrected author list appears below. [Tom Barry1,2*, Tom Christensen3, Carolina Behe4, Catherine Coon5, Joseph M. Culp6, Dag Vongraven7, Sierra Fletcher8, Micheal Gill9, Willem Goedkoop10, Reidar Hindrum11, Cynthia Jacobson12, Tahzay Jones13, Kári Fannar Lárusson14, Jennifer Lento15, Mark Marissink16, Donald McLennan17, Courtney Price14, Mia Rönkä18, Michael Svoboda19, Inge Thaulow20, Jason Taylor21, Susse Wegeberg3, Niels Martin Schmidt3, Risa Smith22 Ævar Petersen23], 1Faculty of Humanities and Social Sciences, University of Akureyri, Akureyri, Iceland 2Stefansson Arctic Institute, Akureyri, Iceland 3Department of Ecoscience, Aarhus University, Roskilde, Denmark 4Independent researcher, Seattle, Washington, DC, United States 5Bureau of Ocean Energy Management - Alaska Regional Office, Department of the Interior Region, Anchorage, AK, United States 6Department of Biology, and Geography and Environmental Studies, Wilfrid Laurier University, Waterloo, ON, Canada 7 Norwegian Polar Institute, Tromso, Norway 8Nuka Research and Planning Group, Seldovia, AK, United States 9Biodiversity Indicators Program, NatureServe, Arlington, VA, United States 10Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden 11Independent researcher, Trondheim, Norway 12Innovative Outcomes, Carbondale, CO, United States 13National Park Service, Anchorage, AK, United States 14Conservation of Arctic Flora and Fauna (CAFF), Akureyri, Iceland 15Canadian Rivers Institute and Department of Biology, University of New Brunswick, Fredericton, NB, Canada 16Swedish Species Information Centre, The Swedish University of Agricultural Sciences (SLU) Artdatabanken, Uppsala, Sweden 17COENOSIS, Martins Brook, NS, Canada 18Biodiversity Unit, Faculty of Science, University of Turku, Turku, Finland 19Environment and Climate Change, Whitehorse, YT, Canada 20Enviromental Affairs, Government of Greenland, Greenland Representation, Copenhagen, Denmark 21Aldo Leopold Wilderness Research Institute, University of Montana, Missoula, MT, United States 22The International Union for Nature Conservation (IUCN), World Commission on Protected Areas, Gland, Switzerland 23 Independent, Researcher, Reykjavík, Iceland The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated.
Bellamy J., Mullin D., Nakamoto B., Hayden B., Edge C. (2023). A Test of Intersexual Trophic Niche Partitioning within a Population of Wood Turtles (Glyptemys insculpta). Journal of Herpetology, 57(4) 428-436.

The Wood Turtle (Glyptemys insculpta) is a semiaquatic turtle species that has been known to exhibit intersexual variation in habitat use during summer. Males often remain near watercourses in riparian areas, whereas females tend to move upland and spend more time in terrestrial environments postnesting. Dietary niche partitioning is one of several hypotheses proposed to explain why females leave aquatic habitats in search of terrestrial food resources. The presence of dietary niche partitioning within a population of Wood Turtles in central New Brunswick, Canada, was assessed using stable isotope analysis. Male and female Wood Turtles were sampled in spring and summer 2021. Potential invertebrate foods were sampled and grouped into pond, stream, and terrestrial food sources. Using stable carbon (d13C) and nitrogen (d15N) isotopic ratios of extracted red blood corpuscle and blood plasma, the resource use and isotopic niche widths of individuals within the population were compared between seasons and sexes. Results indicated no significant differences in d13C and d15N values, dietary contributions, or isotopic niche widths between spring and summer samples or between males and females. We determined that terrestrial invertebrates were an important food source (>72% mean diet contribution) across the entire sampled population, with invasive Arion slug species constituting a large portion of turtle diets. Our findings indicate that dietary niche partitioning is most likely not the explanation for sexual variation in habitat use by Wood Turtles.
Bush A., Compson Z., Rideout N.K., Levenstein B., Kattilakoski M., Hajibabaei M., Monk W.A., Wright M.T.G., Baird D.J. (2023). Replicate DNA metabarcoding can discriminate seasonal and spatial abundance shifts in river macroinvertebrate assemblages. Molecular Ecology Resources, 23(6) 1275-1287.

The delivery of consistent and accurate fine-resolution data on biodiversity using metabarcoding promises to improve environmental assessment and research. Whilst this approach is a substantial improvement upon traditional techniques, critics note that metabarcoding data are suitable for establishing taxon occurrence, but not abundance. We propose a novel hierarchical approach to recovering abundance information from metabarcoding, and demonstrate this technique using benthic macroinvertebrates. To sample a range of abundance structures without introducing additional changes in composition, we combined seasonal surveys with fish-exclusion experiments at Catamaran Brook in northern New Brunswick, Canada. Five monthly surveys collected 31 benthic samples for DNA metabarcoding divided between caged and control treatments. A further six samples per survey were processed using traditional morphological identification for comparison. By estimating the probability of detecting a single individual, multispecies abundance models infer changes in abundance based on changes in detection frequency. Using replicate detections of 184 genera (and 318 species) from metabarcoding samples, our analysis identified changes in abundance arising from both seasonal dynamics and the exclusion of fish predators. Counts obtained from morphological samples were highly variable, a feature that limited the opportunity for more robust comparison, and emphasizing the difficulty standard methods also face to detect changes in abundance. Our approach is the first to demonstrate how quantitative estimates of abundance can be made using metabarcoding, both among species within sites as well as within species among sites. Many samples are required to capture true abundance patterns, particularly in streams where counts are highly variable, but few studies can afford to process entire samples. Our approach allows study of responses across whole communities, and at fine taxonomic resolution. We discuss how ecological studies can use additional sampling to capture changes in abundance at fine resolution, and how this can complement broad-scale biomonitoring using DNA metabarcoding.
Corey E., Linnansaari T., Cunjak R.A. (2023). High temperature events shape the broadscale distribution of juvenile Atlantic salmon (Salmo salar). Freshwater Biology, 68(3) 534-545.

Summer water temperatures within many temperate rivers regularly surpass the incipient lethal temperature for juvenile Atlantic salmon (c. 27°C), causing widescale abandonment of territory in favour of areas of cooler water (thermal refuges). This study aims to highlight the influence of thermal refuges on river-scale abundance patterns. That is, do salmon parr adjust their distribution over time according to proximity to thermal refuges? Twelve reaches (seven reference: five refuge) were chosen along a 17-km section of the Little Southwest Miramichi River in Canada. Reaches were sampled throughout the 2011 and 2012 summer periods; high temperature events were recorded during summer 2012 but not summer 2011. Multivariate principal component analyses indicated no discernible difference in habitat characteristics between the reach-types under normal thermal conditions. However, reaches containing a thermal refuge had a significant increase in relative abundance of parr immediately after a series of high temperature events (water temperature >26°C) in 2012 (p = 0.034). This increase in relative abundance in refuge reaches was not present during the summer of 2011 when no temperature events occurred (p = 0.088), prior to the event of 2012 (p = 0.999), or at the late autumn survey following the 2012 event (p = 0.999). Difference in temperature between refuge and mainstem reaches significantly influenced the suitability of a tributary as a thermal refuge habitat (R2 = 0.84), with preference shown for cooler refuges. River-wide thermal heterogeneity therefore plays a critical role in survival of juvenile salmon throughout summer months and is likely to become necessary under future climate change scenarios.
Cormier J.M., Coffin M.R.S., Pater C.C., Knysh K.M., Gilmour R.F., Guyondet T., Courtenay S.C., van den Heuvel M.R. (2023). Internal nutrients dominate load and drive hypoxia in a eutrophic estuary. Environmental Monitoring and Assessment, 195(10).

The hypothesis that local hypoxia and chlorophyll concentration are spatially tethered to local, sediment-driven nutrient release was examined in a small, nutrient-impacted estuary in the Southern Gulf of St. Lawrence, Canada. Sediment reactor core samples were taken at 10 locations between 0.25 and 100% of the estuary area in spring and fall (2019) and used to estimate nitrogen and phosphate flux. Sediment organic matter, carbonate, percent nitrogen, percent carbon, δ13C, and δ15N were measured from the reactor core stations. Oxygen was recorded continually using oxygen loggers while chlorophyll and salinity were measured bi-weekly. A hydrodynamic model was used to determine water renewal time at each station. The most severe eutrophication effects were in the upper one-fifth of the estuary. There were strong local relationships between sediment biogeochemistry, hypoxia, and chlorophyll metrics but not with water renewal time. Internal nutrient loading represented 65% and 69% of total N loading, and 98% and 89% of total P loading to the estuary in June and September, respectively. Sediment nitrogen flux was highly predictable from a range of local sediment variables that reflect either nutrient content, or organic carbon enrichment in general. Percent nitrogen and percent carbon were highly correlated but sediment P flux was poorly predicted from sediment parameters examined. The highest correlations were with percent nitrogen and percent carbon. These results indicate that incorporating internal nutrient loading into nutrient monitoring programs is a critical next step to improve predictive capacity for eutrophication endpoints and to mitigate nutrient effects.
Culp J.M., Luiker E.A., Brua R.B., Musetta-Lambert J.L., Halliwell D.B., Lento J. (2023). Mackenzie River Basin. Rivers of North America Second Edition 746-792.

The Mackenzie River chapter provides important reference information on the geology, hydrology, climate, ecology, human impacts, special features, and research and management needs for seven tributaries of the Mackenzie Basin. These tributary rivers, namely the Smoky, Steepbank, Hay, South Nahanni, Yellowknife, Arctic Red and Peel, are within the Lower and Upper Mackenzie freshwater ecoregions, include 10 physiographic provinces and Tundra, Taiga, Northwestern Forested Mountains, and Northern Forests Level I terrestrial ecoregions. Most of these basins were covered under the enormous, continental Laurentide Ice Sheet. Because of this glacial history, as well as the very harsh and cold climate where rivers are ice-covered for more than 6months, riverine biodiversity is relatively low. The chapter provides a current review of the available literature on these basins and provides key recommendations for future research and management to protect and conserve these unique ecosystems.
Curry R.A., O’Sullivan A.M. (2023). A waterscape framework for the spawning and incubation habitats of brook trout (Salvelinus fontinalis). Environmental Biology of Fishes, 106(5) 969-978.

The brook char or brook trout, Salvelinus fontinalis, are widely distributed across North America including an expanse of introductions for recreational fishing. They are a popular recreational species and heavily managed in many jurisdictions. Their spawning and incubation habitats are diverse: they use lakes and streams in locations with up- or downwelling water and with or without groundwater present. Their wide distribution across many landscapes and use of a diversity of physical features illustrates the complexity that has hampered a clear, simple definition of the brook trout’s spawning and incubation tactics and habitats. As an alternative, we present a framework that defines habitats based on their waterscape setting, that is, the flowing water on and under the Earth’s surface. The framework classifies habitats by geologies and geomorphologies that (1) create discharging groundwater to waterbodies as either discrete or diffuse upwellings, and (2) in settings without distinct groundwater but with hydraulic conditions that generate flow through incubation environments. It is a synthesis that captures the complexity of behaviors and habitats in a broad definition that can continue to be developed, i.e., it is a meaningful hypothesis with testable predictions, and concurrently creates an effective conservation and management tool that can be used across multiple scales, from landscapes to riverscapes to reaches. Graphical Abstract: Brook trout select spawning and incubation habitats in rivers and lakes, in locations with and without discharging groundwater. A habitat framework classifies selected locations by geologies and geomorphologies that create discharging groundwater to waterbodies as either discrete or diffuse upwellings (A) and (B) and in settings without distinct groundwater but with hydraulic conditions that generate flow through incubation environments (C). [Figure not available: see fulltext.]
de Meo I., Østbye K., Kahilainen K.K., Hayden B., Magnus M., Poléo A.B.S. (2023). Resource use of crucian carp along a lake productivity gradient is related to body size, predation risk, and resource competition. Ecology of Freshwater Fish, 32(1) 10-22.

Generalist fish species can feed on a wide resource spectrum and across trophic levels depending on resource availability and trophic interactions. Crucian carp (Carassius carassius) represents a good candidate species to investigate variation in the trophic ecology of generalist fish as it can be found in highly variable fish communities and its resource use is well documented. In this study, we explored the trophic ecology of crucian carp at the individual and population levels using stable isotope and gut content analysis. We tested if trophic resource use varied according to lake productivity, predation risk, intra- and interspecific competition, or individual fish size. We found that crucian carp resource preference was highly variable among and within lakes. In predator-free lakes, small crucian carp occurred in high densities, showed increased interindividual specialisation, and relied mainly on pelagic zooplankton. In presence of predators, large crucian carp occurred in low densities and included greater proportions of benthic macroinvertebrates in their diet. This shift in resource use was further favoured in productive, shallow lakes where littoral prey were probably abundant. Resource partitioning was an important factor determining crucian carp niche use, as fish had higher trophic position in absence of other cyprinids. Crucian carp showed highly dynamic resource use and food preferences in response to variable environmental conditions. Overlooking complex diet preferences of generalist fish may lead to an oversimplification of freshwater community dynamics.
Devito K.J., O’Sullivan A.M., Peters D.L., Hokanson K.J., Kettridge N., Mendoza C.A. (2023). Runoff Threshold Responses in Continental Boreal Catchments: Nexus of Subhumid Climate, Low-Relief, Surficial Geology, and Land Cover. Water Resources Research, 59(11).

We examined annual runoff from 20 meso-scale catchments over 25 years, to elucidate how interactions between physiography and long-term weather patterns influence the magnitude of spatial–temporal thresholds in annual runoff responses in water-limited, low-relief, glaciated continental Boreal landscapes. Annual runoff ranged over 2 orders of magnitude (<3 to >300 mm) among catchments receiving similar annual precipitation. Threshold relationships were observed with cumulative regional moisture deficits that reflected spatial–temporal differences in effective storage and antecedent moisture among catchments with differing portions of glacial-deposit and land-cover types. The importance of the glacial-deposit texture and forest-peatland cover on runoff behavior among catchments varied with weather patterns and catchment antecedent moisture states. Dry states yielded low annual runoff that ranged by 2 orders of magnitude (0–80 mm), with higher values in catchments with predominantly coarse-textured deposits. During near normal antecedent moisture, annual runoff remained low (<10 mm) in catchments associated with fine-textured, hummocky landforms and deciduous forests. Annual runoff >10 mm was observed only in catchments with extensive peatlands. Infrequent wet states resulted in increased runoff in all catchments; however, ranges in maximum runoff were associated with heterogeneity in catchment landforms and land covers. Integrating cumulative precipitation with the proportion of glacial-deposit and land-cover types within catchments can (a) represent water cycling and regional sink-source dynamics controlling runoff and (b) provide an effective management framework for predicting climate and land use impacts on regional runoff in water-limited, low-relief, glaciated landscapes such as the Boreal Plain.
Dolson R., Curry R.A., Harrison P.M., Yamazaki G., Linnansaari T., MacNevin M., Noakes D.L.G. (2023). A framework for functional fish passage decision-making. Environmental Biology of Fishes, 106(5) 1135-1147.

There are millions of built structures existing today in thousands of rivers. While these structures provide important services to society, e.g., power, transportation, and water for drinking and irrigation, the structures are not without consequences for provisioning the whole of a rivers’ goods and services. A major issue for these structures is their creation of barriers for fish passage. While most provide some form of fish passage, the solutions are restricted to economically important species and barriers in isolation. We are slowly accepting that there are broader ecological consequences of barriers and more holistic approaches are emerging for the planning and managing created barriers in river ecosystems. We develop a holistic and adaptive, fish passage decision-making framework that uses key science questions to inform and support the development of successful fish passage management plans for a barrier and the river ecosystem. The framework builds from the biological needs of fish for functional passage, which can then support the complex social and economic considerations that are entwined in a comprehensive management plan. The framework uses a multi-species, ecosystem focus, embraces uncertainty, and embraces an adaptive approach. We recognize this approach advocates for a paradigm shift in fish passage decision making and management, but cracks in the old paradigm are emerging, and it is imperative that operators, regulators, rightsholders, stakeholders, and science keep working together to build this new paradigm that embraces a whole ecosystem approach.
Dubos V., St-Hilaire A., Bergeron N.E. (2023). Fuzzy logic modelling of anadromous Arctic char spawning habitat from Nunavik Inuit knowledge. Ecological Modelling, 477.

Anadromous Arctic char (Salvelinus alpinus, Iqaluppik) and their freshwater habitats are vulnerable to the effects of climate change. Spawning habitats are critical to ensure the propagation of populations and the fisheries they support. However, detailed descriptions for river systems in the Canadian Arctic are limited, especially in the Nunavik region. As Arctic char is a traditionally important species for culture and subsistence of Inuit, some harvesters have a deep knowledge pertaining to habitat use, including optimal habitat conditions for spawning. Interviews of Inuit knowledge holders on Arctic char, were conducted in three communities of Nunavik, Canada: Kangiqsualujjuaq, Tasiujaq and Kangirsuk. From the knowledge of Inuit experts, the most suitable spawning habitats were located in rivers, at depths between 0.6 m and 1.5 m with velocities > 0.1 m/s. A large range of riverbed substrate was deemed suitable as long as the smaller substrate size class showed some presence of gravel or coarse sand, depending on the local geomorphology. We used fuzzy logic to code natural language description provided by Inuit experts into a numerical value representing the Habitat Suitability Index for spawning sites. The model was able to predict the spawning habitat suitability or unsuitability of 14 out of 15 sites, given values of depth, velocity, and substrate. The methodology presented is well-suited to build quantitative model based on the description of local observations and could be applied for other animal or plant species for which local and/or traditional knowledge exists.
Eissenhauer F., Grunicke F., Wagner A., Linke D., Kneis D., Weitere M., Berendonk T.U. (2023). Active movement to coarse grained sediments by globally endangered freshwater pearl mussels (Margaritifera margaritifera). Hydrobiologia, 850(4) 985-999.

The freshwater pearl mussel Margaritifera margaritifera is an endangered bivalve which is usually regarded as sedentary, although individual movement has been observed both vertically and horizontally. Little is known about the causes and rates of mussel movement. The objective of this study was to test the effect of microhabitat characteristics on the horizontal movement distance and rates of freshwater pearl mussels. A total of 120 mussels (length range 40–59 mm) were marked individually with passive integrated transponder tags, placed in stream microhabitats differing in their sediment composition and monitored biweekly over a period of 10 weeks. Mussels situated in sand-dominated habitats had a significantly higher mean movement rate (3.2 ± 4.2 cm/day, mean ± SD) than mussels situated in gravel-dominated (1.9 ± 2.7 cm/day) or stone-dominated habitats (1.8 ± 3.2 cm/day). The direction of the movements appeared random; however, an emigration from sandy habitats was observed, probably to avoid dislodgment from these hydraulically unstable habitats. This study demonstrates that freshwater pearl mussels can actively emigrate from unsuitable microhabitats. Once suitable streams with respect to physical, chemical, and biological quality were identified, it is therefore only necessary to identify suitable mesohabitats (area of 10–30 m2) when reintroducing or relocating mussels.
Feio M.J., Hughes R.M., Serra S.R.Q., Nichols S.J., Kefford B.J., Lintermans M., Robinson W., Odume O.N., Callisto M., Macedo D.R., Harding J.S., Yates A.G., Monk W., Nakamura K., Mori T., Sueyoshi M., Mercado-Silva N., Chen K., Baek M.J., Bae Y.J., Tachamo-Shah R.D., Shah D.N., Campbell I., Moya N., Arimoro F.O., Keke U.N., Martins R.T., Alves C.B.M., Pompeu P.S., Sharma S. (2023). Fish and macroinvertebrate assemblages reveal extensive degradation of the world's rivers. Global Change Biology, 29(2) 355-374.

Rivers suffer from multiple stressors acting simultaneously on their biota, but the consequences are poorly quantified at the global scale. We evaluated the biological condition of rivers globally, including the largest proportion of countries from the Global South published to date. We gathered macroinvertebrate- and fish-based assessments from 72,275 and 37,676 sites, respectively, from 64 study regions across six continents and 45 nations. Because assessments were based on differing methods, different systems were consolidated into a 3-class system: Good, Impaired, or Severely Impaired, following common guidelines. The proportion of sites in each class by study area was calculated and each region was assigned a Köppen-Geiger climate type, Human Footprint score (addressing landscape alterations), Human Development Index (HDI) score (addressing social welfare), % rivers with good ambient water quality, % protected freshwater key biodiversity areas; and % of forest area net change rate. We found that 50% of macroinvertebrate sites and 42% of fish sites were in Good condition, whereas 21% and 29% were Severely Impaired, respectively. The poorest biological conditions occurred in Arid and Equatorial climates and the best conditions occurred in Snow climates. Severely Impaired conditions were associated (Pearson correlation coefficient) with higher HDI scores, poorer physico-chemical water quality, and lower proportions of protected freshwater areas. Good biological conditions were associated with good water quality and increased forested areas. It is essential to implement statutory bioassessment programs in Asian, African, and South American countries, and continue them in Oceania, Europe, and North America. There is a need to invest in assessments based on fish, as there is less information globally and fish were strong indicators of degradation. Our study highlights a need to increase the extent and number of protected river catchments, preserve and restore natural forested areas in the catchments, treat wastewater discharges, and improve river connectivity.
Ferchichi H., St-Hilaire A. (2023). Are temperature time series measured at hydrometric stations representative of the river’s thermal regime? Canadian Water Resources Journal, 48(2) 149-166.

River temperature is a key variable for water quality assessment. It can alter different chemical water properties. Indeed, it is considered as determining criterion in the adequacy of cold water fish habitat, and the overall health of the river ecosystem and aquatic biota. Consequently, monitoring this variable and understanding the river thermal variation are highly important. Temperature monitoring along the rivers is often done by deploying autonomous temperature loggers. However, recently, temperature sensors were installed at hydrometric stations in conjunction with water level gauges for monitoring the river temperature, thereby providing an opportunity to expand the temperature network across the region and eventually, the country. In this study, a comparative analysis was conducted to find if the temperatures at the hydrometric station are representative of the river thermal variation upstream and downstream of that location. This comparative analysis was completed using a number of different statistical tools: entropy analysis, Gaussian function fit, and thermal sensitivity analysis. These statistical analyses confirm that temperature loggers that are collocated with the level gauges at hydrometric stations are generally representative of the thermal variation of the river main stem over a distance of a few tens of kilometres. However, the thermal variation observed in temperature loggers located at distances of the order of 100 km or in a different river reach than the hydrometric station, is different from that of the temperature logger located at the hydrometric station.
Ferchichi H., St-Hilaire A., Berthot L., Caissie D. (2023). Augmenting environmental flow information with water temperature: case study in Eastern Canada. Canadian Water Resources Journal, 48(2) 111-131.

The increasing global water demand and climate change put freshwater resources and riverine ecosystems at risk of increasing scarcity and conflict in water usage. Stream biota may be confronted with increasing stressful aquatic habitat conditions due in part to increasing water temperatures. In response to these issues, environmental flows play a crucial role in flow assessment, water resource management and the protection of aquatic biota. Environmental flows (eflows), also known as instream flow requirements, refer to the amount of water needed in rivers to maintain a balanced aquatic ecosystem. Recently, the inclusion of river temperature in the assessment of eflows has raised interest, especially in the context of climate change and dam operations, which are altering the river thermal regimes and affecting aquatic habitat. This study focuses on hydrological metrics that can be used to prescribe eflows in Atlantic Canada and Quebec (Eastern Canada). Eflow analyses were conducted jointly with the analyses of river temperatures at 61 sites. The results show that summer environmental flow metrics can be associated with relatively high water temperatures during a period when water withdrawals may be important. Classifying rivers according to their thermal regime during summer low flow periods prior to prescribing an eflow target is therefore recommended.
Forbes R., Nakamoto B., Lysiak N., Wimmer T., Hayden B. (2023). Stable isotope analysis of baleen from North Atlantic right whales Eubalaena glacialis reflects distribution shift to the Gulf of St. Lawrence. Marine Ecology Progress Series, 722 177-193.

Seasonal migration of the Critically Endangered North Atlantic right whale Eubalaena glacialis along the eastern seaboard of North America has been well studied. Since 2010, however, right whales have shifted their summer foraging location from the Bay of Fundy to the Gulf of St. Lawrence. There is a need to better understand right whale distribution to manage anthropogenic activities and mitigate impacts on whales. Stable isotope ratios of baleen plates can provide details about migration and foraging behaviour of an individual over a period of several years. We interpreted δ13C and δ15N cycles, examined whether stable isotope ratios of baleen could detect the right whale distribution shift, and compared variation within and among individuals before and after 2010. δ13C and δ15N values were compared between 8 right whales that died between 1992 and 2005 (pre-2010) and 5 right whales that died in 2019 (post-2010). The correlation between δ13C and δ15N varied considerably between individuals, indicating no clear pattern of annual migration in δ13C among whales. We observed a change in both isotope ratios after 2010, whereby the post-2010 whales were enriched in 13C and 15N relative to the pre-2010 whales (mean ± SE: 0.5 ± 0.1 and 0.9 ± 0.2 ‰, respectively). The isotopic variance among and within whales did not change after 2010. These results suggest that a range shift observed in sighting data is also reflected in the isotope ratios of right whale baleen. Detecting shifts in right whale migration is essential for protecting this species, and stable isotope analyses may be useful in future conservation efforts.
Fraser M.L., Gray M.A., Dobbs K.D.R., Andrews B.I., De Reep S.V., Duffy M.S. (2023). First Reports of Ligula intestinalis and a Schistocephalus sp. Infecting Small-Bodied Fish in New Brunswick, Canada. Journal of Parasitology, 109(4) 288-295.

Morphological characteristics and DNA sequencing were used to identify plerocercoids of a Schistocephalus sp. infecting slimy sculpin (Cottus cognatus) from northern New Brunswick and plerocercoids of Ligula intestinalis infecting blacknose dace (Rhinichthys atratulus) in Fundy National Park (FNP, New Brunswick). To our knowledge, no previous publications documented either cestode from New Brunswick, Canada. Blacknose dace represent a new host record for L. intestinalis. Identifications were made based on the presence or absence of segmentation and sequencing partial nicotinamide adenine dinucleotide dehydrogenase subunit 1 (ND1; mitochondrial DNA) and/or partial cytochrome c oxidase subunit 1 (COI; mitochondrial DNA). Plerocercoids from blacknose dace in FNP were identified as Ligula intestinalis based on >99% nucleotide identity with COI for this species in the NCBI GenBank database. Plerocercoids in slimy sculpin from northern New Brunswick were identified as a Schistocephalus sp. based on high nucleotide identity with congenerics in the NCBI GenBank database. The absence of GenBank entries with sufficient high percent identity to our specimens, and potential species hybrids in this genus, prevents species-level identification of Schistocephalus sp. plerocercoids currently. The absence of previous documentation of these cestodes might reflect recent environmental change promoting the transmission of these parasites that can modulate host fish behavior, induce sterility of host fishes, and contribute to epizootics.
Hasan A., Montoro Girona M., Imbeau L., Lento J., Hof A.R., Grosbois G. (2023). Indicator species reveal the physical and biological singularity of esker ecosystems. Ecological Indicators, 154.

Eskers are complex geological formations shaped with a linear accumulation of sand and gravel under the glaciers during the last ice age and that provide crucial resources such as drinking water, sand/gravel, outdoor recreational sites, and productive forests. Surrounding sand and gravel and connection with the groundwater influences the physicochemical properties of lakes on esker which can benefit different biotic communities in the food web. The sustainable management of resources provided by eskers requires baseline ecological knowledge of these ecosystems. However, very little information exists about the ecology of freshwater ecosystems on eskers. This study uses a food web approach to identify the environmental variables, biological diversity, and indicator species associated with esker lakes to better understand their ecological functioning and biodiversity patterns to benefit their sustainable management and conservation. Fifty lakes were sampled in the Abitibi-Témiscamingue region (Canada), half on eskers and half on the surrounding boreal clay belt to include the most abundant lake ecosystems of the region. Physicochemical, environmental, and anthropogenic variables measured in the two lake types showed that esker lakes differed markedly from clay lakes. Nutrient concentrations, conductivity, and macrophyte cover were significantly lower in esker lakes than in clay lakes, whereas dissolved oxygen saturation and concentration showed the opposite trend. Three interconnected trophic levels of the esker lake food webs—waterbird, fish, and macroinvertebrate communities—were characterized for biological diversity and the associated species. We found a significantly lower Shannon diversity index for waterbirds (mean ± standard deviation; 0.7 ± 0.2), fish (0.4 ± 0.3), and a tendency for a lower value for macroinvertebrates (0.9 ± 0.3) in esker lakes than the clay lakes (1.1 ± 0.4, 0.9 ± 0.3, and 1.3 ± 0.5, respectively). Common goldeneye (Bucephala clangula) and Canada goose (Bucephala clangula) were associated significantly with esker lakes and identified as indicator species for esker lakes. In contrast, ring-necked duck (Aythya collaris) and hooded merganser (Lophodytes cucullatus) were associated significantly with clay lakes. Perlidae was similarly associated with esker lakes as an indicator for macroinvertebrates. Anthropogenic activities such as forest harvesting have altered the waterbird community, and recreational activities around the lakes have modified the fish and macroinvertebrate communities. We conclude that esker lakes differ from other regional lakes and are associated with specific environmental and biological variables and indicator species. The biological diversity in esker lakes is lower than that of clay lakes for all studied trophic levels of the food web, but these waterbodies provide preferential habitats for some species. This research provides the first baseline ecological information necessary to establish sustainable management and conservation strategies for this vulnerable ecosystem.
Heath G., Semple S.L., Rodríguez-Ramos T., Hardy S., Harrison P., Mulder I.M., Power M., Dixon B. (2023). Surface material of acoustic transmitters influences the inflammatory response of rainbow trout (Oncorhynchus mykiss) during long-term implantation. Veterinary Immunology and Immunopathology, 264.

Telemetry tags are a widely used technology for tracking animals that are difficult to observe in their natural environment. This technology has been increasingly used to monitor and study populations of high value salmonid species in Canadian waters. This study expands on a previous study of the impacts of tag implantation on the immune system of Rainbow Trout (Oncorhynchus mykiss). Pro-inflammatory cytokines and protein level markers were examined in fish that underwent peritoneal implantation of three tag types and compared to a sham surgery control group. The different materials on the surface of the tags showed differential immune induction extending over a two-month period. This included peritoneal total protein, IL-1β protein, the immunoglobulins IgT and IgM, as well as pro-inflammatory transcripts in the spleen. These results are suggestive of a prolonged, costly foreign body response which may be differentially induced by the different types of tag coating, with ceramic tags being least immunogenic. Examining tag impacts at the level of the immune system will facilitate the development of more biocompatible tags which will improve data fidelity. This will support more effective strategies for the management of fisheries resources.
Helminen J., Linnansaari T. (2023). Combining Imaging Sonar Counting and Underwater Camera Species Apportioning to Estimate the Number of Atlantic Salmon and Striped Bass in the Miramichi River, New Brunswick, Canada. North American Journal of Fisheries Management, 43(3) 743-757.

A combined method incorporating an imaging sonar and underwater cameras was tested for assessing the size of adult Atlantic Salmon Salmo salar and Striped Bass Morone saxatilis populations in one of the main tributaries of the Miramichi River, New Brunswick, Canada. The number of fish recorded with the sonar in October 2019 was apportioned using the species ratio from the underwater camera data. The combined method estimated 358 Atlantic Salmon and 255 Striped Bass when the species ratio was applied every day and 274 Atlantic Salmon and 337 Striped Bass when the monthly species ratio was applied. The counts were compared to catches in a downstream index trap net using estimated values for trap-net catchability and for the proportion of fish ascending to the same tributary. Depending on the estimated values, the sonar–camera counts were between 40% and 190% of the estimated Atlantic Salmon numbers in the index net. For Striped Bass, the same estimated catchability and proportion values produced a lower agreement (sonar–camera count = 5–24% of the adjusted catch) because unlike Atlantic Salmon, Striped Bass do not deterministically migrate up the tributary in autumn. The fish were mostly detected overnight, and the trends in daily numbers of fish detected with the combined sonar–camera method were similar to the catches in the index net, with most Atlantic Salmon being detected mid-month and most Striped Bass being detected at the end of the month. The similarity of the fish counts with the adjusted trap-net catch and the new information about migration timing demonstrate that the sonar–underwater camera combination can provide tributary-specific and timely information on the Atlantic Salmon population in the Miramichi River.
Hu Y., Zhang F., Luo Z., Badreldin N., Benoy G., Xing Z. (2023). Soil and water conservation effects of different types of vegetation cover on runoff and erosion driven by climate and underlying surface conditions. Catena, 231.

Quantitative analyses of runoff and erosion under specific climatic (precipitation characteristics) and underlying surface conditions (slope, antecedent soil moisture) with different types of vegetation cover (or plant measures hereafter) remains a challenging research topic in semi-arid regions. The research site located in the Anjiagou watershed of Gansu Province, China, and used for this study has long-term monitoring data (1987 to 2019) of precipitation conditions, antecedent soil moisture, and runoff and erosion rates from a set of modified standard erosion plots characterized by different vegetation covers or plant measures (arbor forest land, shrub forest land, artificial grassland, natural grassland, and agricultural land) at three slopes (10°, 15°, 20°). Collected data was subjected to path analysis and stepwise regression to determine the main driving factors of runoff and soil erosion, as well as proper input variables for modeling. The results showed that models could be constructed with different variables for different types of vegetation cover (P < 0.05, r<inf>a</inf> 2 > 0.55). The analyses also showed that moderate rain (10 – 25 mm) accounted for >60% of the variation in runoff and plant effects on runoff and soil erosion varied with the measures. Among plant measures, shrub forest had the best performance in reducing runoff and erosion for short-term precipitation events (shorter than 24 hrs), but under the long-durations (72 hrs) precipitation, natural grassland performed the best to prevent the occurrence of runoff and soil erosion. Compared with agricultural land, the rest of the plant measures had an average erosion reduction rate of 73%, which was about twice the runoff reduction rate (37%). Slope was found to play some role in controlling runoff and erosion variation. Compared to slopes of 10° and 20°, runoff and erosion reduction rates at 15° plots were lower. The key variables determining runoff rates under different plant measures included precipitation and maximum 30-minute precipitation intensity, followed by types of vegetation cover. In contrast, erosion rates mostly depended upon runoff and maximum 30-min precipitation intensity. We also found that coupling precipitation characteristics with antecedent soil moisture in the modelling could help produce a more accurate assessment of runoff and soil and water conservation as part of ecological restoration efforts involving typical plant measures under different topographical conditions in semi-arid areas.
Kebir Z., Chambers C., Frainier A., Hausner V., Lennert A.E., Lento J., Poste A., Ravolainen V., Renner A.H.H., Thomas D.N., Waylen K. (2023). Fifteen research needs for understanding climate change impacts on ecosystems and society in the Norwegian High North. Ambio, 52(10) 1575-1591.

There is an urgent need to understand and address the risks associated with a warming climate for ecosystems and societies in the Arctic and sub-Arctic regions. There are major gaps in our understanding of the complex effects of climate change—including extreme events, cascading impacts across ecosystems, and the underlying socioecological dynamics and feedbacks—all of which need collaborative efforts to be resolved. Here, we present results where climate scientists, ecologists, social scientists, and practitioners were asked to identify the most urgent research needs for understanding climate change impacts and to identify the actions for reducing future risks in catchment areas in the Norwegian High North, a region that encompasses both Arctic and sub-Arctic climates in northern Norway. From a list of 77 questions, our panel of 19 scientists and practitioners identified 15 research needs that should be urgently addressed. We particularly urge researchers to investigate cross-ecosystem impacts and the socioecological feedbacks that could amplify or reduce risks for society.
Khorsandi M., Bateni M.M., Van Oel P. (2023). A mathematical meta-model for assessing the self-sufficient water resources carrying capacity across different spatial scales in Iran. Heliyon, 9(4).

Hydrological modeling, water accounting assessments, and land evaluations are well-known techniques to carry out water resources carrying capacity (WRCC) assessments at multiple spatial levels. Using the results of an existing process-based model for assessing WRCC from very fine to national spatial scales, we propose a mathematical meta-model, i.e., a set of easily applicable simplified equations to assess WRCC as a function of high-quality agricultural lands for optimistic to realistic scenarios. These equations are based on multi-scale spatial results. Scales include national scale (L0), watersheds (L1), sub-watersheds (L2), and water management hydrological units (L3). Applying the meta-model for different scales could support spatial planning and water management. This method can quantify the effects of individual and collective behavior on self-sufficient WRCC and the level of dependency on external food resources in each area. Carrying capacity can be seen as the inverse of the ecological footprint. Hence, using publicly available data on the ecological footprint in Iran, the results of the proposed method are validated and give an estimation of lower and upper bounds for all biocapacity of the lands. Moreover, the results confirm the law of diminishing returns in the economy for the carrying capacity assessment across spatial scales. The proposed meta-model could be considered a complex manifest of land, water, plants, and human interaction for food production, and it could be used as a powerful tool in spatial planning studies.
Khorsandi M., Omidi T., van Oel P. (2023). Water-related limits to growth for agriculture in Iran. Heliyon, 9(5).

Globally, agriculture is the primary water consumption sector. This study used water footprint (WF) as a bottom-up tool and satellite imagery as a top-down tool to estimate the internal water use (WU) in the agricultural sector in an innovative way to show the effects of water-intensive use in agriculture in an arid country. The WF of Iran has been quantified for 19 main crops and for related agricultural products exported from Iran to partner countries. Using a bottom-up approach, Iran's total yearly agriculture net water consumption is estimated to be 42.43 billion cubic meters (BCM) per year. Out of 42.43 BCM total net internal water use, only 1.61 BCM is virtual-water export related to these 19 products, and the remaining 40.82 BCM is for internal use. Our results using satellite imagery show that in case of using all possible lands for agriculture, it would require 77.4 BCM. However, not all these lands are within human reach, and the maximum available water is way lower than this amount. Using satellite imagery, the total evaporation from agricultural lands shows 55.27 BCM for 2020, which agrees with national reports during 2005–2014. This study shows that agricultural water consumption tends to use internal water resources at a maximum level for export and national use, significantly impacting renewable and non-renewable water resource availability, especially in groundwater.
Khorsandi M., St-Hilaire A., Arsenault R. (2023). Assessing the Surface Downward Longwave Irradiance Models Using ERA5 Input Data in Canada. Journal of Hydrometeorology, 24(6) 1175-1190.

Longwave radiation (LR) is one of the energy balance components responsible for warming and cooling water during hot summers. Both downward incoming LR, emitted by the atmosphere, and outgoing LR emitted by the land surface are not widely measured. The influence of clouds on the LR heat budget makes it even harder to establish reliable formulations for all-sky conditions. This paper uses air temperature and cloud cover from the ERA5 reanalysis database to compare 20 models for the downward longwave irradiance (DLI) at Earth’s surface and compare them with ERA5’s DLI product. Our work uses long-time continuous DLI measured data at three stations over Canada, and ERA5 reanalysis, a reliable source for data-scarce regions, such as central British Columbia (Canada). The results show the feasibility of the local calibration of different formulations using ERA5 reanalysis data for all-sky conditions with RMSE metrics ranging from 37.1 to 267.3 W m-2, which is comparable with ERA5 reanalysis data and can easily be applied at broader scales by implementing it into hydrological models. Moreover, it is shown that ERA5 gridded data for DLI shows the best results with RMSE = 31.7 W m-2. This higher performance suggests using ERA5 data directly as input data for hydrological and ecological models.
Khorsandi M., St-Hilaire A., Arsenault R., Martel J.L., Larabi S., Schnorbus M., Zwiers F. (2023). Future flow and water temperature scenarios in an impounded drainage basin: implications for summer flow and temperature management downstream of the dam. Climatic Change, 176(12).

Water temperature is a key variable affecting fish habitat in rivers. The Sockeye salmon (Oncorhynchus nerka), a keystone species in north western aquatic ecosystems of North America, is profoundly affected by thermal regime changes in rivers, and it holds a pivotal role in ecological and economic contexts due to its life history, extensive distribution, and commercial fishery. In this study, we explore the effects of climate change on the thermal regime of the Nechako River (British Columbia, Canada), a relatively large river partially controlled by the Skins Lake Spillway. The CEQUEAU hydrological-thermal model was calibrated using discharge and water temperature observations. The model was forced using the Fifth generation of ECMWF Atmospheric Reanalysis data for the past and meteorological projections (downscaled and bias-corrected) from climate models for future scenarios. Hydrological calibration was completed for the 1980–2019 period using data from two hydrometric stations, and water temperature calibration was implemented using observations for 2005–2019 from eight water temperature stations. Changes in water temperature were assessed for two future periods (2040–2069 and 2070–2099) using eight Coupled Model Intercomparison Project Phase 6 climate models and using two Shared Socioeconomic Pathway scenarios (4.5 and 8.5 W/m2 by 2100) for each period. Results show that water temperatures above 20°C (an upper threshold for adequate thermal habitat for Sockeye salmon migration in this river) at the Vanderhoof station will increase in daily frequency. While the frequency of occurrence of this phenomenon is 1% (0–9 days/summer) based on 2005–2019 observations, this number range is 3.8–36% (0–62 days/summer) according to the ensemble of climate change scenarios. These results show the decreasing habitat availability for Sockeye salmon due to climate change and the importance of water management in addressing this issue.
Knysh K.M., MacIntyre L.P., Cormier J.M., Grove C.M., Courtenay S.C., van den Heuvel M.R. (2023). Comparing Physical Collection and Environmental DNA Methods for Determining Abundance Patterns of Gammarus Species along an Estuarine Gradient. Diversity, 15(6).

Estuaries are productive systems with rapid changes in natural stressors, such as salinity, that make perturbation detection challenging. Amphipods are vital to estuarine assemblages and may serve as anthropogenic stress indicators. However, practical methods of monitoring species composition and abundance are lacking. This study aims to describe the spatial patterns of four Gammarus spp. in northwest Atlantic estuaries and to compare their compositions and abundances between collection methods using artificial substrates, macrophyte raking, light-baited traps, and species-specific quantitative PCR analyses from sediment environmental DNA (eDNA). Sampling occurred in upper, mid, and lower estuary zones within three estuaries of Prince Edward Island (Canada). G. tigrinus was rarely found in the upper zones with any method. G. mucronatus was predominant in the upper–mid zones across the physical methods, and its abundance declined with increasing salinity. G. lawrencianus was a dominant species across zones, but its abundance did not change with salinity. G. oceanicus was predominant in lower-zone artificial substrates. Species abundances generally correlated with physical collection methods. Sediment eDNA did not detect the spatial effects observed via the physical methods but was correlated with the mean counts of G. mucronatus. The Gammarus spp. assemblages are spatially partitioned in short estuaries, though the sampling method is critical when interpreting estuary patterns. Though multiple methods are ideal for compositional comparisons, abundance monitoring should employ light traps.
Kozak N., Kahilainen K.K., Pakkanen H.K., Hayden B., Østbye K., Taipale S.J. (2023). Mercury and amino acid content relations in northern pike (Esox lucius) in subarctic lakes along a climate-productivity gradient. Environmental Research, 233.

Mercury is a highly toxic element for consumers, but its relation to amino acids and physiology of wild fish is not well known. The main aim of this study was to evaluate how total mercury content (THg) of northern pike (Esox lucius) is related to amino acids and potentially important environmental and biological factors along a climate-productivity gradient of ten subarctic lakes. Linear regression between THg and sixteen amino acids content [nmol mg−1 dry weight] from white dorsal muscle of pike from these lakes were tested. Lastly, a general linear model (GLM) for age-corrected THg was used to test which factors are significantly related to mercury content of pike. There was a positive relationship between THg and proline. Seven out of sixteen analysed amino acids (histidine, threonine, arginine, serine, glutamic acid, glycine, and aspartic acid) were significantly negatively related to warmer and more productive lakes, while THg showed a positive relationship. GLM model indicated higher THg was found in higher trophic level pike with lower cysteine content and inhabiting warmer and more productive lakes with larger catchment containing substantial proportion of peatland area. In general, THg was not only related to the biological and environmental variables but also to amino acid content.
LeBlanc N.M., Pavey S.A. (2023). Comparing mixed models and Random Forest association tests using naturalgwas and a Striped Bass SNP data set. Molecular Ecology Resources, 23(1) 145-158.

In this study, we used the phenotype simulation package naturalgwas to test the performance of Zhao's Random Forest method in comparison to an uncorrected Random Forest test, latent factor mixed models (LFMM), genome-wide efficient mixed models (GEMMA), and confounder adjusted linear regression (CATE). We created 400 sets of phenotypes, corresponding to five effect sizes and two, five, 15, or 30 causal loci, simulated from two empirical data sets containing SNPs from Striped Bass representing three and 13 populations. All association methods were evaluated for their ability to detect genotype–phenotype associations based on power, false discovery rates, and number of false positives. Genomic inflation was highest for uncorrected Random Forest and LFMM tests and lowest for Gemma and Zhao's Random Forest. All association tests had similar power to detect causal loci, and Zhao's Random Forest had the lowest false discovery rate in all scenarios. To measure the performance of association tests in small data sets with few loci surrounding a causal gene we also ran analyses again after removing causal loci from each data set. All association tests were only able to find true positives, defined as loci located within 30 kbp of a causal locus, in 3%–18% of simulations. In contrast, at least one false positive was found in 17%–44% of simulations. Zhao's Random Forest again identified the fewest false positives of all association tests studied. The ability to test the power of association tests for individual empirical data sets can be an extremely useful first step when designing a GWAS study.
Lento J., Laske S.M., Luiker E.A., Culp J.M., Jones L., Zimmerman C.E., Monk W.A. (2023). Rivers of Arctic North America. Rivers of North America Second Edition 836-888.

This chapter describes the geomorphology, hydrology, chemistry, biodiversity, and ecology of rivers in the North American Arctic. The history, physiography, climate, and land use of the Arctic regions are also described. The chapter includes details on the Kobuk and Colville rivers in Alaska, the Thelon and Kazan rivers in the central Canadian Arctic, Koroc River and Nakvak Brook in the eastern Canadian low Arctic, Thomsen River on Banks Island in the western Canadian Arctic Archipelago, and Ruggles River on Ellesmere Island in the Canadian high Arctic. The rivers are characteristic of the major ecoregions of the North American Arctic, covering a range of geomorphological and physiographic conditions. The history of use of the rivers by Inuit and Dene First Nations Peoples of the north provides the foundation to understand the social, cultural, and economic importance of the river systems, and potential threats to the rivers from climate change are outlined.
Lento J., Lau D.C.P., Brittain J.E., Culp J.M., Goedkoop W. (2023). Macroinvertebrate traits in Arctic streams reveal latitudinal patterns in physiology and habits that are strongly linked to climate. Frontiers in Ecology and Evolution, 11.

Introduction: Arctic freshwater ecosystems are undergoing rapid environmental transformation because of climate change, which is predicted to produce fundamental alterations in river community structure and function. Methods: We explored how climate change affects benthic invertebrate communities of Arctic streams by examining patterns of their biological traits along latitudinal and climatic gradients in eastern North America (Canada) and northwestern Europe (Sweden, Norway). Results: Despite differences in taxonomic composition between continents, we identified similarities in the functional trait niche (FTN) of predominant macroinvertebrate taxonomic groups. Trait composition differed by latitude in eastern Canada, with a predominance of cold-tolerant taxa, tubular body shape, and cased and attached habits at the highest latitudes. Differences in trait composition were evident among ecoregions in Europe, with trait dominance at the highest latitudes that was comparable to North America. There was a similar increase in the relative abundance of cold tolerance and tubular body shape and a decrease in obligate shredders and trait richness with decreasing temperatures across both continents. Discussion: These patterns are indicative of FTNs that include physiological traits and habits that are advantageous for the low temperatures, short ice-free period, and low riparian vegetation cover at the highest latitudes. We predict that climate change will lead to an increase in functional diversity at high latitudes, as organisms with trait modalities that are currently only found at lower latitudes move northward. However, this change in trait composition will be mediated by the effect of spatial connectivity on dispersal ability, with slower change occurring on Arctic islands. These findings can support modelling of future change in Arctic freshwater assemblages in response to ongoing climate change.
Linnansaari T., O’Sullivan A.M., Breau C., Corey E.M., Collet E.N., Curry R.A., Cunjak R.A. (2023). The Role of Cold-Water Thermal Refuges for Stream Salmonids in a Changing Climate—Experiences from Atlantic Canada. Fishes, 8(9).

Thermal refuges are becoming increasingly influential for dictating the population status and spatial distribution of cold-water stenotherm salmonids in the mid- to southern extent of their range. The global climate is predicted to continue to warm, and therefore, the overall thermal suitability of freshwater habitats for stream salmonids is predicted to decline in concert. However, stream and river thermal heterogeneity will offer considerable resiliency for these populations. Thermal refuges are formed by many physical processes; common natural refuges include cold tributary plumes, groundwater springs, alcoves, and hyporheic upwellings. However, many anthropogenically formed refuges (such as stratified reservoirs or cold-water tailrace outflows) also exist in hydropower-regulated rivers. The significance of these refuges to stream salmonids depends on their size and temperature differential, but also other habitat characteristics such as their depth, flow velocity, Froude number, and many biotic factors within the refuges. Modern technologies such as drone-mounted thermal infrared cameras and other remote sensing techniques allow for the efficient identification of such refuges, and inexpensive options include the identification of refuges during ice cover using orthophotographs. Behavioural thermoregulation, i.e., salmonids aggregating in cold-water refuges, can be either facultative or obligate and the timing of these events is governed by life stage, species, and population-specific physiologically regulated cumulative thresholds that are inherently related to the recent thermal history, or hysteresis, of each individual. Salmonids appear to have an excellent spatial cognition for locating and relocating cold-water refuges, and their spatial distribution is largely affected by the availability of the cold-water refuges during the warm-water period in many thermally stressed rivers. Gregarious behaviour is the norm for salmonid fishes within the thermal refuges; however, the size/microhabitat hierarchy appears to dictate the within-refuge distribution at the micro-scale. There continues to be a great impetus for protecting—and in carefully determined cases creating—cold-water refuges in the future. A thorough understanding of what a “goldilocks” refuge is for various salmonids and their different life stages will be imperative as cold-water restoration is gaining popularity. Finally, disentangling the roles of the climate-induced and landscape activity-induced warming potential of fluvial freshwater will be important to ensure continued environmentally responsible landscape activities in future waterscapes.
Loomer H.A., Kidd K.A., Erdozain M., Benoy G.A., Chambers P.A., Culp J.M. (2023). Stream macroinvertebrate community responses to an agricultural gradient alter consumer-driven nutrient dynamics. Hydrobiologia, 850(2) 315-334.

Although macroinvertebrate communities play a key role in the cycling of nitrogen (N) and phosphorus (P) in streams, this process may be disrupted through decreased macroinvertebrate diversity or abundance from agricultural inputs of nutrients, sediments and pesticides. However, it is unclear how such community changes affect their biological storage of N and P. In 2010 and 2011, we collected water samples and macroinvertebrates from 14 streams in New Brunswick, Canada, with catchments representing a gradient in agricultural cover (0–92%, mainly potatoes). Macroinvertebrate communities were dominated by aquatic insects, and individual families were weighed for biomass and analyzed for N and P content as well as δ15N, an indicator of excess nutrients. Aqueous total P and total N increased significantly with agricultural cover, whereas macroinvertebrate community biomass and richness decreased. Within 6 of 9 taxa, δ15N values increased with agricultural cover. N content varied among families, with the lowest (average ⁓8.5%) values in Baetidae, Ephemerellidae, Chironomidae and Simuliidae, and the highest (average ⁓10.1%) values in Perlidae, Chloroperlidae and Elmidae adults. In addition, P content was significantly higher in Chironomidae (0.63%) than Perlidae (0.42%), Chloroperlidae (0.32%), and Hydropsychidae (0.42%). However, no individual families showed a significant change in their N or P content across sites. Community nutrient storage (CNS g/m2; sum of family nutrient content %N or %P * family biomass g/m2) for both N and P was not related to agriculture in the catchments whereas community nutrient content (CNC; the average %N or %P of all families weighted by their relative biomass) increased for P and decreased for N with higher agriculture. Overall, these results suggest that agricultural inputs of nutrients and other materials affect storage of N and P in stream macroinvertebrate communities, likely through impacts on community biomass and diversity.
McCarron P., Rafuse C., Scott S., Lawrence J., Bruce M.R., Douthwright E., Murphy C., Reith M., Beach D.G. (2023). Anatoxins from benthic cyanobacteria responsible for dog mortalities in New Brunswick, Canada. Toxicon, 227.

In July 2018 three dogs died after visiting the Wolastoq (Saint John River) near Fredericton, New Brunswick, in Atlantic Canada. All showed signs of toxicosis, and necropsies revealed non-specific pulmonary edema and multiple microscopic brain hemorrhages. Liquid chromatography–high-resolution mass spectrometry (LC–HRMS) analysis of vomitus and stomach contents as well as water and biota from the mortality sites confirmed the presence of anatoxins (ATXs), a class of potent neurotoxic alkaloids. The highest levels were measured in a dried benthic cyanobacterial mat that two of the dogs had been eating before falling ill and in a vomitus sample collected from one of the dogs. Concentrations of 357 and 785 mg/kg for anatoxin-a and dihydroanatoxin-a, respectively, were measured in the vomitus. Known anatoxin-producing species of Microcoleus were tentatively identified using microscopy and confirmed by 16S rRNA gene sequencing. The ATX synthetase gene, anaC, was detected in the samples and isolates. The pathology and experimental results confirmed the role of ATXs in these dog mortalities. Further research is required to understand drivers for toxic cyanobacteria in the Wolastoq and to develop methodology for assessing occurrence.
Monk C.T., Power M., Freitas C., Harrison P.M., Heupel M., Kuparinen A., Moland E., Simpfendorfer C., Villegas-Ríos D., Olsen E.M. (2023). Atlantic cod individual spatial behaviour and stable isotope associations in a no-take marine reserve. Journal of Animal Ecology, 92(12) 2333-2347.

Foraging is a behavioural process and, therefore, individual behaviour and diet are theorized to covary. However, few comparisons of individual behaviour type and diet exist in the wild. We tested whether behaviour type and diet covary in a protected population of Atlantic cod, Gadus morhua. Working in a no-take marine reserve, we could collect data on natural behavioural variation and diet choice with minimal anthropogenic disturbance. We inferred behaviour using acoustic telemetry and diet from stable isotope compositions (expressed as δ13C and δ15N values). We further investigated whether behaviour and diet could have survival costs. We found cod with shorter diel vertical migration distances fed at higher trophic levels. Cod δ13C and δ15N values scaled positively with body size. Neither behaviour nor diet predicted survival, indicating phenotypic diversity is maintained without survival costs for cod in a protected ecosystem. The links between diet and diel vertical migration highlight that future work is needed to understand whether the shifts in this behaviour during environmental change (e.g. fishing or climate), could lead to trophic cascades.
Monk W.A., Dugdale S.J. (2023). River temperature: perspectives, applications, and future directions for research in Canada. Canadian Water Resources Journal, 48(2) 67-71.

Variability, duration and magnitude of stream temperature drives direct and indirect effects on aquatic ecosystems. Articles contained within this Special Issue provide an overview of the current modelling and field-based research on stream temperature in Canada, in addition to highlighting the need for better understanding of the ecological impacts of stream temperature. The nine papers in the Special Issue are grouped across four broad themes: river temperature and impoundments, monitoring of river temperature regimes at large scales, understanding river energy budgets, and river temperature and ecology. As a whole, the Special Issue provides commentary on the path forwards for enhanced collaboration and integration of complementary approaches, for better understanding of stream temperature regimes within Canada and further afield.
Monk W.A., Gray M.A., McCarthy J.H., Samways K.M., Curry R.A. (2023). Atlantic Coast Rivers of Canada. Rivers of North America Second Edition 890-924.

Within this chapter, we explore the Atlantic Coast Rivers of Canada through examples from four rivers and two river complexes (each composed of three smaller rivers) distributed across the four Atlantic provinces (New Brunswick, Prince Edward Island, Nova Scotia, and Newfoundland and Labrador) and the Gaspé Peninsula. The rivers represent the diverse regional landscapes reflecting the strong influence of the regional maritime, subboreal and boreal climates, significant geological variation, and key ecosystem transitions. With a strong maritime connection, the region has an extensive Indigenous history that shifted dramatically with the arrival of Europeans and the subsequent social and environmental impacts of colonization followed by a push for economic development. The regional economy has traditionally focused on its rich natural resources including fishing, forestry, agriculture, and mining industries in addition to some large hydropower developments, and these influences are reflected in the basins within the Atlantic Coast region of Canada.
Morgan A.M., O'Sullivan A.M. (2023). Cooler, bigger; warmer, smaller: Fine-scale thermal heterogeneity maps age class and species distribution in behaviourally thermoregulating salmonids. River Research and Applications, 39(2) 163-176.

Behavioural thermoregulation is a survival strategy that occurs in response to an exceedance of thermal stress-inducing thresholds. When salmonids experience exceedance of these thresholds, they seek regions of colder water, known as thermal refuges. During an extreme temperature event of summer 2021 (main stem ~31.5°C) a large aggregation of Atlantic salmon (Salmo salar—all age classes) and brook trout (Salvelinus fontinalis—>20 cm) was observed on the Little Southwest Miramichi River in New Brunswick, Canada. Using a drone-mounted thermal infrared (TIR) sensor, fine-scale TIR imagery of the occupied refuge was acquired. Polarized glasses were worn by an onshore observer to make visual observations. Constructing maps from these data we examined the spatial distribution of fish, and the corresponding temperature of the areas they occupied. Salmonids were found to be distributed by age class and species, with the distribution driven by the mosaic of temperatures in the refuge. Young of the year (YOY), 1+, 2+ and adult Atlantic salmon occupied areas with average temperatures ~30.1, 28.8, 25.7 and 21.9°C, respectively; whilst mature brook trout occupied areas ~21.8°C. Noteworthy is the observation of thermally aggregating young of the year Atlantic salmon, and the range in temperatures they occupied (~8°C). One isolated, shallow, cold water patch (~22°C) exclusively held YOY Atlantic salmon. Our findings highlight the importance of several different thermal characteristics of thermal refuges and their link to salmonid occupancy and can aid the design of ecologically meaningful thermal refuge augmentation/restoration projects.
Morrison M.K., Lacoursière-Roussel A., Wood Z.T., Trudel M., Gagné N., LeBlanc F., Samways K., Kinnison M.T., Pavey S.A. (2023). Including environmental covariates clarifies the relationship between endangered Atlantic salmon (Salmo salar) abundance and environmental DNA. Environmental DNA, 5(5) 987-1003.

Collecting environmental DNA (eDNA) as a nonlethal sampling approach has been valuable in detecting the presence/absence of many imperiled taxa; however, its application to indicate species abundance poses many challenges. A deeper understanding of eDNA dynamics in aquatic systems is required to better interpret the substantial variability often associated with eDNA samples. Our sampling design took advantage of natural variation in juvenile Atlantic salmon (Salmo salar) distribution and abundance along 9 km of a single river in the Province of New Brunswick (Canada), covering different spatial and temporal scales to address the unknown seasonal impacts of environmental variables on the quantitative relationship between eDNA concentration and species abundance. First, we asked whether accounting for environmental variables strengthened the relationship between eDNA and salmon abundance by sampling eDNA during their spring seaward migration. Second, we asked how environmental variables affected eDNA dynamics during the summer as the parr abundance remained relatively constant. Spring eDNA samples were collected over a 6-week period (12 times) near a rotary screw trap that captured approximately 18.6% of migrating smolts, whereas summer sampling occurred (i) at three distinct salmon habitats (9 times) and (ii) along the full 9 km (3 times). We modeled eDNA concentration as a product of fish abundance and environmental variables, demonstrating that (1) with inclusion of abundance and environmental covariates, eDNA was highly correlated with spring smolt abundance and (2) the relationships among environmental covariates and eDNA were affected by seasonal variation with relatively constant parr abundance in summer. Our findings underscore that with appropriate study design that accounts for seasonal environmental variation and life history phenology, eDNA salmon population assessments may have the potential to evaluate abundance fluctuations in spring and summer.
O'Sullivan A.M., Corey E.M., Collet E.N., Helminen J., Curry R.A., MacIntyre C., Linnansaari T. (2023). Timing and frequency of high temperature events bend the onset of behavioural thermoregulation in Atlantic salmon (Salmo salar). Conservation Physiology, 11(1).

The role of temperature on biological activities and the correspondent exponential relationship with temperature has been known for over a century. However, lacking to date is knowledge relating to (a) the recovery of ectotherms subjected to extreme temperatures in the wild, and (b) the effects repeated extreme temperatures have on the temperatures that induce behavioural thermoregulation (aggregations). We examined these questions by testing the hypothesis that thermal thresholds which initiate aggregations in juvenile Atlantic salmon (AS) (Salmo salar) are not static, but are temporally dynamic across a summer and follow a hysteresis loop. To test our hypothesis, we deployed custom-made underwater camera (UWC) systems in known AS thermal refuges to observe the timing of aggregation events in a natural system and used these data to develop and test models that predict the temperatures that induce thermal aggregations. Consistent with our hypothesis our UWC observations revealed a range of aggregation onset temperatures (AOT) ranging from 24.2°C to 27.1°C, thus confirming our hypothesis that AOTs are dynamic across summer. Our models suggest it take ~ 11 days of non-thermally taxing temperatures for the AOT to rebound in the study river. Conversely, we found that as the frequency of events increased, the AOT declined, from 27.1°C to 24.2°C. Integrating both model components led to more robust model performance. Further, when these models were tested against an independent data set from the same river, the results remained robust. Our findings illustrate the complexity underlying behavioural thermoregulation in AS - a complexity that most likely extends to other salmonids. The frequency of extreme heat events is predicted to increase, and this has the capacity to decrease AOT thresholds in AS, ultimately reducing their resilience to extreme temperature events.
Oyinlola M.A., Khorsandi M., Penman R., Earhart M.L., Arsenault R., Brauner C.J., St-Hilaire A. (2023). Hydrothermal impacts of water release on early life stages of white sturgeon in the Nechako river, B.C. Canada. Journal of Thermal Biology, 117.

Water temperature plays a crucial role in the physiology of aquatic species, particularly in their survival and development. Thus, resource programs are commonly used to manage water quality conditions for endemic species. In a river system like the Nechako River system, central British Columbia, a water management program was established in the 1980s to alter water release in the summer months to prevent water temperatures from exceeding a 20 °C threshold downstream during the spawning season of Sockeye salmon (Oncorhynchus nerka). Such a management regime could have consequences for other resident species like the white sturgeon (Acipenser transmontanus). Here, we use a hydrothermal model and white sturgeon life stage-specific experimental thermal tolerance data to evaluate water releases and potential hydrothermal impacts based on the Nechako water management plan (1980–2019). Our analysis focused mainly on the warmest five-month period of the year (May to September), which includes the water release management period (July–August). Our results show that the thermal exposure risk, an index that measures temperature impact on species physiology of Nechako white sturgeon across all early life stages (embryo, yolk-sac larvae, larvae, and juvenile) has increased substantially, especially in the 2010s relative to the management program implementations’ first decade (the 1980s). The embryonic life stage was the most impacted, with a continuous increase in potential adverse thermal exposure in all months examined in the study. We also recorded major impacts of increased thermal exposure on the critical habitats necessary for Nechako white sturgeon recovery. Our study highlights the importance of a holistic management program with consideration for all species of the Nechako River system and the merit of possibly reviewing the current management plan, particularly with the current concerns about climate change impacts on the Nechako River.
Pearce N.J.T., Parsons C.T., Pomfret S.M., Yates A.G. (2023). Periphyton Phosphorus Uptake in Response to Dynamic Concentrations in Streams: Assimilation and Changes to Intracellular Speciation. Environmental Science and Technology, 57(11) 4643-4655.

Effective modeling and management of phosphorus (P) losses from landscapes to receiving waterbodies requires an adequate understanding of P retention and remobilization along the terrestrial-aquatic continuum. Within aquatic ecosystems, the stream periphyton can transiently store bioavailable P through uptake and incorporation into biomass during subscouring and baseflow conditions. However, the capacity of stream periphyton to respond to dynamic P concentrations, which are ubiquitous in streams, is largely unknown. Our study used artificial streams to impose short periods (48 h) of high SRP concentration on stream periphyton acclimated to P scarcity. We examined periphyton P content and speciation through nuclear magnetic resonance spectroscopy to elucidate the intracellular storage and transformation of P taken up across a gradient of transiently elevated SRP availabilities. Our study demonstrates that the stream periphyton not only takes up significant quantities of P following a 48-h high P pulse but also sustains supplemental growth over extended periods of time (10 days), following the reestablishment of P scarcity by efficiently assimilating P stored as polyphosphates into functional biomass (i.e., phospho-monoesters and phospho-diesters). Although P uptake and intracellular storage approached an upper limit across the experimentally imposed SRP pulse gradient, our findings demonstrate the previously underappreciated extent to which the periphyton can modulate the timing and magnitude of P delivery from streams. Further elucidating these intricacies in the transient storage potential of periphyton highlights opportunities to enhance the predictive capacity of watershed nutrient models and potentially improve watershed P management.
Penny F.M., Bugg W.S., Kieffer J.D., Jeffries K.M., Pavey S.A. (2023). Atlantic sturgeon and shortnose sturgeon exhibit highly divergent transcriptomic responses to acute heat stress. Comparative Biochemistry and Physiology Part D Genomics and Proteomics, 45.

In comparison to most modern teleost fishes, sturgeons generally display muted stress responses. While a muted stress response appears to be ubiquitous across sturgeon species, the mechanisms unpinning this muted response have not been fully described. The objective of this study was to determine the patterns of hematological and transcriptomic change in muscle tissue following an acute high temperature stress (critical thermal maxima; CT<inf>max</inf>) in two locally co-occurring but evolutionarily distant sturgeon species (Atlantic and shortnose sturgeon). The most striking pattern found was that Atlantic sturgeon launched a vigorous transcriptomic response at CT<inf>max</inf>, whereas shortnose sturgeon did not. In contrast, shortnose sturgeon have significantly higher cortisol than Atlantics at CT<inf>max</inf>, reconfirming that shortnose have a less muted cortisol stress response. Atlantic sturgeon downregulated a number of processes, included RNA creation/processing, methylation and immune processes. Furthermore, a number of genes related to heat shock proteins were differentially expressed at CT<inf>max</inf> in Atlantic sturgeon but none of these genes were significantly changed in shortnose sturgeon. We also note that the majority of differentially expressed genes of both species are undescribed and have no known orthologues. These results suggest that, while sturgeons as a whole may show muted stress responses, individual sturgeon species likely use different inducible strategies to cope with acute high temperature stress.
Penny F.M., Pavey S.A. (2023). Transcriptomic analyses of juvenile Striped Bass (Morone saxatilis) exposed to chronic and acute temperature change. Plos One, 18(10 October).

Striped Bass are economically important, migratory fishes, which occur across a wide range of latitudes. Given their wide-ranging nature, Striped Bass can cope with a broad range of environmental temperatures, yet the mechanisms underlying this ability have not been thoroughly described. Heat shock proteins (HSPs) are inducible molecular chaperones, which help mitigate protein damage resulting from increased temperatures. The importance of HSPs has been demonstrated in a number of fish species, but their role in Striped Bass is poorly understood. This study characterizes changes in gene expression in juvenile Striped Bass, following acute and chronic temperature change. Fish were acclimated to one of three temperatures (15, 25 or 30◦C) and sampled at one of two treatments (control or after CT<inf>max</inf>), following which we assessed differential gene expression and gene ontology in muscle. It is clear from our differential expression analyses that acclimation to warm temperatures elicits more robust changes to gene expression, compared to acute temperature increases. Our differential expression analyses also revealed induction of many different heat shock proteins, including hsp70, hsp90, hsp40 and other small HSPs, after both acute and chronic temperature increase in white muscle. Furthermore, the most consistent gene ontology pattern that emerged following both acclimation and CT<inf>max</inf> was upregulation of transcripts involved in “protein folding”, which also include heat shock proteins. Gene ontology analyses also suggest changes to other processes after acclimation, including decreased growth pathways and changes to DNA methylation. Overall, these data suggest that HSPs likely play a major role in the Striped Bass’s ability to tolerate warm waters.
Peters D.L., Dibike Y.B., Shudian J., Monk W.A., Baird D.J. (2023). Effects of Climate Change on Navigability Indicators of the Lower Athabasca River, Canada. Water Switzerland, 15(7).

The lower Athabasca River (Canada) has experienced notable declines in streamflow and increasing oil sands development since the 1970s. This study investigates the potential impacts of climate change on navigability using both observed historical and projected future flows derived via hydrological simulations driven by an ensemble of statistically downscaled general circulation model climate data. Our use of proposed indices that form the Aboriginal Navigation Index (ANI) and a new index based on percentage over threshold (POT) occurrences yielded novel insights into anticipated changes to the flow regime. Comparisons of near (2041–2070) and far (2071–2100) future periods with the historical baseline (1981–2010) yielded results that project significant reductions in the 500 m3 s−1 POT during the fall navigability period spanning weeks 34 to 43, as well as reductions in the integrated ANI<inf>Fall</inf>. These results indicate that challenging navigational conditions may become more frequent in the second half of the 21st century, not only during this fall period but also earlier into the summer, due to a shift in the flow regime, with potentially severe impacts on the users of the river channels. Our assessment approach is transferable to other regional study areas and should be considered in water management and environmental flow frameworks.
Przesmycka K., Herdegen-Radwan M., Phillips K.P., Mohammed R.S., Radwan J. (2023). The quest for good genes: Epigamic traits, fitness, MHC and multilocus heterozygosity in the guppy. Molecular Ecology, 32(18) 5055-5070.

The ‘good genes’ hypothesis for the evolution of male secondary sexual traits poses that female preferences for such traits are driven by indirect genetic benefits. However, support for the hypothesis remains ambiguous, and, in particular, the genetic basis for the benefits has rarely been investigated. Here, we use seminatural populations of Trinidadian guppies to investigate whether sexually selected traits (orange, black and iridescent colouration, gonopodium length and body size) predict fitness measured as the number of grandoffspring, a metric that integrates across fitness components and sexes. Furthermore, we tested whether two potential sources of genetic benefits—major histocompatibility complex (MHC) genotypes and multilocus heterozygosity (MLH)—are significant predictors of fitness and of the size of sexually selected traits. We found a significant, nonlinear effect of the area of black pigmentation and male body size on the number of grandoffspring, suggesting stabilizing selection on black area, and nonlinear selection favouring small body size. MLH was heritable (h2 = 0.14) and significantly predicted the number of grandoffspring, indicating the potential for genetic benefits based on heterozygosity. We also found support for local heterozygosity effects, which may reflect a noneven distribution of genetic load across the genome. MHC genotype was not significantly associated with any tested fitness component, or with the load of Gyrodactylus parasites. Neither MHC nor MLH was significant predictor of sexually selected traits. Overall, our results highlight the role of heterozygosity in determining fitness, but do not provide support for male sexually selected traits being indicators of genetic quality.
Reeve C., Robichaud J.A., Fernandes T., Bates A.E., Bramburger A.J., Brownscombe J.W., Davy C.M., Henry H.A.L., McMeans B.C., Moise E.R.D., Sharma S., Smith P.A., Studd E.K., O’Sullivan A., Sutton A.O., Templer P.H., Cooke S.J. (2023). Applied winter biology: threats, conservation and management of biological resources during winter in cold climate regions. Conservation Physiology, 11(1).

Winter at high latitudes is characterized by low temperatures, dampened light levels and short photoperiods which shape ecological and evolutionary outcomes from cells to populations to ecosystems. Advances in our understanding of winter biological processes (spanning physiology, behaviour and ecology) highlight that biodiversity threats (e.g. climate change driven shifts in reproductive windows) may interact with winter conditions, leading to greater ecological impacts. As such, conservation and management strategies that consider winter processes and their consequences on biological mechanisms may lead to greater resilience of high altitude and latitude ecosystems. Here, we use well-established threat and action taxonomies produced by the International Union of Conservation of Nature—Conservation Measures Partnership (IUCN-CMP) to synthesize current threats to biota that emerge during, or as the result of, winter processes then discuss targeted management approaches for winter-based conservation. We demonstrate the importance of considering winter when identifying threats to biodiversity and deciding on appropriate management strategies across species and ecosystems. We confirm our expectation that threats are prevalent during the winter and are especially important considering the physiologically challenging conditions that winter presents. Moreover, our findings emphasize that climate change and winter-related constraints on organisms will intersect with other stressors to potentially magnify threats and further complicate management. Though conservation and management practices are less commonly considered during the winter season, we identified several potential or already realized applications relevant to winter that could be beneficial. Many of the examples are quite recent, suggesting a potential turning point for applied winter biology. This growing body of literature is promising but we submit that more research is needed to identify and address threats to wintering biota for targeted and proactive conservation. We suggest that management decisions consider the importance of winter and incorporate winter specific strategies for holistic and mechanistic conservation and resource management.
Rincón E., St-hilaire A., Bergeron N.E., Dugdale S.J. (2023). Combining Landsat TIR-imagery data and ERA5 reanalysis information with different calibration strategies to improve simulations of streamflow and river temperature in the Canadian Subarctic. Hydrological Processes, 37(10).

Arctic and Subarctic environments are among the most vulnerable regions to climate change. Increases in liquid precipitation and changes in snowmelt onset are cited as the main drivers of change in streamflow and water temperature patterns in some of the largest rivers of the Canadian Arctic. However, in spite of this evidence, there is still a lack of research on water temperature, particularly in the eastern Canadian Arctic. In this paper, we use the CEQUEAU hydrological-water temperature model to derive consistent long-term daily flow and stream temperature time series in Aux Mélèzes River, a non-regulated basin (41 297 km2) in the eastern Canadian subarctic. The model was forced using reanalysis data from the fifth-generation ECMWF atmospheric reanalyses (ERA5) from 1979 to 2020. We used water temperature derived from thermal infrared (TIR) images as reference data to calibrate CEQUEAU's water temperature model, with calibration performed using single-site, multi-site, and upscaling factors approaches. Our results indicate that the CEQUEAU model can simulate streamflow patterns in the river and shows excellent spatiotemporal performance with Kling-Gupta Efficiency (KGE) metric >0.8. Using the best-performing flow simulation as one of the inputs allowed us to produce synthetic daily water temperature time series throughout the basin, with the multi-site calibration approach being the most accurate with root mean square errors (RMSE) <2.0°C. The validation of the water temperature simulations with a three-year in situ data logger dataset yielded an RMSE = 1.38°C for the summer temperatures, highlighting the robustness of the calibrated parameters and the chosen calibration strategy. This research demonstrates the reliability of TIR imagery and ERA5 as sources of model calibration data in data-sparse environments and underlines the CEQUEAU model as an assessment tool, opening the door to its use to assess climate change impact on the arctic regions of Canada.
Smith K.A., O'Sullivan A.M., Kennedy G., Benz S.A., Somers L.D., Kurylyk B.L. (2023). Shallow groundwater temperature patterns revealed through a regional monitoring well network. Hydrological Processes, 37(9).

Groundwater temperature is a critical control on groundwater quality, geothermal system efficiency and ecosystem dynamics in receiving surface waters. Despite the known importance of groundwater temperature, there is a lack of dedicated aquifer thermal monitoring across spatial and temporal scales. Pressure transducers and other sensors installed in groundwater monitoring well networks often record temperature as a secondary function, but these comprehensive groundwater temperature data sets are seldom analysed. In this study, we analysed seasonal, interannual and spatial patterns of shallow groundwater temperatures from a regional groundwater monitoring network in Nova Scotia, Canada and compared these subsurface temperature data to air temperature data from nearby climate stations using linear regressions and Fourier analysis. The results showed that seasonal groundwater temperatures were damped (with seasonal amplitudes 3.6%–42% of air temperature amplitudes) and lagged (phase shifted 43–145 days) compared to air temperature, with notable year-to-year variations in both damping and lagging. Results also highlighted the role of snowpack thickness on the lowest mean monthly groundwater temperatures. Given potential impacts of climate change, land cover change, urbanization and geothermal energy development on groundwater temperatures, we encourage water authorities and regulators to begin or enhance aquifer thermal monitoring and provide guidance for capitalizing on existing monitoring well infrastructure to track temperature dynamics and changes.
Souaissi Z., Ouarda T.B.M.J., St-Hilaire A. (2023). Non-parametric, semi-parametric, and machine learning models for river temperature frequency analysis at ungauged basins. Ecological Informatics, 75.

River water temperature is essential in regulating many physical and biochemical processes in river systems. Consequently, it is crucial to develop reliable tools for predicting extreme river temperatures at sites with little or no available data. This study aims to compare two machine learning models, random forest (RF) and extreme gradient boosting (XGBoost), with non-parametric multivariate adaptive regression splines (MARS) and semi-parametric generalized additive models (GAMs) for the regional estimation of maximum water temperatures at ungauged locations. Three linear and non-linear approaches are also considered in the homogeneous regions delineation step of regional frequency analysis: canonical correlation analysis (CCA), neural network-based canonical correlation analysis (NLCCA), as well as considering all stations (ALL). The results indicate that GAM and MARS lead to the best performances. The performance of NLCCA+GAM is the best in terms of absolute and relative mean square error, followed by CCA + MARS. A significant improvement in the performance of adopted models is achieved by using neighborhood methods. The two machine learning models are tested using two variable selection methods: Recursive Feature Elimination (RFE) and Least Absolute Shrinkage and Selection Operator (LASSO). The results, however, do not show any significant differences. These results may be indicative of the flexibility and ability of the GAM and MARS approaches to reproduce thermal extremes, especially under real-world conditions when a limited amount of data is available.
Souaissi Z., Ouarda T.B.M.J., St-Hilaire A. (2023). Regional thermal index model for river temperature frequency analysis in ungauged basins. Environmental Modelling and Software, 164.
Souaissi Z., Ouarda T.B.M.J., St-Hilaire A., Ouali D. (2023). Regional frequency analysis of stream temperature at ungauged sites using non-linear canonical correlation analysis and generalized additive models. Environmental Modelling and Software, 163.
St-Hilaire A., Oyinlola M.A., Rincón E., Ferchichi H. (2023). Six decades of research on river temperature in Canada. Canadian Water Resources Journal, 48(4) 450-474.

River temperature is a key water quality variable in rivers and streams, as it modulates many other water quality variables as well as the metabolism, dispersion, and behavior of lotic biota. This paper reviews the key research milestones related to river temperature in Canada. The text focuses mostly on how research has been centrally motivated by the need to better understand and mitigate anthropogenic impacts on the thermal regime of rivers. The need for enhanced water temperature monitoring, both in situ and via remote sensing, especially in the Canadian North, is highlighted.
Velichka J., Kidd K.A., Munkittrick K., Shanmuganathan M., Britz-McKibbin P., Curry R.A. (2023). Elements and omega-3 fatty acids in fishes along a large, dammed river. Environmental Pollution, 336.

Damming of a river can trap and elevate levels of sediment-bound elements and alter food web dynamics in created reservoirs. It follows that dams may alter how elements and other nutrients, like the beneficial omega-3 fatty acids (n-3 FAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are accumulated in fish and thus the chemical composition of species above and below this barrier to migration. This study examined the spatial and species differences in contaminants and nutrients in fish from the Wolastoq | Saint John River (New Brunswick, Canada) in association with a large hydroelectric dam (Mactaquac Generating Station; MQGS), a river which supports both recreational fisheries and subsistence fishing by Indigenous communities. In 2020 and 2021, Smallmouth Bass, Yellow Perch, American Eel, and Striped Bass were collected from locations upstream (reservoir and river) and downstream of the MQGS and analyzed for mercury (Hg) and 30 other trace elements, n-3 FAs, δ15N, and δ13C. Fish from the reservoir were highest in the beneficial elements P, S, and K, while fish from upstream of the reservoir had lower levels of toxic elements, including Hg. The dam appeared to alter food web dynamics, as fish from the reservoir and immediately downstream of the dam had higher δ15N and reservoir fish were depleted in δ13C. DHA and Hg were positively corelated with δ15N, and EPA in Smallmouth Bass was higher in sites where fish had higher δ13C. Overall, this study suggests that the dam altered food web dynamics and the uptake of contaminants and nutrients by fish, and that location and species are important factors when examining the risks and benefits of consuming wild fish from a system impacted by a large dam.
Warner M.G., Andrews S.N., Macmillan J.L., Lowles A.G., Collet K., Curry R.A., Linnansaari T., Stokesbury M.J.W. (2023). Past and Present Distribution and Identification of Extant Native Lake Trout (Salvelinus namaycush) Populations in the Canadian Maritime Provinces. Northeastern Naturalist, 30(mo23) 1-59.

Salvelinus namaycush (Lake Trout) occur in the Canadian Maritime Provinces of New Brunswick and Nova Scotia, and are absent in Prince Edward Island. Lake Trout are assumed to be native in parts of New Brunswick, but their ancestry in Nova Scotia is unknown. Starting in 1886, stocking was used to spread Lake Trout across lakes in the Maritime Provinces to bolster existing populations and to create new fishing opportunities. The success of most stocking efforts was not well documented, and it is presumed that many of these efforts failed. After the early stocking from which some populations persist, little effort has been made to understand the distribution, stock structure, or ancestry of Lake Trout in this region. This review is a synthesis of Lake Trout distribution in the Canadian Maritime Provinces, including a comprehensive account of stocking history, proposed native population occurrence, and identification of populations with variable ancestry. At present, Lake Trout occur in 20 lakes in New Brunswick (19 confirmed and 1 potential), and 4 lakes in Nova Scotia (2 confirmed and 2 potential). Native Lake Trout may persist in 12 of 15 New Brunswick lakes and 3 of 9 Nova Scotia lakes that historically contained ancestral Lake Trout populations. Of these lakes with historical populations that persist to this day, 10 in New Brunswick and 1 in Nova Scotia were supplemented with introduced stock; therefore, only 2 lakes in New Brunswick and 2 in Nova Scotia are likely to still contain purely native Lake Trout. By improving the understanding of population structure and origins, this synthesis provides information that is critical for the effective management and conservation of native Lake Trout in the eastern Maritime region.
Wegscheider B., Monk W.A., Lento J., Haralampides K., Ndong M., Linnansaari T., Allen Curry R. (2023). Developing environmental flow targets for benthic macroinvertebrates in large rivers using hydraulic habitat associations and taxa thresholds. Ecological Indicators, 146.

Holistic environmental flows frameworks are built on our understanding of key flow-ecology relationships that support sensitive taxa and critical ecosystem functions under different flow and water level scenarios. Most research on flow-ecology relationships has typically focused on small systems, with less known about flow associations, indicator taxa, and environmental thresholds of assemblage change along hydraulic gradients of large non-wadeable rivers. We assessed benthic macroinvertebrate assemblage structure and applied Taxa Indicator Threshold ANalysis (TITAN) on biomonitoring data collected during a six-year period in the Wolastoq | Saint John River in Atlantic Canada. Flow velocity was strongly associated with the distribution and relative abundance of benthic macroinvertebrates in the river, and taxon associations reflected functional adaptations to flow. We identified 33 genus-level indicator taxa that were either positively or negatively associated with flow velocity. Weaker taxa responses were shown for the gradient in median substrate particle size where 22 negatively and positively responding taxa were identified. We predicted changes in indicator taxon abundance under different flow scenarios using a hydrodynamic model, and characterised the distribution and availability of suitable hydraulic habitat patches within a 20 km reach downstream of a large hydropower generating station. These observations set the stage for the development of ecologically-based flow targets to support holistic environmental flow management in large rivers.
Wynne R., Kaufmann J., Coughlan J., Phillips K.P., Waters C., Finlay R.W., Rogan G., Poole R., McGinnity P., Reed T.E. (2023). Autumn outmigrants in brown trout (Salmo trutta) are not a demographic dead-end. Journal of Fish Biology, 102(6) 1327-1339.

Genetic identity analysis and PIT (passive integrated transponder) tagging were used to examine the freshwater return rates and phenotypic characteristics of n = 1791 downstream migrating juvenile Salmo trutta in the Burrishoole catchment (northwest Ireland) across the period September 2017 to December 2020. In this system, juveniles out-migrate (move from freshwater into brackish or marine habitats) in every month of the year, with distinct seasonal peaks in spring (March through June; mostly silvered smolts) and autumn (September through December; mostly younger, unsilvered fry or parr). Both types exhibited a sex-bias towards females, which was stronger in spring (78% females) than in autumn outmigrants (67%). Sixty-nine returning fish were matched back to previous juvenile outmigrants, and similar return rates were found for spring outmigrants (5.0%), autumn outmigrants (3.3%) and fish that out-migrated outside of spring or autumn (2.8%). Spring and autumn outmigrants returned at similar dates (typically mid to late July), but autumn fish were away for longer periods (median = 612 days; spring outmigrants = 104 days). Autumn outmigrants were 25% smaller than spring outmigrants at outmigration and 6% smaller on their return, and within both groups smaller/younger outmigrants spent longer away than larger/older outmigrants. Autumn outmigrants were more likely to return unsilvered as “slob” trout (84%) than spring outmigrants (31%), suggesting they make greater use of brackish habitats that might be safer, but less productive, than fully marine habitats. Nonetheless, both types also produced silvered “sea trout” (≥1+ sea-age), implying neither is locked into a single life-history strategy. The findings emphasise that autumn outmigrants and the transitional habitats that support their persistence should not be overlooked in salmonid management and conservation.
Yun T., Butler K.E., Macquarrie K.T.B. (2023). Investigation of seepage near the interface between an embankment dam and a concrete structure: monitoring and modelling of seasonal temperature trends. Canadian Geotechnical Journal, 60(4) 453-470.

Seasonal subsurface temperature monitoring, which exploits the fact that increased seepage flow may locally alter the temperature distribution, is a useful approach for leakage monitoring and evaluation within embankment dams and their foundations. At the Mactaquac Generating Station, New Brunswick, Canada, spatial and temporal variations of temperature have been monitored and modelled at the steeply inclined interface between the compacted clay till core of the embankment dam and an abutting concrete diversion sluiceway. Over a 4-year period, two seasonally recurring anomalies at different depths were observed by fibre optic distributed temperature sensing in the concrete structure close to the interface. A 3D coupled flow and heat transport model was developed in FEFLOW to simulate temperature distribution within the dam resulting from seasonal variations in air and reservoir temperature. Leakage zones near the interface were simulated in the concrete and embankment. At a depth of 13 m below the crest, the significant lag time between temperature variations in the reservoir and dam core shows that the leakage responsible for an observed temperature anomaly must be limited to enhanced flow within the concrete. At much shallower depths, where seasonal reservoir and dam core temperatures fluctuate nearly in phase, seepage paths are more challenging to determine.
Zelman K., Harrison P., O'Sullivan A.M., Andrews S., Peake S., Linnansaari T., Pavey S.A., Curry R.A. (2023). Reproductive ecology of muskellunge (Esox masquinongy), an introduced predator, in the lower Wolastoq/Saint John River, New Brunswick, Canada. Journal of Fish Biology, 102(3) 643-654.

Introduced predators can have harmful top-down effects on their newly colonized system through competition with and direct predation on native species. Following an initial introduction of muskellunge in Lac Frontière, Québec in the 1970s at the headwaters of the Wolastoq/Saint John River, the species rapidly migrated downstream, expanding its range by ~500 km over ~20 years. Despite this expansive colonization and concern over possible threats to native species, little is known about the basic ecology of muskellunge in this system. The last downstream barrier is the hydroelectric facility, Mactaquac Generating Station (MGS), 150 km upstream of the sea. While there are no downstream fish passage facilities at MGS, adult muskellunge have been recorded downstream. In this study, muskellunge (n = 23) were surgically tagged with very-high-frequency (VHF) radio or combined acoustic radio telemetry (CART) tags and tracked over two spawning seasons. We sought to determine if there was a reproducing population downstream of MGS and tracked Tagged muskellunge over two spawning seasons. We tracked fish to locate and confirm spawning sites, and followed up with egg and/or juvenile sampling surveys. Tagged muskellunge (90%) moved upstream towards the MGS during the spawning period in each year (2016 and 2017), where they remained throughout the entire spawning period. No spawning or nursery sites were confirmed near MGS, but in 2016 three distinct spawning locations and six distinct nursery sites were confirmed 10–12 km downstream amongst a chain of flooded islands. In 2016, eggs, sac-fry and juveniles were collected and confirmed as muskellunge by genetic sequencing, providing the first empirical observation of successful spawning downstream of MGS.
Alfredsen K., Amundsen P.A., Hahn L., Harrison P.M., Helland I.P., Martins E.G., Twardek W.M., Power M. (2022). A synoptic history of the development, production and environmental oversight of hydropower in Brazil, Canada, and Norway. Hydrobiologia, 849(2) 269-280.

Sustainable global energy production is back-stopped by hydropower which is responsible for a significant share of the green energy produced worldwide. Hydropower, however, does not come without some environmental impacts but has worked to reduce those impacts. Here, we discuss the historical, legislative, and design configurations of hydropower facilities located in three of the world’s most important producers: Brazil, Canada, and Norway. The background is intended to inform the collection of scientific papers from each country aimed at assessing and improving the sustainability of hydropower production that form the core of this special issue on sustainable hydropower. We review the development and key legislative history for hydropower in each country and point out the common backgrounds and interests each nation has in the continued sustainable development of its hydropower resources.
Barrett T.J., Hordyk A.R., Barrett M.A., van den Heuvel M.R. (2022). Spatial and temporal differences in fecundity of Atlantic herring (Clupea harengus) off Nova Scotia and consequences for biological reference points. Canadian Journal of Fisheries and Aquatic Sciences, 79(7) 1086-1096.

The relationships between fecundity and size of Atlantic herring (Clupea harengus) were estimated within five different spawning areas off the coast of Nova Scotia in 2019 and 2020. Statistically significant differences in fecundity relative to body weight were observed among spawning areas and between years. Fecundity-at-length on the German Bank spawning ground was 29%–36% and 22%–28% lower than estimates from 2001 and 1970, respectively. Temporal changes in weight-and relative fecundity-at-age resulted in a decrease in the number of eggs-per-recruit (in an equilibrium unfished state) by 50% and a decrease of 27% in the egg production per tonne of spawning stock biomass (SSB) in 2020 relative to 1970. Decreases in SSB-per-recruit and eggs-per-recruit over time resulted in proportional decreases in equilibrium SSB at maximum sustainable yield (MSY); however, the fishing mortality rate (F) at MSY remained relatively stable over time. Total egg production was shown to be disproportional to SSB. Equilibrium SSB at MSY was greater (and F at MSY lower) when estimated using eggs-per-recruit compared to SSB-per-recruit. Failing to account for fecundity and assuming that egg production is proportional to SSB resulted in an overestimate of stock status.
Bartlett A.D., Lavery J.M., Nafziger J., Cunjak R.A. (2022). A rapid classification tool for deformities in Atlantic salmon (Salmo salar) embryos. Journal of Fish Biology, 101(1) 317-322.

Deformities in fish embryos are important for their survival in later life stages. However, a consistent way to refer to and classify salmonid embryo deformities does not exist. Expanding on reports of alevin deformities, we developed a classification tool for distinguishing the deformities observed in a collection of preserved Atlantic salmon (Salmo salar) embryos. Deformities were classified based on the deformed body part and a qualitative subtype. This classification tool uses external morphology, requires minimal equipment and can be applied from the first appearance of optic vesicles to hatch.
Beach D.G., Bruce M., Lawrence J., McCarron P. (2022). Rapid Quantitation of Anatoxins in Benthic Cyanobacterial Mats Using Direct Analysis in Real-Time-High-Resolution Tandem Mass Spectrometry. Environmental Science and Technology, 56(19) 13837-13844.

Toxic benthic cyanobacterial mats are increasingly reported worldwide as being responsible for animal mortalities due to their production of the potent neurotoxin anatoxin-a (ATX) and its analogues. Improved analytical methods for anatoxins are needed to address public health and watershed management challenges arising from extremely high spatial and temporal variability within impacted systems. We present the development, validation, and application of a direct analysis in real-time-high-resolution tandem mass spectrometry (DART-HRMS/MS) method for analysis of anatoxins in cyanobacterial field samples, including a simplified sample preparation approach. The method showed excellent sensitivity and selectivity for ATX, homoanatoxin-a, and dihydroanatoxin-a. Isotopically labeled ATX was used as an internal standard for all three analogues and successfully corrected for the matrix effects observed (86 ± 16% suppression). The limit of detection and recovery for ATX was estimated as 5 ng/g and 88%, respectively, using spiked samples. The total analysis time was ∼2 min, and excellent agreement was observed with results from a liquid chromatography-HRMS reference method. Finally, the DART-HRMS/MS method was applied to a set of 45 Microcoleus-dominated benthic cyanobacterial mat samples from the Wolastoq near Fredericton, Canada, demonstrating its power and applicability in enabling broad-scale field studies of ATX distribution.
Boudreault J., Bergeron N.E., St-Hilaire A., Chebana F. (2022). A new look at habitat suitability curves through functional data analysis. Ecological Modelling, 467.

Habitat suitability curves (HSC) synthesize the preference of a species for important habitat variables and are, therefore, key components of various fish habitat models. However, HSC are developed at large scales (e.g. river or regional scales) that do not consider the differences that exist in available habitat conditions at smaller scales. To address this problem, a new look at HSC is taken through functional data analysis (FDA). It is an appropriate framework adapted for HSC construction because in FDA, each observation is a curve or a function. To illustrate the potential of FDA for HSC, a dataset of Atlantic salmon (Salmo salar) parr density and habitat variables constructed on two rivers was used. Functional regression models (FRM) were built to predict site-specific HSC based on the available habitat conditions for three salmon parr habitat variables: water depth, mean flow velocity and median substrate size. FRM explained a greater proportion of the variation in site-specific HSC (respectively 38.0%, 53.3% and 45.5% for depth, substrate size and velocity) compared to traditional HSC developed at the scale of each river or regionally that poorly fitted site-specific HSC. When HSC were aggregated into habitat suitability indices (HSI), weak relationships were found between HSI and parr density (R2 < 5%) for all models (traditional HSC and FRM). This study demonstrates that FDA is an innovative framework that can be used to predict more representative site-specific HSC adapted to differences in local available habitat. The results suggested that its potential should be further exploited in habitat modelling.
Brittain J.E., Heino J., Friberg N., Aroviita J., Kahlert M., Karjalainen S.M., Keck F., Lento J., Liljaniemi P., Mykrä H., Schneider S.C., Ylikörkkö J. (2022). Ecological correlates of riverine diatom and macroinvertebrate alpha and beta diversity across Arctic Fennoscandia. Freshwater Biology, 67(1) 49-63.

Arctic freshwaters support biota adapted to the harsh conditions at these latitudes, but the climate is changing rapidly and so are the underlying environmental filters. Currently, we have limited understanding of broad-scale patterns of Arctic riverine biodiversity and the correlates of α- and β-diversity. Using information from a database set up within the scope of the Arctic Council's Conservation of Arctic Flora and Fauna Circumpolar Biodiversity Monitoring Plan, we analysed patterns and correlates of α- and β-diversity in benthic diatom and macroinvertebrate communities across northern Norway, Sweden, and Finland. We analysed variation in total β-diversity and its replacement and richness difference components in relation to location of the river reach and its drainage basin (Baltic Sea in the south, the Barents Sea in the east and the north, and the Norwegian Sea in the west), in addition to climate and environmental variables. In both macroinvertebrates and diatoms, the replacement and richness difference components showed wide variation. For macroinvertebrates, the richness difference component was the more important, whereas for diatoms, the replacement component was the more important in contributing to variation in β-diversity. There was no significant difference in β-diversity between the three main drainage basins, but species composition differed among the drainage basins. Based on the richness difference component of β-diversity, climate variables were most strongly associated with community variation in macroinvertebrates. In diatoms, both environmental and climate variables were strongly correlated with community compositional variation. In both groups, there were also significant differences in α-diversity among the three main drainage basins, and several taxa were significant indicators of one of these drainage basins. Alpha diversity was greater in areas with a continental climate, while the oceanic areas in the west harboured greatly reduced flora and fauna. The correlates of biodiversity were relatively similar in macroinvertebrates and diatoms. Climate variables, in particular temperature, were the most strongly associated with biodiversity patterns in the Arctic rivers of Fennoscandia. Sedimentary geology may be associated with increased productivity and, to a lesser extent, with sensitivity to acidification. There was considerable variation in community composition across Arctic Fennoscandia, indicating the necessity of protecting several stream reaches or even whole catchments within each region to conserve total riverine biodiversity. Furthermore, it is likely that the predicted changes in temperature in Arctic areas will influence riverine diversity patterns across Fennoscandia.
Brown C.J.M., Curry R.A., Gray M.A., Lento J., MacLatchy D.L., Monk W.A., Pavey S.A., St-Hilaire A., Wegscheider B., Munkittrick K.R. (2022). Considering Fish as Recipients of Ecosystem Services Provides a Framework to Formally Link Baseline, Development, and Post-operational Monitoring Programs and Improve Aquatic Impact Assessments for Large Scale Developments. Environmental Management, 70(2) 350-367.

In most countries, major development projects must satisfy an Environmental Impact Assessment (EIA) process that considers positive and negative aspects to determine if it meets environmental standards and appropriately mitigates or offsets negative impacts on the values being considered. The benefits of before-after-control-impact monitoring designs have been widely known for more than 30 years, but most development assessments fail to effectively link pre- and post-development monitoring in a meaningful way. Fish are a common component of EIA evaluation for both socioeconomic and scientific reasons. The Ecosystem Services (ES) concept was developed to describe the ecosystem attributes that benefit humans, and it offers the opportunity to develop a framework for EIA that is centred around the needs of and benefits from fish. Focusing an environmental monitoring framework on the critical needs of fish could serve to better align risk, development, and monitoring assessment processes. We define the ES that fish provide in the context of two common ES frameworks. To allow for linkages between environmental assessment and the ES concept, we describe critical ecosystem functions from a fish perspective to highlight potential monitoring targets that relate to fish abundance, diversity, health, and habitat. Finally, we suggest how this framing of a monitoring process can be used to better align aquatic monitoring programs across pre-development, development, and post-operational monitoring programs.
Bryson G.E., Kidd K.A., Samways K.M. (2022). Food web incorporation of marine-derived nutrients after the reintroduction of endangered inner Bay of Fundy Atlantic salmon (Salmo salar). Canadian Journal of Fisheries and Aquatic Sciences, 79(6) 875-882.

Inner Bay of Fundy Atlantic salmon (Salmo salar) are endangered anadromous fish that have the potential to provide marine-derived nutrients (MDNs) to freshwater ecosystems depending on their population abundance. Salmon have been reintroduced to the Upper Salmon River, but not to the adjacent Point Wolfe River, in Fundy National Park, New Brunswick, Canada. This study determined whether stocking of adult salmon increased the productivity of the river. To examine the incorporation of MDNs, biofilm, leaf litter, Perlidae, Heptageniidae and brook trout (Salvelinus fontinalis) were sampled pre-and post-spawning in 2015–2017 from down-and upstream of a natural barrier in both rivers and analyzed for carbon (d13 C) and nitrogen (d15 N) isotopes. After salmon spawning in each year, all organisms at the downstream site of the stocked river increased in d13 C and d15 N, with the greatest enrichment in brook trout (d13 C: 23.97% to 21.10%, d15 N: +6.36% to +10.73%). The proportion of MDNs in brook trout after salmon spawning (2015: 23.4%, 2016: 40.7%, 2017: 37.4%) also increased with higher numbers of released adult salmon. Results support the importance of salmon restoration for increasing the proportion of MDNs and productivity in rivers in Atlantic Canada.
Charbonneau K.L., Kidd K.A., Kreutzweiser D.P., Sibley P.K., Emilson E.J.S., O'Driscoll N.J., Gray M.A. (2022). Are There Longitudinal Effects of Forest Harvesting on Carbon Quality and Flow and Methylmercury Bioaccumulation in Primary Consumers of Temperate Stream Networks? Environmental Toxicology and Chemistry, 41(6) 1490-1507.

Forest harvesting affects dissolved organic matter (DOM) and aqueous mercury inputs as well as the food web structure in small-headwater streams, but how these upstream changes manifest downstream is unclear. To address this uncertainty, we examined DOM quality, autochthony in the caddisfly Hydropsychidae (using δ2H), and methylmercury (MeHg) concentrations in stream water and the caddisfly along a longitudinal gradient (first- to fourth-order streams, subcatchments of 50–1900 ha) in paired partially harvested and reference catchments in central Ontario, Canada. Although measures of DOM quality (specific ultraviolet absorbance at 254 nm 2.20–11.62) and autochthony in caddisflies (4.9%–34.0%) varied among sites, no upstream-to-downstream differences in these measures were observed between the paired harvested and reference catchments. In contrast, MeHg levels in stream water (0.06–0.35 ng/L) and caddisflies (29.7–192 µg/kg dry wt) were significantly higher in the upstream sites but not the farthest downstream sites in the harvested catchments compared to the reference catchments. This suggests that while current mitigation measures used by forestry companies did not prevent elevated MeHg in water and invertebrates at smaller spatial scales (subcatchments of 50–400 ha), these upstream impacts did not manifest at larger spatial scales (subcatchments of 800–1900 ha). The present study advances our understanding of spatially cumulative impacts within harvested catchments, which is critical to help forest managers maintain healthy forest streams and their provisioning of aquatic ecosystem services. Environ Toxicol Chem 2022;41:1490–1507. © 2022 SETAC.
Compson Z.G., Monk W.A., Sarremejane R., DelVecchia A.G., Burrows R.M., Gao S., Ruddell B.L., Hong Y., Allen D.C. (2022). Dryland Rivers and Streams. Encyclopedia of Inland Waters Second Edition, 2 616-627.

We outline key features of dryland rivers and illustrate how they differ from temperate and tropical rivers, identify gaps in the understanding of dryland rivers, and illustrate how the functioning of these systems is expected to vary under human impacts. The main concepts we cover are (1) defining dryland rivers and distinguishing them from temperate and tropical rivers, (2) exploring the geomorphological, hydrological, and biological processes of dryland rivers, (3) illustrating how dryland rivers fit into the context of riparian forests and how the aquatic and terrestrial components of these systems interact, and (4) detailing how the functioning of dryland rivers is expected to change in the context of anthropogenic drivers, including climate change. We demonstrate key features of dryland rivers, including their high hydrological and geomorphological variation, how the biotic components of these systems are adapted to this variability, and how anthropogenic changes are likely to impact the functioning and aquatic-terrestrial linkages characteristic of these ecosystems. We identify knowledge gaps where research on dryland rivers is needed, particularly in arctic regions and areas experiencing intense human pressures driven by urbanization, deforestation, and agricultural development. We further highlight how common features of dryland rivers (e.g., high degree of seasonal variability, habitat fragmentation caused by disconnected flows) make them ideal systems for studying emerging ideas derived from metacommunity theory. Despite their clear ecological importance, recent political efforts to restrict what falls under the purview of the Clean Water Act by removing dryland rivers from these protections demonstrate ongoing threats to their health and persistence, especially in densely populated regions that rely on these systems for water provisioning and flood control. Bringing awareness to these systems and the key ecosystem services and functions they perform is critical for their conservation and protection.
Costello D.M., Tiegs S.D., Boyero L., Canhoto C., Capps K.A., Danger M., Frost P.C., Gessner M.O., Griffiths N.A., Halvorson H.M., Kuehn K.A., Marcarelli A.M., Royer T.V., Mathie D.M., Albariño R.J., Arango C.P., Aroviita J., Baxter C.V., Bellinger B.J., Bruder A., Burdon F.J., Callisto M., Camacho A., Colas F., Cornut J., Crespo-Pérez V., Cross W.F., Derry A.M., Douglas M.M., Elosegi A., de Eyto E., Ferreira V., Ferriol C., Fleituch T., Follstad Shah J.J., Frainer A., Garcia E.A., García L., García P.E., Giling D.P., Gonzales-Pomar R.K., Graça M.A.S., Grossart H.P., Guérold F., Hepp L.U., Higgins S.N., Hishi T., Iñiguez-Armijos C., Iwata T., Kirkwood A.E., Koning A.A., Kosten S., Laudon H., Leavitt P.R., Lemes da Silva A.L., Leroux S.J., LeRoy C.J., Lisi P.J., Masese F.O., McIntyre P.B., McKie B.G., Medeiros A.O., Miliša M., Miyake Y., Mooney R.J., Muotka T., Nimptsch J., Paavola R., Pardo I., Parnikoza I.Y., Patrick C.J., Peeters E.T.H.M., Pozo J., Reid B., Richardson J.S., Rincón J., Risnoveanu G., Robinson C.T., Santamans A.C., Simiyu G.M., Skuja A., Smykla J., Sponseller R.A., Teixeira-de Mello F., Vilbaste S., Villanueva V.D., Webster J.R., Woelfl S., Xenopoulos M.A., Yates A.G., Yule C.M., Zhang Y., Zwart J.A. (2022). Global Patterns and Controls of Nutrient Immobilization on Decomposing Cellulose in Riverine Ecosystems. Global Biogeochemical Cycles, 36(3).

Microbes play a critical role in plant litter decomposition and influence the fate of carbon in rivers and riparian zones. When decomposing low-nutrient plant litter, microbes acquire nitrogen (N) and phosphorus (P) from the environment (i.e., nutrient immobilization), and this process is potentially sensitive to nutrient loading and changing climate. Nonetheless, environmental controls on immobilization are poorly understood because rates are also influenced by plant litter chemistry, which is coupled to the same environmental factors. Here we used a standardized, low-nutrient organic matter substrate (cotton strips) to quantify nutrient immobilization at 100 paired stream and riparian sites representing 11 biomes worldwide. Immobilization rates varied by three orders of magnitude, were greater in rivers than riparian zones, and were strongly correlated to decomposition rates. In rivers, P immobilization rates were controlled by surface water phosphate concentrations, but N immobilization rates were not related to inorganic N. The N:P of immobilized nutrients was tightly constrained to a molar ratio of 10:1 despite wide variation in surface water N:P. Immobilization rates were temperature-dependent in riparian zones but not related to temperature in rivers. However, in rivers nutrient supply ultimately controlled whether microbes could achieve the maximum expected decomposition rate at a given temperature. Collectively, we demonstrated that exogenous nutrient supply and immobilization are critical control points for decomposition of organic matter.
Culp J.M., Goedkoop W., Christensen T., Christoffersen K.S., Fefilova E., Liljaniemi P., Novichkova A.A., Ólafsson J.S., Sandøy S., Zimmerman C.E., Lento J. (2022). Arctic freshwater biodiversity: Establishing baselines, trends, and drivers of ecological change. Freshwater Biology, 67(1) 1-13.

Climate change is predicted to have dramatic effects on Arctic freshwater ecosystems through changes to the abiotic template that are expected to influence biodiversity. Changes are already ongoing in Arctic systems, but there is a lack of coordinated monitoring of Arctic freshwaters that hinders our ability to assess changes in biodiversity. To address the need for coordinated monitoring on a circumpolar scale, the Arctic Council working group, Conservation of Arctic Flora and Fauna, established the Circumpolar Biodiversity Monitoring Program, which is an adaptive monitoring program for the Arctic centred around four ecosystem themes (i.e., Freshwater, Terrestrial, Coastal, Marine). The freshwater theme developed a monitoring plan for Arctic freshwater biodiversity and recently completed the first assessment of status and trends in Arctic freshwater biodiversity. Circumpolar Biodiversity Monitoring Program–Freshwater has compiled and analysed a database of Arctic freshwater monitoring data to form the first report of the state of circumpolar Arctic freshwater biodiversity. This special issue presents the scientific analyses that underlie the Circumpolar Biodiversity Monitoring Program–Freshwater report and provides analyses of spatial and temporal diversity patterns and the multiple-stressor scenarios that act on the biological assemblages and biogeochemistry of Arctic lakes and rivers. This special issue includes regional patterns for selected groups of organisms in Arctic rivers and lakes of northern Europe, Russia, and North America. Circumpolar assessments for benthic diatoms, macrophytes, plankton, benthic macroinvertebrates, and fish demonstrate how climate change and associated environmental drivers affect freshwater biodiversity. Also included are papers on spatial and temporal trends in water chemistry across the circumpolar region, and a systematic review of documented Indigenous Knowledge that demonstrates its potential to support assessment and conservation of Arctic freshwaters. This special issue includes the first circumpolar assessment of trends in Arctic freshwater biodiversity and provides important baseline information for future assessments and studies. It represents the largest compilation and assessment of Arctic freshwater biodiversity data to date and strives to provide a holistic view of ongoing change in these ecosystems to support future monitoring efforts. By identifying gaps in monitoring data across the circumpolar region, as well as identifying best practices for monitoring and assessment, this special issue presents an important resource for researchers, policy makers, and Indigenous and local communities that can support future assessments of ecosystem change.
Culp J.M., Lento J. (2022). High Latitude Rivers: Ecosystems Shaped by Environmental Extremes. Encyclopedia of Inland Waters Second Edition, 2 586-597.

Aim The unique aspects of high latitude rivers are discussed including environmental drivers of biotic structure and function, and the effects of development and climate warming on these ecosystems. Ecology of high latitude rivers The physical-chemical environment of these rivers is dominated by cold temperatures and river ice. Spring ice breakup creates intense disturbance that affects the substrate and water chemistry. Nutrient limitation typically limits primary production and heterotrophic processes often dominate ecosystem metabolism, which supports benthic invertebrate and fish production. Diversity of benthos and fish decreases at higher latitudes due to cold temperatures and barriers to colonization. Many fish species are important food sources for Indigenous Peoples. Climate change effects on biodiversity Climate-related increases in water temperature cause changes in diversity as species physiological tolerances are exceeded and other species extend their ranges northward. Permafrost thaw mobilizes nutrients and major ions that can increase ecosystem productivity, while mud slurries from thaw slumps can transport large amounts of terrestrial material into stream systems. Effects of human development High latitude rivers receive contaminants from various sources including atmospheric transport, mineral extraction, landuse change, road development, wastewater discharge, and hydropower generation. Pollutant impacts include biomagnification, acid deposition and altered water chemistry. Conclusion Climate warming will cause substantial change to high latitude river ecosystems and associated flora and fauna. Permafrost thaw mobilizes various nutrients and produces thaw slump sedimentation. The cumulative effects of climate change and pollution will be difficult to predict. Improved baseline knowledge of these ecosystems is needed to advance the ability to model and forecast future ecosystem state.
Dadswell M., Spares A., Reader J., McLean M., McDermott T., Samways K., Lilly J. (2022). The Decline and Impending Collapse of the Atlantic Salmon (Salmo salar) Population in the North Atlantic Ocean: A Review of Possible Causes. Reviews in Fisheries Science and Aquaculture, 30(2) 215-258.

Adult returns to many Atlantic salmon wild and hatchery stocks of the North Atlantic have declined or collapsed since 1985. Enhancement, commercial fishery closures, and angling restrictions have failed to halt the decline. Human impacts such as dams, pollution or marine overexploitation were responsible for some stock declines in the past, but adult returns to river and hatchery stocks with no obvious local impacts have also declined or collapsed since 1985. Multiple studies have postulated that the recent widespread occurrence of low adult returns may be caused by climate change, salmon farming, food availability at sea, or marine predators but these possibilities are unsupported by stocks that persist near historic levels, loss of stocks remote from farm sites, a diverse marine prey field, and scarcity of large offshore predators. The decline and collapse of stocks has common characteristics: 1) cyclic annual adult returns cease, 2) annual adult returns flatline, 3) adult mean size declines, and 4) stock collapses occurred earliest among watersheds distant from the North Atlantic Sub-polar Gyre (NASpG). Cyclic annual adult returns were common to all stocks in the past that were not impacted by anthropogenic changes to their natal streams. A flatline of adult abundance and reduction in adult mean size are common characteristics of many overexploited fish stocks and suggest illegal, unreported, and unregulated (IUU) fisheries exploitation at sea. Distance from the NASpG causing higher mortality of migrating post-smolts would increase the potential for collapse of these stocks from IUU exploitation. By-catch of post-smolts and adults in paired-trawl fisheries off Europe and intercept adult fisheries off Greenland, in the Gulf of St. Lawrence, and off Europe have been sources of marine mortality but seem unlikely to be the primary cause of the decline. Distribution in time and space of former, legal high-sea fisheries indicated fishers were well acquainted with the ocean migratory pattern of salmon and combined with lack of surveillance since 1985 outside Exclusive Economic Zones or in remote northern regions may mean high at-sea mortality occurs because of IUU fisheries. The problem of IUU ocean fisheries is acute, has collapsed numerous stocks of desired species worldwide, and is probably linked to the decline and impending collapse of the North Atlantic salmon population.
Danielescu S., MacQuarrie K.T.B., Zebarth B., Nyiraneza J., Grimmett M., Levesque M. (2022). Crop Water Deficit and Supplemental Irrigation Requirements for Potato Production in a Temperate Humid Region (Prince Edward Island, Canada). Water Switzerland, 14(17).

The global increase in potato production and yield is expected to lead to increased irrigation needs and this has prompted concerns with respect to the sustainability of irrigation water sources, such as groundwater. The magnitude, and inter- and intra-annual variation, of the crop water requirements and irrigation needs for potato production together with their impact on aquifer storage in a temperate humid region (Prince Edward Island, Canada) were estimated by using long-term (i.e., 2010–2019) daily soil water content (SWC). The amount of supplemental irrigation required for the minimal irrigation scenario (SWC = 70% of field capacity; 0.7 FC) was relatively small (i.e., 17.0 mm); however, this increased significantly, to 85.2 and 189.6 mm, for the moderate (SWC = 0.8 FC) and extensive (SWC = 0.9 FC) irrigation scenarios, respectively. The water supply requirement for the growing season (GS) increased to 154.9 and 344.7 mm for a moderately efficient irrigation system (55% efficiency) for the SWC = 0.8 FC and SWC = 0.9 FC irrigation scenarios, respectively. Depending on the efficiency and the areal extent of the irrigation system, the irrigation water supply requirement can approach or exceed both the GS and annual groundwater recharge. The methodology developed in this research has been translated into a free online tool (SWIB—Soil Water Stress, Irrigation Requirement and Water Balance), which can be applied to other areas or crops where an estimation of soil water deficit and irrigation requirement is sought.
Erdozain M., Kidd K.A., Emilson E.J.S., Capell S.S., Kreutzweiser D.P., Gray M.A. (2022). Elevated Allochthony in Stream Food Webs as a Result of Longitudinal Cumulative Effects of Forest Management. Ecosystems, 25(6) 1311-1327.

The river continuum concept (RCC) predicts a downstream shift in the reliance of aquatic consumers from terrestrial to aquatic carbon sources, but this concept has rarely been assessed with longitudinal studies. Similarly, there are no studies addressing how forestry related disturbances to the structure of headwater food webs manifest (accumulate/dissipate) downstream and/or whether forest management alters natural longitudinal trends predicted by the RCC. Using stable isotopes of carbon, nitrogen and hydrogen, we investigated how: 1) autochthony in macroinvertebrates and fish change from small streams to larger downstream sites within a basin with minimal forest management (New Brunswick, Canada); 2) longitudinal trends in autochthony and food web length compare among three basins with different forest management intensity [intensive (harvest and replanting), extensive (harvest only), minimal] to detect potential cumulative/dissipative effects; and 3) forest management intensity and other catchment variables are influencing food web dynamics. We showed that, as predicted, the reliance of some macroinvertebrate taxa (especially collector feeders) on algae increased from small streams to downstream waters in the minimally managed basin, but that autochthony in the smallest shaded stream was higher than expected based on the RCC (as high as 90% for some taxa). However, this longitudinal increase in autochthony was not observed within the extensively managed basin and was weaker within the intensively managed one, suggesting that forest management can alter food web dynamics along the river continuum. The dampening of downstream autochthony indicates that the increased allochthony observed in small streams in response to forest harvesting cumulates downstream through the river continuum.
Erdozain M., Kidd K.A., Negrazis L., Capell S.S., Kreutzweiser D.P., Gray M.A., Emilson E.J.S. (2022). Understanding the effects of forest management on streams and rivers: A synthesis of research conducted in New Brunswick (Canada) 2014–2018. Forestry Chronicle, 98(1) 77-88.

Forests play a major role in maintaining healthy streams and in providing ecosystem services such as clean drinking water, flood/drought protection and biodiversity, but studies have shown that some forestry operations can compromise these benefits. To assess whether current forest management practices impact stream ecosystems, a five-year study was conducted in J.D. Irving, Limited’s Black Brook Forestry District (New Brunswick, Canada) and in other watersheds with varying forest management intensity. This study was divided into two phases, with each addressing one main research question: 1) how different intensities of forest management affect the ecological health of headwater streams and, 2) whether the changes observed in headwater streams accumulate or dissipate in larger downstream rivers. A comprehen-sive approach to examining these research questions was taken by measuring multiple abiotic and biotic indicators to assess the integrity of stream ecosystems (sediments, water chemistry, insect communities, leaf decomposition, fish con-dition, mercury concentrations). The purpose of this paper is: 1) to synthesize the results of numerous scientific articles, and 2) to present the science and management implications in terms that regulatory and industrial forest managers can use to incorporate the lessons learned into their decision making. Results in Phase I show that streams in the most intensively managed catchments had greater inputs of terrestrial materials such as sediments, and these were incorporated into food webs, resulting in more terrestrial diets of aquatic consumers. The important stream function of leaf litter breakdown was negatively influenced by increased management intensity. Management practices related to roads warrant spe-cial attention, as roads tended to be more related to changes in stream indicators than tree removal. Additionally, results suggest that wet riparian areas were more sensitive to disturbance than drier riparian areas, which has implications for riparian buffer zone configurations. Regarding Phase II, some of the effects of forest management on small streams accu-mulated in larger downstream rivers (e.g., sediments, use of terrestrial resources by aquatic organisms), while others dis-sipated (e.g., water temperature, mercury contents). Interestingly, the impacts of forest management on streams were greater in the basin with tree removal but less silviculture than in the basin with more of both, suggesting that greater overall intensity of forest practices does not necessarily translate into greater environmental impacts, for example when considering partial versus clearcut harvesting. Overall, the study suggests that while current best management practices do not eliminate all effects, they do still offer good protection of biological integrity downstream.
Ferchichi H., St-Hilaire A., Ouarda T.B.M.J., Benoît Lévesque (2022). Prediction of Coastal Water Temperature Using Statistical Models. Estuaries and Coasts, 45(7) 1909-1927.

Water temperature plays an important role in the equilibrium of the aquatic system and the overall health of aquaculture biota. Two machine learning models (random forests and artificial neural network) and regression model (multiple linear regression) were developed to estimate coastal sea surface temperatures (SST) in the Estuary and Gulf of St. Lawrence (Eastern Canada) after being trained on in situ data from available stations. The SST prediction is formulated as a regression model in function of a selected set of predictors. Different measures of correlation were used to examine the evolution of the SST as a function of meteorological (air temperature and wind speed), oceanographic (tidal range), and hydrological (flow) variables as well as teleconnection patterns in order to select the best inputs for the tested models. This study tested the abilities of commonly used regression model (Multiple Linear Regression) and machine learning models (Random Forests and Artificial Neural Network) to predict the daily SST, given the most relevant predictors. The results showed the importance of the selected predictors in SST prediction accuracy using the machine learning models, given that they capture the complex and non-linear relationship between the targeted SST and explanatory variables. The ANN model had shown the lowest root-mean-square error (RMSE) ranging between 0.82 °C and 2.64 °C, with an overall RMSE of 1.72 °C across all the stations against 1.96 °C using the RF.
Frenette A.P., Benfey T.J., Burt M.D.B., Duffy M.S. (2022). Experimental Loma morhua (Microsporidia) infections reveal early-onset production implications for Atlantic cod (Gadus morhua) aquaculture. Aquaculture, 549.

Widespread Loma morhua (Microsporidia) epizootics in cultured Atlantic cod populations have been linked to reduced immune function and growth. Importantly, the lack of appropriate diagnostics and basic knowledge of the L. morhua life-cycle have limited the development of disease management strategies for mitigating infection during aquaculture. As a consequence, L. morhua epizootics are commonplace within hatchery facilities and during net-pen grow-out and limit commercialization of cod culture. Herein, we detail experimental L. morhua infections in naïve Atlantic cod to mimic infection phenotypes observed during natural epizootics, to better validate diagnostic procedures and to understand the effect parasitism has on cod growth. An integrative approach for parasite detection incorporating xenoma enumeration (via gross morphological examination) and quantitative PCR (qPCR) analyses reveals that intraperitoneal (IP) delivery of L. morhua spores was dramatically more effective for experimental infection, relative to gastric intubation (GI), with 100% prevalence of infection achieved by 28 weeks post-exposure (WPE). Subclinical infections persisted in 31.8% of IP-injected fish, as detected via qPCR analysis. This supports previous observations that individual cod vary widely in their response to infection and require such integrative diagnostic approaches for parasite detection. Quantification of parasite xenomas reveal static intensities in spleens 16–28 WPE (Kruskal-Wallis, p = 0.3), but a phasic reduction in gill xenoma intensities during this same period (Mann-Whitney-Wilcoxon, W = 113, p = 0.037). In situ examination of gills in live fish also support the significant reduction in gill xenoma intensity observed 22–28 WPE (2–37 fold reduction, Wilcoxon signed rank test, V = 78, p = 0.0004) and offers a useful in vivo monitoring approach. Importantly, experimental infections induce a period of considerable growth rate suppression at 2–4 WPE. Though growth rates recovered, the effect of early growth impairment persisted at 28 WPE, with ~19.3% fillet loss occurring in parasitized fish as compared with uninfected controls. The negative consequences of L. morhua infections on cod growth emphasize the translational importance of incorporating eukaryotic pathogens like microsporidians into management, biosecurity, and selective breeding programs for fish species of importance for basic and applied research, or for aquaculture.
Garneau C., Duchesne S., St-Hilaire A. (2022). Corrigendum to “Comparison of modelling approaches to estimate trapping efficiency of sedimentation basins on peatlands used for peat extraction” [Ecological Engineering 133 (2019) 60–68] (Ecological Engineering (2019) 133 (60–68), (S0925857419301429), (10.1016/j.ecoleng.2019.04.025)). Ecological Engineering, 174.

The authors regret that the units for the vertical axis of Fig. 6 and Fig. 7 should be “g/l” instead of “mg/l”. Here are the modified Figures: [Figure presented] Fig. 6. Observed SSC entering basin 1 during the flood of August 11th, 2015. The various colors highlight the contributions of each particle class. [Figure presented] Fig. 7. Modelled and observed SSC exiting Basin 1 during the flood of August 11th, 2015. The various colors highlight the contributions of each grain size class. The authors would like to apologise for any inconvenience caused.
Goedkoop W., Culp J.M., Christensen T., Christoffersen K.S., Fefilova E., Guðbergsson G., Lárusson K.F., Liljaniemi P., Novichkova A.A., Ólafsson J.S., Sandøy S., Lento J. (2022). Improving the framework for assessment of ecological change in the Arctic: A circumpolar synthesis of freshwater biodiversity. Freshwater Biology, 67(1) 210-223.

Climate warming and subsequent landscape transformations result in rapid ecological change in Arctic freshwaters. Here we provide a synthesis of the diversity of benthic diatoms, plankton, macrophytes, macroinvertebrates, and fish in Arctic freshwaters. We developed a multi-organism measure of α diversity to characterise circumpolar spatial patterns and their environmental correlates, and we assessed ecoregion-level β diversity for all organism groups across the Arctic. Alpha diversity was lowest at high latitudes and elevations and where dispersal barriers exist. Diversity was positively related to temperature, and both temperature and connectivity limited diversity on high latitude islands. Beta diversity was highly variable among ecoregions for most organism groups, ranging from 0 (complete similarity) to 1 (complete dissimilarity). The high degree of dissimilarity within many ecoregions illustrates the uniqueness of many Arctic freshwater communities. Northward range expansion of freshwater taxa into Arctic regions may lead to increased competition for cold-stenothermic and cold-adapted species, and ultimately lead to the extinction of unique Arctic species. Societal responses to predicted impacts include: (1) actions to improve detection of changes (e.g., harmonised monitoring, remote sensing) and engagement with Arctic residents and Indigenous Peoples; and (2) actions to reduce the impact of unwanted changes (e.g., reductions of CO<inf>2</inf> emissions, action against the spread of invasive species). Current Arctic freshwater monitoring shows large gaps in spatial coverage, while time series data are scarce. Arctic countries should develop an intensified, long-term monitoring programme with routine reporting. Such an approach will allow detection of long-term changes in water quality, biodiversity, and ecosystem services of Arctic freshwaters.
González-Sansón G., Aguilar-Betancourt C.M., Flores-Ortega J.R., Velasco-Reyes L.E., Padilla-Gutierrez S.C., Benítez-Mondragón B.D. (2022). Estuarine fishes feeding on benthic invertebrates and small fishes: Evidence of fine resource partitioning in a tropical coastal lagoon. Estuarine Coastal and Shelf Science, 276.

The main goal of the present study was to carry out an integrated analysis of the feeding habits of a set of species which use the same general food source (benthic invertebrates and small fishes) in a coastal lagoon of the Mexican Pacific. The specific objectives were to explore the patterns of diet overlap among the 12 species included; to relate the differences in diet composition with differences in species morphology and to measure the predator-prey size relationship across the whole set of species. Original primary data on diet composition were obtained from former research whose results were already published in five separated papers dealing with different species or groups of species. Data included information on stomach content (percentage weight) from a total of 2138 individuals pertaining to 12 species (nine of them further split in size groups) and 3953 pairs of prey's size vs predator's size measurements. Eight prey categories made 74% of all food consumed, namely non-identified fishes, penaeids, gobiids, polychaeta, alpheids, upogebiids and engraulids. Using a combination of diet overlap testing based on a null model approach, multivariate methods and regression analyses (linear and quantile), it is concluded that the existence of a relatively homogenous functional group of 12 fish species consuming invertebrates and small fishes is not a realistic assumption. Indeed, several species-size group subsets are clearly identifiable based on the percentage of different prey categories in their diets. The most plausible explanation for the observed patterns of diet composition are the differences in morphological characteristics of the species involved. Other factors allowing the sharing of food resources are the ontogenic change in the size of main prey consumed, notable differences in the abundance of fish species with higher diet overlap values and, perhaps, a high abundance of food resources.
González-Sansón G., Rodríguez F.N., Aguilar-Betancourt C.M., Páez Y.C. (2022). Estuarine fish diversity as indicator of natural environmental gradients. Marine Biodiversity, 52(3).

The main goal of the research was the assessment of the relationship between estuarine fish species diversity and some abiotic factors as salinity, temperature, and sediment grain size in a tropical coastal lagoon. Fish samples were collected using an experimental trawl net at eight sites in four months during three annual cycles. Multivariate analyses were applied for the identification of spatial and seasonal changes in fish assemblages’ composition along environmental gradients. Extrapolated values of Hill´s numbers were used as diversity measures and compared to same indices calculated without extrapolation on original samples. Strong evidence was found for a high correlation of some fish diversity indices with percentage of mud in sediments and in less degree with bottom salinity. An explanation for this correlation is proposed based on a variable response of main food items of the dominant fish species to abiotic factors (mostly sediment characteristics) and its subsequent effect on the spatial variability of the abundance and composition of fish assemblages, which is reflected in diversity measures. Results obtained in this study can be considered a contribution to the understanding of the relationships between fish assemblages´ diversity and natural abiotic gradients. They provide also a base line for future research on the effects of anthropogenic impacts in the studied lagoon.
Graco-Roza C., Aarnio S., Abrego N., Acosta A.T.R., Alahuhta J., Altman J., Angiolini C., Aroviita J., Attorre F., Baastrup-Spohr L., Barrera-Alba J.J., Belmaker J., Biurrun I., Bonari G., Bruelheide H., Burrascano S., Carboni M., Cardoso P., Carvalho J.C., Castaldelli G., Christensen M., Correa G., Dembicz I., Dengler J., Dolezal J., Domingos P., Erös T., Ferreira C.E.L., Filibeck G., Floeter S.R., Friedlander A.M., Gammal J., Gavioli A., Gossner M.M., Granot I., Guarino R., Gustafsson C., Hayden B., He S., Heilmann-Clausen J., Heino J., Hunter J.T., Huszar V.L.M., Janišová M., Jyrkänkallio-Mikkola J., Kahilainen K.K., Kemppinen J., Kozub Ł., Kruk C., Kulbiki M., Kuzemko A., Christiaan le Roux P., Lehikoinen A., Teixeira de Lima D., Lopez-Urrutia A., Lukács B.A., Luoto M., Mammola S., Marinho M.M., Menezes L.S., Milardi M., Miranda M., Moser G.A.O., Mueller J., Niittynen P., Norkko A., Nowak A., Ometto J.P., Ovaskainen O., Overbeck G.E., Pacheco F.S., Pajunen V., Palpurina S., Picazo F., Prieto J.A.C., Rodil I.F., Sabatini F.M., Salingré S., De Sanctis M., Segura A.M., da Silva L.H.S., Stevanovic Z.D., Swacha G., Teittinen A., Tolonen K.T., Tsiripidis I., Virta L., Wang B., Wang J., Weisser W., Xu Y., Soininen J. (2022). Distance decay 2.0 – A global synthesis of taxonomic and functional turnover in ecological communities. Global Ecology and Biogeography, 31(7) 1399-1421.

Aim: Understanding the variation in community composition and species abundances (i.e., β-diversity) is at the heart of community ecology. A common approach to examine β-diversity is to evaluate directional variation in community composition by measuring the decay in the similarity among pairs of communities along spatial or environmental distance. We provide the first global synthesis of taxonomic and functional distance decay along spatial and environmental distance by analysing 148 datasets comprising different types of organisms and environments. Location: Global. Time period: 1990 to present. Major taxa studied: From diatoms to mammals. Method: We measured the strength of the decay using ranked Mantel tests (Mantel r) and the rate of distance decay as the slope of an exponential fit using generalized linear models. We used null models to test whether functional similarity decays faster or slower than expected given the taxonomic decay along the spatial and environmental distance. We also unveiled the factors driving the rate of decay across the datasets, including latitude, spatial extent, realm and organismal features. Results: Taxonomic distance decay was stronger than functional distance decay along both spatial and environmental distance. Functional distance decay was random given the taxonomic distance decay. The rate of taxonomic and functional spatial distance decay was fastest in the datasets from mid-latitudes. Overall, datasets covering larger spatial extents showed a lower rate of decay along spatial distance but a higher rate of decay along environmental distance. Marine ecosystems had the slowest rate of decay along environmental distances. Main conclusions: In general, taxonomic distance decay is a useful tool for biogeographical research because it reflects dispersal-related factors in addition to species responses to climatic and environmental variables. Moreover, functional distance decay might be a cost-effective option for investigating community changes in heterogeneous environments.
Harrison T.M.R., Rudar J., Ogden N., Steeves R., Lapen D.R., Baird D., Gagné N., Lung O. (2022). In silico identification of multiple conserved motifs within the control region of Culicidae mitogenomes. Scientific Reports, 12(1).

Mosquitoes are important vectors for human and animal diseases. Genetic markers, like the mitochondrial COI gene, can facilitate the taxonomic classification of disease vectors, vector-borne disease surveillance, and prevention. Within the control region (CR) of the mitochondrial genome, there exists a highly variable and poorly studied non-coding AT-rich area that contains the origin of replication. Although the CR hypervariable region has been used for species differentiation of some animals, few studies have investigated the mosquito CR. In this study, we analyze the mosquito mitogenome CR sequences from 125 species and 17 genera. We discovered four conserved motifs located 80 to 230 bp upstream of the 12S rRNA gene. Two of these motifs were found within all 392 Anopheles (An.) CR sequences while the other two motifs were identified in all 37 Culex (Cx.) CR sequences. However, only 3 of the 304 non-Culicidae Dipteran mitogenome CR sequences contained these motifs. Interestingly, the short motif found in all 37 Culex sequences had poly-A and poly-T stretch of similar length that is predicted to form a stable hairpin. We show that supervised learning using the frequency chaos game representation of the CR can be used to differentiate mosquito genera from their dipteran relatives.
Hayden B., Harrod C., Thomas S., Kahilainen K.K. (2022). Winter ecology of specialist and generalist morphs of European whitefish, Coregonus lavaretus, in subarctic northern Europe. Journal of Fish Biology, 101(2) 389-399.

European whitefish is a model species for adaptive radiation of fishes in temperate and subarctic lakes. In northern Europe the most commonly observed morphotypes are a generalist (LSR) morph and a pelagic specialist (DR) morph. The evolution of a pelagic specialist morph is something of an enigma, however, as this region is characterized by long, dark winters with pelagic primary production limited to a brief window in late summer. We conducted the first winter-based study of polymorphic whitefish populations to determine the winter ecology of both morphs, and we combined seasonal diet and stable isotope analysis with several proxies of condition in three polymorphic whitefish populations. The generalist LSR morph fed on benthic and pelagic prey in summer but was solely reliant on benthic prey in winter. This was associated with a noticeable but moderate reduction in condition, lipid content and stomach fullness in winter relative to summer. In contrast, the DR whitefish occupied a strict pelagic niche in both seasons. A significant reduction in pelagic prey during winter resulted in severe decrease in condition, lipid content and stomach fullness in DR whitefish in winter relative to summer, with the pelagic morph apparently approaching starvation in winter. We suggest that this divergent approach to seasonal foraging is associated with the divergent life-history traits of both morphs.
Hernández-Vázquez S., González-Sansón G., Aguilar-Betancourt C.M., Castillo-Guerrero J.A. (2022). Spatio-temporal associations of waterbird species during diurnal tidal cycles in the Barra de Navidad coastal lagoon of the central Mexican Pacific. Revista De Biologia Marina Y Oceanografia, 57(2) 89-101.

Hydrological dynamics driven by tidal cycles in estuaries affect waterbird distributions and the availability of their prey. To evaluate the effect of tides on waterbird abundance, distributions, and activity, monthly censuses were conducted from March 2011 to February 2012 (12 at high tide and 12 at low tide) along a transect parallel to the edge of the Barra de Navidad lagoon, which contains substrates that are used by migratory and resident birds as feeding and resting sites. The lagoon perimeter was divided into four zones; A, B, C, and D. In total, 52 species were identified with 7,775 records at high tide and 68 species with 16,469 records at low tide. At high tide, seabirds (14 species, 3,590 records) and waders (15 species, 2,075 records) predominated, whereas shorebirds (23 species, 5,975 records) and waders (17 species, 5,458 records) predominated at low tide. The seasonal abundance patterns indicated increases in winter (January to March) for all bird groups except ducks and related species (Podicipedidae and Rallidae), which showed low abundances year-round. The tidal cycle significantly affected wader and shorebird abundance, with greater abundance observed during low tides. The greatest waterbird abundance occurred in the mudflats, primarily in those located in the southeastern portion of the lagoon (zone C), which were mainly used as feeding areas during low tides. The information generated in this study can be used to inform decision-making in urban and tourism projects planned for the lagoon to ensure adequate substrate availability for the waterbird species present.
Huser B.J., Futter M.N., Bogan D., Brittain J.E., Culp J.M., Goedkoop W., Gribovskaya I., Karlsson J., Lau D.C.P., Rühland K.M., Schartau A.K., Shaftel R., Smol J.P., Vrede T., Lento J. (2022). Spatial and temporal variation in Arctic freshwater chemistry—Reflecting climate-induced landscape alterations and a changing template for biodiversity. Freshwater Biology, 67(1) 14-29.

Freshwater chemistry across the circumpolar region was characterised using a pan-Arctic data set from 1,032 lake and 482 river stations. Temporal trends were estimated for Early (1970–1985), Middle (1986–2000), and Late (2001–2015) periods. Spatial patterns were assessed using data collected since 2001. Alkalinity, pH, conductivity, sulfate, chloride, sodium, calcium, and magnesium (major ions) were generally higher in the northern-most Arctic regions than in the Near Arctic (southern-most) region. In particular, spatial patterns in pH, alkalinity, calcium, and magnesium appeared to reflect underlying geology, with more alkaline waters in the High Arctic and Sub Arctic, where sedimentary bedrock dominated. Carbon and nutrients displayed latitudinal trends, with lower levels of dissolved organic carbon (DOC), total nitrogen, and (to a lesser extent) total phosphorus (TP) in the High and Low Arctic than at lower latitudes. Significantly higher nutrient levels were observed in systems impacted by permafrost thaw slumps. Bulk temporal trends indicated that TP was higher during the Late period in the High Arctic, whereas it was lower in the Near Arctic. In contrast, DOC and total nitrogen were both lower during the Late period in the High Arctic sites. Major ion concentrations were higher in the Near, Sub, and Low Arctic during the Late period, but the opposite bulk trend was found in the High Arctic. Significant pan-Arctic temporal trends were detected for all variables, with the most prevalent being negative TP trends in the Near and Sub Arctic, and positive trends in the High and Low Arctic (mean trends ranged from +0.57%/year in the High/Low Arctic to −2.2%/year in the Near Arctic), indicating widespread nutrient enrichment at higher latitudes and oligotrophication at lower latitudes. The divergent P trends across regions may be explained by changes in deposition and climate, causing decreased catchment transport of P in the south (e.g. increased soil binding and trapping in terrestrial vegetation) and increased P availability in the north (deepening of the active layer of the permafrost and soil/sediment sloughing). Other changes in concentrations of major ions and DOC were consistent with projected effects of ongoing climate change. Given the ongoing warming across the Arctic, these region-specific changes are likely to have even greater effects on Arctic water quality, biota, ecosystem function and services, and human well-being in the future.
Hu Y., Tian Q., Zhang J., Benoy G., Badreldin N., Xing Z., Luo Z., Zhang F. (2022). Effectiveness of Chinese pine (Pinus tabulaeformis) plantation at reducing runoff and erosion rates in Anjiagou Watershed in Semi-arid Region of Gansu, China. Plos One, 17(7 July).

China's Loess Plateau regions have experienced severe soil erosion for many decades due to fragmented landscapes, steep slopes, and concentrated rainfall storm-events. Restoring sub-optimal or marginal farming fields, mostly on steep, hilly terrain, to plantation forests has been a long-standing strategic policy in China aimed at rehabilitating degraded environments and reducing soil and water erosion. While there are numerous studies that have focused on the effects of forests at controlling soil erosion at relatively short time scales, few have addressed longer-term effects of plantation forests on reducing runoff and the mechanisms that inhibit erosion. Chinese pine (Pinus tabulaeformis) has been widely planted in abandoned or reclaimed lands that were formerly farmed in Northwest China; however, there is limited knowledge about the effectiveness of the tree species at reducing soil and water erosion. In this study, we examined reduction rates of runoff and erosion by Chinese pine plantation in comparison with agricultural land as a control (i.e., wheat, a dominant agricultural commodity in the region), based on long-term monitoring of modified standard erosion plots with slopes of 10°, 15°, and 20°. Results showed that as the slope of the land increased, rates of erosion increased for both plantation and agricultural land use. However, the runoff and soil erosion rates under Chinese pine plantation forest were about 11% and 60% lower, respectively, than those under agricultural land use of the same slope. Scaling with the slope, the highest reduced runoff and erosion rates by Chinese pine forest were 17% and 72%, respectively, on 20° slope. Also, it was found that runoff rates from the forested land were positively related to erosive rainfall (i.e., rainfall when runoff generated), and varied with forest canopy coverage. The rates of runoff and erosion can be well model led with multiple regression models. Taken together, this study provides insight into the importance and potential of Chinese pine plantations in the conservation of soil and water in China's Loess Plateau.
Kahlert M., Rühland K.M., Lavoie I., Keck F., Saulnier-Talbot E., Bogan D., Brua R.B., Campeau S., Christoffersen K.S., Culp J.M., Karjalainen S.M., Lento J., Schneider S.C., Shaftel R., Smol J.P. (2022). Biodiversity patterns of Arctic diatom assemblages in lakes and streams: Current reference conditions and historical context for biomonitoring. Freshwater Biology, 67(1) 116-140.

Comprehensive assessments of contemporary diatom distributions across the Arctic remain scarce. Furthermore, studies tracking species compositional differences across space and time, as well as diatom responses to climate warming, are mainly limited to paleolimnological studies due to a lack of routine monitoring in lakes and streams across vast areas of the Arctic. The study aims to provide a spatial assessment of contemporary species distributions across the circum-Arctic, establish contemporary biodiversity patterns of diatom assemblages to use as reference conditions for future biomonitoring assessments, and determine pre-industrial baseline conditions to provide historical context for modern diatom distributions. Diatom assemblages were assessed using information from ongoing regulatory monitoring programmes, individual research projects, and from surface sediment layers obtained from lake cores. Pre-industrial baseline conditions as well as the nature, direction and magnitude of changes in diatom assemblages over the past c.200 years were determined by comparing surface sediment samples (i.e. containing modern assemblages) with a sediment interval deposited prior to the onset of significant anthropogenic activities (i.e. containing pre-1850 assemblages), together with an examination of diatoms preserved in contiguous samples from dated sediment cores. We identified several biotypes with distinct diatom assemblages using contemporary diatom data from both lakes and streams, including a biotype typical for High Arctic regions. Differences in diatom assemblage composition across circum-Arctic regions were gradual rather than abrupt. Species richness was lowest in High Arctic regions compared to Low Arctic and sub-Arctic regions, and higher in lakes than in streams. Dominant diatom taxa were not endemic to the Arctic. Species richness in both lakes and streams reached maximum values between 60°N and 75°N but was highly variable, probably reflecting differences in local and regional environmental factors and possibly sampling effort. We found clear taxon-specific differences between contemporary and pre-industrial samples that were often specific to both ecozone and lake depth. Regional patterns of species turnover (β-diversity) in the past c.200 years revealed that regions of the Canadian High Arctic and the Hudson Bay Lowlands to the south showed most compositional change, whereas the easternmost regions of the Canadian Arctic changed least. As shown in previous Arctic diatom studies, global warming has already affected these remote high latitude ecosystems. Our results provide reference conditions for future environmental monitoring programmes in the Arctic. Furthermore, diatom taxa identification and harmonisation require improvement, starting with circum-Arctic intercalibrations. Despite the challenges posed by the remoteness of the Arctic, our study shows the need for routine monitoring programmes that have a wide geographical coverage for both streams and lakes.
Khorsandi M., St-Hilaire A., Arsenault R. (2022). Multisite calibration of a semi-distributed hydrologic and thermal model in a large Canadian watershed. Hydrological Sciences Journal, 67(14) 2147-2174.

This study compares single-site and multisite calibration methods with upscaled parameters for thermal modelling. Multisite calibration and parameter upscaling are novel for calibrating a hydrological–thermal model. To this end, model calibration and simulations are carried out using a semi-distributed hydrological–thermal model (CEQUEAU). First, a hydrological calibration is carried out. The same calibrated hydrological model outputs are used for all thermal calibrations. The covariance matrix adaptation evolution strategy (CMA-ES) single-objective optimization algorithm is applied to calibrate the thermal module using observed water temperatures at seven monitoring sites within the Nechako Watershed in British Columbia, Canada. Single-site calibration provided the best performance for individual sites, but these sets of parameters performed poorly when applied to the other sites. The multisite calibration and the upscaled methods perform adequately for all sites with overall Root Mean Square Error (RMSE)<2°C as an acceptable threshold. However, the multisite method resulted in the best performance metrics and shortest computing time.
Klaus J., Monk W.A., Zhang L., Hannah D.M. (2022). Ecohydrological interactions during drought. Ecohydrology, 15(5).
Knopp J.A., Levenstein B., Watson A., Ivanova I., Lento J. (2022). Systematic review of documented Indigenous Knowledge of freshwater biodiversity in the circumpolar Arctic. Freshwater Biology, 67(1) 194-209.

Indigenous Peoples in the Arctic have for millennia relied on freshwaters for drinking water and freshwater species that comprise important subsistence harvests, which promotes a strong connection to the land and unique understanding of organisms and ecosystem processes and changes. Despite the importance of freshwater biodiversity and ecosystem services to Arctic Indigenous communities, there have been limited attempts to summarise available Indigenous Knowledge (IK) regarding Arctic freshwater systems and to understand how conservation can benefit from this knowledge base. This paper presents a systematic review of literature documenting circumpolar Arctic IK with a focus on freshwater biodiversity in Canada, Greenland, Fennoscandia (Norway, Sweden, and Finland), Russia, and the U.S.A. (Alaska). Standardised search terms and methodologies were used to locate relevant documents using Google Scholar and Google Advanced search engines. Thematic coding was used to identify freshwater biodiversity themes within the identified documents. Documented IK of freshwater biodiversity was found from all five geographic regions and included data on both species presence and habitat changes with potential to affect biodiversity. Canada had the highest number of relevant documents (n = 127), followed by the U.S.A. (Alaska; n = 116), Fennoscandia (n = 38), Russia (n = 27), and Greenland (n = 5). The number of relevant documents with IK published per year was highest in most recent years, from 2010 onwards, in all geographic regions. Fish represented the highest number of faunal observations with 59 species observed, approximately half of which were Salmonidae (29 species). Local-scale assessment of fish diversity found observations of the highest number of species (11–25) in Alaska, and individual observations of 6–10 species were found throughout Alaska, mainland areas of Canada, and the Kola Peninsula in Russia. Documented IK also contributed new information on historical fish diversity and indicated local-scale loss or gain of species. Such information is of vital importance to provide long-term records of fish composition and abundance, especially when this information does not exist in other knowledge bases such as western science datasets. Indigenous Knowledge included observations of changes in freshwater and terrestrial habitat associated with a warming climate, such as: decreasing water levels and more draining/drying of lakes and rivers, a shorter period of ice cover (late freeze and early break-up), decreasing ice thickness, and increasing occurrence of permafrost thaw and eroding banks. Such observations by those who actively rely on Arctic freshwater ecosystem services are important because they signify that change is occurring and that action is needed to mitigate the impacts on freshwater habitats and the biodiversity therein. This study demonstrates that previously documented IK provides valuable information towards determining freshwater biodiversity baselines and patterns of change in the circumpolar Arctic. However, these results do not sufficiently cover the depth and breadth of IK on freshwater biodiversity and ecology held by Indigenous communities. Further work incorporating Indigenous worldviews around freshwater ecology would provide context to the knowledge collected and a deeper understanding of Arctic circumpolar freshwater environments.
Knysh K.M., Saunders M.D., Macintyre L.P., Courtenay S.C., Van Den Heuvel M.R. (2022). Sometimes You Can Add a Bit of Salt: Additional Freshwater Insect Species in Canadian Estuaries. Northeastern Naturalist, 29(1) N9-N17.

Along the river-ocean transition, few freshwater species persist into polyhaline zones. Among those insect species capable of living in estuaries, it is unclear which Odonata, Trichoptera, and Coleoptera species can occur at intermittent or average salinities above 18 PSU. During surveys of fish and crustaceans in Prince Edward Island (PEI), we noted 3 unexpected insect species from within subtidal-channels. Multiple instars of Coenagrionidae n. det. and Enallagma civile (Familiar Bluet) were collected around marine macroalgae at 5 localities with 6-26 PSU salinities and observed emerging atop macroalgae. Also, collections of the larvae of the caddisfly Limnephilus externus (Limniphilidae), and adult Haliplus cribrarius (Haliplidae) beetles at sites with maxima of 23 and 20 PSU, respectively, suggest rare occurrences of these species within estuarine ecotones.
Laske S.M., Amundsen P.A., Christoffersen K.S., Erkinaro J., Guðbergsson G., Hayden B., Heino J., Holmgren K., Kahilainen K.K., Lento J., Orell P., Östergren J., Power M., Rafikov R., Romakkaniemi A., Svenning M.A., Swanson H., Whitman M., Zimmerman C.E. (2022). Circumpolar patterns of Arctic freshwater fish biodiversity: A baseline for monitoring. Freshwater Biology, 67(1) 176-193.

Climate change, biological invasions, and anthropogenic disturbance pose a threat to the biodiversity and function of Arctic freshwater ecosystems. Understanding potential changes in fish species distribution and richness is necessary, given the great importance of fish to the function of freshwater ecosystems and as a resource to humans. However, information gaps limit large-scale studies and our ability to determine patterns and trends in space and time. This study takes the first step in determining circumpolar patterns of fish species richness and composition, which provides a baseline to improve both monitoring and conservation of Arctic freshwater biodiversity. Information on species presence/absence was gathered from the Circumpolar Biodiversity Monitoring Program's Freshwater Database and used to examine patterns of freshwater fish γ-, α-, and β-diversity across 234° of longitude in the Arctic. The metrics of diversity provided information on species richness and composition across hydrobasins, ecoregions, and Arctic zones. Circumpolar patterns of fish species biodiversity varied with latitude, isolation, and coarse ecoregion characteristics; patterns were consistent with historic and contemporary barriers to colonisation and environmental characteristics. Gamma-diversity was lower in the high Arctic compared to lower latitude zones, but α-diversity did not decrease with increasing latitude below 71°N, reflecting glacial history. Alpha-diversity was reduced to a single species, Arctic charr Salvelinus alpinus, in ecoregions above 71°N, where γ-diversity was the lowest. Beta-diversity indicated little variation in the composition and richness of species across the High Arctic; at lower latitudes, ecoregions contained more species, although species composition turned over across large spatial extents. In an analysis of five ecoregions in the circumpolar Arctic, physical isolation, and ecoregion area and topography were identified as strong drivers of γ-, α-, and β-diversity. Physical isolation reduced the γ- and α-diversity, and changes in β-diversity between adjacent locations were due mainly to losses in species richness, rather than due to differences in species composition. Heterogeneity of habitats, environmental gradients, and geographic distance probably contributed to patterns of fish dissimilarity within and across ecoregions. This study presents the first analysis of large-scale patterns of freshwater fish biodiversity in the circumpolar Arctic. However, information gaps in space, time, and among taxonomic groups remain. Future inclusion of extensive archive and new data will allow future studies to test for changes and drivers of the observed patterns of biodiversity. This is important given the potential impacts of ongoing and accelerating climate change, land use, and biotic exchange on Arctic fish biodiversity.
Lau D.C.P., Christoffersen K.S., Erkinaro J., Hayden B., Heino J., Hellsten S., Holmgren K., Kahilainen K.K., Kahlert M., Karjalainen S.M., Karlsson J., Forsström L., Lento J., Mjelde M., Ruuhijärvi J., Sandøy S., Schartau A.K., Svenning M.A., Vrede T., Goedkoop W. (2022). Multitrophic biodiversity patterns and environmental descriptors of sub-Arctic lakes in northern Europe. Freshwater Biology, 67(1) 30-48.

Arctic and sub-Arctic lakes in northern Europe are increasingly threatened by climate change, which can affect their biodiversity directly by shifting thermal and hydrological regimes, and indirectly by altering landscape processes and catchment vegetation. Most previous studies of northern lake biodiversity responses to environmental changes have focused on only a single organismal group. Investigations at whole-lake scales that integrate different habitats and trophic levels are currently rare, but highly necessary for future lake monitoring and management. We analysed spatial biodiversity patterns of 74 sub-Arctic lakes in Norway, Sweden, Finland, and the Faroe Islands with monitoring data for at least three biological focal ecosystem components (FECs)—benthic diatoms, macrophytes, phytoplankton, littoral benthic macroinvertebrates, zooplankton, and fish—that covered both pelagic and benthic habitats and multiple trophic levels. We calculated the richness<inf>relative</inf> (i.e. taxon richness of a FEC in the lake divided by the total richness of that FEC in all 74 lakes) and the biodiversity metrics (i.e. taxon richness, inverse Simpson index (diversity), and taxon evenness) of individual FECs using presence–absence and abundance data, respectively. We then investigated whether the FEC richness<inf>relative</inf> and biodiversity metrics were correlated with lake abiotic and geospatial variables. We hypothesised that (1) individual FECs would be more diverse in a warmer and wetter climate (e.g. at lower latitudes and/or elevations), and in hydrobasins with greater forest cover that could enhance the supply of terrestrial organic matter and nutrients that stimulated lake productivity; and (2) patterns in FEC responses would be coupled among trophic levels. Results from redundancy analyses showed that the richness<inf>relative</inf> of phytoplankton, macrophytes, and fish decreased, but those of the intermediate trophic levels (i.e. macroinvertebrates and zooplankton) increased with decreasing latitude and/or elevation. Fish richness<inf>relative</inf> and diversity increased with increasing temporal variation in climate (temperature and/or precipitation), ambient nutrient concentrations (e.g. total nitrogen) in lakes, and woody vegetation (e.g. taiga forest) cover in hydrobasins, whereas taxon richness of macroinvertebrates and zooplankton decreased with increasing temporal variation in climate. The similar patterns detected for richness<inf>relative</inf> of fish, macrophytes, and phytoplankton could be caused by similar responses to the environmental descriptors, and/or the beneficial effects of macrophytes as habitat structure. By creating habitat, macrophytes may increase fish diversity and production, which in turn may promote higher densities and probably more diverse assemblages of phytoplankton through trophic cascades. Lakes with greater fish richness<inf>relative</inf> tended to have greater average richness<inf>relative</inf> among FECs, suggesting that fish are a potential indicator for overall lake biodiversity. Overall, the biodiversity patterns observed along the environmental gradients were trophic-level specific, indicating that an integrated food-web perspective may lead to a more holistic understanding of ecosystem biodiversity in future monitoring and management of high-latitude lakes. In future, monitoring should also focus on collecting more abundance data for fish and lower trophic levels in both benthic and pelagic habitats. This may require more concentrated sampling effort on fewer lakes at smaller spatial scales, while continuing to sample lakes distributed along environmental gradients.
Lento J., Culp J.M., Levenstein B., Aroviita J., Baturina M.A., Bogan D., Brittain J.E., Chin K., Christoffersen K.S., Docherty C., Friberg N., Ingimarsson F., Jacobsen D., Lau D.C.P., Loskutova O.A., Milner A., Mykrä H., Novichkova A.A., Ólafsson J.S., Schartau A.K., Shaftel R., Goedkoop W. (2022). Temperature and spatial connectivity drive patterns in freshwater macroinvertebrate diversity across the Arctic. Freshwater Biology, 67(1) 159-175.

Warming in the Arctic is predicted to change freshwater biodiversity through loss of unique taxa and northward range expansion of lower latitude taxa. Detecting such changes requires establishing circumpolar baselines for diversity, and understanding the primary drivers of diversity. We examined benthic macroinvertebrate diversity using a circumpolar dataset of >1,500 Arctic lake and river sites. Rarefied α diversity within catchments was assessed along latitude and temperature gradients. Community composition was assessed through region-scale analysis of β diversity and its components (nestedness and turnover), and analysis of biotic–abiotic relationships. Rarefied α diversity of lakes and rivers declined with increasing latitude, although more strongly across mainland regions than islands. Diversity was strongly related to air temperature, with the lowest diversity in the coldest catchments. Regional dissimilarity was highest when mainland regions were compared with islands, suggesting that connectivity limitations led to the strongest dissimilarity. High contributions of nestedness indicated that island regions contained a subset of the taxa found in mainland regions. High Arctic rivers and lakes were predominately occupied by Chironomidae and Oligochaeta, whereas Ephemeroptera, Plecoptera, and Trichoptera taxa were more abundant at lower latitudes. Community composition was strongly associated with temperature, although geology and precipitation were also important correlates. The strong association with temperature supports the prediction that warming will increase Arctic macroinvertebrate diversity, although low diversity on islands suggests that this increase will be limited by biogeographical constraints. Long-term harmonised monitoring across the circumpolar region is necessary to detect such changes to diversity and inform science-based management.
Lento J., Laske S.M., Lavoie I., Bogan D., Brua R.B., Campeau S., Chin K., Culp J.M., Levenstein B., Power M., Saulnier-Talbot É., Shaftel R., Swanson H., Whitman M., Zimmerman C.E. (2022). Diversity of diatoms, benthic macroinvertebrates, and fish varies in response to different environmental correlates in Arctic rivers across North America. Freshwater Biology, 67(1) 95-115.

Climate change poses a significant threat to Arctic freshwater biodiversity, but impacts depend upon the strength of organism response to climate-related drivers. Currently, there is insufficient knowledge about Arctic freshwater biodiversity patterns to guide assessment, prediction, and management of biodiversity change. As part of the Circumpolar Biodiversity Monitoring Program's first freshwater assessment, we evaluated diversity of diatoms, benthic macroinvertebrates, and fish in North American Arctic rivers. Alpha diversity was assessed in relation to temperature, water chemistry, bedrock geology, and glaciation history to identify important environmental correlates. Biotic composition was compared among groups to evaluate response to environmental gradients. Macroinvertebrate α-diversity declined strongly with increasing latitude from 48°N to 82°N, whereas diatom and fish diversity peaked around 70°N without a clear latitudinal decline. Macroinvertebrate diversity was significantly positively related to air temperature. Diatom diversity was related to bedrock geology and temperature, whereas fish diversity was related to glaciation history. Fish and macroinvertebrate assemblages differed between sites in western Canada, where invertebrate composition was more variable, and Alaska, where fish composition was more variable. In sites with both diatom and macroinvertebrate data, diatom composition was distinct in Alaska, where richness was highest in former glacial refugia. Macroinvertebrate composition was distinct in lowest-latitude eastern and high-latitude western Canadian sites where temperature was highest. Temperature, precipitation, geology, calcium, and substrate size were important environmental correlates for diatoms and macroinvertebrates, although the relative importance of each correlate differed. Diatom taxa were most strongly associated with water chemistry, whereas benthic invertebrate composition related most strongly to precipitation and temperature. This large-scale study provides the most substantial integration and analysis of river diatom, macroinvertebrate, and fish data from the North American Arctic to date. Findings suggest that macroinvertebrates will show the strongest response to climate-related shifts in temperature, whereas diatoms and fish are more likely to respond to climate-induced shifts in nutrients and hydraulic connectivity. However, significant gaps in data coverage limited our ability to reliably evaluate spatial patterns and detect change. These gaps could be reduced by improving collaborative efforts between the U.S.A. and Canada to harmonise future monitoring.
Lucano-Ramírez G., Santana-Cornejo A.S., Ruiz-Ramírez S., González-Sansón G., Aguilar-Betancourt C., Perez-Toledo A. (2022). Reproductive aspects of Paranthias colonus (Perciformes: Serranidae) on the Pacific coast of central Mexico. Ciencias Marinas, 48.

Many species in the family Serranidae are hermaphrodites and of commercial importance. Paranthias colonus belongs to this family, and its reproductive traits are unknown. The present research was carried out with specimens taken from the commercial fishery on the southern coast of Jalisco, Mexico. A total of 1,541 specimens were processed, with an average length of 30.30 ± 0.10 cm and a length interval of 19.80 to 38.00 cm. Specimen gonads were analyzed macro-and microscopically. The sex ratio was 1.00:0.97 (F:M). According to the maximum monthly values of the gonadosomatic index, gonad maturity stages, and oocyte diameters, P. colonus has 2 broad reproductive periods, from March to June and from November to December. A significant correlation was found between the monthly mean values of the gonadosomatic index and the relative condition factor. Gonads in the mature stage had oocytes in 6 different development phases, with diameters that ranged from 14.30 to 417.40 µm, which means that oocyte development is asynchronous. In the testicle, the development of the germ line is of the unrestricted lobular type. This organ did not present the typical arrangement found in teleost fish, since lobes seem to be delimited by lamellae. The information developed in this study indicates that P. colonus is a gonochoric species. Average length at sexual maturity was 26.80 cm for females and 26.90 cm for males. Average catch lengths indicated that 79.70% of females and 83.30% of males had already reproduced at least once before being caught.
McGee K.M., Robinson C., Porter T.M., Compson Z.G., Hajibabaei M., Baird D.J. (2022). eDNA and Bioassessment of Rivers. Encyclopedia of Inland Waters Second Edition, 2 537-548.

River bioassessment programs require robust methods to accurately observe the status of aquatic biodiversity, as it is well understood that physico-chemical monitoring alone is not sufficient to support current policy and management objectives. Whereas traditional microscopy-based identification of organisms can be expensive and laborious, direct sampling of environmental DNA, coupled with high-throughput sequencing technologies, now provides a rapid and accurate alternative to support bioassessment analysis and interpretation. Here, we discuss the various insights that can be generated from eDNA, illustrate how river monitoring can benefit from eDNA approaches, knowledge gaps, and how this can support bioassessment from local to national and international scales.
Negrazis L., Kidd K.A., Erdozain M., Emilson E.J.S., Mitchell C.P.J., Gray M.A. (2022). Effects of forest management on mercury bioaccumulation and biomagnification along the river continuum. Environmental Pollution, 310.

Forest management can alter the mobilization of mercury (Hg) into headwater streams and its conversion to methylmercury (MeHg), the form that bioaccumulates in aquatic biota and biomagnifies through food webs. As headwater streams are important sources of organic materials and nutrients to larger systems, this connectivity may also increase MeHg in downstream biota through direct or indirect effects of forestry on water quality or food web structure. In this study, we collected water, seston, food sources (biofilm, leaves, organic matter), five macroinvertebrate taxa and fish (slimy sculpin; Cottus cognata) at 6 sites representing different stream orders (1–5) within three river basins with different total disturbances from forestry (both harvesting and silviculture). Methylmercury levels were highest in water and some food sources from the basin with moderate disturbance (greater clearcutting but less silviculture). Water, leaves, stoneflies and fish increased in MeHg or total Hg along the river continuum in the least disturbed basin, and there were some dissipative effects of forest management on these spatial patterns. Trophic level (δ15N) was a significant predictor of MeHg (and total Hg in fish) within food webs across all 18 sites, and biomagnification slopes were significantly lower in the basin with moderate total disturbance but not different in the other two basins. The elevated MeHg in lower trophic levels but its reduced trophic transfer in the basin with moderate disturbance was likely due to greater inputs of sediments and of dissolved organic carbon that is more humic, as these factors are known to both increase transport of Hg to streams and its uptake in primary producers but to also decrease MeHg bioaccumulation in consumers. Overall, these results suggest that the type of disturbance from forestry affects MeHg bioaccumulation and trophic transfer in stream food webs and some longitudinal patterns along a river continuum.
O'Sullivan A.M., Devito K.J., D'Orangeville L., Curry R.A. (2022). The waterscape continuum concept: Rethinking boundaries in ecosystems. Wiley Interdisciplinary Reviews Water, 9(4).

Continuity and discontinuity are fundamental concepts of ecosystem science. In reality, both continuities and discontinuities can exist; lentic and lotic systems can expand and contract as can soil/rock moisture and groundwater systems. Surface water, soil moisture, rock moisture, and groundwater, represent hydrological domains that are interconnected. Under a state of expansion each domain may be characterized by spatial continuity; for instance, a river may be entirely flow connected. However, under a state of contraction, discontinuities may appear, and the river may become fragmented. The rate of expansion and contraction in each domain, that is land-, lentic-, and lotic-scapes, is a function of topography, geology, climate, and biota. In an effort to reconcile older, and sometimes incongruous, concepts of continuity and discontinuity we present a view of water-connected ecosystems, such as riverscapes and catchments that are nested upon and within the uppermost layer of Earth. This layer is the key interface between the lithosphere, atmosphere, hydrosphere, and biosphere, and is known as the critical zone (CZ). We present the waterscape continuum and define it as the spatially and temporally dynamic water upon and within the CZ. To guide ecosystem research (across the land-, lentic-, and lotic-scapes), we introduce the waterscape continuum template (WCT). We propose the waterscape continuum and the WCT can enhance our understanding of ecosystem processes and mechanisms. This article is categorized under: Science of Water > Hydrological Processes Water and Life > Nature of Freshwater Ecosystems.
O'Sullivan A.M., Linnansaari T., Leavitt J., Samways K.M., Kurylyk B.L., Curry R.A. (2022). The salmon-peloton: Hydraulic habitat shifts of adult Atlantic salmon (Salmo salar) due to behavioural thermoregulation. River Research and Applications, 38(1) 107-118.

In recent decades, there has been an increase in conservation and restoration projects targeting Atlantic salmon (Salmo salar – AS), as populations in eastern Canada decline. Missing however, is an understanding of thermo-hydraulic habitat use by adult AS during summer, and thus the actual benefits of altering in-river physical structures. Here, we illustrated how optical and thermal infrared (TIR) imagery acquired from a UAV can be used in concert with in-situ depth and velocity data to map adult AS and develop models of thermo-hydraulic habitats in the Miramichi River, New Brunswick. We found during normal temperature conditions (<19°C) boulder proximity, depth, velocity, and Froude number, a non-dimensional hydraulic metric, were key parameters that characterized adult AS habitat. However, during behavioural thermoregulation events (>19°C), proximity to the cool thermal plume and Froude number were critical controls on habitat use. We also observed AS forming a distinct geometric formation during behavioural thermoregulation events, and term this formation a “thermal-peloton”; in reference to competitive cycling in which groups of cyclists pack together. The primary function of the peloton is undoubtedly to reduce thermally induced stressed; however, we conceptualize that the geometry of the peloton attenuates hydraulic-drag, and reduces the energetic expenditure of individuals practicing behavioural thermoregulation. These data provide a blue print for Atlantic salmon restoration work. The use of UAV-based sensors has the potential to initiate a paradigm shift for river sciences.
Ouarda T.B.M.J., Charron C., St-Hilaire A. (2022). Regional estimation of river water temperature at ungauged locations. Journal of Hydrology X, 17.

River water temperature measurement networks suffer from an inadequate spatial coverage and a lack of data. No methods exist for the regional estimation of river water temperature at ungauged sites based on data series from gauged sites. The development of such methods is hence of significant importance. It is proposed in this study to develop a Temperature-Duration-Curve (TDC) based method to estimate river water temperature at ungauged sites on a real-time basis. A Generalised Additive Model (GAM) based method is used to estimate TDCs at ungauged sites. The estimated TDCs are then used in combination with a spatial interpolation method to obtain daily temperature estimates at ungauged sites. Results are compared with a simple method based on the geographical distance weighted average of neighboring stations. The approaches are applied to 126 river thermal stations located on Atlantic salmon rivers in eastern Canada. Leave-one-out cross validation results indicate that the TDC based methods are robust and outperform the geographical distance weighted method.
O’Sullivan A.M., Kurylyk B.L. (2022). Limiting External Absorptivity of UAV-Based Uncooled Thermal Infrared Sensors Increases Water Temperature Measurement Accuracy. Remote Sensing, 14(24).

Thermal mapping of surface waters and the land surface via UAVs offers exciting opportunities in many scientific disciplines; however, unresolved issues persist related to accuracy and drift of uncooled microbolometric thermal infrared (TIR) sensors. Curiously, most commercially available UAV-based TIR sensors are black, which will theoretically facilitate heating of the uncooled TIR sensor via absorbed solar radiation. Accordingly, we tested the hypothesis that modifying the surface absorptivity of uncooled TIR sensors can reduce thermal drift by limiting absorptance and associated microbolometer heating. We used two identical uncooled TIR sensors (DJI Zenmuse XT2) but retrofitted one with polished aluminum foil to alter the surface absorptivity and compared the temperature measurements from each sensor to the accurate measurements from instream temperature loggers. In addition, because TIR sensors are passive and measure longwave infrared radiation emitted from the environment, we tested the hypotheses that overcast conditions would reduce solar irradiance, and therefore induce thermal drift, and that increases in air temperature would induce thermal drift. The former is in contrast with the conceptual model of others who have proposed that flying in overcast conditions would increase sensor accuracy. We found the foil-shielded sensor yielded temperatures that were on average 2.2 °C more accurate than those of the matte black sensor (p < 0.0001). Further, we found positive correlations between light intensity (a proxy for incoming irradiance) and increased sensor accuracy for both sensors. Interestingly, light intensity explained 73% of the accuracy variability for the black sensor, but only 40% of the variability in accuracy deviations for the foil-shielded sensor. Unsurprisingly, an increase in air temperature led to a decrease in accuracy for both sensors, where air temperature explained 14% of the variability in accuracy for the black sensor and 31% of the accuracy variability for the foil-shielded sensor. We propose that the discrepancy between the amount of variability explained by light intensity and air temperature is due to changes in the heat energy budget arising from changes in the surface absorptivity. Additionally, we suggest fine-scale changes in river-bed reflectance led to errors in UAV thermal measurements. We conclude with a suite of guidelines for increasing the accuracy of uncooled UAV-based thermal mapping.
Peters D.L., Skelly R., Niemann K.O., Hopkinson C., Brisco B., Baird D.J. (2022). A visual and numerical aid to detecting surface water connectivity points in deltaic floodplains. Hydrological Processes, 36(12).
Peters D.L., Watt D., Devito K., Monk W.A., Shrestha R.R., Baird D.J. (2022). Changes in geographical runoff generation in regions affected by climate and resource development: A case study of the Athabasca River. Journal of Hydrology Regional Studies, 39.

Study region: This study is focused on the lower Athabasca Basin in northwestern Canada that has experienced rapid expansion of oil sands development. Study focus: The goal of this study is to enhance the understanding of the regional role of the lower Athabasca Basin areas in overall runoff delivery to the downstream Peace-Athabasca Delta. The Cold-regions Hydrological Indicators of Change framework was applied to examine key hydro-ecological relevant indicators influencing the delta. New hydrological insights for the region: Our novel approach yielded new insights that should be considered in water management. Primarily, a combined flow magnitude and relative flow contributions analysis by geography provides an improved understanding of contrasting runoff generation changes, in terms of opposing responses occurring within a basin. For instance, open-water low flows emanated from the upper regions and a generally increasing tendency from the lower regions. Furthermore, peak summer flows generally experienced decreases from the upper and portions of the lower basin, while contrary increasing tendencies emerged for the east bank of the lower Athabasca River mainstem. Moving beyond the traditional approach of looking only at the climate, landscape and geology were considered as potential causal factors for divergent runoff generation responses. Our approach is transferable to other regional studies.
Puncher G.N., Hanke A., Busawon D., Sylvester E.V.A., Golet W., Hamilton L.C., Pavey S.A. (2022). Individual assignment of Atlantic bluefin tuna in the northwestern Atlantic Ocean using single nucleotide polymorphisms reveals an increasing proportion of migrants from the eastern Atlantic Ocean. Canadian Journal of Fisheries and Aquatic Sciences, 79(1) 111-123.

Identifying the origin of fish contained in a mixed fishery is critical for accurate stock assessments and the subsequent development of appropriate management strategies. Using a panel of 92 single-nucleotide polymorphisms (SNPs) developed to differentiate Atlantic bluefin tuna (Thunnus thynnus) from the two main spawning areas (Gulf of Mexico and Mediterranean Sea), we used individual assignment to determine composition of feeding aggregations in the northwestern Atlantic Ocean (Gulf of Maine, Bay of Fundy, Scotian Shelf, Gulf of St. Lawrence, coastal Newfoundland). Among the 3163 individuals collected between 2004 and 2018, we found that among lower age groups (<15 years) the spawning stock providing the most recruits to the Canadian fishery transitioned from western Atlantic to Mediterranean origin over time. While the majority of older adults (>15 years) have consistently been of western Atlantic origin, the disparity in the proportional contribution of western and eastern spawning groups narrowed significantly over the 14-year study period. Our results can be used to inform population-specific exploitation rates, improve stock assessments, and identify age-dependent habitat use and areas suitable for additional conservation efforts.
Páez Y.C., Betancourt C.M.A., Sansón G.G., Kidd K.A., Curry R.A., Aceves D.K. (2022). Mercury concentrations and stable isotopes (δ15N and δ13C) in fish muscle indicate human impacts in tropical coastal lagoons. Marine Pollution Bulletin, 176.

Coastal lagoons are essential nursery habitats of many marine fishes, but they are often sites of intense human activities that impact water quality and potentially the fish using these habitats. We compared the variability in nutrient uptake (using δ15N and δ13C) and total mercury (THg) levels in juveniles and adults of three common species in two lagoons on the central Mexican coast of the Pacific Ocean during the wet and dry seasons. One of three species, Achirus mazatlanus had higher THg, δ15N, and δ13C levels in the lagoon with the greatest wastewater inputs (Barra de Navidad). Delta13C varied seasonally for all three species and THg was higher in the dry season for Lutjanus argentiventris and in males of A. mazatlanus. Our results demonstrate that mercury and stable isotopes can identify impacts of human activities on estuarine ichthyofauna and the importance of understanding seasonal and spatial variability of measures that could impact monitoring and predictions of impacts in these lagoons.
Rideout N.K., Compson Z.G., Monk W.A., Bruce M.R., Hajibabaei M., Porter T.M., Wright M.T.G., Baird D.J. (2022). Environmental filtering of macroinvertebrate traits influences ecosystem functioning in a large river floodplain. Functional Ecology, 36(11) 2791-2805.

The biodiversity–ecosystem function hypothesis postulates that higher biodiversity is correlated with faster ecosystem process rates and increased ecosystem stability in fluctuating environments. Exhibiting high spatiotemporal habitat diversity, floodplains are highly productive ecosystems, supporting communities that are naturally resilient and highly diverse. We examined linkages among floodplain wetland habitats, invertebrate communities and their associated traits, and ecosystem function across 60 sites within the floodplain wetlands of the lower Wolastoq | Saint John River, New Brunswick, using structural equation modelling and Threshold Indicator Taxa ANalysis. We identified key environmental filters structuring invertebrate communities, by linking increased niche differentiation through shoreline change, flood pulse dynamics, and macrophyte bed complexity with increased taxa and functional diversity. Examination of traits linked to ecosystem functions revealed that more resilient wetlands with balance between primary productivity and decomposition as carbon sources were associated with greater functional evenness and richness, while habitat patches with elevated decomposition rates had lower functional richness, reflecting a simplified, more disturbed habitat. While our more complex overarching SEM model was ultimately compromised by an overspecified number of pathways, our results nevertheless are indicative of a divergence between wetland and riverine ecosystems in their relationships linking biodiversity and ecosystem function, illustrating how to define ecosystem health in wetland habitats, and demonstrating how critical functions support healthy wetland habitats by providing increased resilience to disturbance. Read the free Plain Language Summary for this article on the Journal blog.
Rideout N.K., Lapen D.R., Peters D.L., Baird D.J. (2022). Ditch the low flow: Agricultural impacts on flow regimes and consequences for aquatic ecosystem functions. Ecohydrology, 15(5).

Large-scale, intensive agriculture is a critical activity supporting global food production, yet it has taken a significant toll on the equally critical ecosystem services supplied by global biodiversity. This is particularly true for the planet's most threatened ecosystems: freshwaters. As one of the world's largest agricultural producers, Canada is also home to much of the world's freshwater. As Canada's agricultural capacity expands under climate warming into more northerly latitudes—and in some cases regions with large carbon sinks—it is imperative that this sectoral shift is accompanied by careful management to avoid exacerbating ecosystem service losses. Across Canada, agricultural practices vary in terms of their impact on freshwater ecosystems. Agricultural water extraction, storage behind dams, diversions, dredging and clearing of riparian vegetation can impact more naturalized flow regimes. This review explores the influence of managed low flows on ecosystem functioning in man-made drainage/irrigation ditch systems. We examine how low flows in these systems can impact ecosystem functions in agricultural watersheds with fragmented natural capital. We provide management options to protect ecosystem functions under a changing climate, recognizing that in agro-ecosystems, drainage/irrigation ditch systems provide a critical remnant habitat to support biodiversity in otherwise depauperate landscapes.
Roberts K.N., Lund T., Hayden B., Poesch M. (2022). Season and species influence stable isotope ratios between lethally and non-lethally sampled tissues in freshwater fish. Journal of Fish Biology, 100(1) 229-241.

The field of stable isotope ecology is moving away from lethal sampling (internal organs and muscle) towards non-lethal sampling (fins, scales and epidermal mucus). Lethally and non-lethally sampled tissues often differ in their stable isotope ratios due to differences in metabolic turnover rate and isotopic routing. If not accounted for when using non-lethal tissues, these differences may result in inaccurate estimates of resource use and trophic position derived from stable isotopes. To address this, the authors tested whether tissue type, season and their interaction influence the carbon and nitrogen stable isotope ratios of fishes and whether estimates of species trophic position and resource use are affected by tissue type, season and their interaction. This study developed linear conversion relationships between two fin types and dorsal muscle, accounting for seasonal variation. The authors focused on three common temperate freshwater fishes: northern pike Esox lucius, yellow perch Perca flavescens and lake whitefish Coregonus clupeaformis. They found that fins were enriched in 13C and depleted in 15N compared to muscle in all three species, but the effect of season and the interaction between tissue type and season were species and isotope dependent. The estimates of littoral resource use based on fin isotope ratios were between 13% and 36% greater than those based on muscle across species. Season affected this difference for some species, suggesting the potential importance of using season-specific conversions when working with non-lethal tissues. Fin and muscle stable isotopes produced similar estimates of trophic position for northern pike and yellow perch, but fin-based estimates were 0.2–0.4 trophic positions higher than muscle-based estimates for lake whitefish. The effect of season was negligible for estimates of trophic position in all species. Strong correlations existed between fin and muscle δ13C and δ15N values for all three species; thus, linear conversion relationships were developed. The results of this study support the use of non-lethal sampling in stable isotope studies of fishes. The authors suggest that researchers use tissue conversion relationships and account for seasonal variation in these relationships when differences between non-lethal tissues and muscle, and seasonal effects on those differences, are large relative to the scale of isotope values under investigation and/or the trophic discrimination factors under use.
Roloson S.D., Knysh K.M., Landsman S.J., James T.L., Hicks B.J., van den Heuvel M.R. (2022). The Lifetime Migratory History of Anadromous Brook Trout (Salvelinus fontinalis): Insights and Risks from Pesticide-Induced Fish Kills. Fishes, 7(3).

Brook trout populations in Prince Edward Island, Canada, have experienced over 50 pesticide-related fish kills since the 1960s. Life history evaluation of large sea-run brook trout recovered following two fish kill events was compared with a reference river using strontium:calcium otolith microchemistry. This study examined the dual hypotheses that anadromous brook trout are more likely to arise from sea-run mothers, and that freshwater entry timing makes them vulnerable to pesticide-induced fish kills. A total 89% of the fish exhibited an anadromous life history, and 77% of these were offspring of anadromous mothers, suggesting that anadromy is dominant in progeny of sea-run mothers. This study adds to our understanding of the maternal inheritance of anadromy in sea-run brook trout populations. Additionally, freshwater entry precedes the majority of fish kill events, illustrating that the overlap between migration and pesticide runoff contributes to the cumulative population risks to sea-run brook trout.
Schartau A.K., Mariash H.L., Christoffersen K.S., Bogan D., Dubovskaya O.P., Fefilova E.B., Hayden B., Ingvason H.R., Ivanova E.A., Kononova O.N., Kravchuk E.S., Lento J., Majaneva M., Novichkova A.A., Rautio M., Rühland K.M., Shaftel R., Smol J.P., Vrede T., Kahilainen K.K. (2022). First circumpolar assessment of Arctic freshwater phytoplankton and zooplankton diversity: Spatial patterns and environmental factors. Freshwater Biology, 67(1) 141-158.

Arctic freshwaters are facing multiple environmental pressures, including rapid climate change and increasing land-use activities. Freshwater plankton assemblages are expected to reflect the effects of these stressors through shifts in species distributions and changes to biodiversity. These changes may occur rapidly due to the short generation times and high dispersal capabilities of both phyto- and zooplankton. Spatial patterns and contemporary trends in plankton diversity throughout the circumpolar region were assessed using data from more than 300 lakes in the U.S.A. (Alaska), Canada, Greenland, Iceland, the Faroe Islands, Norway, Sweden, Finland, and Russia. The main objectives of this study were: (1) to assess spatial patterns of plankton diversity focusing on pelagic communities; (2) to assess dominant component of β diversity (turnover or nestedness); (3) to identify which environmental factors best explain diversity; and (4) to provide recommendations for future monitoring and assessment of freshwater plankton communities across the Arctic region. Phytoplankton and crustacean zooplankton diversity varied substantially across the Arctic and was positively related to summer air temperature. However, for zooplankton, the positive correlation between summer temperature and species numbers decreased with increasing latitude. Taxonomic richness was lower in the high Arctic compared to the sub- and low Arctic for zooplankton but this pattern was less clear for phytoplankton. Fennoscandia and inland regions of Russia represented hotspots for, respectively, phytoplankton and zooplankton diversity, whereas isolated regions had lower taxonomic richness. Ecoregions with high α diversity generally also had high β diversity, and turnover was the most important component of β diversity in all ecoregions. For both phytoplankton and zooplankton, climatic variables were the most important environmental factors influencing diversity patterns, consistent with previous studies that examined shorter temperature gradients. However, barriers to dispersal may have also played a role in limiting diversity on islands. A better understanding of how diversity patterns are determined by colonisation history, environmental variables, and biotic interactions requires more monitoring data with locations dispersed evenly across the circumpolar Arctic. Furthermore, the importance of turnover in regional diversity patterns indicates that more extensive sampling is required to fully characterise the species pool of Arctic lakes.
Thera J.C., Kidd K.A., Stewart A.R., Bertolo R.F., O'Driscoll N.J. (2022). Using tissue cysteine to predict the trophic transfer of methylmercury and selenium in lake food webs. Environmental Pollution, 311.

The biomagnification of toxic methylmercury (MeHg) and selenium (Se) through aquatic food webs using nitrogen stable isotopes (δ15N) varies among ecosystems but underlying mechanisms are yet unexplained. Given the strong links between MeHg and thiol-containing amino acids and proteins containing selenocysteine, our hypothesis was that cysteine content is a better predictor of MeHg and Se transfer through lake food webs than δ15N. Food web samples were collected from six lakes in Kejimkujik National Park, Nova Scotia, Canada, and the regression slopes of log MeHg or Se versus protein-bound cysteine or bulk δ15N were compared. Across all six lakes, MeHg varied by a factor of 10 among taxa and was significantly and positively related to both cysteine (R2 = 0.65–0.80, p < 0.001) and δ15N (R2 = 0.88–0.94, p < 0.001), with no among-system differences in these slopes. In contrast, total Se concentrations varied by less than a factor of 2 among taxa in four lakes and were significantly related to cysteine in only two food webs (R2 = 0.20 & 0.37, p = 0.014 & < 0.001); however, δ15N was not a predictor of Se in any lake (p = 0.052–0.777). Overall, these novel results indicate that cysteine content predicts MeHg, and sometimes Se, across trophic levels, providing a potential mechanism for among-system differences in their biomagnification.
Thomas K.E., Alexander A.C., Chambers P.A. (2022). Contribution of rain events to surface water loading in 3 watersheds in Canada's Alberta Oil Sands region. Journal of Hydrology Regional Studies, 40.

Study region: In the oil sands region of Canada, hydrology of rivers is strongly influenced by snowmelt and a shifting climate resulting in shortening of snow cover duration and increases in the frequency of rain events. Study focus: To evaluate the importance of rain events to these rivers, discharge and water quality sampling was conducted at river sites in this region. Two approaches were used to collect water quality samples: (1) event-based automated samplers that triggered repeated sampling in response to 10% increases in surface flow, and (2) an intensive program of routine sampling at daily, weekly or biweekly intervals from April 2013 to January 2014. New hydrological insights for the region: The importance of rain events as contributors to loading of nutrients and priority pollutants differed temporally. During fall, when baseflow conditions prevailed, average daily loads differed when calculated using routine only versus routine + rain-event data. However, on an annual basis, the inclusion of rain-event sampling did not change pollutant loads. Thus, when assessing loads on an annual basis, rain event sampling may not provide enough benefit to warrant the additional logistical considerations for this remote region. However, when monitoring focuses on capturing fall conditions, efforts should be expanded to include rain event sampling in order to capture spikes in chemical concentration during this ecologically important time period. Predictions of a shorter snow season with more precipitation falling as rain rather than snow reinforce the need to adapt monitoring schemes to ensure that the timing and frequency of water chemistry sampling reflects changing climate and hydrological patterns.
Tyrrell C.D., Chambers P.A., Culp J.M. (2022). Harnessing aquatic plant growth forms to apply European nutrient-enrichment bioindicators to Canadian waters. Applications in Plant Sciences, 10(4).

Premise: Aquatic macrophyte species abundance and nutrient affinity are used in metrics to assess the trophic condition of lakes and rivers. The development of these indices is often regional, with inter-regional comparisons being complicated by the lack of taxonomic overlap. Here, we use a traits-based approach to expand the geographic scope of existing metrics. Methods: We generalized European trophic affinity values using the response of plant growth form to the light–nutrient gradient, then applied these values to sites in Canada. We evaluated the method's performance against the measured total phosphorus concentration (TP). Results: Free-floating and emergent growth forms were associated with enriched waters (>0.2 mg/L TP), whereas rosette forms were associated with oligotrophic conditions (<0.05 mg/L TP). The responses were longitudinally consistent, and the site scores among indices were highly collinear. Growth form–based scores were more strongly correlated with TP than were species-based scores (0.42–0.56 versus 0.008–0.25). Discussion: We leveraged the ecological relationship between increased surface water nutrient enrichment and the dominance of particular aquatic plant growth forms to generalize aquatic plant trophic indices. We demonstrated an approach for adapting species-based indices to plant traits to facilitate a broader geographic application and simpler data collection, which could be used to develop an easily applied trait-based method of assessing water nutrient status.
Velasco-Reyes L.E., Aguilar-Betancourt C.M., González-Sansón G., Flores-Ortega J.R., Ambriz-Casillas M.F. (2022). Feeding and Diet Overlap of Six Estuarine Fishes (Family Carangidae) from the Mexican Pacific Region. Estuaries and Coasts, 45(1) 302-313.

Caranx caninus, C. sexfasciatus, Chloroscombrus orqueta, Selene brevoortii, S. peruviana, and Selar crumenophthalmus are species with economic importance for local artisanal fisheries and are regular components of the fish assemblage at Barra de Navidad coastal lagoon in the Pacific coast of Mexico. The working hypothesis was that carangid species in the lagoon share a common food base but the proportion of main food categories in the diet will be different for some groups of species due to differences in key morphological characteristics of the carangids. A total of 1251 individuals were used for diet analyses. Stomach content analyses showed that five species feed on benthic invertebrates and small fish while one species was mostly a plankton feeder. A partial sharing of main food resources was found for most of the studied species, but significant differences in the proportion of food categories in the diet were identified for several groups of species. Another aspect of diet variation was associated with predator size whereby larger individuals tended to consume the largest prey. A plausible explanation for the variation observed in feeding habits is based on morphological differences among groups of species which favor piscivory or planktivory in some cases. This paper is the first published report on the feeding habits of all six species in any Mexican estuarine habitat and of four species in Eastern Pacific estuarine waters.
Wegscheider B., Linnansaari T., Monk W.A., Ndong M., Haralampides K., St-Hilaire A., Schneider M., Curry R.A. (2022). Quantitative modelling of fish habitat in a large regulated river in a changing climate. Ecohydrology, 15(5).

The expansion of hydropower in combination with the already existing infrastructure and a changing climate are significantly influencing the world's rivers. The resulting alteration in flow regimes is expected to strongly affect fish habitat and associated fish communities both spatially and temporally. Using habitat modelling, this study identified habitat bottlenecks during the critical summer low flow period and fish assemblages that will be most susceptible to regulated and predicted future flow regimes in the Saint John River downstream the Mactaquac Generating Station. Expert knowledge-based habitat models were applied at the meso-scale to evaluate the influence of alternative future flow regimes on habitat suitability indices of fish assemblages. Dam renewal and removal scenarios predicted low habitat suitability for rheophilic fish species, particularly during prolonged low flow periods in dry years. Limnophilic and eurytopic fish assemblages were not expected to be limited in habitat conditions. Overall, the proposed modelling approach represents a promising tool to support the development of environmental flows in large regulated rivers that face challenges with ageing infrastructure and a changing climate.
West D.W., Ling N., Hicks B.J., van den Heuvel M.R., Tremblay L.A. (2022). Effects of point source discharges on common bully (Gobiomorphus cotidianus) along the Waikato River, New Zealand. New Zealand Journal of Marine and Freshwater Research, 56(1) 150-166.

The common bully (Gobiomorphus cotidianus) was used as a bioindicator to assess the impacts of geothermal, bleached kraft mill effluent (BKME), sewage, and thermal discharges in the Waikato River, Northern New Zealand. A range of morphological and physiological parameters were measured to assess fitness in fish sampled upstream and downstream from these point sources. Isotopic signatures gave evidence that fish were resident at sites and showed a gradient corresponding to site-specific sources of carbon and nitrogen along the river. There were changes in the size range and age structure of the populations but, no physiological responses were detected. Limited impacts were observed on common bully health at individual discharge sites, or downstream where the river showed gradual deterioration in water quality, particularly nutrient enrichment, and increased turbidity. Despite the gradual deterioration in water quality no concomitant cumulative impacts were observed in common bully. Responses were largely local in nature, responding to point-source discharges. Population responses at the geothermal and BKME discharge sites warrant further study to investigate possible effects on fish recruitment.
Andrews A.J., Puncher G.N., Bernal-Casasola D., Di Natale A., Massari F., Onar V., Toker N.Y., Hanke A., Pavey S.A., Savojardo C., Martelli P.L., Casadio R., Cilli E., Morales-Muñiz A., Mantovani B., Tinti F., Cariani A. (2021). Ancient DNA SNP-panel data suggests stability in bluefin tuna genetic diversity despite centuries of fluctuating catches in the eastern Atlantic and Mediterranean. Scientific Reports, 11(1).

Atlantic bluefin tuna (Thunnus thynnus; BFT) abundance was depleted in the late 20th and early 21st century due to overfishing. Historical catch records further indicate that the abundance of BFT in the Mediterranean has been fluctuating since at least the 16th century. Here we build upon previous work on ancient DNA of BFT in the Mediterranean by comparing contemporary (2009–2012) specimens with archival (1911–1926) and archaeological (2nd century BCE–15th century CE) specimens that represent population states prior to these two major periods of exploitation, respectively. We successfully genotyped and analysed 259 contemporary and 123 historical (91 archival and 32 archaeological) specimens at 92 SNP loci that were selected for their ability to differentiate contemporary populations or their association with core biological functions. We found no evidence of genetic bottlenecks, inbreeding or population restructuring between temporal sample groups that might explain what has driven catch fluctuations since the 16th century. We also detected a putative adaptive response, involving the cytoskeletal protein synemin which may be related to muscle stress. However, these results require further investigation with more extensive genome-wide data to rule out demographic changes due to overfishing, and other natural and anthropogenic factors, in addition to elucidating the adaptive drivers related to these.
Andrews S.N., Roth D.H., Kidd K.A., Linnansaari T., Curry R.A. (2021). Harvest and Mercury Levels of Striped Bass in Miramichi River, New Brunswick, Canada. North American Journal of Fisheries Management, 41(5) 1490-1498.

The Striped Bass Morone saxatilis is an apex predator that supports recreational, commercial, and First Nations traditional fisheries in the Miramichi River, New Brunswick, Canada. Historic exploitation resulted in steep population declines, forcing a complete fisheries moratorium in 2000. After 13 years of recovery, a recreational fishery was reopened (May 2013) followed by a commercial fishery in 2018. These new opportunities for harvesting raised concerns about mercury levels in fish for human consumption as past levels have exceeded Health Canada guidelines of 0.5 mg/kg. We collected Striped Bass from the northwest Miramichi River in spring during the main recreational and commercial fishing seasons. Fish in the legal harvest slot for the recreational (50–65 cm TL) and commercial (50–80 cm TL) fisheries had total mercury in muscle tissue ranging from 0.08 to 0.43 mg/kg and from 0.08 to 0.63 mg/kg wet weight, respectively. Mercury levels in Striped Bass have decreased since the 1990s, but some individuals were close to or exceeded consumption guidelines. In addition, a preliminary angler creel survey revealed that only 8% of anglers retained their legal, three-fish limit (average harvest = 0.7 fish/angler/day). However, harvest of oversized fish was observed (11%), and a removal of ˜100,000 adults in the first month of the fishery by the recreational, commercial, and Indigenous fisheries is possible and represents a significant portion of the estimated adult population. We conclude that effective management of the Striped Bass fishery in the Miramichi River will require continued and more detailed angler surveys and population size and structure assessments accompanied by communication of current mercury levels in this species.
Babin A.B., Ndong M., Haralampides K., Peake S., Jones R., Curry R.A., Linnansaari T. (2021). Overwintering and migration behaviour of post-spawned Atlantic salmon Salmo salar in a large hydropower-regulated river and reservoir. Journal of Fish Biology, 99(3) 856-874.

Tracking 47 post-spawned adult Atlantic salmon Salmo salar L. in a hydropower-regulated river through autumn, winter and spring revealed that winter survival was 56% and 75% in two study years, respectively, with higher mortality of males than females (50% vs. 33% and 100% vs. 13%, respectively). Some kelts (n = 7) displayed nondirected movements that were interpreted as a reconditioning period for an average of 9–17 days prior to directed downstream movements indicating the initiation of migration. Survival after the initiation of migration in spring was 83% and 94% to the hydropower dam in the first and second study years, and decreased to 60 and 63%, respectively, after dam passage. There were no further losses in the downriver reach in the second year, with the first year having a cumulative survival estimate of 53% to the river mouth. Kelts approached the dam when the spillway gates were available as a passage option most of the time (64%–75%), but some kelts arrived at the dam or had not yet passed when spillways were closed (n = 6) and the only remaining passage option was restricted to the turbines. However, all but one kelt that must have passed via turbine were successful in reaching the river mouth. Migratory delay presumably due to searching behaviour caused by low water flow was estimated at approximately 6 days as migration rates were significantly slower in the reservoir (median ± s.e. 8.5 ± 2.5 km day−1) than up- (29.7 ± 5.0 km day−1) or downriver (22.1 ± 3.1 km day−1). The proportion of time (median 30%) that kelts spent swimming upstream (searching behaviour) in the reservoir was a significant variable for migration success.
Boudreault J., St-Hilaire A., Chebana F., Bergeron N.E. (2021). Modelling fish physico-thermal habitat selection using functional regression. Journal of Ecohydraulics, 6(2) 105-120.

In this paper, a new fish habitat modelling approach is introduced using the full probability density functions (PDF), rather than single measurements or central tendency metrics, to describe each predictor. To model habitat selection using PDFs, functional regression models (FRM) are used to allow for the inclusion of curves or functions (smoothed empirical PDFs) in regression models compared to scalars or vectors in classical contexts. The benefits of FRM are exemplified by comparing results with those obtained using generalized additive models (GAM), one of the most recent and performing models in the field. Abundance of juvenile Atlantic salmon sampled at 26 sites (75 m-long x river width) of the Sainte-Marguerite River (Quebec, Canada) was modelled with PDFs of four potential predictors: flow velocity, water depth, substrate size and water temperature. The latter has been less frequently used in habitat modelling and the results showed that it was the most significant predictor. Overall, FRM explained more of the variability in habitat selection than GAM (+14.9% for fry and +8.1% for 1+ parr), mainly due to their ability to use complete distributions of the habitat variables rather than aggregated values (mean). A leave-one-out cross validation showed that both GAM and FRM had similar performance to predict fish abundance. The use of FRM in fish habitat modelling is innovative and its potential should be further developed, especially in the current context where habitat variables are becoming increasingly easy to obtain due to rapid progress of remote measurement techniques.
Cabrera-Páez Y., Aguilar-Betancourt C.M., González-Sansón G., Hinojosa-Larios A. (2021). Spatial and seasonal variation in littoral fish assemblages of four estuarine lagoons on the Mexican Pacific coast. Regional Studies in Marine Science, 48.

The shallowest zones of coastal lagoons are particularly appropriate nursery habitat for many fish species by providing refuge from predators and abundant food, among other benefits. However, little is known about the characteristics of fish assemblages and their relationship with environmental factors in these areas. The main objective of this study was to investigate the abundance and composition of the fish assemblages in the shallow zones (≤1 m) of four coastal lagoons in the Central Mexican Pacific and determine the correlation of their spatial and seasonal variations with selected abiotic variables. Fish samples were taken with a beach seine in the months of May and December during two consecutive years. Simultaneously, the physical and chemical variables of the water were measured, and the particle size of the sediment and content of organic matter were determined. A total of 26016 fish belonging to 60 species were collected, but only eight species (Poeciliopsis turrubarensis, Lile stolifera, Poecilia butleri, Eucinostomus currani, Anchoa sp, Gerres simillimus, Atherinella guatemalensis and Mugil setosus) accounted for more than 80% of the specimens. Significant differences in the composition of the fish assemblages between lagoons were found. The changes were principally related to the type of communication with the ocean, second to physical and chemical variables, primarily salinity, followed by size of the sediment particles (% of mud or sand). Observed seasonal changes could have been related to environmental and biological factors (e.g. recruitment) acting synergistically. No evidence was found that the state of eutrophication of the lagoons is severe and could be affecting the composition of the fish assemblages.
Camaclang A.E., Currie J., Giles E., Forbes G.J., Edge C.B., Monk W.A., Nocera J.J., Stewart-Robertson G., Browne C., O'Malley Z.G., Snider J., Martin T.G. (2021). Prioritizing threat management across terrestrial and freshwater realms for species conservation and recovery. Conservation Science and Practice, 3(2).

The need to manage threats to biodiversity, and to do so cost-effectively, is urgent. Cross-realm conservation management is recognized as a cost-effective approach, but it requires collaboration between agencies and jurisdictions, and local knowledge of anthropogenic threats to biodiversity. With its emphasis on stakeholder engagement and use of structured expert elicitation, Priority Threat Management (PTM) facilitates rapid, cross-realm planning at the regional scale. We used PTM to identify cost-effective management strategies with the aim of securing nine ecological groups, comprised of 45 species and one ecological community of conservation concern, across terrestrial and freshwater realms within the Wolastoq|Saint John River watershed in Canada. Under business-as-usual, four of nine groups are expected to have >50% probability of persistence over the next 25 years. Investment of $141 million over 25 years in three management strategies could secure seven groups across both realms with >50% probability of persistence. Achieving higher levels of persistence comes at a cost—securing six groups with >60% probability of persistence requires investing $218 million over 25 years in seven strategies. Through a structured, iterative process, whereby stakeholders cooperate to clarify objectives, devise management strategies, and collate data, PTM can support timely and cost-effective management across multiple realms.
Carvalho Carneiro de Mendonça B., Mao L., Belletti B. (2021). Spatial scale determines how the morphological diversity relates with river biological diversity. Evidence from a mountain river in the central Chilean Andes. Geomorphology, 372.

Rivers shape the landscape and determine spatial connectivity for a variety of riverine and terrestrial organisms. Rivers impacted by human disturbances are often in need of restoration in order to increase their functionality and ecological diversity, and ultimately to improve the ecosystems services that they offer. Because it is usually assumed that physical diversity of river systems promotes biological diversity or riverine species, river restoration practices often tend to enhance simplified rivers by increasing structural morphological complexity of river reaches. However, the relationship between the variability of physical features and the biological communities in riverine environments is not necessarily straightforward to assume due to the high degree of complexity and feedback in the relationship. This work presents a case study with the application of a recent geomorphological method developed in Europe for the assessment and characterization of geomorphic conditions in combination with biological surveys, along a mountain river basin in Central Chile (Clarillo River). Although representing a single “snapshot” in the pulsating nature of a river system, our results suggest that availability of habitats provides the conditions to support different levels of biodiversity in a hierarchical way in terms of spatial scale. In particular, we found that abundance and diversity of macroinvertebrates are more related with composition of geomorphic units, whereas the presence of fish is more related with the geomorphic nature of the reaches, and the presence of anurans is more related with the geomorphic nature of river segments.
Charron C., St-Hilaire A., Ouarda T.B.M.J., van den Heuvel M.R. (2021). Water temperature and hydrological modelling in the context of environmental flows and future climate change: Case study of the wilmot river (Canada). Water Switzerland, 13(15).

Simulation of surface water flow and temperature under a non-stationary, anthropogeni-cally impacted climate is critical for water resource decision makers, especially in the context of environmental flow determination. Two climate change scenarios were employed to predict stream-flow and temperature: RCP 8.5, the most pessimistic with regards to climate change, and RCP 4.5, a more optimistic scenario where greenhouse gas emissions peak in 2040. Two periods, 2018–2050 and 2051–2100, were also evaluated. In Canada, a number of modelling studies have shown that many regions will likely be faced with higher winter flow and lower summer flows. The CEQUEAU hydrological and water temperature model was calibrated and validated for the Wilmot River, Canada, using historic data for flow and temperature. Total annual precipitation in the region was found to remain stable under RCP 4.5 and increase over time under RCP 8.5. Median stream flow was expected to increase over present levels in the low flow months of August and September. However, increased climate variability led to higher numbers of periodic extreme low flow events and little change to the frequency of extreme high flow events. The effective increase in water temperature was four-fold greater in winter with an approximate mean difference of 4◦ C, while the change was only 1◦ C in summer. Overall implications for native coldwater fishes and water abstraction are not severe, except for the potential for more variability, and hence periodic extreme low flow/high temperature events.
Coffin M., Knysh K., Roloson S., Pater C., Theriaul E., Cormier J., Courtenay S., van den Heuvel M. (2021). Influence of nutrient enrichment on temporal and spatial dynamics of dissolved oxygen within northern temperate estuaries. Environmental Monitoring and Assessment, 193(12).

In temperate estuaries of the southern Gulf of St. Lawrence, intermittent seasonal anoxia coupled with phytoplankton blooms is a regular occurrence in watersheds dominated by agricultural land use. To examine the spatial relationship between dissolved oxygen and phytoplankton throughout the estuary to assist in designing monitoring programs, oxygen depth profiles and chlorophyll measurements were taken bi-weekly from May to December in 18 estuaries. In five of those estuaries, dissolved oxygen data loggers were set to measure oxygen at hourly intervals and at multiple locations within the estuary the subsequent year. The primary hypothesis was that dissolved oxygen in the upper estuary (first 10% of estuary area) is predictive of dissolved oxygen mid-estuary (50% of estuary area). The second hypothesis was that hypoxia/superoxia in the estuary is influenced by temperature and tidal flushing. Oxygen depth profiles conducted in the first year of study provided preliminary support that dissolved oxygen in the upper estuary was related to dissolved oxygen throughout the estuary. However, dissolved oxygen from loggers deployed at 10% and 50% of estuary area did not show as strong a correlation as expected (less than half the variance explained). The strength of the correlation declined towards the end of summer. Spatial decoupling of oxygen within the estuary suggested influence of local conditions. Chlorophyll concentration seemed also to be dependent on local conditions as it appeared to be coupled with the presence of sustained anoxia in the upper estuary with blooms typically occurring within 7 to 14 days of anoxia. The practical implication for oxygen monitoring is that one location within the most severely impacted part of the estuary is not sufficient to fully evaluate the severity of eutrophication effects.
Cormier S.N., Musetta-Lambert J.L., Painter K.J., Yates A.G., Brua R.B., Culp J.M. (2021). Sources of nitrogen to stream food webs in tributaries of the Red River Valley, Manitoba. Journal of Great Lakes Research, 47(3) 751-760.

Lake Winnipeg has undergone rapid eutrophication over the last several decades with a large portion of the associated nutrient loads delivered via the Red River. Consequently, subcatchments of the Red River Valley (RRV) are priorities for nutrient management, an aim that requires identification of key nutrient sources to stream food webs. We identified the primary sources of nitrogen to food webs of rural streams of the RRV, as well as variation in nitrogen input between spring and summer. We measured δ15N of particulate organic matter (POM) and collector-gatherer invertebrates collected in spring and summer from 20 subcatchments, which exhibited a range of agricultural intensity and size of municipal wastewater lagoons. δ15N values of POM and collector-gatherer invertebrates were best predicted by the presence of wastewater treatment lagoons, with δ15N values increasing with the number of people served by lagoons in spring and summer. When present, wastewater contributed a greater proportion of nitrogen to stream food webs than agricultural sources. Waste sources also had a greater relative contribution to food webs in summer than spring. Despite wastewater lagoons releasing nitrogen in short-term, pulsed discharges, the influence of wastewater on food web nitrogen persisted from the summer release into the following spring. Based on the observed importance of wastewater as a source of nitrogen to stream food webs, we recommend management agencies consider additional actions to reduce nutrient losses from wastewater treatment facilities as well as agricultural lands to more effectively protect aquatic ecosystems.
Cox K., Brocious E., Courtenay S.C., Vinson M.R., Mason S.A. (2021). Distribution, abundance and spatial variability of microplastic pollution on the surface of Lake Superior. Journal of Great Lakes Research, 47(5) 1358-1364.

In 2014, 94 paired neuston net samples (0.5 mm mesh) were collected from the surface waters of Lake Superior. These samples comprise the most comprehensive surface water survey for microplastics of any of the Great Lakes to date, and the first to employ double net trawls. Microplastic abundance estimates showed wide variability, ranging between 4000 to more than 100,000 particles/km2 with most locations having abundances between 20,000 to 50,000 particles/km2. The average abundance in Lake Superior was ~30,000 particles/km2 which was similar to previous estimates within this Laurentian Great Lake and suggests a total count of more than 2.4 billion (1.7 to 3.3 billion, 95% confidence interval) particles across the lake's surface. Distributions of plastic particles, characterized by size fraction and type, differed between nearshore and offshore samples, and between samples collected in the eastern versus western portion of the lake. Most of the particles found were fibers (67%), and most (62%) were contained in the smallest classified size fraction (0.50–1 mm). The most common type of polymer found was polyethylene (51%), followed by polypropylene (19%). This is consistent with global plastics production and results obtained from other studies. No statistically significant difference was detected between the paired net samples, indicating that single net sampling should produce a representative estimate of microplastic particle abundance and distribution within a body of water.
Dey C.J., Rego A.I., Bradford M.J., Clarke K.D., McKercher K., Mochnacz N.J., de Paiva A., Ponader K., Robichaud L., Winegardner A.K., Berryman C., Blanchfield P.J., Boston C.M., Braun D., Brownscombe J.W., Burbidge C., Campbell S., Cassidy A., Chu C., Cooke S.J., Coombs D., Cooper J., Curry A., Cvetkovic M., Demers A., Docker M., Doherty A., Doka S.E., Dunmall K., Edwards B., Enders E.C., Fisher N., Gauthier-Ouellet M., Glass W., Harris L.N., Hasler C., Hill J., Hinch S.G., Hodgson E.E., Hwang J., Jeffries K.M., King L., Kiriluk R., Knight R., Levy A., Macdonald J., Mackereth R., McLaughlin R., Minns C.K., Moore J.W., Nantel K., Nessman C., Normand C., O’connor C.M., Paulic J., Phalen L., Post J., Pratt T.C., Reid S.M., Rose C.A., Rosenfeld J., Smokorowski K.E., Sooley D., Taylor M.K., Treberg J., Trottier J., Tunney T.D., Veilleux M.P., Watkinson D.A., Watts D., Winfield K., Ziegler J.P., Midwood J.D., Koops M.A. (2021). Research priorities for the management of freshwater fish habitat in canada. Canadian Journal of Fisheries and Aquatic Sciences, 78(11) 1744-1754.

Effective management of freshwater fish habitat is essential to supporting healthy aquatic ecosystems and sustainable fisheries. In Canada, recent changes to the Fisheries Act enhanced the protection of fish habitat, but application of those provisions relies on sound scientific evidence. We employed collaborative research prioritization methods to identify scientific research questions that, if addressed, would significantly advance the management of freshwater fish habitat in Canada. This list was generated by a diverse group of freshwater fish experts, including substantial contributions from practitioners who administer provisions of the Fisheries Act. The research questions generated in this study identify priority topics for future research, while highlighting issues that could be addressed with different funding models. As a result, this study should support evidence-based management of Canada’s aquatic resources by identifying scientific knowledge gaps faced by practitioners, and suggesting mechanisms to address them. Given the important contribution of Canadian freshwater systems to global ecosystem values, and the similar scientific challenges facing fish habitat managers in other jurisdictions, this study is likely to have broad applicability.
Eger S.L., Courtenay S.C. (2021). Integrated coastal and marine management: Insights from lived experiences in the Bay of Fundy, Atlantic Canada. Ocean and Coastal Management, 204.

This paper examines ‘the governance gap’ regarding the operationalization of integrated coastal and marine management (ICM). ICM offers a holistic and strategic governance arrangement employed worldwide to help move beyond conventional sector-based approaches to contribute to the sustainability of complex and dynamic social-ecological systems. The context within which we investigate this gap is the Bay of Fundy, Atlantic Canada where a diversity of habitats and activities (e.g., eelgrass beds, mudflats, and estuaries) exist, along with a rich cultural attachment of coastal communities to marine resources. In-person, semi-structured interviews were carried out with 68 individuals across multiple sectors and scales with experience and interest in past or future integrative management interventions, or initiatives, in the Bay of Fundy. Participants identified 60 initiatives that they felt were integrative. However, our results indicate that few initiatives have been operationalized due to a ‘business as usual’ mentality. Five critical challenges were identified relating to: capacity to sustain initiatives; commitment from legal authorities; engagement of diverse actor groups; vertical integration of policies; and, informal structures that facilitate horizontal integration. These results shape how scholars, practitioners, and managers consider ICM as a governance approach. Understanding the governance dimensions of ICM will allow for initiatives to be operationalized more successfully.
Eger S.L., de Loë R.C., Pittman J., Epstein G., Courtenay S.C. (2021). A systematic review of integrated coastal and marine management progress reveals core governance characteristics for successful implementation. Marine Policy, 132.

Integrated coastal and marine management (ICM) holds considerable promise for addressing gaps in conventional sector-based approaches to the management of coastal and marine areas. Progress in operationalizing ICM has been hindered by a lack of appropriate governance arrangements (e.g., mechanisms for making collective decisions about the use and management of coastal systems). This paper develops a framework for analyzing ICM governance based upon a preliminary scoping review, and uses the framework to conduct a structured systematic review of the peer-reviewed literature on ICM between 2010 and 2019 (n = 69). Results suggest that coastal stakeholders have struggled to fully operationalize ICM across many contexts, and that certain characteristics appear to enhance prospects for operationalizing ICM. These include formal governance structures, engagement with diverse actors and innovative mechanisms for coordination and cooperation among multi-actor groups. The paper concludes by revising the ICM framework, based upon the relative importance of topics discussed in the literature, with particular attention to monitoring, evaluation and adaptation stages. The resulting Elements and Characteristics of ICM framework summarizes the state of the field while providing a practical resource for planning and management.
Eger S.L., Stephenson R.L., Armitage D., Flannery W., Courtenay S.C. (2021). Revisiting Integrated Coastal and Marine Management in Canada: Opportunities in the Bay of Fundy. Frontiers in Marine Science, 8.

Limited progress has been made in implementing integrated coastal and marine management (ICM) policies globally. A renewed commitment to ICM in Canada offers an opportunity to implement lessons from previous efforts over the past 20 years. This study applies three core ICM characteristics identified from the literature (formal structures; meaningful inclusion; and, innovative mechanisms) to identify opportunities for operationalizing ICM from participants’ lived experiences in Atlantic Canada. These characteristics are employed to assess and compare ICM initiatives across two case studies in the Upper Bay and the Lower Bay of Fundy. The assessments are based on semi-structured interviews conducted with key participants and a supplementary document analysis. The following insights for future ICM policies were identified: adaptive formal structures are required for avoiding previous mistakes; a spectrum of approaches will support meaningful engagement in ICM; local capacity is needed for effective innovative mechanisms; and, policy recommendations should be implemented in parallel. Although these insights are relevant to each of the two sub-regional case studies, the paths taken to incorporating and realizing them appear to be location-specific. To account for these site-specific differences, we suggest more attention be given to strategies that incorporate local history, unique capacity of actor groups and location-specific social-ecological systems objectives. We provide the following recommendations on policy instruments to assist in moving toward enhanced regional ICM in the Bay of Fundy, and that may also be transferable to international ICM efforts: update policy statements to incorporate lessons from previous experiences; strengthen commitment to ICM in Federal law; create a regional engagement strategy to enhance involvement of local actor groups; and, enhance the role of municipal governments to support local capacity building and appropriate engagement of local actors in ICM processes.
Erdozain M., Kidd K.A., Emilson E.J.S., Capell S.S., Kreutzweiser D.P., Gray M.A. (2021). Forest management impacts on stream integrity at varying intensities and spatial scales: Do abiotic effects accumulate spatially? Science of the Total Environment, 753.

Though effects of forest harvesting on small streams are well documented, little is known about the cumulative effects in downstream systems. The hierarchical nature and longitudinal connectivity of river networks make them fundamentally cumulative, but lateral and vertical connectivity and instream processes can dissipate the downstream transport of water and materials. To elucidate such effects, we investigated how a suite of abiotic indicators changed from small streams to larger downstream sites (n = 6) within three basins ranging in forest management intensity (intensive, extensive, minimal) in New Brunswick (Canada) in the summer and fall of 2017 and 2018. Inorganic sediments, the inorganic/organic ratios and water temperatures significantly increased longitudinally, whereas nutrients and the fluorescence index of dissolved organic carbon (DOC; indication of terrestrial source) decreased. However, some longitudinal trends differed across basins and indicated downstream cumulative (inorganic sediments, the inorganic/organic ratios and to a lesser extent DOC concentration and humification) as well as dissipative (temperatures, nutrients, organic sediments) effects of forest management. Overall, we found that the effects previously reported for small streams with managed forests also occur at downstream sites and suggest investigating whether different management practices can be used within the extensive basin to reduce these cumulative effects.
Erdozain M., Kidd K.A., Emilson E.J.S., Capell S.S., Luu T., Kreutzweiser D.P., Gray M.A. (2021). Forest management impacts on stream integrity at varying intensities and spatial scales: Do biological effects accumulate spatially? Science of the Total Environment, 763.

The effects of forest harvesting on headwaters are quite well understood, yet our understanding of whether impacts accumulate or dissipate downstream is limited. To address this, we investigated whether several biotic indicators changed from smaller to larger downstream sites (n = 6) within three basins that had intensive, extensive or minimal forest management in New Brunswick (Canada). Biofilm biomass and grazer abundance significantly increased from upstream to downstream, whereas organic matter decomposition and the autotrophic index of biofilms decreased. However, some spatial trends differed among basins and indicated either cumulative (macroinvertebrate abundance, predator density, sculpin GSI) or dissipative (autotrophic index, cotton decomposition) effects downstream, potentially explained by sediment and nutrient dynamics related to harvesting. No such among-basin differences were observed for leaf decomposition, biofilm biomass, macroinvertebrate richness or sculpin condition. Additionally, results suggest that some of the same biological impacts of forestry observed in small headwaters also occurred in larger systems. Although the intensive and extensive basins had lower macroinvertebrate diversity, there were no other signs of biological impairment, suggesting that, overall, current best management practices protect biological integrity downstream despite abiotic effects.
Feio M.J., Hughes R.M., Callisto M., Nichols S.J., Odume O.N., Quintella B.R., Kuemmerlen M., Aguiar F.C., Almeida S.F.P., Alonso-Eguíalis P., Arimoro F.O., Dyer F.J., Harding J.S., Jang S., Kaufmann P.R., Lee S., Li J., Macedo D.R., Mendes A., Mercado-Silva N., Monk W., Nakamura K., Ndiritu G.G., Ogden R., Peat M., Reynoldson T.B., Rios-Touma B., Segurado P., Yates A.G. (2021). The biological assessment and rehabilitation of theworld’s rivers: An overview. Water Switzerland, 13(3).

The biological assessment of rivers i.e., their assessment through use of aquatic assemblages, integrates the effects of multiple-stressors on these systems over time and is essential to evaluate ecosystem condition and establish recovery measures. It has been undertaken in many countries since the 1990s, but not globally. And where national or multi-national monitoring networks have gathered large amounts of data, the poor water body classifications have not necessarily resulted in the rehabilitation of rivers. Thus, here we aimed to identify major gaps in the biological assessment and rehabilitation of rivers worldwide by focusing on the best examples in Asia, Europe, Oceania, and North, Central, and South America. Our study showed that it is not possible so far to draw a world map of the ecological quality of rivers. Biological assessment of rivers and streams is only implemented officially nation-wide and regularly in the European Union, Japan, Republic of Korea, South Africa, and the USA. In Australia, Canada, China, New Zealand, and Singapore it has been implemented officially at the state/province level (in some cases using common protocols) or in major catchments or even only once at the national level to define reference conditions (Australia). In other cases, biological monitoring is driven by a specific problem, impact assessments, water licenses, or the need to rehabilitate a river or a river section (as in Brazil, South Korea, China, Canada, Japan, Australia). In some countries monitoring programs have only been explored by research teams mostly at the catchment or local level (e.g., Brazil, Mexico, Chile, China, India, Malaysia, Thailand, Vietnam) or implemented by citizen science groups (e.g., Southern Africa, Gambia, East Africa, Australia, Brazil, Canada). The existing large-extent assessments show a striking loss of biodiversity in the last 2-3 decades in Japanese and New Zealand rivers (e.g., 42% and 70% of fish species threatened or endangered, respectively). A poor condition (below Good condition) exists in 25% of South Korean rivers, half of the European water bodies, and 44% of USA rivers, while in Australia 30% of the reaches sampled were significantly impaired in 2006. Regarding river rehabilitation, the greatest implementation has occurred in North America, Australia, Northern Europe, Japan, Singapore, and the Republic of Korea. Most rehabilitation measures have been related to improving water quality and river connectivity for fish or the improvement of riparian vegetation. The limited extent of most rehabilitation measures (i.e., not considering the entire catchment) often constrains the improvement of biological condition. Yet, many rehabilitation projects also lack pre-and/or post-monitoring of ecological condition, which prevents assessing the success and shortcomings of the recovery measures. Economic constraints are the most cited limitation for implementing monitoring programs and rehabilitation actions, followed by technical limitations, limited knowledge of the fauna and flora and their life-history traits (especially in Africa, South America and Mexico), and poor awareness by decision-makers. On the other hand, citizen involvement is recognized as key to the success and sustainability of rehabilitation projects. Thus, establishing rehabilitation needs, defining clear goals, tracking progress towards achieving them, and involving local populations and stakeholders are key recommendations for rehabilitation projects (Table 1). Large-extent and long-term monitoring programs are also essential to provide a realistic overview of the condition of rivers worldwide. Soon, the use of DNA biological samples and eDNA to investigate aquatic diversity could contribute to reducing costs and thus increase monitoring efforts and a more complete assessment of biodiversity. Finally, we propose developing transcontinental teams to elaborate and improve technical guidelines for implementing biological monitoring programs and river rehabilitation and establishing common financial and technical frameworks for managing international catchments. We also recommend providing such expert teams through the United Nations Environment Program to aid the extension of biomonitoring, bioassessment, and river rehabilitation knowledge globally.
Ferchichi H., St-Hilaire A., Ouarda T.B.M.J., Lévesque B. (2021). Impact of the future coastal water temperature scenarios on the risk of potential growth of pathogenic Vibrio marine bacteria. Estuarine Coastal and Shelf Science, 250.

Vibrio (V), a genus of marine bacteria, are common inhabitants of warm coastal waters and estuaries. Vibrio includes V. parahaemolyticus and V. vulnificus species that can cause human infections through the consumption of contaminated shellfish (as bivalve molluscs). The growth of pathogenic Vibrio is related to ambient water temperature and seems to increase at 15 °C and over. The expansion of Vibrio infection outbreak is increasing worldwide due to the increase of the sea surface temperature as a result of ocean warming. Canada's coast is not an exception to this worldwide Vibrio spread. Faced with this issue, this study focuses on modelling the future potential Vibrio growth risk along the coasts of the St. Lawrence Gulf and Estuary, where the shellfish industry is well developed. This is done using the adequate machine learning model with explanatory variables that include air temperature and wind speed for predicting future water temperatures. Based on the predicted future water temperature scenarios and a threshold of 15 °C to determine the conditions favorable to the growth of Vibrio bacteria, we modelled the Vibrio growth risk indicator, i.e. the number of days exceeding the minimum temperature for Vibrio pathogenic growth (15 °C), in the horizon 2040–2100. Simulations show that the number of days, where the minimum temperature (15 °C) will be reached, will increase spatially and even seasonally and all the shellfish beds would meet the temperature condition for Vibrio growth regardless of the climate scenario (optimistic and pessimistic).
Fischer-Rush J., Rochette R., Paton E., Dickey A., Hayden B. (2021). An arithmetic correction for the effect of lipid on carbon stable isotope ratios in muscle and digestive glands of the American lobster (Homarus americanus). Rapid Communications in Mass Spectrometry, 35(24).

Rationale: Lipid correction models use elemental carbon-to-nitrogen ratios to estimate the effect of lipids on δ13C values and provide a fast and inexpensive alternative to chemically removing lipids. However, the performance of these models varies, especially in whole-body invertebrate samples. The generation of tissue-specific lipid correction models for American lobsters, both an ecologically and an economically important species in eastern North America, will aid ecological research of this species and our understanding of the function of these models in invertebrates. Method: We determined the δ13C and δ15N values before and after lipid extraction in muscle and digestive glands of juvenile and adult lobster. We assessed the performance of four commonly used models (nonlinear, linear, natural logarithm (LN) and generalized linear model (GLM)) at estimating lipid-free δ13C values based on the non-lipid-extracted δ13C values and elemental C:N ratios. The accuracy of model predictions was tested using paired t-tests, and the performance of the different models was compared using the Akaike information criterion score. Results: Lipid correction models accurately estimated post-lipid-extraction δ13C values in both tissues. The nonlinear model was the least accurate for both tissues. In muscle, the three other models performed well, and in digestive glands, the LN model provided the most accurate estimates throughout the range of C:N values. In both tissues, the GLM estimates were not independent of the post-lipid-extraction δ13C values, thus reducing their transferability to other datasets. Conclusions: Whereas previous work found that whole-body models poorly estimated the effect of lipids in invertebrates, we show that tissue-specific lipid correction models can generate accurate and precise estimates of lipid-free δ13C values in lobster. We suggest that the tissue-specific logarithmic models presented here are the preferred models for accounting for the effect of lipid on lobster isotope ratios.
Furze S., O’sullivan A.M., Allard S., Pronk T., Allen Curry R. (2021). A high-resolution, random forest approach to mapping depth-to-bedrock across shallow overburden and post-glacial terrain. Remote Sensing, 13(21).

Regolith, or unconsolidated materials overlying bedrock, exists as an active zone for many geological, geomorphological, hydrological and ecological processes. This zone and its processes are foundational to wide-ranging human needs and activities such as water supply, mineral exploration, forest harvesting, agriculture, and engineered structures. Regolith thickness, or depth-to-bedrock (DTB), is typically unavailable or restricted to finer scale assessments because of the technical and cost limitations of traditional drilling, seismic, and ground-penetrating radar surveys. The objective of this study was to derive a high-resolution (10 m2) DTB model for the province of New Brunswick, Canada as a case study. This was accomplished by developing a DTB database from publicly available soil profiles, boreholes, drill holes, well logs, and outcrop transects (n = 203,238). A Random Forest model was produced by modeling the relationships between DTB measurements in the database to gridded datasets derived from both a LiDAR-derived digital elevation model and photo-interpreted surficial geology delineations. In developing the Random Forest model, DTB measurements were split 70:30 for model development and validation, respectively. The DTB model produced an R2 = 92.8%, MAE = 0.18 m, and RMSE = 0.61 m for the training, and an R2 = 80.3%, MAE = 0.18 m, and RMSE = 0.66 m for the validation data. This model provides an unprecedented resolution of DTB variance at a landscape scale. Additionally, the presented framework provides a fundamental understanding of regolith thickness across a post-glacial terrain, with potential application at the global scale.
Hayden B., Tongnunui S., Beamish F.W.H., Nithirojpakdee P., Soto D.X., Cunjak R.A. (2021). Functional and trophic diversity of tropical headwater stream communities inferred from carbon, nitrogen and hydrogen stable isotope ratios. Food Webs, 26.

Tropical freshwaters support an immense diversity of fishes and invertebrates but are understudied in comparison to temperate systems. This is especially true of headwater streams, as only a small number of studies has assessed the trophic dynamics underpinning food web structure in these streams. We used stable isotopes of carbon, nitrogen and hydrogen to determine the resource use of dominant invertebrate guild and fishes in seven headwater streams in Eastern and Western Thailand, and assessed the functional and trophic diversity of each community using isotope food web metrics. Benthic invertebrates (95% credibility interval: 37–85%) and fishes (39–79%) obtained most of their resources from autochthonous sources in each stream but allochthonous and autochthonous specialists were evident in each community. We observed an increase in isotopic diversity of fishes associated with increasing stream size, but this was primarily driven by an increase in the range of isotope ratios of allochthonous and autochthonous food web endmembers rather than an increase in functional diversity. Maximum trophic position did increase with stream size. The snakehead, Channa gachua, was enriched in 2H relative to all other fishes, possibly reflecting facultative air breathing by this species. Fish communities in the headwater streams analysed filled a variety of trophic niches, predominantly fuelled by autochthonous primary production.
Helminen J., Linnansaari T. (2021). Object and behavior differentiation for improved automated counts of migrating river fish using imaging sonar data. Fisheries Research, 237.

Imaging sonars, such as the Adaptive Resolution Imaging Sonar (ARIS; Sound Metrics Corp.) produce continuous stream of sonar video footage, and they are commonly used for counting and sizing migrating fish in rivers. Although automated methods have been developed for processing imaging sonar data, manual analysis of the data is still common in fish population monitoring projects. In this study, we used Echoview software to automatically produce fish counts from long-range (up to 30 m) imaging sonar data in a prominent Atlantic salmon (Salmo salar) river; the Little Southwest Miramichi River, New Brunswick, Canada. We added postprocessing steps to address sources of error that have been reported in previous studies: 1) Major Axis Distance was used to filter out erroneous fish tracks (89 % of dynamic noise and 67 % of milling fish in the test-set) and to calculate the swimming direction (96 % correct), and 2) a logistic regression (target length, average speed, and absolute fish track change in range) was used to predict downstream moving fish from other objects with a test-set accuracy of 84 %. When 15-min tally counts were compared between computer-generated data and multiple human-generated counts, the mean of differences varied between -39 % and 65 % in the upstream counts in different datasets, and different analysis methods were in a good agreement between each other (ICC = 0.79). There were larger differences in the downstream counts where the mean of differences varied between 14 % and 115 % and there was no agreement between the datasets (ICC = 0.03). With a double-tracking method where the fish were tracked twice, the computer analysed the 24 -h datasets in 500−600 min and was slower than human-generated counts that required 200−600 min, however, computer generated-counts can be derived in the background without the presence of a technician and may produce significant savings in personnel cost.
Helminen J., O’Sullivan A.M., Linnansaari T. (2021). Measuring Tailbeat Frequencies of Three Fish Species from Adaptive Resolution Imaging Sonar Data. Transactions of the American Fisheries Society, 150(5) 627-636.

Imaging sonars, such as the Adaptive Resolution Imaging Sonar (ARIS), provide high-resolution sonar data that are used in fisheries research and management. While sonar methods have enormous potential for making population estimates, species identification via sonar remains an unresolved challenge. One method that may overcome this challenge involves measuring tailbeat frequencies to guide species differentiation. The tailbeat frequencies of three commonly sympatric anadromous fish species of eastern North America, Atlantic Salmon Salmo salar, Striped Bass Morone saxatilis, and American Shad Alosa sapidissima, were measured from imaging sonar data collected in an experimental low-flow, short-range setup. The frequencies were significantly different between the species (mean ± 1 SD beats/s: 0.6 ± 0.3 [Atlantic Salmon], 0.9 ± 0.2 [Striped Bass], and 1.4 ± 0.3 [American Shad]) when measured using a previously established manual method. Building on this, an automated method was developed and tested, and the method showed promising results. However, when compared to manually identified number of beats the error was large (on average, 1.1 [Atlantic Salmon], 4.8 [Striped Bass], and −0.4 [American Shad] beats in a fish track), especially in high fish densities. Despite the limitations, the automated method has utility in fisheries management when high-quality data can be collected for species with differing tailbeat frequencies.
Henriksson P.J.G., Troell M., Banks L.K., Belton B., Beveridge M.C.M., Klinger D.H., Pelletier N., Phillips M.J., Tran N. (2021). Interventions for improving the productivity and environmental performance of global aquaculture for future food security. One Earth, 4(9) 1220-1232.

Aquatic foods are increasingly being recognized as having an important role to play in an environmentally sustainable and nutritionally sufficient food system. Proposals for increasing aquatic food production often center around species, environments, and ambitious hi-tech solutions that mainly will benefit the 16% of the global population living in high-income countries. Meanwhile, most aquaculture species and systems suffer from large performance gaps, meaning that targeted interventions and investments could significantly boost aquatic food supply and access to nutritious foods without a concomitant increase in environmental footprints. Here we contend that the dialogue around aquatic foods should pay greater attention to identifying and implementing interventions to improve the productivity and environmental performance of low-value commodity species that have been relatively overlooked in this regard to date. We detail a range of available technical and institutional intervention options and evaluate their potential for increasing the output and environmental performance of global aquaculture.
Huynh H.M., McAlpine D.F., Pavey S.A. (2021). First evidence of White-footed Deer Mouse (Peromyscus leucopus) on mainland New Brunswick, Canada. Canadian Field Naturalist, 135(3) 245-249.

White-footed Deer Mouse (Peromyscus leucopus) and the closely related, and more northerly ranging, Deer Mouse (Peromyscus maniculatus) broadly overlap in distribution and are often difficult to distinguish from each other. Based on molecular genetic data (cytochrome b gene), we report two new distribution records for P. leucopus for New Brunswick, Canada, the first mainland localities for this species in the province. Previous sampling of Peromyscus in New Brunswick may have overlooked the presence of P. leucopus, possibly because the specimens collected were all assumed to be P. maniculatus. However, current detection in New Brunswick may be part of a broader recent northward range expansion documented to be underway in P. leucopus. Although our use of a single mitochondrial gene to identify P. leucopus does not eliminate the possibility that the New Brunswick specimens are of hybrid origin, our results support the presence of P. leucopus in New Brunswick and suggest more detailed analyses will be required to determine the nature of any genetic interaction between P. leucopus and P. maniculatus in the province. Recognition of morphologically cryptic Peromyscus in southern New Brunswick also emphasizes the need to incorporate comprehensive methods to ensure the correct identification of specimens of this genus in Maritime Canada. We also note the potential implications of this discovery with respect to the incidence of Lyme disease in New Brunswick.
Izral N.M., Brua R.B., Culp J.M., Yates A.G. (2021). Crayfish tissue metabolomes effectively distinguish impacts of wastewater and agriculture in aquatic ecosystems. Science of the Total Environment, 760.

Environmental metabolomics has been proposed as a tool for biomonitoring because organisms regulate production or consumption of metabolites in response to environmental conditions. We evaluated the efficacy of the metabolome of three tissues (hepatopancreas, gill, and tail muscle) from the northern crayfish (Faxonius virilis) to detect and differentiate between impacts of human activities (i.e., reference, municipal wastewater, and agriculture). We conducted a reciprocal transfer study exposing crayfish for 1 or 2 weeks in three streams with different amounts and types of human activities in southern Manitoba, Canada. Tissue samples were analyzed using nuclear magnetic resonance spectroscopy to generate a metabolic profile. Findings indicated the gill tissue metabolome best detected and differentiated between human activities. In particular, the gill metabolome was able to rapidly integrate abrupt changes in environmental conditions associated with municipal wastewater activity. In contrast, the tail metabolome best differentiated between crayfish collected at the reference site from those collected at the two impacted sites. Metabolites extracted from hepatopancreas tissue showed limited and inconsistent detection of among site differences. Based on our findings, we conclude that the metabolome of the northern crayfish can be an effective biomonitoring tool, but monitoring purpose will dictate tissue selection. Indeed, we recommend the gill metabolome be used for short-term assays aimed at detecting acute effects, whereas the tail be applied for survey monitoring aimed at detecting deviations in ecological condition at test sites from reference site conditions.
Keva O., Taipale S.J., Hayden B., Thomas S.M., Vesterinen J., Kankaala P., Kahilainen K.K. (2021). Increasing temperature and productivity change biomass, trophic pyramids and community-level omega-3 fatty acid content in subarctic lake food webs. Global Change Biology, 27(2) 282-296.

Climate change in the Arctic is outpacing the global average and land-use is intensifying due to exploitation of previously inaccessible or unprofitable natural resources. A comprehensive understanding of how the joint effects of changing climate and productivity modify lake food web structure, biomass, trophic pyramid shape and abundance of physiologically essential biomolecules (omega-3 fatty acids) in the biotic community is lacking. We conducted a space-for-time study in 20 subarctic lakes spanning a climatic (+3.2°C and precipitation: +30%) and chemical (dissolved organic carbon: +10 mg/L, total phosphorus: +45 µg/L and total nitrogen: +1,000 µg/L) gradient to test how temperature and productivity jointly affect the structure, biomass and community fatty acid content (eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) of whole food webs. Increasing temperature and productivity shifted lake communities towards dominance of warmer, murky-water-adapted taxa, with a general increase in the biomass of primary producers, and secondary and tertiary consumers, while primary invertebrate consumers did not show equally clear trends. This process altered various trophic pyramid structures towards an hour glass shape in the warmest and most productive lakes. Increasing temperature and productivity had negative fatty acid content trends (mg EPA + DHA/g dry weight) in primary producers and primary consumers, but not in secondary nor tertiary fish consumers. The massive biomass increment of fish led to increasing areal fatty acid content (kg EPA + DHA/ha) towards increasingly warmer, more productive lakes, but there were no significant trends in other trophic levels. Increasing temperature and productivity are shifting subarctic lake communities towards systems characterized by increasing dominance of cyanobacteria and cyprinid fish, although decreasing quality in terms of EPA + DHA content was observed only in phytoplankton, zooplankton and profundal benthos.
Kidd J.A., Boudreau M., Bailey R.C., van den Heuvel M.R., Servos M.R., Courtenay S.C. (2021). Evaluating the sampling design of a long-term community-based estuary monitoring program. Fishes, 6(3).

Community-based monitoring programs (CBMPs) are a cost-effective option to collect the long-term data required to effectively monitor estuaries. Data quality concerns have caused some CBMP datasets, which could fill knowledge gaps for aquatic ecosystems, to go unused. The Community Aquatic Monitoring Program (CAMP) is a CBMP that has collected littoral nekton assemblage data from estuaries in the southern Gulf of St. Lawrence since 2003. Concerns with the CAMP sampling design (station placement and numbers) have prevented decision-makers from using the data to inform estuary health assessments. This study tested if CAMP’s sampling design that accommodates volunteer participation provides similar information as a scientific sampling approach. Six CAMP stations and six stations selected using a stratified random design were sampled at ten estuaries. A permutational-MANOVA revealed nekton assemblages were generally not significantly different between the two sampling designs. The current six CAMP stations are sufficient to detect the larger differences in species abundances that may indicate differences in estuary condition. The predicted increase in precision (2%) with twelve stations is not substantive enough to warrant an increased sampling effort. CAMP’s scientific utility is not limited by station selection bias or numbers. Furthermore, well-designed CBMPs can produce comparable data to scientific studies.
Knysh K.M., Courtenay S.C., Grove C.M., van den Heuvel M.R. (2021). The Differential Effects of Salinity Level on Chlorpyrifos and Imidacloprid Toxicity to an Estuarine Amphipod. Bulletin of Environmental Contamination and Toxicology, 106(5) 753-758.

Agricultural activity within coastal watersheds results in estuaries becoming the receiving environment for pesticide inputs. In estuaries, salinity can alter insecticide responses of exposed crustaceans. The acute toxicity of environmentally relevant doses of chlorpyrifos and imidacloprid were examined using the euryhaline amphipod Gammarus lawrencianus at 20 and 30 Practical Salinity Units (PSU). Responses were recorded every 24 h until an incipient (threshold) L(E)C<inf>50</inf> was reached. For chlorpyrifos, LC<inf>50</inf> ranged from 0.1 to 0.5 µg/L and was two-fold higher at 30 vs. 20 PSU at all time-points over the 96 h exposure. Imidacloprid immobility EC<inf>50</inf> ranged from 4 to 40 µg/L over the 144 h exposure. An effect of salinity was only observed at 48 h and the EC<inf>50</inf> values showed 1.4 times more potency at 20 PSU compared to 30 PSU. Measured concentrations of both compounds did not differ between salinities. Acetylcholinesterase activity in chlorpyrifos exposed amphipods showed no salinity effect at 96 h. We conclude that salinity level alters G. lawrencianus susceptibility to chlorpyrifos exposure, but not imidacloprid.
Kozak N., Ahonen S.A., Keva O., Østbye K., Taipale S.J., Hayden B., Kahilainen K.K. (2021). Environmental and biological factors are joint drivers of mercury biomagnification in subarctic lake food webs along a climate and productivity gradient. Science of the Total Environment, 779.

Subarctic lakes are getting warmer and more productive due to the joint effects of climate change and intensive land-use practices (e.g. forest clear-cutting and peatland ditching), processes that potentially increase leaching of peat- and soil-stored mercury into lake ecosystems. We sampled biotic communities from primary producers (algae) to top consumers (piscivorous fish), in 19 subarctic lakes situated on a latitudinal (69.0–66.5° N), climatic (+3.2 °C temperature and +30% precipitation from north to south) and catchment land-use (pristine to intensive forestry areas) gradient. We first tested how the joint effects of climate and productivity influence mercury biomagnification in food webs focusing on the trophic magnification slope (TMS) and mercury baseline (THg baseline) level, both derived from linear regression between total mercury (log<inf>10</inf>THg) and organism trophic level (TL). We examined a suite of environmental and biotic variables thought to explain THg baseline and TMS with stepwise generalized multiple regression models. Finally, we assessed how climate and lake productivity affect the THg content of top predators in subarctic lakes. We found biomagnification of mercury in all studied lakes, but with variable TMS and THg baseline values. In stepwise multiple regression models, TMS was best explained by negative relationships with food chain length, climate-productivity gradient, catchment properties, and elemental C:N ratio of the top predator (full model R2 = 0.90, p < 0.001). The model examining variation in THg baseline values included the same variables with positive relationships (R2 = 0.69, p = 0.014). Mass-standardized THg content of a common top predator (1 kg northern pike, Esox lucius) increased towards warmer and more productive lakes. Results indicate that increasing eutrophication via forestry-related land-use activities increase the THg levels at the base of the food web and in top predators, suggesting that the sources of nutrients and mercury should be considered in future bioaccumulation and biomagnification studies.
Lavoie C., Wellband K., Perreault A., Bernatchez L., Derome N. (2021). Artificial rearing of atlantic salmon juveniles for supportive breeding programs induces long-term effects on gut microbiota after stocking. Microorganisms, 9(9).

In supportive breeding programs for wild salmon populations, stocked parr experience higher mortality rates than wild ones. Among other aspects of phenotype, the gut microbiota of artificially raised parr differs from that of wild parr before stocking. Early steps of microbiota ontogeny are tightly dependent upon environmental conditions, both of which exert long-term effects on host physiology. Therefore, our objective was to assess to what extent the resilience capacity of the microbiota of stocked salmon may prevent taxonomic convergence with that of their wild congeners after two months in the same natural environment. Using the 16S SSU rRNA marker gene, we tested the general hypothesis that environmental conditions during the very first steps of microbiota ontogeny imprint a permanent effect on later stages of microbiota recruitment. Our results first showed that gut microbiota composition of stocked and wild parr from the same genetic population, and sharing the same environment, was dependent on the early rearing environment. In contrast, skin microbiota in stocked individuals converged to that of wild individuals. Taxonomic composition and co-occurrence network analyses suggest an impairment of wild bacteria recruitment and a higher instability for the gut microbiota of stocked parr. This study is the first to demonstrate the long-term effect of early microbiota ontogeny in artificial rearing for natural population conservation programs, raising the need to implement microbial ecology.
Levenstein B., Lento J., Culp J. (2021). Effects of prolonged sedimentation from permafrost degradation on macroinvertebrate drift in Arctic streams. Limnology and Oceanography, 66(S1) S157-S168.

Retrogressive thaw slumps are areas of unstable degraded permafrost that often drain into nearby watersheds, leading to increased sediment loads and changes in water quality. Thaw slumps are prevalent across the Arctic, including western Canada, Alaska, and Russia, and high-altitude areas of western China. Over the past several decades, increased temperatures and precipitation in the Arctic have led to increases in the size and frequency of thaw slumps. Our study explored the effects of prolonged sedimentation from thaw slumps in the Peel Plateau, NWT, Canada on benthic macroinvertebrate drift, an important biological function of stream ecosystems. Though sedimentation is known to initiate a catastrophic drift response, studies have generally not considered the drift response to ongoing, long-term perturbation. Drift densities and sediment loads were measured using drift nets and sediment traps at paired sites upstream and downstream of thaw slumps. We compared drift densities and sediment loads between sites and examined how drift differed over a fine-sediment gradient. The amount of suspended and settling fine sediments increased significantly at downstream sites. Drift densities decreased at downstream sites; however, when drift was corrected for benthic abundance at each site, there was an increase in proportional drift density associated with increased fine sediments. These results indicate that prolonged impacts from thaw slumps result in lower macroinvertebrate abundance and higher proportional drift relative to undisturbed sites. Ultimately, increased sediment loads from thaw slumps represent a chronic stressor that will continue to prevent recovery of macroinvertebrate communities at impacted sites until these features stabilize.
Loughery J.R., Crowley E., Kidd K.A., Martyniuk C.J. (2021). Behavioral and hypothalamic transcriptome analyses reveal sex-specific responses to phenanthrene exposure in the fathead minnow (Pimephales promelas). Comparative Biochemistry and Physiology Part D Genomics and Proteomics, 40.

Environmental concentrations of the polycyclic aromatic hydrocarbon phenanthrene can become elevated with petroleum processing, industrial activities, and urban run-off into waterbodies. However, mechanisms related to its neurotoxicity in fish are not fully described. Here, we exposed adult fathead minnows (FHM) to an average measured concentration of 202 μg phenanthrene/L over a 47-d period. Behaviors of male and female FHM were assessed using a novel aquarium test. Phenanthrene exposed females displayed equilibrium loss, while phenanthrene exposed males spent less time in the aquarium bottom, suggesting phenanthrene reduced anxiety-related behavior. To elucidate putative mechanisms underlying behaviors, we determined the hypothalamic transcriptome profile, a critical integration centre for the regulation of behaviors. There were 1075 hypothalamic transcripts differentially expressed between males and females (sex-specific) while 15 transcripts were phenanthrene-specific. Thus, sex of the animal was more pervasive at influencing the transcriptome compared to phenanthrene and this may partially explain the divergent behavioral responses between sexes. Transcripts altered by phenanthrene included palmitoylated 3 membrane protein, plectin 1, ATP synthase membrane subunit c, and mitochondrial ribosomal protein S11. Gene set enrichment analysis revealed less than 5% of the gene networks perturbed by phenanthrene were shared between males and females, thus phenanthrene altered the hypothalamic transcriptome in a sex-specific manner. Gene networks shared between both sexes and associated with phenanthrene-induced neurotoxicity included processes related to mitochondrial respiratory chain dysfunction, epinephrine/norepinephrine release, and glutamate biosynthesis pathways. Such energy deficits and neurotransmitter disruptions are hypothesized to lead to behavioral deficits in fish. This study provides mechanistic insights into phenanthrene-induced neurotoxicity and how it may relate to changes in fish behaviors.
Mattos K.J., Mulhern R., Naughton C.C., Anthonj C., Brown J., Brocklehurst C., Brooks C., Desclos A., Garcia N.E.E., Gibson J.M., Linden K.G., Lindsay C.A., Newby J., Sinclair R., Smith A. (2021). Reaching those left behind: Knowledge gaps, challenges, and approaches to achieving SDG 6 in high-income countries. Journal of Water Sanitation and Hygiene for Development, 11(5) 849-858.

Even as progress has been made in extending access to safe water and sanitation under the Sustainable Development Goals (SDGs), substantial disparities in water, sanitation, and hygiene (WASH) services persist in high-income countries around the world. These gaps in service occur disproportionately among historically marginalized, rural, informal, and Indigenous communities. This paper synthesizes results from a side session convened at the 2020 University of North Carolina, Chapel Hill, Water and Health conference focused on knowledge gaps, challenges, and approaches to achieve SDG 6 among marginalized communities in high-income countries. We provide approaches and next steps to advance sustainable WASH services in communities that have often been overlooked.
Mechai S., Bilodeau G., Lung O., Roy M., Steeves R., Gagne N., Baird D., Lapen D.R., Ludwig A., Ogden N.H. (2021). Mosquito Identification from Bulk Samples Using DNA Metabarcoding: A Protocol to Support Mosquito-Borne Disease Surveillance in Canada. Journal of Medical Entomology, 58(4) 1686-1700.

Approximately 80 species of mosquitoes (Diptera: Culicidae) have been documented in Canada. Exotic species such as Aedes albopictus (Skuse) (Diptera: Culicidae) are becoming established. Recently occurring endemic mosquito-borne diseases (MBD) in Canada including West-Nile virus (WNV) and Eastern Equine Encephalitis (EEE) are having significant public health impacts. Here we explore the use of DNA metabarcoding to identify mosquitoes from CDC light-trap collections from two locations in eastern Canada. Two primer pairs (BF2-BR2 and F230) were used to amplify regions of the cytochrome c oxidase subunit I (CO1) gene. High throughput sequencing was conducted using an Illumina MiSeq platform and GenBank-based species identification was applied using a QIIME 1.9 bioinformatics pipeline. From a site in southeastern Ontario, Canada, 26 CDC light trap collections of 72 to >300 individual mosquitoes were used to explore the capacity of DNA metabarcoding to identify and quantify captured mosquitoes. The DNA metabarcoding method identified 33 species overall while 24 species were identified by key. Using replicates from each trap, the dried biomass needed to identify the majority of species was determined to be 76 mg (equivalent to approximately 72 mosquitoes), and at least two replicates from the dried biomass would be needed to reliably detect the majority of species in collections of 144-215 mosquitoes and three replicates would be advised for collections with >215 mosquitoes. This study supports the use of DNA metabarcoding as a mosquito surveillance tool in Canada which can help identify the emergence of new mosquito-borne disease potential threats.
Meo I.d., Østbye K., Kahilainen K.K., Hayden B., Fagertun C.H.H., Poléo A.B.S. (2021). Predator community and resource use jointly modulate the inducible defense response in body height of crucian carp. Ecology and Evolution, 11(5) 2072-2085.

Phenotypic plasticity can be expressed as changes in body shape in response to environmental variability. Crucian carp (Carassius carassius), a widespread cyprinid, displays remarkable plasticity in body morphology and increases body depth when exposed to cues from predators, suggesting the triggering of an antipredator defense mechanism. However, these morphological changes could also be related to resource use and foraging behavior, as an indirect effect of predator presence. In order to determine whether phenotypic plasticity in crucian carp is driven by a direct or indirect response to predation threat, we compared twelve fish communities inhabiting small lakes in southeast Norway grouped by four categories of predation regimes: no predator fish, or brown trout (Salmo trutta), perch (Perca fluviatilis), or pike (Esox lucius) as main piscivores. We predicted the body shape of crucian carp to be associated with the species composition of predator communities and that the presence of efficient piscivores would result in a deeper body shape. We use stable isotope analyses to test whether this variation in body shape was related to a shift in individual resource use—that is, littoral rather than pelagic resource use would favor the development of a specific body shape—or other environmental characteristics. The results showed that increasingly efficient predator communities induced progressively deeper body shape, larger body size, and lower population densities. Predator maximum gape size and individual trophic position were the best variables explaining crucian carp variation in body depth among predation categories, while littoral resource use did not have a clear effect. The gradient in predation pressure also corresponded to a shift in lake productivity. These results indicate that crucian carp have a fine-tuned morphological defense mechanism against predation risk, triggered by the combined effect of predator presence and resource availability.
O'Sullivan A.M., Corey E., Cunjak R.A., Linnansaari T., Curry R.A. (2021). Salmonid thermal habitat contraction in a hydrogeologically complex setting. Ecosphere, 12(10).

Broadening our understanding of river thermal variability is of paramount importance considering the role temperature plays in aquatic ecosystem health. At the catchment scale, spatial statistical river network models (SSN) are popular for analyses of river temperature, as these are less “data hungry” than other modeling methods, and have offered invaluable insights into how thermal habitats of salmonids may change with climate warming. However, recent work has demonstrated that hydrogeological complexity can disrupt river temperature spatial autocorrelation. We test the prediction that the non-linearity of hydrological processes inherent in a hydrogeologically complex setting, such as the Miramichi River, invalidates the SSN approach, and a Random Forest (RF) model can overcome these complexities. In all instances, RFs outperformed SSNs when predicting average (T<inf>wA</inf>) and maximum (T<inf>wM</inf>) August river temperature during 2017, and were quite robust (T<inf>wA</inf> and T<inf>wM</inf>: R2 = 0.93; RMSE = 0.6°C; R2 = 0.91; RMSE = 1.0°C, respectively). We conclude that RF models can capture the inherent non-linearity of hydrological processes in complex hydrogeologic settings. We examined thermal habitat change for adult and 1+/2+ Atlantic salmon—AS—(Salmo salar), and all age classes of brook trout—BKT—(Salvelinus fontinalis), during August 2017, with thresholds of behavioral thermoregulation specific to the catchment. We assumed a baseline = T<inf>wA</inf> and investigated river network contraction (km) for T<inf>wM</inf>. During T<inf>wA,</inf> all habitat was suggested to be thermally suitable for 1+/2+ AS (<23°C), but 4.2% was unsuitable for adult AS and BKT of all ages (>20°C). For T<inf>wM,</inf> ~80% of the catchment was predicted to be unsuitable for adult AS and BKT. We examined two boundaries for behavorial thermoregulation in 1+/2+ AS: >23°C and >27°C. For the >23°C boundary, ~27.7% of the catchment is thermally unsuitable during T<inf>wM</inf>, and 4.9% is thermally unsuitable for the >27°C boundary. T<inf>wA</inf> in August 2017 was identical to long-term (1970–1999) July–August T<inf>wA</inf>, as such these thermal maps will be useful for resource managers.
Painter K.J., Brua R.B., Chambers P.A., Culp J.M., Chesworth C.T., Cormier S.N., Tyrrell C.D., Yates A.G. (2021). An ecological causal assessment of tributaries draining the Red River Valley, Manitoba. Journal of Great Lakes Research, 47(3) 773-787.

Water resources on the Canadian Prairies are at risk due to human settlement, agricultural intensification, and climatic change. The Red River Valley (RRV), Manitoba, Canada, represents a nexus of these cumulative stressors. Here land use change, combined with a recent increase in precipitation and runoff, imperils the protective function of tributaries draining to Lake Winnipeg. A concerted research effort over the past decade has greatly improved availability of data and knowledge about the RRV. However, a full synthesis of these data and information remain lacking. We undertook a review to identify and compare contemporary and historical land use, climatic, hydrologic, and water quality condition within the RRV. Then, using current knowledge of the ecological condition of streams in the RRV and elsewhere, we completed an ecological causal assessment of RRV tributaries to identify linkages and knowledge gaps between anthropogenic drivers and ecological endpoints. We found wastewater to be the candidate cause of ecological effects in RRV streams best supported by empirical evidence. A lack of complete lines of evidence linking agriculture, the greatest diffuse source of nutrient inputs, and ecological effects in RRV tributaries underscored a need for stressor-specific indicators and improved biomonitoring strategies to better detect likely impacts of land use. We also identified a need for research to connect well-known causal elements in the RRV, such as climatic variables and hydrological alteration, to ecological effects. Our findings provide direction for future research and can aid in development of an adaptive management strategy for tributaries of the RRV.
Painter K.J., Brua R.B., Koehler G., Spoelstra J., Yates A.G. (2021). Contribution of nitrogen sources to streams in mixed-use catchments varies seasonally in a cold temperate region. Science of the Total Environment, 764.

Intensive agriculture and growing human populations are important nitrogen (N) sources thought to be associated with eutrophication. However, the contribution and seasonality of N delivery to streams from human activities is poorly understood and knowledge of the role of stream communities in the assimilation of N from human activities is limited. We used N and oxygen stable isotope ratios of dissolved inorganic N (DIN) and concentrations of artificial sweeteners to identify the relative contribution of key sources of anthropogenic N (i.e., fertilizers, human, and livestock waste) to tributaries of the Red River Valley (RRV), Manitoba, Canada. Water and algae were sampled in 14 RRV tributaries during snowmelt, spring, summer, and autumn; and water was sampled at three locations in the Red River in spring, summer, and autumn. δ15N values of DIN in tributary water differed seasonally and were greatest during snowmelt. Incorporation of ammonium δ15N provided evidence for the importance of manure N to tributaries during snowmelt. Fertilizer and municipal lagoons served as principal sources of N to streams in spring and summer. Human and livestock waste sources of N were the dominant contributor to algae at greater than 90% of sites and algae δ15N was greatest at sites downstream of municipal lagoons. We also showed that the tributaries contribute human and livestock waste N to the Red River, though much of the nitrate in the river originates outside of Manitoba. Overall, our study determined that the anthropogenic sources of N to RRV streams vary seasonally, likely due to regional hydrologic conditions. Our study also showed the potential of artificial sweeteners and ammonium δ15N as tools for identifying N sources to rivers. Moreover, we demonstrate the need for the management of N sources and the protection of stream function to control downstream transfer of N from landscapes to waterbodies.
Pearce N.J.T., Lavoie I., Thomas K.E., Chambers P.A., Yates A.G. (2021). Nutrient enrichment effects are conditional on upstream nutrient concentrations: Implications for bioassessment in multi-use catchments. Ecological Indicators, 124.

Human impacts on stream ecosystems are expected to intensify with population growth and climate change. Decisive information on how stream communities respond to cumulative human impacts is therefore integral for protecting streams draining multi-use catchments. To determine cumulative influences of nutrient enrichment and assess more nuanced approaches for the evaluation of human impacts, we present results from one factorial and two gradient assessment designs applied to benthic algae and macroinvertebrate data from 14 mid-order streams in southern Ontario, Canada with pre-existing human impacts (i.e., sewage effluent and agriculture). We found that among stream variability in ecological indicators measured downstream of sewage effluent outfalls confounded our generalized factorial assessment and provided inconclusive information on a known human impact. Despite our gradient assessment also not having strong statistical support, accounting for the extent of nutrient enrichment associated with differences in sewage effluent and agricultural inputs revealed that larger longitudinal changes in stream communities were associated with increased nutrient enrichment. However, re-weighting our nutrient enrichment gradient based on upstream nutrient concentrations to account for nonlinearities in the response of stream communities to nutrient enrichment produced more robust assessment results that were consistent with predicted effects of nutrients on stream ecosystems. Thus, while our factorial assessment suggests that the communities are resistant to nutrients from cumulative human impacts, our targeted gradient assessment demonstrates that the effects of nutrient enrichment are highly conditional on upstream ecosystem conditions. Future assessments may need to go beyond traditional approaches (i.e., impact presence/absence) and more explicitly consider the environmental stressors and their associated complexities related to the impact under investigation.
Penny F.M., Pavey S.A. (2021). Increased acute thermal tolerance and little change to hematology following acclimation to warm water in juvenile Striped Bass, Morone saxatilis. Environmental Biology of Fishes, 104(4) 489-500.

Striped Bass naturally inhabit a wide range of temperatures, yet little is known about the processes that control their acute and chronic temperature limits. The objective of this study was to determine the effect of temperature acclimation on acute thermal maxima and physiology of juvenile Striped Bass. Juvenile fish were acclimated to 15, 25 or 30 °C for 4 weeks, then split into two sampling groups: post-acclimation and post-critical thermal maximum trials. We found that fish survived in all acclimation temperatures with little change to underlying hematology, and that critical thermal maximum (CT<inf>max</inf>) increased with increasing acclimation temperature. At CT<inf>max</inf>, fish acclimated to 30 °C had elevated plasma cortisol, lactate and potassium levels. These results suggest that, while 30 °C is likely to be outside their thermal optima, Striped Bass can survive at high temperatures. This ability to cope with warm temperatures may provide an advantage with increasing global temperatures.
Pomfret S.M., Brua R.B., Milani D., Yates A.G. (2021). Metabolomic Analysis of Hexagenid Mayflies Exposed to Sublethal Concentrations of Naphthenic Acid. Frontiers in Molecular Biosciences, 8.

The oil sands region in northeastern Alberta, Canada contain approximately 165 billion barrels of oil making it the third largest oil reserves in the world. However, processing of extracted bitumen generates vast amounts of toxic byproduct known as oil sands process waters. Naphthenic acids and associated sodium naphthenate salts are considered the primary toxic component of oil sands process waters. Although a significant body of work has been conducted on naphthenic acid toxicity at levels comparable to what is observed in current oil sands process waters, it is also important to understand any impacts of exposure to sublethal concentrations. We conducted a microcosm study using the mayfly Hexagenia spp. to identify sublethal impacts of naphthenic acid exposure on the survival, growth, and metabolome across a concentration gradient (0–100 μg L−1) of sodium naphthenate. Nuclear magnetic resonance-based metabolomic analyses were completed on both the polar and lipophilic extracted fractions of whole organism tissue. We observed a positive relationship between sodium naphthenate concentration and mean principal component score of the first axis of the polar metabolome indicating a shift in the metabolome with increasing naphthenic acid exposure. Eleven metabolites correlated with increased naphthenic acid concentration and included those involved in energy metabolism and apoptosis regulation. Survival and growth were both high and did not differ among concentrations, with the exception of a slight increase in mortality observed at the highest concentration. Although lethal concentrations of naphthenic acids in other studies are higher (150–56,200 μg L−1), our findings suggest that physiological changes in aquatic invertebrates may begin at substantially lower concentrations. These results have important implications for the release of naphthenic acids into surface waters in the Alberta oil sands region as an addition of even small volumes of oil sands process waters could initiate chronic effects in aquatic organisms. Results of this research will assist in the determination of appropriate discharge thresholds should oil sands process waters be considered for environmental release.
Puncher G.N., Rowe S., Rose G.A., Parent G.J., Wang Y., Pavey S.A. (2021). Life-stage-dependent supergene haplotype frequencies and metapopulation neutral genetic patterns of Atlantic cod, Gadus morhua, from Canada's Northern cod stock region and adjacent areas. Journal of Fish Biology, 98(3) 817-828.

Among highly migratory fish species, nursery areas occupied by juveniles often differ from adult habitats. To better understand the spatial dynamics of Canada's Northern cod stock, juveniles caught off the east coast of Newfoundland and Labrador were compared to adults from the same region as well as individuals from other areas in Atlantic Canada using double-digest restriction site-associated DNA sequencing–derived single nucleotide polymorphisms. A reduced proportion of homozygotes with a chromosomal inversion located in linkage group 1 (LG1) was detected between juvenile and adult samples in the Northern cod stock region, potentially indicating age-dependent habitat use or ontogenetic selection for attributes associated with the many genes located in LG1. No selectively neutral genetic differences were found between samples from the Northern cod stock; nevertheless, significant differences were found between some of these samples and cod collected from St. Pierre Bank, Bay of Fundy, Browns Bank and the southern Scotian Shelf. Clustering analysis of variants at neutral loci provided evidence for three major genetic units: (a) the Newfoundland Atlantic Coast, (b) eastern and southern Gulf of St. Lawrence and Burgeo Bank and (c) the Bay of Fundy, Browns Bank and southern Scotian Shelf. Both adaptive and neutral population structure within the Northern cod stock should be considered by managers to promote demographic rebuilding of the stock.
Puncher G.N., Wang Y., Martin R., DeCelles G., Cadrin S.X., Zemeckis D., Rowe S., Leblanc N.M., Parent G.J., Pavey S.A. (2021). Transborder Gene Flow between Canada and the USA and Fine-Scale Population Structure of Atlantic Cod in the Broader Gulf of Maine Region. Transactions of the American Fisheries Society, 150(5) 560-577.

Fishery managers have struggled for decades to rebuild stocks of Atlantic Cod Gadus morhua in the northwestern Atlantic Ocean, and the resolution of current fine-scale population structure will surely help those efforts. Using double digest restriction-site associated DNA sequencing, we analyzed 248 adult and 215 juvenile Atlantic Cod collected from areas bordering the Canada–USA boundary in 2017–2018. Chromosomal inversions from linkage group (LG) 2 and LG 7 contribute the largest amount of variance to the data set. A southwesterly decrease in the proportion of LG 1 inversion haplotypes may indicate gene flow from areas north of 45°N. Samples from both the northern Gulf of Maine and Bay of Fundy were genetically distinct from all other samples, suggesting that local spawning groups may still be active. Genetic similarities between Atlantic Cod from Browns Bank and eastern Georges Bank indicate that transborder gene flow is ongoing. These results will help to better define the stocks in order to guide the implementation of management strategies in the USA and Canada, which should consider rebuilding exhausted and genetically isolated populations.
Rideout N.K., Compson Z.G., Monk W.A., Bruce M.R., Baird D.J. (2021). The Beautiful and the Dammed: Defining Multi-Stressor Disturbance Regimes in an Atlantic River Floodplain Wetland. Frontiers in Ecology and Evolution, 9.

Natural hydrological fluctuations within river floodplains generate habitat diversity through variable connections between habitat patches and the main river channel. Human modification of floodplains can alter the magnitude and frequency of large floods and associated sediment movement by interrupting these floodplain connections. The lower Wolastoq | Saint John River and its associated floodplain wetlands are experiencing anthropogenic disturbances arising from climate change, increased urbanization in the watershed, changing upstream agricultural landscape practices, and, most notably, major road and dam construction. By comparing digitized aerial images, we identified key periods of change in wetland extent throughout an ecologically significant component of the floodplain, the Grand Lake Meadows and Portobello Creek wetland complex, with significant erosion evident in coves and backwater areas across the landscape following dam construction and significant accretion around the Jemseg River following highway construction. Connectivity and hydrological regime also influenced other habitat components, namely nutrients and metals retention, as well as the composition of the local macrophyte community. These findings address two key aspects of floodplain management: (1) understanding how hydrological alteration has historically influenced floodplain wetlands can inform us of how the ecosystem may respond under future conditions, such as climate change, and (2) the mechanisms by which habitat diversity and disturbance regimes filter biological communities, with the potential for patches to host a rich biodiversity continuously supporting critical ecosystem functions.
Rideout N.K., Wegscheider B., Kattilakoski M., McGee K.M., Monk W.A., Baird D.J. (2021). Rewilding watersheds: Using nature's algorithms to fix our broken rivers. Marine and Freshwater Research, 72(8) 1118-1124.

Rewilding is an ecological restoration concept that promotes the natural recovery of ecosystems, through (initial) active or passive removal of human influence. To support the application of rewilding approaches in rivers and their watersheds, we propose a framework to assess 'rewilding potential' based on measurement of basic river ecosystem functions (e.g. restoring flood and nutrient pulses), including examples of specific indicators for these processes. This includes a discussion of the challenges in implementing rewilding projects, such as lack of spatio-temporal data coverage for certain ecosystem functions or tackling ongoing problems once active management is removed. We aim to stimulate new thinking on the restoration of wild rivers, and also provide an annotated bibliography of rewilding studies to support this.
Robinson C.V., Baird D.J., Wright M.T.G., Porter T.M., Hartwig K., Hendriks E., Maclean L., Mallinson R., Monk W.A., Paquette C., Hajibabaei M. (2021). Combining DNA and people power for healthy rivers: Implementing the STREAM community-based approach for global freshwater monitoring. Perspectives in Ecology and Conservation, 19(3) 279-285.

There is an urgent need for rapid, standardised, accurate and accessible monitoring techniques to better detect and quantify change given the increasing threat of degradation and biodiversity loss in freshwater ecosystems. Community-based monitoring projects have been proven successful for the collection of meaningful biological data from a range of target species and ecosystems. The STREAM (Sequencing the Rivers for Environmental Assessment and Monitoring) project combines community-based monitoring with a DNA metabarcoding approach to assess aquatic ecosystem health by determining biodiversity of benthic macroinvertebrate species across Canadian watersheds. STREAM consists of outreach and recruitment, training and dissemination of results obtained from sequence data, allowing rapid generation of watershed biodiversity reports (e.g. in 2 months). We emphasise the benefits of partnering with community groups in these DNA biomonitoring efforts, highlighting the value of environmental stewardship and eliminating bottlenecks for scientific data collection. We believe the approach taken in STREAM is not only applicable to Canada, but functions as an ideal model for freshwater monitoring on a global scale.
Roloson S.D., Coffin M.R.S., Knysh K.M., van den Heuvel M.R. (2021). Movement of non-native rainbow trout in an estuary with periodic summer hypoxia. Hydrobiologia, 848(17) 4001-4016.

Many present-day aquatic ecosystems are defined by anthropogenic activities such as the introduction of non-native species, habitat loss, and eutrophication. On Prince Edward Island, Canada, non-native rainbow trout (Oncorhynchus mykiss) have established in highly agricultural coastal watersheds. We used acoustic telemetry with continual oxygen and temperature monitoring to explore the relationship between rainbow trout movements, low dissolved oxygen, high temperature, and other environmental parameters in the eutrophic Dunk River estuary. We tested the hypothesis that rainbow trout capitalize on increased productivity from nutrient stimulation but face a trade-off with disturbed water quality. We divided the salinity transition gradient into zones representing the transition from freshwater to seawater and established that temperature and hypoxia increased with salinity. During hypoxic periods, movements decreased, and residence increased in low salinity habitat (< 1 Practical Salinity Units, PSU) Movement between zones increased from September to November, when conditions improved. A boosted regression tree model showed that dissolved oxygen, discharge, and temperature were related to occupancy which was greatest at dissolved oxygen levels > 6 mg L−1, discharge averaging 2 m3 s−1, and temperatures below 23 °C. This study provides insights into the success of rainbow trout in eutrophic estuaries.
Rundle K.I., Sharaf M.S., Stevens D., Kamunde C., van den Heuvel M.R. (2021). Adamantane carboxylic acids demonstrate mitochondrial toxicity consistent with oil sands-derived naphthenic acids. Environmental Advances, 5.

Naphthenic acids (NAs) are thought to be a primary cause of toxicity of oil sands process-affected water (OSPW). The purpose of this study was to determine if commercially available adamantane carboxylic acids act by mitrochondrial mechanisms similar to NAs found in OSPW. Mitochondria isolated from rainbow trout (Oncorhynchus mykiss) liver were exposed to commercially available adamantane acids, 3-hydroxyadamantane-1-carboxylic acid (CAS 42711-75-1) and 3,5-dimethyladamantane-1-carboxylic acid (CAS 14670-94-1), or to NAs extracted and purified from OSPW. The effects of these compounds on state 3 and 4 respiration, mitochondrial membrane potential, and mitochondrial reactive oxygen species (ROS; H<inf>2</inf>O<inf>2</inf> production) were quantified. The compound 3-hydroxyadamantane-1-carboxylic acid only inhibited state 3 respiration at the highest concentration (2560 mg/L) and showed a concentration-dependent reduction in H<inf>2</inf>O<inf>2</inf> production. Consistent with extracted OSPW NAs, 3,5-dimethyladamantane-1-carboxylic acid inhibited state 3 respiration and increased H<inf>2</inf>O<inf>2</inf> production, but with a two-fold greater EC50 than the NA mixture extracted from OSPW. All three compounds uncoupled mitochondrial membrane potential and increased state 4 respiration. Based on these results, the adamantane 3,5-dimethyladamantane-1-carboxylic NAs may act via similar mitrochondrial mechanisms as NAs extracted from OSPW and could be used to further explore toxic mechanisms.
Shlepr K.R., Ronconi R.A., Hayden B., Allard K.A., Diamond A.W. (2021). Estimating the relative use of anthropogenic resources by herring gull (Larus argentatus) in the bay of fundy, Canada. Avian Conservation and Ecology, 16(1) 1-18.

Gulls (Larus spp.) are described as generalist, opportunistic feeders that show great flexibility in habitat use. Despite an apparent advantage in changing landscapes, many Larus populations have declined in eastern North America since the 1990s. The main hypothesis explaining gull declines at a broad scale is a decrease in total food availability, especially anthropogenically derived fisheries discards and human refuse as industries and cities have improved their management practices. However, it is difficult to quantify the total proportion of gull diet subsidized by humans to test this hypothesis because many common prey items can be traced to both anthropogenic and nonanthropogenic sources. Our aim was to estimate the proportion of diet derived from anthropogenic food sources for Herring Gull (L. argentatus) during the breeding season at the two largest colonies in the Bay of Fundy, Canada, which are located 36 km apart. GPS loggers were deployed to quantify spatiotemporal movement patterns, and whole blood and feather samples were collected for δ13C and δ15N stable-isotope analysis to estimate diet composition during the incubation and chick-rearing stages of the breeding season. Results indicate that there is spatial segregation in the foraging areas used by gulls from the two colonies. All gulls relied on a variety of anthropogenic food sources, with some individuals selecting heavily on fisheries (i.e., active town wharfs, fish packaging plants, aquaculture pens) and mink (Neovison vison) fur farms. Landfills were not a significant source of food during the breeding season. Our study provides valuable information about the relative reliance of gulls on anthropogenic food subsidies, providing insight into how changing industry practices may affect patterns in nesting and foraging by gulls in the region.
St-Hilaire A., Ferchichi H., Berthot L., Caissie D. (2021). The fate of stationary tools for environmental flow determination in a context of climate change. Water Switzerland, 13(9).

Environmental flows (eflows) refer to the amount of water required to sustain aquatic ecosystems. In its formal definition, three flow characteristics need to be minimally maintained: quantity, timing and quality. This overview paper highlights the challenges of some of the current methods used for eflow determination in the context of an evolving climate. As hydrological methods remain popular, they are first analyzed by describing some of the potential caveats associated with their usage when flow time series are non-stationarity. The timing of low-flow events will likely change within a season but will also likely shift in seasonality in some regions. Flow quality is a multi-faceted concept. It is proposed that a first simple step to partly incorporate flow quality in future analyses is to include the water temperature as a covariate. Finally, holistic approaches are also critically revisited, and simple modifications to the Ecological Limits of Flow Alteration (ELOHA) framework are proposed.
Studd E.K., Bates A.E., Bramburger A.J., Fernandes T., Hayden B., Henry H.A.L., Humphries M.M., Martin R., Mcmeans B.C., Moise E.R.D., O'Sullivan A.M., Sharma S., Sinclair B.J., Sutton A.O., Templer P.H., Cooke S.J. (2021). Nine Maxims for the Ecology of Cold-Climate Winters. Bioscience, 71(8) 820-830.

Frozen winters define life at high latitudes and altitudes. However, recent, rapid changes in winter conditions have highlighted our relatively poor understanding of ecosystem function in winter relative to other seasons. Winter ecological processes can affect reproduction, growth, survival, and fitness, whereas processes that occur during other seasons, such as summer production, mediate how organisms fare in winter. As interest grows in winter ecology, there is a need to clearly provide a thought-provoking framework for defining winter and the pathways through which it affects organisms. In the present article, we present nine maxims (concise expressions of a fundamentally held principle or truth) for winter ecology, drawing from the perspectives of scientists with diverse expertise. We describe winter as being frozen, cold, dark, snowy, less productive, variable, and deadly. Therefore, the implications of winter impacts on wildlife are striking for resource managers and conservation practitioners. Our final, overarching maxim, "winter is changing,"is a call to action to address the need for immediate study of the ecological implications of rapidly changing winters.
Sutton A.O., Studd E.K., Fernandes T., Bates A.E., Bramburger A.J., Cooke S.J., Hayden B., Henry H.A.L., Humphries M.M., Martin R., McMeans B., Moise E., O’sullivan A.M., Sharma S., Templer P.H. (2021). Frozen out: Unanswered questions about winter biology. Environmental Reviews, 29(4) 431-442.

Winter conditions impose dramatic constraints on temperate, boreal, and polar ecosystems, and shape the abiotic and biotic interactions underpinning these systems. At high latitudes, winter can last longer than the growing season and may have a disproportionately large impact on organisms and ecosystems. Even so, our understanding of the ecological implications of winter is often lacking. Indeed, even what exactly defines winter is currently unclear, and boundaries that delineate this season are blurred across marine, freshwater, and terrestrial realms and fields of biology. Here, we discuss the complexity of defining winter, and highlight the importance of maintaining the capacity to test hypotheses across seasons, realms, and domains of life. We then outline questions drawn from diverse fields of research that address current gaps in our understanding of winter ecology and how winter influences multiple levels of biological organization, from individuals to ecosystems. Finally, we highlight the potential consequences of changes to both the length and severity of winter due to climate change, and discuss the role winter may play in mediating ecosystem function in the future.
Sánchez-Hernández J., Hayden B., Harrod C., Kahilainen K.K. (2021). Population niche breadth and individual trophic specialisation of fish along a climate-productivity gradient. Reviews in Fish Biology and Fisheries, 31(4) 1025-1043.

A mechanistic understanding of how environmental change affects trophic ecology of fish at the individual and population level remains elusive. To address this, we conducted a space-for-time approach incorporating environmental gradients (temperature, precipitation and nutrients), lake morphometry (visibility, depth and area), fish communities (richness, competition and predation), prey availability (richness and density) and feeding (population niche breadth and individual trophic specialisation) for 15 native fish taxa belonging to different thermal guilds from 35 subarctic lakes along a marked climate-productivity gradient corresponding to future climate change predictions. We revealed significant and contrasting responses from two generalist species that are abundant and widely distributed in the region. The cold-water adapted European whitefish (Coregonus lavaretus) reduced individual specialisation in warmer and more productive lakes. Conversely, the cool-water adapted Eurasian perch (Perca fluviatilis) showed increased levels of individual specialism along climate-productivity gradient. Although whitefish and perch differed in the way they consumed prey along the climate-productivity gradient, they both switched from consumption of zooplankton in cooler, less productive lakes, to macrozoobenthos in warmer, more productive lakes. Species with specialist benthic or pelagic feeding did not show significant changes in trophic ecology along the gradient. We conclude that generalist consumers, such as warmer adapted perch, have clear advantages over colder and clear-water specialised species or morphs through their capacity to undergo reciprocal benthic–pelagic switches in feeding associated with environmental change. The capacity to show trophic flexibility in warmer and more productive lakes is likely a key trait for species dominance in future communities of high latitudes under climate change.
Taylor L.J., Clark K.F., Daoud D., van den Heuvel M.R., Greenwood S.J. (2021). Exposure of American lobster (Homarus americanus) to the pesticide chlorpyrifos results in changes in gene expression. Comparative Biochemistry and Physiology Part D Genomics and Proteomics, 40.

Chlorpyrifos is an organophosphate that is currently used to reduce arthropod pests for the protection of agricultural crops. Coastal marine ecosystems may be exposed to agricultural pesticides via runoff and pesticide exposure can impact the health and survival of non-target species such as the American lobster (Homarus americanus). In the current study, the gene expression changes of H. americanus stage IV larvae were evaluated to understand the physiological mechanisms affected by exposure to sublethal concentrations of chlorpyrifos. After 48 h chlorpyrifos exposure, surviving lobsters were processed for Illumina RNA sequencing (RNA-seq). Genes of interest that showed significant changes using RNA-seq were verified using reverse transcriptase quantitative polymerase chain reaction (RT-qPCR). Analysis of RNA-seq and the confirmation of gene expression patterns via RT-qPCR found altered expression in genes related to stress response (glutathione peroxidase 3 and heat shock protein 60), hypoxia response (hairy, astakine 2, hemocyanin), moulting (cytochrome P450 307a1 and chitinase), and immunity (astakine 2) pathways. Changes to gene expression were most notable in lobsters exposed to 0.57 μg/L chlorpyrifos.
Thellman A., Jankowski K.J., Hayden B., Yang X., Dolan W., Smits A.P., O'Sullivan A.M. (2021). The Ecology of River Ice. Journal of Geophysical Research Biogeosciences, 126(9).

Many of the world's rivers are ice-covered during winter months but increasing evidence indicates that the extent of river ice will shift substantially as winters warm. However, our knowledge of rivers during winter lags far behind that of the growing season, limiting our understanding of how ice loss will affect rivers. Physical, chemical, and biological processes change from headwaters to large rivers; thus, we expect ice processes and resulting effects on the ecology of rivers could also vary with river size, as a result of the associated changes in geomorphology, temperature regimes, and connectivity. To conceptualize these relationships, we review typically disparate literature on ice processes and winter ecology and compare what is known in the smallest and largest rivers. In doing so, we show that our ability to link ice with ecology across river networks is made difficult by a primary focus on ice processes in larger rivers and a lack of study of ecosystem processes during winter. To address some of these gaps, we provide new scenarios of river ice loss and analyses of how the annual importance of winter gross primary productivity (GPP) varies with river size. We show projected ice loss varied with large-scale watershed characteristics such as north-south orientation and that the importance of winter to annual GPP was greatest in the smallest rivers. Finally, we highlight information needed to fill knowledge gaps on winter across river networks and improve our understanding of how rivers may change as climate and ice regimes shift.
Van Guelpen L., Goodwin C., Milne R., Pohle G., Courtenay S. (2021). Distribution and structure of coastal ichthyoplankton communities of the Bay of Fundy in southern New Brunswick, Canada. Marine Biodiversity, 51(1).

Ichthyoplankton communities from Saint John Harbour and Passamaquoddy Bay on the New Brunswick shore of the Bay of Fundy, Canada, were sampled seasonally between 2011 and 2014. Saint John Harbour is an industrialised port whereas Passamaquoddy Bay is less developed, with a focus on aquaculture. In total, 32 species of fish eggs and larvae were recorded: 26 species in Saint John Harbour and 25 in Passamaquoddy Bay. Nineteen species were common to both areas. The dominant species in Passamaquoddy Bay were Enchelyopus cimbrius, Urophycis sp., Scophthalmus aquosus, and Tautogolabrus adspersus. In Saint John Harbour, E. cimbrius, Urophycis sp., Clupea harengus, and Pseudopleuronectes americanus were most abundant. The communities of the two areas were significantly different. This was most pronounced in summer when Saint John Harbour had a much higher proportion of C. harengus and much lower overall abundances, relative to Passamaquoddy Bay. Saint John Harbour demonstrated higher taxonomic diversity than Passamaquoddy Bay, attributable to the wider variety of salinity regimes present within the harbour. In both areas, the ichthyoplankton communities were strongly seasonal with the highest abundance and diversity in summer. Surface temperature was the best predictor of community composition. Given its industrialisation, Saint John Harbour had a surprisingly diverse ichthyoplankton community, comparable to the less impacted Passamaquoddy Bay. The strong flushing in the harbour by high riverine output and tidal exchange may diminish industrial impact. We strongly recommend incorporating ichthyoplankton into the long-term monitoring of Saint John Harbour and provide guidance to this end.
Wellband K., Roth D., Linnansaari T., Allen Curry R., Bernatchez L. (2021). Environment-driven reprogramming of gamete DNA methylation occurs during maturation and is transmitted intergenerationally in Atlantic Salmon. G3 Genes Genomes Genetics, 11(12).

An epigenetic basis for transgenerational plasticity in animals is widely theorized, but convincing empirical support is limited by taxaspecific differences in the presence and role of epigenetic mechanisms. In teleost fishes, DNA methylation generally does not undergo extensive reprogramming and has been linked with environmentally induced intergenerational effects, but solely in the context of early life environmental differences. Using whole-genome bisulfite sequencing, we demonstrate that differential methylation of sperm occurs in response to captivity during the maturation of Atlantic Salmon (Salmo salar), a species of major economic and conservation significance. We show that adult captive exposure further induces differential methylation in an F1 generation that is associated with fitness-related phenotypic differences. Some genes targeted with differential methylation were consistent with genes differential methylated in other salmonid fishes experiencing early-life hatchery rearing, as well as genes under selection in domesticated species. Our results support a mechanism of transgenerational plasticity mediated by intergenerational inheritance of DNA methylation acquired late in life for salmon. To our knowledge, this is the first-time environmental variation experienced later in life has been directly demonstrated to influence gamete DNA methylation in fish.
Williams M.A., Hernandez C., O'Sullivan A.M., April J., Regan F., Bernatchez L., Parle-McDermott A. (2021). Comparing CRISPR-Cas and qPCR eDNA assays for the detection of Atlantic salmon (Salmo salar L.). Environmental DNA, 3(1) 297-304.

Molecular techniques offer sensitive, specific, noninvasive monitoring of target species from a variety of environmental samples. We recently developed a CRISPR-Cas-based eDNA assay for rapid single-species detection as a route to a simple, cost-effective biosensor device. CRISPR-Cas-based diagnostic assays use isothermal conditions in combination with a highly specific sequence recognition system. This CRISPR-Cas assay was designed to target Salmo salar, and we previously demonstrated its utility in eDNA samples from sites in Ireland. The aim of this study was to validate our assay in two larger sample sets from Canada (n = 16/n = 63) in comparison with an independent S. salar qPCR assay. We demonstrate that overall, the CRISPR-Cas assay performs similarly to qPCR for assessing the presence or absence of S. salar from eDNA and provides a viable alternative approach where qPCR assay design and application have proven to be challenging.
Wood Z.T., Lacoursière-Roussel A., LeBlanc F., Trudel M., Kinnison M.T., Garry McBrine C., Pavey S.A., Gagné N. (2021). Spatial Heterogeneity of eDNA Transport Improves Stream Assessment of Threatened Salmon Presence, Abundance, and Location. Frontiers in Ecology and Evolution, 9.

The integration of environmental DNA (eDNA) within management strategies for lotic organisms requires translating eDNA detection and quantification data into inferences of the locations and abundances of target species. Understanding how eDNA is distributed in space and time within the complex environments of rivers and streams is a major factor in achieving this translation. Here we study bidimensional eDNA signals in streams to predict the position and abundance of Atlantic salmon (Salmo salar) juveniles. We use data from sentinel cages with a range of abundances (3–63 juveniles) that were deployed in three coastal streams in New Brunswick, Canada. We evaluate the spatial patterns of eDNA dispersal and determine the effect of discharge on the dilution rate of eDNA. Our results show that eDNA exhibits predictable plume dynamics downstream from sources, with eDNA being initially concentrated and transported in the midstream, but eventually accumulating in stream margins with time and distance. From these findings we developed a fish detection and distribution prediction model based on the eDNA ratio in midstream versus bankside sites for a variety of fish distribution scenarios. Finally, we advise that sampling midstream at every 400 m is sufficient to detect a single fish at low velocity, but sampling efforts need to be increased at higher water velocity (every 100 m in the systems surveyed in this study). Studying salmon eDNA spatio-temporal patterns in lotic environments is essential to developing strong quantitative population assessment models that successfully leverage eDNA as a tool to protect salmon populations.
Alexander A.C., Levenstein B., Sanderson L.A., Blukacz-Richards E.A., Chambers P.A. (2020). How does climate variability affect water quality dynamics in Canada's oil sands region? Science of the Total Environment, 732.

In Canada's oil sands region, classic boreal hydrology (i.e., winter low flow followed by peaks during spring freshet and then summer flow recession) combined with erosion of both natural and anthropogenically-exposed bitumen results in seasonal and inter-annual variability in stream water chemistry. Using data collected from all seasons over three years (2012–2015), we investigated the mechanisms driving spatial and temporal change in the concentration of 26 water quality parameters for six rivers draining Canada's oil sands region. Mantel tests showed a strong spatial aggregation of climatic drivers (average daily precipitation, accumulated precipitation, snow water equivalent) associated with west versus east discharge patterns. Wavelet analysis highlighted unique watershed attributes, in particular the importance of developed area in lowering responsiveness to seasonal precipitation. Concentrations of most chemical parameters (20 of 23) showed distinct temporal patterns that were correlated with seasonal changes in hydrology which, in turn, were related to changes in weather. Comparison of concentrations observed in this study with those reported in the scientific literature for the same watersheds showed 81% of comparisons differed significantly. This was likely due to the short duration of previous field campaigns and thus the sampling of a very narrow window of the annual streamflow regime.
Algera D.A., Ward T., Zemlak R., Crossman J., Harrison P., Leake A., Power M., Cooke S.J. (2020). Stranded Kokanee Salvaged from Turbine Intake Infrastructure Are at Low Risk for Reentrainment: A Telemetry Study in a Hydropower Facility Forebay. North American Journal of Fisheries Management, 40(6) 1545-1552.

Entrainment at hydropower facilities, where fish (volitionally and nonvolitionally) enter hydropower infrastructure such as intake towers, can lead to fish becoming stranded for considerable periods of time rather than being flushed to downstream areas. To reduce fish injury and/or mortality from entrainment stranding events, hydropower operators will salvage stranded fish and release them back into the upstream reservoir. We documented the postrelease movements of salvaged fish to determine their vulnerability to reentrainment at a large hydropower facility. Kokanee Oncorhynchus nerka were collected from the turbine intake towers at the W. A. C. Bennett Dam in northeastern British Columbia, surgically implanted with small acoustic transmitters, and released in the forebay area of the hydropower facility. Fish movements were tracked using an array of hydrophones in the forebay area. While the depths and hydraulics of the forebay resulted in low detection efficiency of the receiver array, detection data for 25 fish revealed that 72% (n = 18) of fish were last detected at hydrophones located >1,000 m from the turbine intakes (considered low risk to restranding or reentrainment), 24% (n = 6) of fish were last detected at hydrophones <500 m to the turbine intakes (considered vulnerable to restranding), and one reentrainment event (n = 1; 4% maximal entrainment rate) was observed. Our results indicate there is a low risk associated with kokanee reentrainment events at this large hydropower facility and that manual salvage appears to be a reasonable approach to mitigate fish loss.
Andrews S.N., Linnansaari T., Curry R.A., Leblanc N.M., Pavey S.A. (2020). Winter ecology of striped bass (Morone saxatilis) near its northern limit of distribution in the Saint John River, New Brunswick. Environmental Biology of Fishes, 103(11) 1343-1358.

Winter habitat selection by Striped Bass (Morone saxatilis) has been described as opportunistic, but due to the length and severity of winter at its northern range, winter habitats in the north are predicted to be restricted in distribution and carefully selected. Here we describe the locations and environmental conditions supporting winter aggregations of adult Striped Bass including periods under ice cover in the Saint John River, New Brunswick using acoustic telemetry. Striped Bass of both Saint John River (72%) and other ancestry (28%) were observed to overwinter within the river’s four mainstem lakes and embayments to which the individuals returned each fall. Most non-Saint John River ancestry Striped Bass were observed in habitats nearest the river mouth in winter. Striped Bass travelled to winter habitats from fall feeding locations from October to November, and only four tagged individuals departed the river at this time. Temperature, dissolved oxygen, and salinity conditions best described the winter habitats. By demonstrating the non-random distribution of Striped Bass during winter and identifying a gradient of habitat use by Saint John River ancestry Striped Bass in this northern river system, it is apparent that protection of these locations is critical for the long term conservation of Striped Bass populations in Canada.
Andrews S.N., Linnansaari T., Leblanc N., Pavey S.A., Curry R.A. (2020). Interannual variation in spawning success of striped bass (Morone saxatilis) in the Saint John River, New Brunswick. River Research and Applications, 36(1) 13-24.

Barriers such as dams have been cited as a serious threat to striped bass survival, especially when they affect or impede migration and access to spawning grounds. On the Saint John River, New Brunswick, the installation of the large Mactaquac Dam in the immediate vicinity of a historic striped bass spawning location was suspected to have caused the arrest of striped bass reproduction and the collapse of the native striped bass population. In 2014, juvenile striped bass of confirmed Saint John River origin were documented in the river for the first time since 1979. In the current study, we examined juveniles from 6 years of sampling to determine corresponding years of successful recruitment. We also tracked adult striped bass matching the ancestry of native Saint John River juveniles to determine the timing and location of spawning. Over 5 years, we observed an annual upstream migration by adult striped bass to historic spawning areas near Fredericton, identified a dominant year class of Saint John River origin juveniles reproduced in 2013, and linked the apparent successful production of year classes to definable discharge conditions, that is, extended periods of sustained flow >36 hr downstream from the Mactaquac Dam. The results of this study suggest important first management actions towards recovering and sustaining the re-discovered striped bass population in the Saint John River, New Brunswick.
Andrews S.N., Linnansaari T., Leblanc N.M., Pavey S.A., Curry R.A. (2020). Movements of juvenile and sub-adult striped bass Morone saxatilis in the Saint John River, New Brunswick, Canada. Endangered Species Research, 43 281-289.

Juvenile striped bass (age-1) of distinct genetic ancestry were re-discovered in the Saint John River, New Brunswick in 2014 after a 35 yr hiatus of recognition. These juveniles were determined to be highly genetically divergent from all possible source populations, hypothesized to be of Saint John River ancestry, and thus considered evidence of the continued existence of the native stock. Successful recruitment of strong year classes of striped bass within the Saint John River, however, appears to be infrequent. We acoustically tagged and tracked juvenile and sub-adult striped bass (n = 37; age 2–4) in the Saint John River in both 2015 and 2016, and identified summer feeding and overwintering habitats that established an in-river residency. Following decades of poor or no recruitment, it is now imperative that managers quickly include monitoring of juvenile and sub-adult striped bass and protection of their habitats in the conservation and recovery efforts for Saint John River striped bass stock.
Andrews S.N., Mazerolle D.M., Leblanc F., Linnansaari T., Curry R.A. (2020). The History of Striped Bass (Morone saxatilis) Conservation and Management in Kouchibouguac National Park, New Brunswick, Canada. Northeastern Naturalist, 27(4) 723-745.

The Kouchibouguac region, located in Atlantic Canada on New Brunswick's eastern coast was declared a provincial game refuge in 1969 and a National Park in 1979. Morone saxatilis (Striped Bass), a species of ecological and socio-economic importance, has long been considered a conservation priority within the park and the surrounding region. The creation of the National Park resulted in the closure of the region's commercial Striped Bass fishery and regulation of recreational fishery retention, turning the area into a key focal point for monitoring and conservation of Striped Bass within the southern Gulf of St. Lawrence. In the early 1990s, the Northwest Miramichi River was confirmed as a key spawning location for Striped Bass and the likely origin of all southern Gulf of St. Lawrence Striped Bass, a discovery which would remove the burden of local Striped Bass conservation and recovery from the park. Now, following a precipitous population decline, a 13-year fishing moratorium, and an unprecedented population recovery, Striped Bass have returned in great numbers to the southern Gulf of St. Lawrence. This review summarizes the history of the study of Striped Bass in Kouchibouguac National Park to prompt the continuation of research of Striped Bass under the climate of a presently recovered population. It remains possible that the recovered population could once again re-colonize spawning habitat within the rivers of Kouchibouguac National Park that may have been occupied historically.
Andrews S.N., O'Sullivan A.M., Helminen J., Arluison D.F., Samways K.M., Linnansaari T., Curry R.A. (2020). Development of active numerating side-scan for a high-density overwintering location for endemic shortnose sturgeon (Acipenser brevirostrum) in the Saint John River, New Brunswick. Diversity, 12(1).

In 1979, the Shortnose Sturgeon (Acipenser brevirostrum) population of the Saint John River, New Brunswick, was estimated at 18,000 5400 individuals. More recently, an estimate of 4836 ± 69 individuals in 2005, and between 3852 and 5222 individuals in 2009 and 2011, was made based on a single Shortnose Sturgeon winter aggregation in the Kennebecasis Bay of the Saint John River, a location thought to contain a large proportion of the population. These data, in combination with the Saint John River serving as the sole spawning location for Shortnose Sturgeon in Canada prompted a species designation of "Special Concern" in 2015 under Canada's Species at Risk Act (SARA). A three-decade span of scientific observations amplified by the traditional knowledge and concerns of local indigenous groups have pointed to a declining population. However, the endemic Shortnose Sturgeon population of the Saint John River has not been comprehensively assessed in recent years. To help update the population estimate, we tested a rapid, low-cost side-scan sonar mapping method coupled with supervised image classification to enumerate individual Sturgeon in a previously undescribed critical winter location in the Saint John River. We then conducted an underwater video camera survey of the area, in which we did not identify any fish species other than Shortnose Sturgeon. These data were then synchronized with four years of continuous acoustic tracking of 18 Shortnose Sturgeon to produce a population estimate in each of the five identified winter habitats and the Saint John River as a whole. Using a side-scan sonar, we identified > 12,000 Shortnose Sturgeon in a single key winter location and estimated the full river population as > 20,000 individuals > ~40 cm fork length. We conclude that the combined sonar/image processing method presented herein provides an effective and rapid assessment of large fish such as Sturgeon when occurring in winter aggregation. Our results also indicate that the Shortnose Sturgeon population of the Saint John River could be similar to the last survey estimate conducted in the late 1970s, but more comprehensive and regular surveys are needed to more accurately assess the state of the population.
Babin A.B., Ndong M., Haralampides K., Peake S., Jones R., Curry R.A., Linnansaari T. (2020). Migration of atlantic salmon (Salmo Salar) smolts in a large hydropower reservoir. Canadian Journal of Fisheries and Aquatic Sciences, 77(9) 1463-1476.

Migration rates, delay, timing, and success of acoustic-tagged Atlantic salmon (Salmo salar) presmolts (n = 120) and smolts (n = 57) are reported as they moved through the large Mactaquac Generating Station (MGS) reservoir and subsequently the lower Saint John River (SJR). The potential relationship between fish movements and the MGS operations was examined directly and via a hydrodynamic model. Migration rates were 15.4-29.3 km day−1 within the river sections and 5.0-13.3 km day−1 through the reservoir, a significant reduction of 32%-57%. Migratory timing was temporally mismatched with dam operations such that only a few (n = 3) smolts had the option of dam passage via spill. Migration success estimated as apparent survival was high through the reservoir (81%-100%), declined by 8%-32% during passage at the MGS, and additional losses (27%-55%) occurred during the migration to the lower SJR, such that overall survival to the estuary for the groups tagged as autumn presmolts was 61%-65%, and survival for those tagged as spring smolts was 6%-10%.
Barrett T.J., Rossong M.A., van den Heuvel M.R., Munkittrick K.R. (2020). Assessing reproductive effects on fish populations: an evaluation of methods to predict the reproductive strategy of fishes. Environmental Monitoring and Assessment, 192(9).

Many environmental monitoring programs include an assessment of the health of fish populations using a sentinel species and include an indicator of reproductive potential. Knowledge of the reproductive strategy of the fish species is critical for data interpretation but is not always known. The reproductive strategy of a species can be determined from detailed histological analyses of ovaries throughout the reproductive cycle; however, these studies can be costly and can delay the implementation of a monitoring program. Three quick and cost-effective methods of predicting the reproductive strategy (annual single spawning or annual multiple spawning) are evaluated in this study using predicted probabilities from binary logistic regression models as a means of classifying the reproductive strategies of 18 different fish species in Atlantic Canada. The first method was based on the hypothesis that the variability in the ovary weight-body weight relationship in prespawning females is higher in multiple spawners. This method did not have a good classification rate due to some multiple spawners having low variability. The other two methods involved predictor variables representing the proportion of oocytes in different stages of development and predictor variables representing the distribution of oocyte sizes during the prespawning season for 111 fish (25 different samples for species). Predicted probabilities from these regression models could be used to correctly classify the reproductive strategies of all 25 samples (development stage model) and all but one sample (oocyte size distribution model). These models can be used to estimate the reproductive strategy of a species from a single sample of fish collected during the prespawning period to support species selection and data interpretation in environmental monitoring programs.
Beaupré J., Boudreault J., Bergeron N.E., St-Hilaire A. (2020). Inclusion of water temperature in a fuzzy logic Atlantic salmon (Salmo salar) parr habitat model. Journal of Thermal Biology, 87.

As water temperature is projected to increase in the next decades and its rise is clearly identified as a threat for cold water fish species, it is necessary to adapt and optimize the tools allowing to assess the quantity and quality of habitats with the inclusion of temperature. In this paper, a fuzzy logic habitat model was improved by adding water temperature as a key determinant of juvenile Atlantic salmon parr habitat quality. First, salmon experts were consulted to gather their knowledge of salmon parr habitat, then the model was validated with juvenile salmon electrofishing data collected on the Sainte-Marguerite, Matapedia and Petite-Cascapedia rivers (Québec, Canada). The model indicates that when thermal contrasts exist at a site, cooler temperature offered better quality of habitat. Our field data show that when offered the choice, salmon parr significantly preferred to avoid both cold areas (<15 °C) and warm areas (>20.5 °C). Because such thermal contrasts were not consistently present among the sites sampled, the model was only validated for less than 60% of the sites. The results nevertheless indicate a significant correlation between median Habitat Quality Index and parr density for the Sainte-Marguerite River (R2 = 0.38). A less important, albeit significant (F-test; p = 0.036) relationship was observed for the Petite-Cascapedia river (R2 = 0.14). In all instances, the four-variable (depth, velocity, substrate size and temperature) model provided a better explanation of parr density than a similar model excluding water temperature.
Beaupré L., St-Hilaire A., Daigle A., Bergeron N. (2020). Comparison of a deterministic and statistical approach for the prediction of thermal indices in regulated and unregulated river reaches: Case study of the fourchue river (Québec, Canada). Water Quality Research Journal, 55(4) 394-408.

Water temperature is an important factor modifying fish distribution patterns and community abundance in streams, and this is especially true for salmonids. Knowing that dams often modify the thermal regime of rivers, understanding these changes is of crucial importance for fish habitat management. This study aims to improve knowledge about the impact of dams on the thermal regime of rivers during the summer season and to assess the relative efficiency of two modelling tools used to predict water temperature downstream of dams. A deterministic model (Stream Network Temperature (SNTEMP)) and a statistical model based on a canonical correlation analysis were calibrated on the Fourchue River (St-Alexandre-de-Kamouraska, Québec, Canada) upstream and downstream of a reservoir. SNTEMP was used to simulate mean water temperature time series using meteorological inputs and discharge. The statistical model was used to directly estimate thermal indices (descriptive statistics of the thermal regime). The two models were compared based on their efficiency to estimate thermal indices such as mean and maximum monthly water temperatures and other parameters of importance in the understanding of the distribution and growth of ichthyofauna. Water temperature was monitored at 18 locations in the Fourchue River during the summers of 2011 and 12 locations in 2012 to describe the thermal regime and calibrate the models. The statistical model achieved better results than SNTEMP in estimating most of the thermal indices, especially the mean and maximum daily ranges with root mean square errors of 4.1 and 4.9° C, respectively, for SNTEMP as compared to 0.5 and 1.1° C for the leave-one-out validation and 0.6 and 1.4° C for the split-sample mode for the statistical model. The better performance of the statistical model for metrics related to thermally stressful events for fish makes it more appealing as a management tool for water resources and fisheries managers. However, SNTEMP should be considered when the objective is to investigate the impact of climate change, reservoir operations or other anthropogenic impacts.
Bush A., Monk W.A., Compson Z.G., Peters D.L., Porter T.M., Shokralla S., Wright M.T.G., Hajibabaei M., Baird D.J. (2020). DNA metabarcoding reveals metacommunity dynamics in a threatened boreal wetland wilderness. Proceedings of the National Academy of Sciences of the United States of America, 117(15) 8539-8545.

The complexity and natural variability of ecosystems present a challenge for reliable detection of change due to anthropogenic influences. This issue is exacerbated by necessary trade-offs that reduce the quality and resolution of survey data for assessments at large scales. The Peace-Athabasca Delta (PAD) is a large inland wetland complex in northern Alberta, Canada. Despite its geographic isolation, the PAD is threatened by encroachment of oil sands mining in the Athabasca watershed and hydroelectric dams in the Peace watershed. Methods capable of reliably detecting changes in ecosystem health are needed to evaluate and manage risks. Between 2011 and 2016, aquatic macroinvertebrates were sampled across a gradient of wetland flood frequency, applying both microscope-based morphological identification and DNA metabarcoding. By using multispecies occupancy models, we demonstrate that DNA metabarcoding detected a much broader range of taxa and more taxa per sample compared to traditional morphological identification and was essential to identifying significant responses to flood and thermal regimes. We show that family-level occupancy masks high variation among genera and quantify the bias of barcoding primers on the probability of detection in a natural community. Interestingly, patterns of community assembly were nearly random, suggesting a strong role of stochasticity in the dynamics of the metacommunity. This variability seriously compromises effective monitoring at local scales but also reflects resilience to hydrological and thermal variability. Nevertheless, simulations showed the greater efficiency of metabarcoding, particularly at a finer taxonomic resolution, provided the statistical power needed to detect change at the landscape scale.
Cabrera-Paez Y., Aguilar-Betancourt C.M., González-Sansón G. (2020). Substrate influence on ichthyofaunal composition in shallow areas of barra de navidad coastal Lagoon, Mexico. Revista De Biologia Tropical, 68(4) 1322-1336.

Introduction: Coastal lagoons are important habitats for coastal fishes playing an essential role as nursery areas for many species. While the effects of salinity and temperature on fish abundance spatial and temporal variation have been well documented, research on the influence of substrate characteristics is scarce. Objective: To investigate the correlation of salinity, temperature and sediment characteristics with spatial and temporal variations of the ichthyofauna composition in Barra de Navidad coastal lagoon´s shallow zones. Methods: Samples of ichthyofauna were taken with a beach purse seine along a period of two years in four sites. Water salinity and temperature were measured simultaneously with fish sampling operations. Sediment particle size and organic matter content were determined four times at each site during the sampling period. Multivariate methods were used for data analyses. Results: A total of 13 487 fish pertaining to 69 species were collected, but only five taxa (Eucinostomus currani, Mugil setosus, Anchoa sp., Diapterus brevirostris, Centropomus robalito) made up more than 80 % of the individuals. Significant differences among all sampling sites and between seasons were found for the ichthyofauna composition. Redundancy analysis showed that changes in ichthyofaunal composition were mainly related to the percentage of mud and organic matter in sediments expressing a spatial gradient. The influence of salinity and temperature was also significant, but these variables explained a smaller proportion of the observed variability and were related mainly to seasonal changes. Conclusions: Sediment particle size and organic matter content are the most important abiotic factors influencing spatial changes in shallow water ichthyofaunal composition. Seasonal changes were correlated with changes in salinity and temperature but could also be related to biological processes such as reproduction and recruitment.
Cantonati M., Kelly M.G., Demartini D., Angeli N., Dörflinger G., Papatheodoulou A., Armanini D.G. (2020). Overwhelming role of hydrology-related variables and river types in driving diatom species distribution and community assemblage in streams in Cyprus. Ecological Indicators, 117.

Mediterranean streams are naturally highly-stressed environments mainly due to wide seasonal and inter-annual fluctuations in water quantity. This natural pressure will be exacerbated by climate change and is a significant challenge when establishing efficient assessment methods. We studied environmental parameters (hydromorphology, hydrology, physical and chemical variables) and analysed 171 diatom samples from 65 stations in Cyprus (south-western part). Analyses revealed 290 taxa (273 identified to the species -or intraspecific- level) belonging to 65 genera. Even a tentative application of a Red-List approach underlined the overwhelming importance of hydrology-related variables and river types in determining species distribution and community ecological attributes in the water-stressed island of Cyprus. Somewhat unexpectedly, both species from threat categories of the diatom Red List for Central Europe (2018) and species one might predict would be included in such categories in a possible future Red List tailored for Cyprus occurred more frequently and were more relevant in assemblages from sites in intermittent streams. We found a majority of motile, medium- to small-sized, diatom species, including a small number of colony-forming species. We found several species known to be effective first colonizers (pioneer species) and, among these, there was a striking preponderance (80%) of Achnanthidium species, often with several species co-occurring, particularly at reference sites. A four-factor PERMANOVA found that all type (essentially hydrology-related) variables were significant, and there was also a significant effect of season. Agglomerative hierarchical cluster analysis revealed three end-groups, with groups being separated on ecohydro(geo)logical grounds (lentic/lotic), sediment grain size, discharge and pH. The reference sites were analysed in more detail to identify environmental determinants. 28% of the variation in diatom assemblage composition was explained by the measured variables, with those associated with stream type and hydrology explaining the greatest proportions (12 and 10%, respectively) whilst season accounted for the remainder. Our study emphasised a need for detailed investigations of ecological and distributional (including Red List status) traits of diatom species, and to acknowledge the importance of the hydrological peculiarities of Mediterranean streams, in particular the dramatic seasonal variability, when developing ecological assessment protocols for the region.
Corey E., Linnansaari T., Dugdale S.J., Bergeron N., Gendron J.F., Lapointe M., Cunjak R.A. (2020). Comparing the behavioural thermoregulation response to heat stress by Atlantic salmon parr (Salmo salar) in two rivers. Ecology of Freshwater Fish, 29(1) 50-62.

Climate change is expected to increase the frequency and magnitude of extreme thermal events in rivers. The Little Southwest Miramichi River (LSWM) and the Ouelle River (OR) are two Atlantic salmon (Salmo salar) rivers located in eastern Canada, where in recent years, water temperatures have exceeded known thermal limits (~23°C). Once temperature surpasses this threshold, juvenile salmon exploit thermal heterogeneity to behaviourally thermoregulate, forming aggregations in coolwater refuges. This study aimed to determine whether the behavioural thermoregulation response is universal across rivers, arising from common thermal cues. We detailed the temperature and discharge patterns of two geographically distinct rivers from 2010 to 2012 and compared these with aggregation onset temperature. PIT telemetry and snorkelling were used to confirm the presence of aggregations. Mean daily maximum temperature in 2010 was significantly greater in the OR versus the LSWM (p = 0.005), but not in other years (p = 0.090–0.353). Aggregations occurred on 14 and 9 occasions in the OR and LSWM respectively. Temperature at onset of aggregation was significantly greater in the OR (T<inf>onset</inf> = 28.3°C) than in the LSWM (T<inf>onset</inf> = 27.3°C; p = 0.049). Logistic regression models varied by river and were able to predict the probability of aggregation based on the preceding number of hours >23°C (R2 = 0.61 & 0.65; P<inf>50</inf> = 27.4°C & 28.9°C; in the OR and LSWM respectively). These results imply the preceding local thermal regime may influence behaviour and indicate a degree of phenotypic plasticity, illustrating a need for localised management strategies.
Cote D., Tibble B., Curry R.A., Peake S., Adams B.K., Clarke K.D., Perry R. (2020). Seasonal and diel patterns in activity and habitat use by brook trout (Salvelinus fontinalis) in a small Newfoundland lake. Environmental Biology of Fishes, 103(1) 31-47.

Despite the challenges winter poses to salmonids inhabiting temperate and northern environments, there are relatively few studies that evaluate the factors that influence activity and habitat use during this season, particularly for lake environments that are ice-covered. This study examines brook trout depth distribution and movement (activity and range) in relation to temperature, light, and time of day across a 17-month period in a small lake in Newfoundland, Canada. Brook trout maintained elevated diurnal activity patterns throughout the year, despite seasonal changes in temperature, shifts in depth use, and prolonged, ice-induced darkness. Despite the tendency for relatively lower activity at night, brook trout remained active nocturnally, inferring a shift in foraging modes rather than a cessation of feeding. Winter movement velocities and ranges were less than other seasons but they occupied littoral areas that overlapped extensively with spring and fall core ranges. In contrast, summer core ranges of brook trout were principally comprised of areas with cooler water in the deep portion of the lake. As water temperature increased, daytime movement velocities increased in a log-linear fashion, whereas modeled nighttime movement velocity relationships with temperature were curvilinear and included the lowest movement velocities at 2–3 °C and the highest at the extremes of the occupied temperature range. The ability of brook trout to maintain diurnal activity patterns throughout a wide spectrum of environmental conditions suggests a strong behavioral and physiological capacity to adapt to their seasonally variable environment.
Curry R.A., Yamazaki G., Linnansaari T., Monk W., Samways K.M., Dolson R., Munkittrick K.R., Bielecki A. (2020). Large dam renewals and removals—Part 1: Building a science framework to support a decision-making process. River Research and Applications, 36(8) 1460-1471.

Altered rivers and managed flows are a hallmark of civilization and dams are a principal agent of alteration. Peak dam construction occurred at the turn of the last century in Western countries, and many of the largest dams are reaching the end of their service life. As a result, dam operators are increasingly facing a complex renewal/removal decision-making process in a large part because the economic and social values of dams have changed. The Mactaquac Hydroelectric Generating Station (New Brunswick, Canada), operated by NB Power Corporation (NB Power), is Canada's 25th largest dam and it is reaching the end of its service life. A decision is required for the dam's future state and three options were originally proposed: renew, rebuild, or remove. An overarching science framework was developed with NB Power to inform and support decision-making for the dam's decision process and an impending Environmental Impact Assessment. The framework guides research and monitoring for dam renewal/removal using science-based solutions that aim to minimize impacts on the aquatic environment while supporting an efficient and cost-effective decision-making process. The framework has five components: (a) establish long-term baselines of environmental conditions; (b) develop normal ranges describing the river's natural variability; (c) integrated physical and biological modelling; (d) assess the specific and cumulative state of fish passage; and (e) create and sustain a user-friendly geospatial data management system. In this paper we present a case study that implements the science framework (Part 1) through the Mactaquac Aquatic Ecosystem Study (MAES) with a view to revisit and assess its final impact post-project completion (Part 2).
Dixon H.J., Harrison G., Lister A.L., MacLatchy D.L. (2020). Reproductive status of walleye (Sander vitreus) and lake whitefish (Coregonus clupeaformis) in two large, shallow Canadian subarctic lakes. Environmental Biology of Fishes, 103(9) 1119-1136.

The reproductive status of walleye (Sander vitreus) and lake whitefish (Coregonus clupeaformis) is largely unstudied in the northern extent of their ranges. Tathlina Lake and Kakisa Lake are large, shallow lakes in the Northwest Territories, Canada, supporting important commercial and subsistence fisheries for these species while being threatened by climate change. Fish were sampled in both lakes across multiple years in the spring and autumn to assess differences in reproductive status in the pre- and post-spawning periods for both species. Condition factor (K), gonadosomatic index (GSI), liversomatic index (LSI), and fecundity were calculated, and plasma samples were also taken from each fish to determine levels of reproductive hormones, specifically 17β-estradiol in females, and 11-ketotestosterone in males. Significant temporal (intra- and interannual) and spatial (between lakes) variation was found for both species and both sexes for all metrics. Expected differences in hormones and indices of reproductive success between pre- and post- spawning periods were demonstrated. When compared with previously published data, a latitudinal gradient for LSI, GSI and fecundity was evident for walleye, but not for lake whitefish. The differences in the reproductive biology of lake whitefish and walleye in these two neighbouring lakes highlights limitations in the use of a reference lake approach in biomonitoring studies. The data in this study can be used and expanded upon to provide information for the sustainable management of these fish stocks for the future.
Eadie A., Vásquez-Vélez I.C., Liang X., Wang X., Souders C.L., El Chehouri J., Hoskote R., Feswick A., Cowie A.M., Loughery J.R., Martyniuk C.J. (2020). Residual molecular and behavioral effects of the phenylpyrazole pesticide fipronil in larval zebrafish (Danio rerio) following a pulse embryonic exposure. Comparative Biochemistry and Physiology Part D Genomics and Proteomics, 36.

Pesticides are typically applied to crops as acute applications, and residual effects of such intermittent exposures are not often characterized in developing fish. Fipronil is an agricultural pesticide that inhibits γ-amino-butyric acid (GABA) gated chloride channels. In this study, zebrafish (Danio rerio) embryos were exposed for 48 h (starting at ~3 h post fertilization, hpf) to various concentrations of fipronil (0.02 μg/L up to 4000 μg/L). Following this acute exposure, a subset of fish was transferred to clean water for a 7-day depuration phase. We hypothesized that a pulse exposure to fipronil during critical periods of central nervous system development would adversely affect fish later in life. After a 48 hour pulse exposure, survival was reduced in embryos exposed to 2 μg fipronil/L or greater. However, there was no further mortality during the depuration phase, nor were there changes in body length nor notochord length in larvae 9 dpf (days post-fertilization) compared to controls. Additional experiments were carried out at higher concentrations over 96 h (up to 4 dpf) to also elucidate developmental effects and teratogenicity of fipronil (43.7 μg/L up to 4370 μg/L). Fipronil at these higher concentrations significantly impacted the development of zebrafish, and the following morphometric and teratogenic effects were observed in 4 dpf fish; reduced body length, yolk sac and pericardial edema, reduced midbrain length, reduced optic and otic diameter, and truncation of the lower jaw. In depurated fish, we hypothesized that there would exist residual effects of exposure at the molecular level. Transcriptome profiling was therefore conducted on 9 dpf depurated larvae exposed initially for 48 h to one dose of either 0.2 μg/L, 200 μg/L or 2000 μg/L fipronil. The expression of gene networks associated with glycogen and omega-3-fatty acid metabolism were decreased in larvae exposed to each of the three concentrations of fipronil, suggesting metabolic disruption. Moreover, transcriptomics revealed that fipronil suppressed gene networks related to light-dark adaptation, photoperiod sensing, and circadian rhythm. Based on these data, we tested fish for altered behavioral responses in a Light-Dark preference test. Larvae exposed to >200 μg fipronil/L as embryos showed fewer number of visits (20–30% less) to the dark zone compared to controls. Larvae also spent a lower amount of time in the dark zone compared to controls, suggesting that fipronil strengthened dark avoidance behavior which is indicative of anxiety. This study demonstrates that a short pulse exposure to fipronil can affect transcriptome networks for metabolism, circadian rhythm, and response to light in fish after depuration, and these molecular responses are hypothesized to be related to aberrant behavioral effects observed in the light-dark preference test.
Eadie A., Vásquez I.C., Liang X., Wang X., Souders C.L., Chehouri J.E., Hoskote R., Feswick A., Cowie A.M., Loughery J.R., Martyniuk C.J. (2020). Transcriptome network data in larval zebrafish (Danio rerio) following exposure to the phenylpyrazole fipronil. Data in Brief, 33.

Fipronil is a phenylpyrazole pesticide that is used in both residential and agricultural applications. Fipronil is detected in run-off and water systems that are near areas in which the pesticide has been applied. The pesticide acts to antagonize gamma aminobutyric acid receptors, leading to over-excitation in the central nervous system. Fipronil has relatively high toxicity to fish, but the mechanisms underlying the toxicity are not well understood in embryonic stages. Zebrafish embryos were exposed to a single concentration of fipronil for 48 h at ∼3-4 h-post-fertilization. Following a 7-day depuration phase, transcriptome and behavioral analyses were conducted. Transcriptomics identified neural processes as those differentially expressed with different doses of fipronil (0.2 µg, 200 µg and 2 mg fipronil/L). Gene networks associated with astrocyte differentiation, myelination, neural tube development, brain stem response, innervation, nerve regeneration, astrocyte differentiation, among other pathways were altered with exposure. In addition, miRNA-related events are disrupted by fipronil exposure and genes associated with primary or pri-miRNA processing were increased in larval fish exposed to the pesticide. These data present putative mechanisms associated with neurological impacts at later ages of zebrafish. This is important because it is not clear how early exposure to pesticides like fipronil affect central nervous system function and organisms later in life.
Edge T.A., Baird D.J., Bilodeau G., Gagné N., Greer C., Konkin D., Newton G., Séguin A., Beaudette L., Bilkhu S., Bush A., Chen W., Comte J., Condie J., Crevecoeur S., El-Kayssi N., Emilson E.J.S., Fancy D.L., Kandalaft I., Khan I.U.H., King I., Kreutzweiser D., Lapen D., Lawrence J., Lowe C., Lung O., Martineau C., Meier M., Ogden N., Paré D., Phillips L., Porter T.M., Sachs J., Staley Z., Steeves R., Venier L., Veres T., Watson C., Watson S., Macklin J. (2020). The Ecobiomics project: Advancing metagenomics assessment of soil health and freshwater quality in Canada. Science of the Total Environment, 710.

Transformative advances in metagenomics are providing an unprecedented ability to characterize the enormous diversity of microorganisms and invertebrates sustaining soil health and water quality. These advances are enabling a better recognition of the ecological linkages between soil and water, and the biodiversity exchanges between these two reservoirs. They are also providing new perspectives for understanding microorganisms and invertebrates as part of interacting communities (i.e. microbiomes and zoobiomes), and considering plants, animals, and humans as holobionts comprised of their own cells as well as diverse microorganisms and invertebrates often acquired from soil and water. The Government of Canada's Genomics Research and Development Initiative (GRDI) launched the Ecobiomics Project to coordinate metagenomics capacity building across federal departments, and to apply metagenomics to better characterize microbial and invertebrate biodiversity for advancing environmental assessment, monitoring, and remediation activities. The Project has adopted standard methods for soil, water, and invertebrate sampling, collection and provenance of metadata, and nucleic acid extraction. High-throughput sequencing is located at a centralized sequencing facility. A centralized Bioinformatics Platform was established to enable a novel government-wide approach to harmonize metagenomics data collection, storage and bioinformatics analyses. Sixteen research projects were initiated under Soil Microbiome, Aquatic Microbiome, and Invertebrate Zoobiome Themes. Genomic observatories were established at long-term environmental monitoring sites for providing more comprehensive biodiversity reference points to assess environmental change.
Erdozain M., Emilson C.E., Kreutzweiser D.P., Kidd K.A., Mykytczuk N., Sibley P.K. (2020). Forest management influences the effects of streamside wet areas on stream ecosystems. Ecological Applications, 30(4).

Riparian zones contain areas of strong hydrological connectivity between land and stream, referred to as variable source areas (VSAs), and are considered biogeochemical control points. However, little is known about whether VSAs influence stream communities and whether this connectivity is affected by forest management. To address this, we used multiple biotic and abiotic indicators to (1) examine the influence of VSAs on riparian vegetation and stream ecosystems by comparing VSA and non-VSA reaches and (2) explore how forest management may affect the influence of VSAs on stream ecosystems. We detected some significant differences between VSA and non-VSA reaches in the riparian vegetation (greater understory and lower tree density) and stream ecosystem indicators (greater dissolved organic matter aromaticity, microbial biomass, peroxidase activity and collector-gatherer density, and lower dissolved organic carbon concentrations, algal biomass, and predatory macroinvertebrate density), which suggests that VSAs may create a more heterotrophic ecosystem locally. However, we show some evidence that forest management activities (specifically, road density) can alter the influence of VSAs and eliminate the differences observed at lower forest management intensities, and that the most hydrologically connected areas seem more sensitive to disturbance. Therefore, we suggest that the heterogeneity in hydrological connectivity along riparian zones should be considered when planning forest harvesting operations and road building (e.g., wider riparian buffers around VSAs).
Foulon É., Rousseau A.N., Benoy G., North R.L. (2020). A global scan of how the issue of nutrient loading and harmful algal blooms is being addressed by governments, non-governmental organizations, and volunteers. Water Quality Research Journal, 55(1) 1-23.

Harmful algal blooms (HABs) in aquatic ecosystems are of concern worldwide. This review deals with how jurisdictions around the world are addressing this water quality issue to inform recommendations regarding nutrient loading and HABs in Missisquoi Bay-Lake Champlain and Lake Memphremagog; transboundary lakes located in the USA and Canada that suffer from symptoms of eutrophication. A global scan of the literature resulted in the consideration of 12 case studies of large water bodies within large watersheds, excluding in-lake geoengineering approaches. Although all of the systems experience excessive nutrient loading, they vary in two key ways: sources of nutrients and manifestations of eutrophication ranging from HABs, to limited recreational uses, to the additional complexity of internal loadings and fish kills, up to drinking water shutdowns. The case studies were analyzed with respect to four categories of approaches, namely: (i) regulatory; (ii) incentive-based; (iii) risk mitigation; and (iv) outreach, engagement, and educational. We found that the management frameworks are based on integrated watershed management planning and national standards. National water quality standards, however, are not stringent enough to prevent HABs. Overall, identified case studies did not successfully remediate HABs, they simply managed them.
Frenette A.P., Harrold T., Bentzen P., Paterson I.G., Malenfant R.M., Nardi G., Burt M.D.B., Duffy M.S. (2020). Loma morhua infections in Atlantic cod (Gadus morhua) reveal relative parasite resistance and differential effects on host growth among family lines. Aquaculture, 522.

Microsporidia are emerging as a threat to productivity of commercial finfish aquaculture because of high-prevalence infections facilitated by direct transmission. Infection dynamics are poorly understood for most microsporidians and inability to reliably quantify differential infections impedes disease mitigation strategies that could select broodstock with inherent disease-resistant phenotypes. Moreover, investigations of suitable biomarkers that link immune function with disease susceptibility of fishes are limited. Herein, we observe an inverse relationship between fish growth and infection status with the microsporidium Loma morhua among 50 different Atlantic cod (Gadus morhua) family lines. We present a standardized template for quantifying parasite infection intensity, with the spleen being the most reliable organ for comparing natural infections and for monitoring experimental infections. Variability in infection intensities among 50 cod families suggests that differential susceptibility to L. morhua has a genetic basis. Ultra-deep Illumina sequencing identified 299 major histocompatibility class I (MH-I) variants from this regionally restricted 50-family cod population. Variation in Atlantic cod susceptibility might reflect hyper-diversification of MH-I genes and individual variability in the ability to present endogenous pathogen antigens during cell-mediated immune responses. Relevance of MH-I expansion to selective breeding for disease resistance remains poorly characterized. Importantly, differential susceptibility to L. morhua revealed impaired fish growth, resulting in a 14% reduction in fillet mass in susceptible individuals. These data imply that relative resistance to L. morhua exists in cod, that it is heritable, and that broodstock selection could be used to limit the impact of microsporidian infections on growth during finfish aquaculture.
Gao L., Qi J., Li S., Benoy G., Xing Z., Meng F.R. (2020). Effects of sampling frequency on estimation accuracies of annual loadings for water quality parameters in different sized watersheds. Water Quality Research Journal, 55(3) 261-277.

Potential errors or uncertainties of annual loading estimations for water quality parameters such as suspended solids (SS), nitrate-nitrogen (NO<inf>3</inf>-N), ortho-phosphorus (Ortho-P), potassium (K), calcium (Ca), and magnesium (Mg) can be greatly affected by sampling frequencies. In this study, annual loading estimation errors were assessed in terms of the coefficient of variation, relative bias, and probability of potential errors that were estimated with statistical samples taken at a series of sampling frequencies for a watershed in northwestern New Brunswick, Canada, and one of its sub-watersheds. Results indicate that annual loading estimation errors increased with decreasing sampling frequency for all water quality parameters. At the same sampling frequencies, the estimation errors were several times greater for the smaller watershed than those for the larger watershed, possibly due to the flushing nature of streamflows in the smaller watershed. We also found that low sampling frequency tended to underestimate the annual loadings of water quality parameters dominated by stormflow events (SS and K) and overestimate water quality parameters dominated by baseflow (Mg and Ca). These results can be used by hydrologists and water quality managers to determine sampling frequencies that minimize costs while providing acceptable estimation errors. This study also demonstrates a novel approach to assess potential errors when analyzing existing water quality data.
Grizard P., Macquarrie K.T.B., Jiang Y. (2020). Land-use based modeling approach for determining freshwater nitrate loadings from small agricultural watersheds. Water Quality Research Journal, 55(3) 278-294.

Nitrate released from a variety of land-use activities is a major factor in the degrading conditions observed in many watersheds and estuaries. In this research a spatially lumped model is developed to estimate annual nitrate loads and concentrations from over 100 small watersheds in the Canadian province of Prince Edward Island (PEI). Nitrate source concentrations are associated with major land-use categories, and nitrate attenuation, based on the width of riparian zones, and transport delay due to groundwater residence time are simulated. To investigate the uncertainty of the results, model parameters were selected using a Latin hypercube sampling method. Nitrate concentrations from 12 watersheds were used for model calibration (R2 = 0.91), while 118 other watersheds were used for verification purposes (R2 = 0.82). Overall, the lumped parameter model is shown to be a useful tool for simulating annual nitrate loadings from agricultural watersheds when detailed spatiotemporal agricultural land-use data are available. For PEI the model results indicate that nitrate loadings to estuaries are strongly related to agricultural land, especially the land area in potato production.
Harrison P.M., Ward T., Algera D.A., Culling B., Euchner T., Leake A., Crossman J.A., Cooke S.J., Power M. (2020). A comparison of turbine entrainment rates and seasonal entrainment vulnerability of two sympatric char species, bull trout and lake trout, in a hydropower reservoir. River Research and Applications, 36(7) 1033-1045.

Potadromous salmonids that reside in hydropower reservoirs often have a high recreational and conservation value. However, the potential seasonal turbine entrainment vulnerability patterns of potadromous salmonids are not well understood. Here, we use acoustic telemetry to test the hypothesis that adults of two species of the Salvelinus genus (bull trout and lake trout) differ in their seasonal patterns of entrainment and entrainment vulnerability over a 2-year period. Our results show that while both species were entrained at similarly low annual rates (~1%), these two salmonids differed in their patterns of forebay residency and proximity, with implications for entrainment risk. Bull trout occupied the forebay at low rates across all seasons, with no clear seasonal pattern of forebay proximity. In contrast, lake trout displayed a strongly seasonal pattern of entrainment vulnerability with a distinct movement away from the forebay during the summer, and a large increase in forebay proximity and use in the winter and spring. These findings provide a novel species-specific demonstration of the potential entrainment vulnerability of lake trout. The seasonal patterns of entrainment vulnerability seen in previous bull trout studies, where bull trout occupied top pelagic predator niches, were not replicated in our study where bull trout occur in sympatry with another top pelagic predator. These findings, which indicate that species composition plays an important role determining entrainment vulnerability, have important implications for the conservation of indigenous lake trout and bull trout populations, and together highlight the need for a site-specific approach to entrainment quantification.
Heino J., Culp J.M., Erkinaro J., Goedkoop W., Lento J., Rühland K.M., Smol J.P. (2020). Abruptly and irreversibly changing Arctic freshwaters urgently require standardized monitoring. Journal of Applied Ecology, 57(7) 1192-1198.

Arctic regions support a wide variety of freshwater ecosystems. These naturally oligotrophic and cold-water streams, rivers, ponds and lakes are currently being impacted by a diverse range of anthropogenic pressures, such as accelerated climate change, permafrost thaw, land-use change, eutrophication, brownification and the replacement of northern biota with the range expansion of more southern species. Multiple stressors are rapidly changing Arctic freshwater systems as aquatic habitats are becoming more suitable for species originating from more southerly regions and thereby threatening biota adapted to cold waters. The livelihoods of Indigenous Peoples of the north will be altered when ecosystem services associated with changes in biodiversity are affected. Unfortunately, monitoring of biodiversity change in Arctic freshwaters is currently inadequate, making it difficult, if not impossible, to predict changes in ecosystem services. Synthesis and applications. We propose a three-step approach to better address and facilitate monitoring of the rapid ecological changes that Arctic freshwater ecosystems are currently experiencing as a result of climate change. First, we should increase our efforts in the monitoring of freshwaters across all Arctic countries by setting up a network of monitoring sites and devoting more effort to a broad-scale baseline survey using standardized methods. Second, we should enhance modelling efforts to include both ecological change and socio-economic development. These models should help pinpoint species, ecosystems and geographical areas that are likely to show abrupt changes in response to any changes. Third, we should increase interaction among scientists, policymakers and different stakeholder groups. In particular, Indigenous Peoples must be involved in the leadership, planning and execution of monitoring and assessment activities of Arctic freshwaters. The proposed approach, which is critical to detecting the effects of climate change in the circumpolar region, has broader applications for global coordination of Arctic freshwater biomonitoring. Through routine monitoring, standardization of methods, enhanced modelling of integrated scientific and socio-economic change, and increased collaboration within and among sectors, more effective monitoring and management of climate change impacts on freshwater biodiversity will be possible in the Arctic and globally.
Helminen J., Dauphin G.J.R., Linnansaari T. (2020). Length measurement accuracy of adaptive resolution imaging sonar and a predictive model to assess adult Atlantic salmon (Salmo salar) into two size categories with long-range data in a river. Journal of Fish Biology, 97(4) 1009-1026.

Imaging sonars are used around the world for fish population monitoring. The accuracy of the length measurements has been reported in multiple studies for relatively short (<15 m) ranges and high image resolution. However, imaging sonars are often used at longer ranges (i.e., >15 m) where the images produced from sonar returns become less detailed. The accuracy of the length measurements from the Adaptive Resolution Imaging Sonar (ARIS) was tested by releasing n = 69 known-sized adult Atlantic salmon (Salmo salar) directly into the sonar field at ranges between 15 and 29 m, and measuring their echoes manually by four users and semi-automatically using a computer workflow in Echoview software. Overall, the length measurements were very variable: compared to true (fork) lengths, the mean of differences varied between −9.9 cm and 7.8 cm in the human-generated datasets, and between −42.8 cm and −20 cm in the computer-generated dataset. In addition, the length measurements in different datasets were only in poor or moderate agreement with each other (intraclass correlation <0.61). Contrary to our expectations, the distance from the transducer or the subjectively assessed echo quality did not have an effect on the measurement accuracy in most of the datasets and when it did, the effect was not systematic between the datasets. Therefore, a size class and length prediction model was implemented in a Bayesian framework to group salmon into two size categories: One-Sea-Winter (<63 cm) and Multi-Sea-Winter (≥63 cm) groups. The model correctly predicted the size category in 83% of the fish in the computer-generated dataset and ranged from 68% to 74% in the human-generated datasets. We conclude that fish length measurements derived from long-range imaging sonar data should be used with caution, but post-processing can improve the usefulness of the data for specific purposes, such as adult Atlantic salmon population monitoring.
Ho E., Trant A.J., Gray M.A., Courtenay S.C. (2020). Comparison of freshwater monitoring approaches: strengths, opportunities, and recommendations. Environmental Monitoring and Assessment, 192(9).

This review identifies strengths and weaknesses of water monitoring programs selected by Canadian water managers. We used 22 criteria, guided by outcomes of an exploratory study and supported by 21 semi-structured key informant interviews. The highest-scoring programs include the Slave Watershed Environmental Effects Program (Canada), the Government of Canada’s Environmental Effects Monitoring Program, and Healthy Land and Water (Australia). We describe five recommendations for improving future freshwater monitoring frameworks: (1) recognize different knowledge approaches (especially Indigenous), (2) use multiple reporting formats, (3) clarify monitoring and management roles, (4) apply a whole-watershed approach, and (5) link monitoring to management and decision-making.
Irwin C.E., Culp J.M., Yates A.G. (2020). Spatio-temporal variation of benthic metabolism in a large, regulated river. Canadian Water Resources Journal, 45(2) 144-157.

Large rivers provide important ecosystem services to society, yet little is known about patterns and controls of key ecological functions, such as benthic metabolism, in these ecosystems. This study describes patterns of temporal and spatial variation of benthic metabolism (gross primary production (GPP) and community respiration (CR)) in the Saint John River, New Brunswick, Canada; a large, regulated river. Temporal variation and drivers of metabolism were assessed throughout the summer using measurements of dissolved oxygen from benthic chambers in the river’s wadeable margins. Differences in metabolism between channel locations (main and side channel) and patches of cobble and sand substrates were also determined. Rates of GPP and CR varied in accordance with a quadratic function throughout the summer months with peak rates attained in mid-July. Variability in metabolism was associated with light and water temperature. Spatial heterogeneity in metabolism was not observed between channel locations. Differences in metabolism between substrates were dependent upon time of year, as differences were only observed in early summer. Findings of this study suggest benthic metabolism in the margins of the Saint John River is controlled by variations temperature and light availability that vary with climatic patterns in the summer months. Consequently, these findings have implications for management of river health given projected scenarios of climate change.
James T.L., Landsman S.J., Ramsay L.L., Giffin M.D., Bris A.L. (2020). Migration patterns of atlantic halibut captured in the southern gulf of st. Lawrence as assessed with pop-up satellite archival and floy tags. Canadian Journal of Fisheries and Aquatic Sciences, 77(7) 1233-1242.

This study provides evidence of two subpopulations of Atlantic halibut (Hippoglossus hippoglossus) in the southern Gulf of St. Lawrence. The migrations of 20 Atlantic halibut captured in the coastal waters of Prince Edward Island, Canada, were evaluated using pop-up satellite archival tags (PSAT). Geolocation data showed that Atlantic halibut migrated north to the Laurentian Channel via distinct eastern or western routes. Floy tagging and recapture (recapture of 18.4%) showed that less than 7.0% of Atlantic halibut exhibited dispersive behaviour outside of their annual migratory route. Overwintering occurred on the slope and in the deepest waters of the Laurentian Channel. Atlantic halibut in the deepest waters of the Laurentian Channel exhibited rapid, ~100 m rises, presumed to be associated with spawning from January to March. The eastern and western migratory cohorts exhibited this behaviour~350kmapart, suggesting reproductive isolation as the basis of subpopulations. The results of this study indicate a need to reconsider the management of Gulf of St. Lawrence Atlantic halibut as one continuous population.
Jardine T.D., Galloway A.W.E., Kainz M.J. (2020). Unlocking the power of fatty acids as dietary tracers and metabolic signals in fishes and aquatic invertebrates. Philosophical Transactions of the Royal Society B Biological Sciences, 375(1804).

Determining the transfer and transformation of organic matter in food webs is a fundamental challenge that has implications for sustainable management of ecosystems. Fatty acids (FA) offer a potential approach for resolving complex diet mixtures of organisms because they provide a suite of molecular tracers. Yet, uncertainties in the degree of their biochemical modification by consumers, due to selective retention or metabolism, have limited their application. Here, we consolidated 316 controlled feeding studies of aquatic ectotherms (fishes and invertebrates) involving 1404 species-diet combinations to assess the degree of trophic modification of FA in muscle tissue. We found a high degree of variability within and among taxa in the %FA in consumer muscle tissue versus %FA in diet regression equations. Most saturated FA had weak relationships with the diet (r2 < 0.30) and shallow slopes (m < 0.30), suggesting a lack of retention in muscle when fed in increasing amounts. Contrarily, several essential FA, including linoleic (18:2n-6) and a-linolenic acid (18:3n-3), exhibited significant relationships with the diet (m > 0.35, r2 > 0.50), suggesting supply limitations and selective retention in muscle by consumers. For all FA, relationships strengthened with increasing taxonomic specificity. We also demonstrated the utility of new correction equations by calculating the potential contributions of approximately 20 prey items to the diet of selected species of generalist fishes using a FA mixing model. Our analyses further reveal how a broad range of fishes and invertebrates convert or store these compounds in muscle tissue to meet physiological needs and point to their power in resolving complex diets in aquatic food webs. This article is part of the theme issue 'The next horizons for lipids as 'trophic biomarkers': evidence and significance of consumer modification of dietary fatty acids'.
Kidd K.A., Graves S.D., McKee G.I., Dyszy K., Podemski C.L. (2020). Effects of Whole-Lake Additions of Ethynylestradiol on Leech Populations. Environmental Toxicology and Chemistry, 39(8) 1608-1619.

Leeches are widespread, found in many freshwater habitats, and have diverse dietary habits. Despite their close phylogenetic relationships to Mollusca, a phylum with species affected by exogenous estrogens, it is unclear whether Hirudinea may also be impacted. A whole-lake experiment was done at the Experimental Lakes Area in Ontario, Canada, to assess whether 17α-ethynylestradiol (EE2) affected fishes and other species. Herein, we examined whether EE2 impacted leech community composition, species abundance, growth rates, gonad size, and cocoon production, when compared with reference lakes using a before-after-control-impact design. Each month baited leech traps were set overnight in the littoral zone at 10 sites around experimental Lake 260 and 2 reference lakes, and individuals were identified, weighed, and measured. Male and female organs of common species Haemopis marmorata were measured. Across all lakes, 9 species representing 3 families were collected. There were no apparent effects of EE2 on numbers, species richness, or community composition; however, condition in 1 of 5 species increased significantly after EE2 exposures. Total gonadosomatic index (GSI) and the GSI for all male or all female organs combined for H. marmorata were not affected by EE2 additions. However, some individual reproductive organs including relative sperm sac length (+), relative epididymis weight (–), relative vaginal bulb length (+), and relative ovisac + albumen gland length (+) changed after EE2 additions. Finally, whereas overall cocoon production was similar, it occurred earlier in the EE2-amended lake. In summary, few individual through community measures of leeches responded to low ng/L concentrations of EE2, suggesting that Hirudinea are less sensitive to this endocrine disruptor than other invertebrates and vertebrates. Environ Toxicol Chem 2020;39:1608–1619. © 2020 SETAC.
Kroetsch S.A., Kidd K.A., Monk W.A., Culp J.M., Compson Z.G., Pavey S.A. (2020). The effects of taxonomy, diet, and ecology on the microbiota of riverine macroinvertebrates. Ecology and Evolution, 10(24) 14000-14019.

Freshwater macroinvertebrates play key ecological roles in riverine food webs, such as the transfer of nutrients to consumers and decomposition of organic matter. Although local habitat quality drives macroinvertebrate diversity and abundance, little is known about their microbiota. In most animals, the microbiota provides benefits, such as increasing the rate at which nutrients are metabolized, facilitating immune system development, and defending against pathogenic attack. Our objectives were to identify the bacteria within aquatic invertebrates and determine whether their composition varied with taxonomy, habitat, diet, and time of sample collection. In 2016 and 2017, we collected 264 aquatic invertebrates from the mainstem Saint John (Wolastoq) River in New Brunswick, Canada, representing 15 orders. We then amplified the V3-V4 hypervariable region of the 16S rRNA gene within each individual, which revealed nearly 20,000 bacterial operational taxonomic units (OTUs). The microbiota across all aquatic invertebrates were dominated by Proteobacteria (69.25% of the total sequence reads), but they differed significantly in beta diversity, both among host invertebrate taxa (genus-, family-, and order-levels) and temporally. In contrast to previous work, we observed no microbiota differences among functional feeding groups or traditional feeding habits, and neither water velocity nor microhabitat type structured microbiota variability. Our findings suggest that host invertebrate taxonomy was the most important factor in modulating the composition of the microbiota, likely through a combination of vertical and horizontal bacterial transmission, and evolutionary processes. This is one of the most comprehensive studies of freshwater invertebrate microbiota to date, and it underscores the need for future studies of invertebrate microbiota evolution and linkages to environmental bacteria and physico-chemical conditions.
Krynak E.M., Yates A.G. (2020). Intensive agriculture alters the biomass size spectrum and body-mass of benthic insects: evidence from a reciprocal transfer experiment. Hydrobiologia, 847(5) 1221-1235.

The aim of this study was to test the effects of agricultural land use on benthic insect population body-mass and community biomass size spectrum. Agricultural land use effects were assessed by conducting a reciprocal transfer experiment between two stream reaches exposed to differing intensities of row crop and livestock agricultural activity representing best attainable and highly developed agricultural land use scenarios. We found that transferred insect communities showed no change in richness, abundance, distribution or biomass, indicating that exposure to increased agricultural intensity did not have selective lethal effects on transferred benthic insect communities. However, populations of Ephemerellidae and Hydropsyche demonstrated an increase and decrease, respectively, in body-mass following the transfer to the best attainable agriculture site. Furthermore, the community biomass size spectrum at the best attainable agriculture site contained large, predatory insects not found at the intensive agriculture site. Our findings suggest that taxon-specific body-mass and biomass size spectra have the potential to detect environmental effects prior to long-term community changes. Further research is needed to explore the mechanisms by which changes in the biomass size spectrum link agricultural intensity to shifts in benthic insect community structure.
Landsman S.J., McLellan N.R., Platts J., Van Den Heuvel M.R. (2020). Fishway Effectiveness and Upstream Residency of Three Fish Species at Four Fishways in Prince Edward Island, Canada. Northeastern Naturalist, 27(1) 48-76.

We evaluated passage of Osmerus mordax (Rainbow Smelt), Salvelinus fontinalis (Brook Trout), and Alosa pseudoharengus (Alewife) at 4 fishways on Prince Edward Island, Canada. We implanted fish with passive integrated transponder (PIT) tags and recorded their movements using stationary PIT antennas. Passage at different fishway types was highly variable. Nature-like fishways passed over 96% of Brook Trout and a maximum of 41.8% of Rainbow Smelt. The latter percentage is the highest yet reported in the literature for Rainbow Smelt. Pool-and-weir fishways passed nearly 100% of Brook Trout, 13.2% of Rainbow Smelt, and only 5.6% of Alewife. After passing a fishway, upstream residency was highly variable both among species as well as among individuals within species. Rainbow Smelt were observed spawning within nature-like fishways, suggesting that this type of fishway may also provide spawning habitat. Results highlight the challenge of passing non-salmonid species and indicate nature-like fishways are more appropriate than technical designs for passing Rainbow Smelt.
LeBlanc N.M., Gahagan B.I., Andrews S.N., Avery T.S., Puncher G.N., Reading B.J., Buhariwalla C.F., Curry R.A., Whiteley A.R., Pavey S.A. (2020). Genomic population structure of Striped Bass (Morone saxatilis) from the Gulf of St. Lawrence to Cape Fear River. Evolutionary Applications, 13(6) 1468-1486.

Striped Bass, Morone saxatilis (Walbaum, 1792), is an anadromous fish species that supports fisheries throughout North America and is native to the North American Atlantic Coast. Due to long coastal migrations that span multiple jurisdictions, a detailed understanding of population genomics is required to untangle demographic patterns, understand local adaptation, and characterize population movements. This study used 1,256 single nucleotide polymorphism (SNP) loci to investigate genetic structure of 477 Striped Bass sampled from 15 locations spanning the North American Atlantic coast from the Gulf of St. Lawrence, Canada, to the Cape Fear River, United States. We found striking differences in neutral divergence among Canadian sites, which were isolated from each other and US populations, compared with US populations that were much less isolated. Our SNP dataset was able to assign 99% of Striped Bass back to six reporting groups, a 39% improvement over previous genetic markers. Using this method, we found (a) evidence of admixture within Saint John River, indicating that migrants from the United States and from Shubenacadie River occasionally spawn in the Saint John River; (b) Striped Bass collected in the Mira River, Cape Breton, Canada, were found to be of both Miramichi River and US origin; (c) juveniles in the newly restored Kennebec River population had small and nonsignificant differences from the Hudson River; and (d) tributaries within the Chesapeake Bay showed a mixture of homogeny and small differences among each other. This study introduces new hypotheses about the dynamic zoogeography of Striped Bass at its northern range and has important implications for the local and international management of this species.
Lento J., Gray M.A., Ferguson A.J., Curry R.A. (2020). Complementary responses of stream fish and benthic macroinvertebrate assemblages to environmental drivers in a shale-gas development area. Facets, 5(1) 200-227.

Shale-gas production could impact freshwater quality through contamination of the physical and chemical habitat (e.g., fracturing fluids, untreated or treated effluent) or development-related impacts. Despite environmental concerns, information is lacking to support biomonitoring as a diagnostic tool to assess impacts of shale-gas production. We characterized water quality and biota in areas of high shale gas potential (Early Carboniferous bedrock in New Brunswick, Canada) and surrounding geologic areas, and we assessed patterns in benthic macroinvertebrate (BMI) and fish assemblages. Early Carboniferous stations differed primarily based on water chemistry, and BMI were associated with a gradient in conductivity and temperature across geologic classes. Concordance analysis indicated similar classification of stations by both organism groups, though fish were more related to turbidity and nutrients. Concordance among fish and BMI was strongest at high conductivity, Early Carboniferous stations. These results suggest that geology plays a strong role in driving abiotic habitats and biotic communities of streams, even at small spatial scales. Furthermore, they suggest BMI and fish can provide complementary information for biomonitoring in shale-gas development areas, with BMI responding to increased ion concentrations from surface water contamination, and fish responding to changes in nutrients and turbidity resulting from development.
Leone A., Puncher G.N., Ferretti F., Sperone E., Tripepi S., Micarelli P., Gambarelli A., Sarà M., Arculeo M., Doria G., Garibaldi F., Bressi N., Dall'Asta A., Minelli D., Cilli E., Vanni S., Serena F., Díaz-Jaimes P., Baele G., Cariani A., Tinti F. (2020). Pliocene colonization of the Mediterranean by Great White Shark inferred from fossil records, historical jaws, phylogeographic and divergence time analyses. Journal of Biogeography, 47(5) 1119-1129.

Aim: Determine the evolutionary origin of the heretofore poorly characterized contemporary Great White Shark (GWS; Carcharodon carcharias) of the Mediterranean Sea, using phylogenetic and dispersal vicariance analyses to trace back its global palaeo-migration pattern. Location: Mediterranean Sea. Taxon: Carcharodon carcharias. Methods: We have built the largest mitochondrial DNA control region (CR) sequence dataset for the Mediterranean GWS from referenced historical jaws spanning the 19th and 20th centuries. Mediterranean and global GWS CR sequences were analysed for genetic diversity, phylogenetic relationships and divergence time. A Bayes factor approach was used to assess two scenarios of GWS lineage divergence and emergence of the Mediterranean GWS line using fossil records and palaeo-geographical events for calibration of the molecular clock. Results: The results confirmed a closer evolutionary relationship between Mediterranean GWS and populations from Australia–New Zealand and the North-eastern Pacific coast rather than populations from South African and North-western Atlantic. The Mediterranean GWS lineage showed the lowest genetic diversity at the global level, indicating its recent evolutionary origin. An evaluation of various divergence scenarios determined the Mediterranean GWS lineage most likely appeared some 3.23 million years ago by way dispersal/vicariance from Australian/Pacific palaeo-populations. Main conclusion: Based on the fossil records, phylogeographic patterns and divergence time, we revealed that the Mediterranean GWS population originated in the Pliocene following the Messinian Salinity Crisis. Colonization of the Mediterranean by GWS likely occurred via an eastward palaeo-migration of Australian/eastern Pacific elements through the Central American Seaway, before the complete closure of the Isthmus of Panama. This Pliocene origin scenario contrasts with a previously proposed scenario in which Australian GWS colonized the Mediterranean via antipodean northward migration resulting from navigational errors from South Africa during Quaternary climatic oscillations.
Lynn T.J., Jeong J.W., Duffy M.S. (2020). Bet hedging and cold-temperature termination of diapause in the life history of the Atlantic salmon ectoparasite Argulus canadensis. Parasitology, 147(14) 1774-1785.

Argulus canadensis is a crustacean ectoparasite observed increasingly on wild migrating adult Atlantic salmon. We investigated temperature and salinity tolerance regarding development, survival and hatch of A. canadensis eggs to help understand spatiotemporal features of transmission. Argulus canadensis eggs differentiate to pharate embryos by 35 days buttheir hatch is protracted to ∼7 months. Cold treatment 75 days mimics overwintering and terminates egg diapause, with 84.6% (72.1-100%) metanauplius hatch induced 13 °C and synchronized to 3-4 weeks. Inter- and intra-clutch variability and protracted hatch in the absence of cold-temperature termination of diapause is compatible with bet hedging. Whereas diapause likely promotes phenological synchrony for host colocalization, bet hedging could afford temporal plasticity to promote host encounter during environmental change. Our egg storage and hatch induction/synchronization methodologies can be exploited for empirical investigations. Salinity tolerance reveals both significantly higher embryonic development (94.4 ± 3.5% vs 61.7 ± 24.6%) and metanauplius hatch (53.3 ± 7.5% vs 10.1 ± 8.2%) for eggs in freshwater than at 17 ppt. Unhatched embryos were alive in freshwater by the end of the trial (213 days) but were dead/dying at 17 ppt. Eggs did not develop at 34 ppt. Salinity tolerance of A. canadensis eggs supports riverine transmission to adult Atlantic salmon during return to freshwater for mating each year.
Macdonald G.Z., Hogan N.S., van den Heuvel M.R. (2020). Effects of habitat and pulp and paper mill contamination on a population of brook stickleback (Culaea inconstans). Water Quality Research Journal, 55(1) 52-66.

This study examined the responses of a population of brook stickleback (Culaea inconstans) exposed to pulp mill effluent at Jackfish Bay, Lake Superior, Canada, in May 2007 and May 2011. Brook stickleback were extirpated from the effluent-receiving site, presumably due to anoxia after this period. Females at the effluent-receiving site had significantly larger gonad sizes in 2007 and 2011. In 2011, effluent-exposed female gonadal development was significantly advanced when compared with reference sites; they were the second most mature when compared among three different reference sites. Analysis of 7-ethoxyresorufin-O-deethylase activity revealed that effluent-receiving site females had greater CYP1A induction in 2007 and significantly greater CYP1A induction in 2011. Effluent-receiving site males showed significantly reduced CYP1A induction in 2007 and significantly greater induction in 2011. Chemical evaluation of sediment from the receiving environment showed elevated levels of resin acids and the polycyclic aromatic hydrocarbon, retene. Higher condition factors and more mature gonads were consistent with higher winter and spring temperatures modified by effluent or by lake vs. stream environments. Overall, effects on effluent-exposed brook stickleback were not consistent with reported effects in white sucker exposed to the same effluent in previous studies.
Makiola A., Compson Z.G., Baird D.J., Barnes M.A., Boerlijst S.P., Bouchez A., Brennan G., Bush A., Canard E., Cordier T., Creer S., Curry R.A., David P., Dumbrell A.J., Gravel D., Hajibabaei M., Hayden B., van der Hoorn B., Jarne P., Jones J.I., Karimi B., Keck F., Kelly M., Knot I.E., Krol L., Massol F., Monk W.A., Murphy J., Pawlowski J., Poisot T., Porter T.M., Randall K.C., Ransome E., Ravigné V., Raybould A., Robin S., Schrama M., Schatz B., Tamaddoni-Nezhad A., Trimbos K.B., Vacher C., Vasselon V., Wood S., Woodward G., Bohan D.A. (2020). Key Questions for Next-Generation Biomonitoring. Frontiers in Environmental Science, 7.

Classical biomonitoring techniques have focused primarily on measures linked to various biodiversity metrics and indicator species. Next-generation biomonitoring (NGB) describes a suite of tools and approaches that allow the examination of a broader spectrum of organizational levels—from genes to entire ecosystems. Here, we frame 10 key questions that we envisage will drive the field of NGB over the next decade. While not exhaustive, this list covers most of the key challenges facing NGB, and provides the basis of the next steps for research and implementation in this field. These questions have been grouped into current- and outlook-related categories, corresponding to the organization of this paper.
Martyniuk C.J., Feswick A., Munkittrick K.R., Dreier D.A., Denslow N.D. (2020). Twenty years of transcriptomics, 17alpha-ethinylestradiol, and fish. General and Comparative Endocrinology, 286.

In aquatic toxicology, perhaps no pharmaceutical has been investigated more intensely than 17alpha-ethinylestradiol (EE2), the active ingredient of the birth control pill. At the turn of the century, the fields of comparative endocrinology and endocrine disruption research witnessed the emergence of omics technologies, which were rapidly adapted to characterize potential hazards associated with exposures to environmental estrogens, such as EE2. Since then, significant advances have been made by the scientific community, and as a result, much has been learned about estrogen receptor signaling in fish from environmental xenoestrogens. Vitellogenin, the egg yolk precursor protein, was identified as a major estrogen-responsive gene, establishing itself as the premier biomarker for estrogenic exposures. Omics studies have identified a plethora of estrogen responsive genes, contributing to a wealth of knowledge on estrogen-mediated regulatory networks in teleosts. There have been ~40 studies that report on transcriptome responses to EE2 in a variety of fish species (e.g., zebrafish, fathead minnows, rainbow trout, pipefish, mummichog, stickleback, cod, and others). Data on the liver and testis transcriptomes dominate in the literature and have been the subject of many EE2 studies, yet there remain knowledge gaps for other tissues, such as the spleen, kidney, and pituitary. Inter-laboratory genomics studies have revealed transcriptional networks altered by EE2 treatment in the liver; networks related to amino acid activation and protein folding are increased by EE2 while those related to xenobiotic metabolism, immune system, circulation, and triglyceride storage are suppressed. EE2-responsive networks in other tissues are not as comprehensively defined which is a knowledge gap as regulated networks are expected to be tissue-specific. On the horizon, omics studies for estrogen-mediated effects in fish include: (1) Establishing conceptual frameworks for incorporating estrogen-responsive networks into environmental monitoring programs; (2) Leveraging in vitro and computational toxicology approaches to identify chemicals associated with estrogen receptor-mediated effects in fish (e.g., male vitellogenin production); (3) Discovering new tissue-specific estrogen receptor signaling pathways in fish; and (4) Developing quantitative adverse outcome pathway predictive models for estrogen signaling. As we look ahead, research into EE2 over the past several decades can serve as a template for the array of hormones and endocrine active substances yet to be fully characterized or discovered.
McAlpine D.F., Soto D.X., Wilson J.G. (2020). Stable Isotope Analysis Supports First Occurrence of a Wild-Origin Greylag Goose (Anser anser) to Make Landfall in North America. Waterbirds, 43(1) 107-112.

In North America, the Greylag Goose (Anser anser) has been added to the list of vagrant North American waterfowl based on a bird observed in 2005 on a stationary oil ship in the Atlantic Ocean 167 km southeast of the island of Newfoundland, and on single birds observed in Connecticut and Nova Scotia in 2009 and 2010, respectively. Here, feather and toe-claw hydrogen isotope values (2H) linked to spatial hydrological hydrogen isotope patterns are used to demonstrate the origin of the first probable wild-origin Greylag Goose known to make landfall in North America. The bird in question, shot by hunters on Grand Manan Island, New Brunswick, in December 2007 and subsequently deposited at the New Brunswick Museum (specimen NBM 11143), was identified as Anser anser and potentially a wild-origin bird. Isotope data indicates the bird is of probable Greenlandic origin. This supports and pre-dates recent (2014) reports of the Greenlandic molting of Icelandic Greylag Geese, until recently believed to molt exclusively on Iceland. Greylag Geese recorded in North America appear to be part of a pattern of increasing numbers and diversity of geese of northeastern Atlantic origin detected in eastern North America in recent decades.
McMahon H.M., Arciszewski T.J., Munkittrick K.R., Kidd K.A. (2020). Regional and Long-Term Analyses of Stable Isotopes of Fish and Invertebrates Show Evidence of the Closure of a Pulp Mill and the Influence of Additional Stressors. Environmental Toxicology and Chemistry, 39(6) 1207-1218.

A bleached kraft pulp mill discharging effluent to the Mattagami River in northern Ontario, Canada, closed after almost 90 yr of operation. During its operation, effluent from the mill influenced biota in the downstream areas. To assess shifts in the reliance of biota from mill-derived nutrients, the isotopic composition (δ13C and δ15N) of white sucker (Catostomus commersoni) muscle and whole mayflies (Hexagenia sp.) were compared before (1990s) and after the pulp mill's closure (2012–2014). To better understand other potential sources of spatial and temporal change, samples from 3 other tributaries in the basin with dams, ongoing pulp mill operations, sites receiving sewage, and at several reference sites were collected and compared. Irrespective of time period, biota collected at sites downstream of both dams and active pulp mills tended to have elevated δ13C values, but variable changes in δ15N (negligible in most cases) when compared with upstream samples. The isotopic composition of mayflies varied at reference sites over time, with decreasing values of δ13C and δ15N (mayflies only) with increasing depth, and there was evidence of lower δ13C in fish after the pulp mill closure. Overall, these results suggest the importance of long-term, regional-scale measurements for documenting the effects of stressors on nutrient use by aquatic species. Environ Toxicol Chem 2020;39:1207–1218. © 2020 SETAC.
O'Sullivan A.M., Devito K.J., Ogilvie J., Linnansaari T., Pronk T., Allard S., Curry R.A. (2020). Effects of Topographic Resolution and Geologic Setting on Spatial Statistical River Temperature Models. Water Resources Research, 56(12).

River temperature exerts a critical control on habitat for aquatic biota. As the climate warms in eastern Canada, threats to habitats of cold-water species will increase, underpinning the necessity to develop an understanding of landscape-scale, thermal regimes of flowing waters. We assessed the performance of spatial statistical network (SSN) models of river temperature using high-resolution thermal infrared imagery (0.6 m) and LiDAR (1 m) compared to NASA's Shuttle Radar Topography Mission (SRTM—30 m) topographic data and interrogate LiDAR derived fine-scale models (3 ha) to describe groundwater connectivity to surface waters in catchments with shallow overburden and varied bedrock geology. LiDAR improved model performance in a catchment underlain by a homogeneous, high hydraulic conductance bedrock (Cains River) but did not improve model performance in a catchment with heterogeneous bedrock and variable hydraulic conductance (North Pole Stream). We hypothesize that differences in bedrock conductance modified topographic controls on subsurface flows and discharge patterns to the rivers and thus produced the mixed performance of the SSN models. At finer scales, river reaches in steep valleys incising high conductance bedrock produced groundwater discharge, which was absent in incised valleys with low conductance bedrock. These findings indicate that while topography exerts an important control on landscape-scale hydrological processes, geologic setting is a similarly important influence on hydrological processes. We suggest the inclusion of a third dimension of spatial autocorrelation, representative of the vertical plane that captures the geologic setting, would broaden the geographic applicability of spatial statistical models for river temperature studies.
O'Sullivan A.M., Samways K.M., Perreault A., Hernandez C., Gautreau M.D., Curry R.A., Bernatchez L. (2020). Space invaders: Searching for invasive Smallmouth Bass (Micropterus dolomieu) in a renowned Atlantic Salmon (Salmo salar) river. Ecology and Evolution, 10(5) 2588-2596.

Humans have the ability to permanently alter aquatic ecosystems and the introduction of species is often the most serious alteration. Non-native Smallmouth Bass (Micropterus dolomieu) were identified in Miramichi Lake c. 2008, which is a headwater tributary to the Southwest Miramichi River, a renowned Atlantic Salmon (Salmo salar) river whose salmon population is dwindling. A containment programme managed by the Department of Fisheries and Oceans, Canada (DFO) was implemented in 2009 to confine Smallmouth Bass (SMB) to the lake. We utilized environmental DNA (eDNA) as a detection tool to establish the potential escape of SMB into the Southwest Miramichi River. We sampled at 26 unique sites within Miramichi Lake, the outlet of Miramichi Lake (Lake Brook), which flows into the main stem Southwest Miramichi River, and the main stem Southwest Miramichi River between August and October 2017. We observed n = 6 positive detections located in the lake, Lake Brook, and the main stem Southwest Miramichi downstream of the lake. No detections were observed upstream of the confluence of Lake Brook and the main stem Southwest Miramichi. The spatial pattern of positive eDNA detections downstream of the lake suggests the presence of individual fish versus lake-sourced DNA in the outlet stream discharging to the main river. Smallmouth Bass were later confirmed by visual observation during a snorkeling campaign, and angling. Our results, both eDNA and visual confirmation, definitively show Smallmouth Bass now occupy the main stem of the Southwest Miramichi.
Orr J.A., Vinebrooke R.D., Jackson M.C., Kroeker K.J., Kordas R.L., Mantyka-Pringle C., van den Brink P.J., de Laender F., Stoks R., Holmstrup M., Matthaei C.D., Monk W.A., Penk M.R., Leuzinger S., Schäfer R.B., Piggott J.J. (2020). Towards a unified study of multiple stressors: Divisions and common goals across research disciplines. Proceedings of the Royal Society B Biological Sciences, 287(1926).

Anthropogenic environmental changes, or ‘stressors’, increasingly threaten biodiversity and ecosystem functioning worldwide. Multiple-stressor research is a rapidly expanding field of science that seeks to understand and ultimately predict the interactions between stressors. Reviews and meta-analyses of the primary scientific literature have largely been specific to either freshwater, marine or terrestrial ecology, or ecotoxicology. In this cross-disciplinary study, we review the state of knowledge within and among these disciplines to highlight commonality and division in multiple-stressor research. Our review goes beyond a description of previous research by using quantitative bibliometric analysis to identify the division between disciplines and link previously disconnected research communities. Towards a unified research framework, we discuss the shared goal of increased realism through both ecological and temporal complexity, with the overarching aim of improving predictive power. In a rapidly changing world, advancing our understanding of the cumulative ecological impacts of multiple stressors is critical for biodiversity conservation and ecosystem management. Identifying and overcoming the barriers to interdisciplinary knowledge exchange is necessary in rising to this challenge. Division between ecosystem types and disciplines is largely a human creation. Species and stressors cross these borders and so should the scientists who study them.
Ouellet V., St-Hilaire A., Dugdale S.J., Hannah D.M., Krause S., Proulx-Ouellet S. (2020). River temperature research and practice: Recent challenges and emerging opportunities for managing thermal habitat conditions in stream ecosystems. Science of the Total Environment, 736.

There is growing evidence that river temperatures are increasing under climate change, which is expected to be exacerbated by increased abstractions to satisfy human water demands. Water temperature research has experienced crucial advances, both in terms of developing new monitoring and modelling tools, as well as understanding the mechanisms of temperature feedbacks with biogeochemical and ecological processes. However, water practitioners and regulators are challenged with translating the widespread and complex technological, modelling and conceptual advances made in river temperature research into improvements in management practice. This critical review provides a comprehensive overview of recent advances in the state-of-the-art monitoring and modelling tools available to inform ecological research and practice. In so doing, we identify pressing research gaps and suggest paths forward to address practical research and management challenges. The proposed research directions aim to provide new insights into spatio-temporal stream temperature dynamics and unravel drivers and controls of thermal river regimes, including the impacts of changing temperature on metabolism and aquatic biogeochemistry, as well as aquatic organisms. The findings of this review inform future research into ecosystem resilience in the face of thermal degradation and support the development of new management strategies cutting across spatial and temporal scales.
O’Malley Z.G., Compson Z.G., Orlofske J.M., Baird D.J., Curry R.A., Monk W.A. (2020). Riparian and in-channel habitat properties linked to dragonfly emergence. Scientific Reports, 10(1).

In freshwater ecosystems, habitat alteration contributes directly to biodiversity loss. Dragonflies are sentinel species that are key invertebrate predators in both aquatic (as larvae) and terrestrial ecosystems (as adults). Understanding the habitat factors affecting dragonfly emergence can inform management practices to conserve habitats supporting these species and the functions they perform. Transitioning from larvae to adults, dragonflies leave behind larval exoskeletons (exuviae), which reveal information about the emergent population without the need for sacrificing living organisms. Capitalizing on Atlantic Canada’s largest freshwater wetland, the Grand Lake Meadows (GLM) and the associated Saint John/Wolastoq River (SJWR), we studied the spatial (i.e., across the mainstem, tributary, and wetland sites) and temporal (across 3 years) variation in assemblages of emergent dragonflies (Anisoptera) and assessed the relative contribution of aquatic and terrestrial factors structuring these assemblages. The GLM complex, including the lotic SJWR and its tributaries and associated lentic wetlands, provided a range of riparian and aquatic habitat variability ideal for studying dragonfly emergence patterns across a relatively homogenous climatic region. Emergent dragonfly responses were associated with spatial, but not temporal, variation. Additionally, dragonfly communities were associated with both aquatic and terrestrial factors, while diversity was primarily associated with terrestrial factors. Specific terrestrial factors associated with the emergence of the dragonfly community included canopy cover and slope, while aquatic factors included water temperature, dissolved oxygen, and baseflow. Our results indicate that management of river habitats for dragonfly conservation should incorporate riparian habitat protection while maintaining aquatic habitat and habitat quality.
O’Sullivan A.M., Wegscheider B., Helminen J., Cormier J.G., Linnansaari T., Wilson D.A., Curry R.A. (2020). Catchment-scale, high-resolution, hydraulic models and habitat maps–a salmonid's perspective. Journal of Ecohydraulics, 6(1) 53-68.

The advent of remotely-sensed high-resolution imagery has led to the development of methods to map river bathymetry. In this study, we utilized high-resolution imagery to map river depth and quantify hydraulic habitats at the catchment scale (>1000 km2) during low flows. Using 0.3-m airborne multi-spectral imagery (resampled to 0.5 m), we mapped contiguous river depth (124 km) within a well-established Atlantic Salmon (Salmo salar) and Brook Trout (Salvelinus fontinalis) river–The Little Southwest Miramichi, New Brunswick. We built image-derived depth maps with and without field data calibration. The model without field calibration data (flow resistance equation‐based imaging of river depths) accurately described river depths (R 2 = 72.7; RMSE = 0.167 m; n = 762); however, it overestimated shallow depths. The field-calibrated model removed shallow depth errors (R 2 = 76.4; RMSE = 0.155 m; n = 762). We mapped velocity using a relationship between river geometry and discharge, and coalesced the field-calibrated depth and velocity maps to create Froude and Reynolds number maps. Finally, we performed an unsupervised classification model to delineate the hydraulically relevant habitat units for salmonids. This approach provides an unprecedented view of catchment-scale hydraulic habitats that will advance both hydrological process research and river resources management.
Padilla-Gutierrez S.C., González-Sansón G., Aguilar-Betancourt C.M., Floresortega J.R. (2020). Comparative analysis of the diet composition and its relation to morphological characteristics in achirus mazatlanus and syacium ovale (Pleuronectiformes: Osteichthyes) from a mexican pacific coastal lagoon. Neotropical Ichthyology, 18(1).

The purpose of this research was to investigate differences in diet composition between Achirus mazatlanus and Syacium ovale, two flatfishes inhabiting in a tropical coastal lagoon and to investigate the relationship of their feeding habits to size, body morphometry and mouths characteristics. Fish were collected during sampling trips conducted regularly from 2011 to 2016 using several types of fishing gear. Total number of analyzed stomachs with some food content was 328 for Achirus mazatlanus from 1.4 to 21.3 cm total length (TL) and 203 for Syacium ovale with 1.3 to 24.0 cm TL. Results indicate that both species share a general diet based on benthic invertebrates and fishes but S. ovale has a more piscivorous habit, which can be explained by a more slender body shape and larger teeth, characteristics which increase prey fish catching performance. Important changes in composition of food categories related to size were not found for any species, but larger fish of both species eat larger ranges of prey sizes, and this ontogenetic change is consistent with recent developments on optimal foraging theory.
Painter K.J., Brua R.B., Spoelstra J., Koehler G., Yates A.G. (2020). Fate of bioavailable nutrients released to a stream during episodic effluent releases from a municipal wastewater treatment lagoon. Environmental Science Processes and Impacts, 22(12) 2374-2387.

Municipal wastewater lagoons are common across North America and, unlike larger mechanical wastewater treatment plants, typically release nutrient-rich effluent directly to rivers in intermittent pulses. However, little is known about the fate of nutrients from these episodic events, which may happen under varying hydrologic or thermal conditions. We assessed fate of nitrogen (N) and phosphorus (P) from lagoon effluent during three releases to Deadhorse Creek, Manitoba, Canada. Using net nutrient uptake lengths and natural abundance stable isotope ratios of dissolved inorganic nitrogen (DIN) and primary producers, we found that DIN was processed during the summer releases though the dominant mechanism was unclear. However, nitrate was largely exported in autumn. Primary producers assimilated lagoon N but did not appear to reduce DIN concentrations. The longitudinal pattern of soluble reactive phosphorus (SRP) varied between releases and in summer 2019 the stream became a net source of SRP despite concomitant processing of DIN. We hypothesize that low demand for P in Deadhorse Creek, as suggested by upstream SRP > 0.05 mg P L-1, and nutrient ratios indicative of N limitation, reduced instream processing of P. Furthermore, our results indicated that cool or high flow conditions may result in the export of much of the lagoon nutrient load downstream. Our findings suggest the processes that transform wastewater nutrients are overwhelmed during effluent releases. Managers should consider increasing effluent dilution via continuous release of effluent rather than pulsed delivery. However, management of upstream nutrient supply may also be needed when relying upon the self-purifying capacity of rivers. This journal is
Pearce N.J.T., Thomas K.E., Chambers P.A., Venkiteswaran J.J., Yates A.G. (2020). Metabolic regimes of three mid-order streams in southern Ontario, Canada exposed to contrasting sources of nutrients. Hydrobiologia, 847(8) 1925-1942.

Light, temperature, and discharge control stream metabolism, but the response of gross primary production (GPP) and ecosystem respiration (ER) to seasonal variation in these physical drivers may differ in accordance with the types of human activities present in the catchment. Our study examined three mid-order streams in southern Ontario, Canada that differed in anthropogenic nutrient sources (i.e., sewage treatment plant effluent, sewage lagoon effluent, and agriculture), but had comparable light, temperature, and discharge regimes. For each stream, GPP and ER were estimated daily from June through November. Comparisons of paired daily metabolic rates revealed pairwise differences among all streams, with streams receiving sewage effluent having greater rates and variability of GPP and ER than the stream draining agricultural land. The two sewage influenced streams differed only in ER. Temporal patterns of GPP and ER were correlated for all streams throughout the study period and were most affected by seasonal variation in temperature, whereby effluent receiving streams responded more rapidly to increases in temperature. Our findings suggest that managers may need to balance effects of human activities with regional environmental constraints on stream metabolism to maintain and enhance the ecological condition and services of stream ecosystems.
Pearce N.J.T., Thomas K.E., Lavoie I., Chambers P.A., Yates A.G. (2020). Episodic loadings of phosphorus influence growth and composition of benthic algae communities in artificial stream mesocosms. Water Research, 185.

Phosphorus (P) is an essential macronutrient for algal communities, but in excess can exacerbate stream eutrophication. However, P loadings to streams vary temporally from continuous to episodic as a result of inputs from point and non-point sources, respectively. P loading pattern can thus alter the temporal availability of P and may influence effects of P enrichment on algal communities. We assessed how P loading pattern influences algal biomass and composition by conducting a 29-day P enrichment experiment in nine artificial streams exposed to either: (1) continuous P enrichment; (2) episodic P enrichment, or; (3) no P enrichment. P enrichment increased algal biomass accrual, but peak biomass did not differ between continuously and episodically enriched treatments. Maximum absolute growth rates were also comparable between P enriched treatments. However, episodic P additions sustained elevated rates of biomass accrual, whereas absolute growth rates in the continuously enriched communities declined towards the end of the experiment. P enrichment resulted in comparable increases in relative abundance of chlorophytes and decreased proportions of bacillariophytes and charophytes in algal communities for continuously and episodically enriched treatments. However, composition of bacillariophyte (diatom) assemblages differed significantly among all P enrichment treatments in accordance with species autecological attributes for P. Our results demonstrate that episodic and continuous P enrichment may augment algal biomass similarly. Yet, P loading pattern regulated the composition of algal communities. Thus, remedial management strategies for the control of nuisance algae production may require focus on the predominant source of P to streams. Finally, species specific responses of diatom assemblages to P enrichment and associated loading patterns suggests this taxonomic group may have potential as diagnostic indicators for identifying the presence of key nutrient sources associated with eutrophication of stream ecosystems.
Pearce N.J.T., Yates A.G. (2020). Spatial and temporal patterns in macronutrient concentrations and stoichiometry of tributaries draining the lower Great Lakes-St. Lawrence basin. Journal of Great Lakes Research, 46(4) 989-1000.

Nutrient management in the Great Lakes-St. Lawrence basin has focused on the reduction of tributary phosphorus inputs to control lake eutrophication. However, the regional implications of nutrient enrichment on stream eutrophication and management remain understudied. We compared nutrient concentrations and stoichiometric ratios of carbon, nitrogen, and phosphorus to evaluate spatial and temporal patterns in the potential for nutrient limitation in streams of the lower Great Lakes-St. Lawrence basin in Ontario, Canada. Monitoring data from 127 streams was used to describe macronutrient concentrations and stoichiometry over a 10-year period (2007–2016). Nutrient enrichment was widespread as 65% and 68% of studied streams had nitrogen and phosphorus concentrations above regional guidelines, respectively. Macronutrient stoichiometry indicated that 35% of streams were depleted for phosphorus and 65% were co-depleted for nitrogen and phosphorus relative to the Redfield ratio. However, algal production in most streams was likely nutrient saturated such that only 2% of streams showed the potential for phosphorus limitation and 21% for nitrogen and phosphorus co-limitation. Temporal assessment of individual nutrients that were depleted indicated minimal variation within most streams. In contrast, macronutrient stoichiometry was associated with spatial patterns in catchment land-cover whereby a shift from nitrogen and phosphorus co-depletion to phosphorus depletion occurred with increasing agriculture and decreasing natural and wetland cover. Our results suggest that phosphorus reductions alone may be insufficient to manage stream eutrophication in the Great Lakes-St. Lawrence basin and that dual nutrient reductions needed to improve stream conditions may be achievable through land-cover management.
Peters D.L., Baird D.J., Culp J., Lento J., Monk W.A., Shrestha R.R. (2020). Overview of environmental flows in permafrost regions. Arctic Hydrology Permafrost and Ecosystems 219-261.

River ecosystems have adapted to a natural range of variability in magnitude, timing, duration, and predictability of key hydrograph components, such as high- and low-flow periods. However, the timing, magnitude, and variability of cold region flow regimes are changing in response to a warming climate, water abstraction, and building of impoundments. Changes in water quantity flowing down a river at a given time have the potential to adversely and/or positively affect habitat conditions and sustainability of ecological diversity within both the river and associated riparian and floodplain zones. There is a growing need to incorporate environmental flow assessments in the management of permafrost regions in response to changing flow regimes in order to preserve these diverse ecosystems. Environmental flows are defined as the quantity, timing, and quality of freshwater flows and levels necessary to sustain aquatic ecosystems. The goal of this Chapter is to present an overview of environmental flows for permafrost regions, with a focus on North America where information is most readily available. This goal is achieved via a review of (i) cold regions hydro-ecology, (ii) history and application of environmental flows internationally, (iii) environmental flow guidelines and policy in Arctic states, and (iv) riverine monitoring in northern regimes to support environmental flow frameworks. Several key recommendations to address knowledge and data gaps to better manage natural resources are provided.
Pomfret S.M., Brua R.B., Izral N.M., Yates A.G. (2020). Metabolomics for biomonitoring: An evaluation of the metabolome as an indicator of aquatic ecosystem health. Environmental Reviews, 28(1) 89-98.

Global degradation of aquatic ecosystems has initiated widespread use of biomonitoring to inform management. Current biomonitoring programs typically apply biomarkers (e.g., vitellogenin) and (or) measurements of community composition (e.g., algae or benthic macroinvertebrates) as indicators to assess ecosystem condition. However, independently these indicators may fail to provide either ecologically significant (a limitation of biomarkers) or early warning (a limitation of population and community measures) information to aquatic managers. Environmental metabolomics studies the relationship between an organism’s environment and its metabolome (i.e., description of the state of molecules produced or consumed during an organism’s metabolic processes, e.g., amino acids). Shifts in the metabolome occur because of stress-driven changes in resource allocation and are often indicative of changes in organism fitness. The metabolome of target species may thus be an effective bioindicator; however, it has not been evaluated for use in aquatic biomonitoring. Our objectives were threefold: introduce and describe metabolomics, evaluate the metabolome as a bioindicator, and provide recommendations for integration of metabolomics into biomonitoring. We conclude that the metabolome meets many bioindicator criteria and the potential to meet the remaining criteria following further research. Specifically, we concluded the metabolome is grounded in sound ecological theory while also having the potential to be a priori predictive and to assess ecological functions. Although the reliability of the metabolome to detect change needs further study, there is growing evidence that the metabolome can detect changes in human impact and discriminate between stressors. We provide an example of this capability with a case study assessment of municipal wastewater. Practically, the metabolome can be readily integrated into existing biomonitoring protocols. However, the ability of agencies to adopt metabolomics-based biomonitoring may be impeded by a lack of understanding of metabolomics within institutions and difficulty of communication with stakeholders. We suggest training or hiring of appropriate personnel and the generation of a common metabolomics language as mechanisms for overcoming this impediment. We conclude that background knowledge for metabolomics-based monitoring is sufficient for agency-based pilot projects aimed at assessing ecological status of aquatic ecosystems. However, continued development may ultimately provide early warning and diagnostic assessments of aquatic impacts.
Roldán-Wong N.T., Kidd K.A., Ceballos-Vázquez B.P., Rivera-Camacho A.R., Arellano-Martínez M. (2020). Polycyclic aromatic hydrocarbons (PAHs) in mussels (Modiolus capax) from sites with increasing anthropogenic impact in La Paz Bay, Gulf of California. Regional Studies in Marine Science, 33.

The composition, distribution and source of 16 polycyclic aromatic hydrocarbons (PAHs) in surface sediments and tissues of the mussel Modiolus capax from three sites with increasing anthropogenic impact in La Paz Bay on the Gulf of California, were determined. Levels of total PAHs in sediments (18.9-94.5 ng/g dw) were below the effect range low for marine sediments at all sites. PAHs in mussels (147.01-271.09) were higher than in sediments and similar to mussels from other moderately contaminated sites. The origin of PAHs was predominantly petrogenic, attributed to port activities and a thermoelectric plant. The mussels of Las Pacas and Pichilingue showed the lowest condition indexes and some organisms with the presence of benzo(a)pyrene in their tissues, which is among the most toxic hydrocarbons and may represent a risk to human health. However, this study only represents a baseline for future studies, which are necessary to dismiss risks to human health and the ecosystem.
Roloson S.D., Landsman S.J., Tana R., Hicks B.J., Carr J.W., Whoriskey F., Van Den Heuvel M.R. (2020). Otolith microchemistry and acoustic telemetry reveal anadromy in non-native rainbow trout (Oncorhynchus mykiss) in prince Edward Island, Canada. Canadian Journal of Fisheries and Aquatic Sciences, 77(7) 1117-1130.

This study examined the migratory patterns of introduced rainbow trout (Oncorhynchus mykiss) in three rivers in Prince Edward Island, Canada, using acoustic telemetry and otolith microchemistry. Only 6% of acoustically tagged fish in three river systems left coastal embayments. A cohort of rainbow trout in all three rivers entered saline waters. Habitat use differed among migrants in the three rivers, as Montague River fish occupied estuary habitat (mean 20.79 PSU) more often than West River and Dunk River fish that tended to occupy both riverine tidal (mean 1.27 and 4.29 PSU, respectively) and freshwater habitats (<0.5 PSU), particularly during summer months (July and August). A second cohort of rainbow trout remained exclusively in fresh water. Migratory individuals were more likely to arise from anadromous mothers, but freshwater mothers produced migratory offspring in all sites. Migratory individuals were significantly larger than nonmigratory freshwater residents. This study suggests that partial residency was the primary strategy, with prominent tidal occupation, while secondary marine and freshwater contingents were included in the full range of successful migratory strategies.
Sirabahenda Z., St-Hilaire A., Courtenay S.C., van den Heuvel M.R. (2020). Assessment of the effective width of riparian buffer strips to reduce suspended sediment in an agricultural landscape using ANFIS and SWAT models. Catena, 195.

Riparian buffers are important features that help to mitigate suspended sediment loads within rivers running through agricultural landscapes. Evaluating their effectiveness for sediment control by different modelling approaches can help direct beneficial management practices. The Soil and Water Assessment Tool (SWAT) model and the Adapted Neuro-Fuzzy Inference System (ANFIS) based model were used for prediction of suspended sediment concentrations (SSC) and sediment loads in the Mill River watershed (PEI, Canada). Those models were then used to assess the impact of riparian buffer widths in reducing sediment loads. The ANFIS model predicted measured SSC more accurately than the SWAT model. The relationship between buffer width and sediment reduction was asymptotic, and the relationship begins to plateau when the width reaches 50 m. Increasing the buffer width from 15 to 100 m led to an increase in sediment loads retention of 30.5% and 36.2% of the total stream sediment load for the SWAT and ANFIS models, respectively. This study highlighted that a data-driven ANFIS based model can be used to simulate the impact of land use changes on the sediment delivery in a river.
Thera J.C., Kidd K.A., Bertolo R.F. (2020). Amino acids in freshwater food webs: Assessing their variability among taxa, trophic levels, and systems. Freshwater Biology, 65(6) 1101-1113.

Although the amino acid composition of fishes and some marine invertebrates varies among taxa and systems, similar information is lacking for freshwater invertebrates. The objectives were to characterise and compare the amino acid composition among different aquatic species, dietary habits, and environmental conditions. Benthic macroinvertebrates from different functional feeding groups (FFG), bulk zooplankton, biofilm, and fishes representing 12 families (21 genera or species) were collected from temperate lakes in eastern Canada during the summers of 2013 and 2014. Fifteen protein-bound amino acids, including thiols, were measured in whole invertebrates, biofilm, or fish muscle. We hypothesised that the amino acid composition will differ among species and systems. Multiple discriminant analyses revealed significant differences in the amino acid composition among species—based on varying percentages of cysteine (as cysteic acid) and histidine—and among FFG/trophic designations—based on histidine and lysine—where the primary consumers were more variable than the predators. Overall, the results suggest that patterns were based on phylogenetics, biological characteristics, and the FFG/trophic designations of biota. The within-taxon variability in composition was also related to differences among lakes. Characteristics of their environment, including lake pH and the food web structure (abundance and composition of taxa), probably influenced their dietary habits and amino acid composition of diet. These results expand the currently limited knowledge of the biochemical composition of freshwater biota and provide impetus for further studies on nutritional values in predator-prey relationships, trophic guilds, and the biomagnification of protein-bound contaminants through food webs.
Wegscheider B., Linnansaari T., Curry R.A. (2020). Mesohabitat modelling in fish ecology: A global synthesis. Fish and Fisheries, 21(5) 927-939.

Modelling the linkage between physical habitat and aquatic organisms on multiple spatial scales has become an important tool in the management of rivers. The mesoscale (100–102 m) represents an intermediate resolution in modelling that bridges the gap between available resources and conservation efforts for riverine species. However, existing mesohabitat classification schemes for lotic systems vary significantly in the definition of habitat types as well as in their application in the field. This article aims to provide an overview of current attempts to model the mesoscale pattern of physical habitats with a focus on fish. First, we outline descriptive, qualitative as well as objective, quantitative classification methods that are available in the literature. Next, the ecological relevance of the mesohabitat concept is being discussed, using single-species and community-level approaches as examples. Different modelling approaches that describe and quantify riverine mesohabitats are presented, and finally, limitations and uncertainties in the modelling process are discussed, followed by an outline of future perspectives in mesohabitat modelling.
Wegscheider B., Linnansaari T., Monk W.A., Curry R.A. (2020). Linking fish assemblages to hydro-morphological units in a large regulated river. Ecohydrology, 13(7).

Flow-related changes of physical habitat represent a potentially significant environmental filter determining the presence and composition of fish assemblages in rivers. The mesoscale (100–103 m) of river habitat has been identified as an appropriate resolution to model linkages between fish and their abiotic environment that are relevant yet logistically feasible for management of large rivers with complex habitats and diverse fish assemblages. This study identified well-defined mesohabitat types (i.e. hydro-morphological units) that influence the fish community of the lower Saint John River, New Brunswick, downstream of a large hydropower generating station (the Mactaquac Generating Station). Four hydro-morphological units or habitats (i.e. pool, riffle, run and slack water) were identified and linked to three distinct fish assemblages. Eurytopic species represent habitat generalists that were common among all habitats throughout the study area. Rheophilic species preferred fast-flowing run habitat, whereas limnophilic species were mainly associated with slack water habitat. Riffle habitats that frequently run dry during low flows were mostly vacant of fish species, suggesting that fish assemblages that would naturally occur in these environments could be affected by fluctuations in flow (i.e. hydropeaking) due to dam operation. Our improved understanding of the relationship between fish assemblages and hydro-morphological units is a fundamental first step to develop meaningful habitat models that can facilitate the effective evaluation of flow management options regarding hydropower and other flow manipulation activities in large rivers with diverse fish fauna.
Wegscheider B., Linnansaari T., Wall C.C., Gautreau M.D., Monk W.A., Dolson-Edge R., Samways K.M., Curry R.A. (2020). Diel patterns in spatial distribution of fish assemblages in lentic and lotic habitat in a regulated river. River Research and Applications, 36(7) 1014-1023.

Fish assemblages in large rivers are governed by spatio-temporal changes in habitat conditions, which must be accounted for when designing effective monitoring programmes. Using boat electrofishing surveys, this study contrasts species richness, catch per unit effort (CPUE), total biomass, and spatial distribution of fish species in the Saint John River, New Brunswick, Canada, sampled during different diel periods (day and night) and macrohabitats (hydropower regulated river and its reservoir) in the vicinity of the Mactaquac (hydropower) Generating Station. Taxa richness, total CPUE, and total biomass were significantly higher during night surveys, resulting in marked differences in community composition between the two diel periods. Furthermore, the magnitude of diel differences in catch rate was more pronounced in lentic than in lotic macrohabitats. The required sampling effort (i.e., number of sites) to increase accuracy and precision of CPUE estimates varied widely between fish species, diel periods, and macrohabitats and ranged from 15 to 185 electrofishing sites. Determining a correction factor to contrast accuracy and precision of day- with night-time surveys provide useful insights to improve the design of long-term monitoring programmes for fish communities in large rivers. The study also shows the importance of multihabitat surveys to detect differences in the magnitude of diel changes in fish community metrics.
White C.F.H., Gray M.A., Kidd K.A., Duffy M.S., Lento J., Monk W.A. (2020). Prevalence and Intensity of Salmincola edwardsii in Brook Trout in Northwest New Brunswick, Canada. Journal of Aquatic Animal Health, 32(1) 11-20.

Parasites can compromise the health and fitness of individual fish, and it is important to generate baseline information that can then be used to document changes in the abundance and distribution of potentially pathogenic parasites. The ectoparasitic copepod Salmincola edwardsii was assessed with respect to prevalence (percentage of infected fish per site), infection intensity (number of parasites per infected fish), and attachment location on Brook Trout Salvelinus fontinalis in northwest New Brunswick, Canada. Ten sample sites were assessed, with six sites on two streams in the Quisibis River basin and four sites on three streams in the Restigouche River basin. Parasite species identity was supported by 100% sequence identity with S. edwardsii in a variable region within 28S rDNA. The prevalence of fish infected per site ranged from 19.0% to 79.6%, with an overall prevalence of 48.5 ± 19.1% (mean ± SD) per site. Mean infection intensity was 1.5 ± 0.9 copepods/fish (range = 1–7), with parasites almost exclusively surrounding the dorsal fin and/or adipose fin (97.6%). There was no influence of trout age-class on parasite prevalence. Some fish presented with fin erosion at the site of parasite attachment (12.5%), and 6.2% also presented with hyperplastic skin lesions where no parasites were observed, that could be misinterpreted as secondary bacterial or fungal infections. Skin and fin damage were significantly more common when fish were infected with three or more individual parasites. The pathogenic potential of this parasite makes its presence noteworthy as a risk to salmonids that are both recreationally and ecologically important.
Wilbur N.M., O'Sullivan A.M., MacQuarrie K.T.B., Linnansaari T., Curry R.A. (2020). Characterizing physical habitat preferences and thermal refuge occupancy of brook trout (Salvelinus fontinalis) and Atlantic salmon (Salmo salar) at high river temperatures. River Research and Applications, 36(5) 769-783.

Anthropogenic influences, including climate change, are increasing river temperatures in northern and temperate regions and threatening the thermal habitats of native salmonids. When river temperatures exceed the tolerance levels of brook trout and Atlantic salmon, individuals exhibit behavioural thermoregulation by seeking out cold-water refugia – often created by tributaries and groundwater discharge. Thermal infrared (TIR) imagery was used to map cold-water anomalies along a 53 km reach of the Cains River, New Brunswick. Trout and salmon parr did not use all identified thermal anomalies as refugia during higher river temperature periods (>21°C). Most small-bodied trout (8–30 cm) were observed in 80% of the thermal anomalies sampled. Large-bodied trout (>35 cm) required a more specific set of physical habitat conditions for suitable refugia, that is, 100% of observed large trout used 30% of the anomalies sampled and required water depths >65 cm within or adjacent to the anomaly. Densities of trout were significantly higher within anomalies compared with areas of ambient river temperature. Salmon parr were less aligned with thermal anomalies at the observed temperatures, that is, 59% were found in 65% of the sampled anomalies; and densities were not significantly different within/ outside anomalies. Salmon parr appeared to aggregate at 27°C, and after several events over 27°C variability in aggregation behaviour was observed – some fish aggregated at 25°C, others did not. We stipulate this is due to variances of thermal fatigue. Habitat suitability curves were developed for velocity, temperature, depth, substrate, and deep water availability to characterize conditions preferred by fish during high-temperature events. These findings are useful for managers as our climate warms, and can potentially be used as a tool to help conserve and enhance thermal refugia for brook trout and Atlantic salmon in similar systems.
Yee-Duarte J.A., Racotta I.S., Camacho-Mondragón M.A., Roldán-Wong N.T., Carreño-León D.P., Shumilin E., Kidd K.A., Arellano-Martínez M. (2020). Contrasting reproductive health of female clams Megapitaria squalida from two nearby metal-polluted sites in the Gulf of California: Potential effects of copper, lead, and cobalt. Marine Pollution Bulletin, 160.

We studied the effects of chronic exposure to metals on energy reserves and reproduction in the clam Megapitaria squalida in two nearby populations exposed to different levels of pollution from mining operations in the Gulf of California, Mexico. Female M. squalida from San Lucas beach had good reproductive health status, whereas Santa Rosalia specimens consistently showed low energy reserves, massive oocyte resorption throughout the year, high frequencies of undifferentiated individuals, low proportions of ripe and spawning organisms, smaller and fewer oocytes per follicle, and significantly lower follicular areas. Ovarian levels of Co, Cu, Pb, Mn, and Zn were consistently higher in clams from Santa Rosalia. The poor reproductive health of clams inhabiting this site may be attributed to their long-term exposure to high Co, Cu, and Pb concentrations, as these have been shown to cause toxicity and reproductive impairments in other marine organisms.
Andrews S.N., Buhariwalla C.F., Fleet-Pardy B., Dadswell M.J., Linnansaari T., Curry R.A. (2019). Left out in the cold: the understudied overwintering ecology of striped bass in Canada. Environmental Biology of Fishes, 102(3) 499-518.

Striped Bass in Canadian waters occur at the most northern extent of the species range. At these latitudes, overwintering represents a significant portion of annual activities (Nov- May). During the winter period, Striped Bass generally occupy inland waterways, aggregate densely, feed little, and conduct minimal movements rendering them vulnerable to fisheries exploitation, pollution and habitat alterations. Despite the importance of winter survival to population viability, the winter period remains an understudied aspect of Striped Bass ecology throughout the species range. Here we review what is known as well as the knowledge gaps regarding the overwintering ecology for Striped Bass in Canadian waters. We discuss: all reported Canadian Striped Bass overwintering locations and their characteristics; environmental conditions that may be required for Striped Bass winter survival; environmental cues that may cause Striped Bass to enter overwintering habitats in late fall and depart in early spring; possible threats to overwintering habitat; and we propose numerous research questions necessary for improving Striped Bass conservation and management both within Canada and across the species range.
Andrews S.N., Dadswell M.J., Buhariwalla C.F., Linnansaari T., Curry R.A. (2019). Looking for Striped Bass in Atlantic Canada: The Reconciliation of Local, Scientific, and Historical Knowledge. Northeastern Naturalist, 26(1) 1-30.

Morone saxatilis (Striped Bass) occurs throughout the provinces of Atlantic Canada, but its full distribution in the region is undescribed. Canadian Striped Bass populations are grouped by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) into 3 geographically distinct Designatable Units: Saint Lawrence River, Southern Gulf of St. Lawrence, and Bay of Fundy. Striped Bass also occurs in many other unclassified Canadian regions, and growing evidence suggests that some of these locations may support distinct, uncharacterized populations. The recreational fisheries for Striped Bass are rapidly increasing in popularity in Canada, and thus, it has become of great importance to both recognize the species' full distribution and manage the fisheries therein. We compiled recent research, certified angling catches, historic accounts, grey literature, and anecdotal reports to identify coastal sites and rivers where Striped Bass have been reported. Our findings will help managers and researchers target rivers and coastal areas for assessment and study to encompass the entirety of the species' range in Canadian waters. Our report suggests that a fourth Designatable Unit for Eastern Cape Breton Island and Northeastern Nova Scotia is needed to both monitor and manage assemblages of Canadian Striped Bass.
Andrews S.N., Hirtle S.V., Linnansaari T., Curry R.A. (2019). Consumption of atlantic salmon smolt by striped bass: A review of the predator–prey encounter and implications for the design of effective sampling strategies. Fishes, 4(4).

The native striped bass (Morone saxatilis) population of the Miramichi River, New Brunswick is undergoing an unprecedented recovery while Atlantic salmon (Salmo salar) numbers within that system continue to decline. Atlantic salmon smolt depart from the Miramichi system during the striped bass spawning period and it is hypothesized that elevated striped bass abundances will increase encounter rates and predation on smolts. We summarize all available striped bass diet studies occurring within the native range of Atlantic salmon and present a review of the feeding behavior and diet preferences of striped bass before, during, and after their spawning period. The key studies vary in methodologies and interpretability. We present a standardized approach for assessing striped bass predation threats and smolt vulnerability and thus an improved understanding of the species interactions to guide future management in the Miramichi River.
Babin A., Fitzpatrick L., Linnansaari T., Curry R.A. (2019). Detection range of acoustic receivers in a large hydropower reservoir. Fishes, 4(4).

Acoustic telemetry manufacturers report estimated detection ranges under idealized conditions, but environmental conditions such as water depth, substrate type, and turbulence can affect the range of reliable detection. Range testing of low (Vemco V7 136 dB re 1µPa@1m) and high power (V13 147 dB re 1µPa@1m) acoustic transmitters (tags) was performed near a hydropower generating station and its associated reservoir using both active (mobile; VR100) and passive (stationary; VR2W/VR2Tx) receivers. Low power tags are typically used to track small fish such as juvenile Atlantic salmon (Salmo salar), whereas high power tags are typically used to track larger fish such as adult salmon. The results found herein were applied to concurrent salmon telemetry studies. Detection ranges of the low power tags were within 246–351 ± 20–70 m (mean ± SE), and the high power tags were within 537–1106 ± 53–272 m. Observed detection ranges were comparable or higher to manufacturer estimates for both tag types being detected by passive receivers, and were lower than expected for both tag types being detected by active receivers. Passive receivers were further tested by mooring a fixed sentinel tag (low power) on a receiver line at the hydropower site for 50 days. The sentinel tag detection range of 212 m was less than the expected range of 280–292 m, and was not found to be significantly impacted by wind speed. There was evidence of a hydropower effect on detection probability (up to 95% reduction) of both tag types for the active receiver, and detection ranges were significantly lower at the hydropower site than the reservoir site for the high power tag. The results of this study give insight to the initial design of acoustic telemetry studies beyond what can be gathered from manufacturer’s estimates, but rather near hydropower facilities and within large reservoirs; however, detection ranges reported herein do not replace the importance of range testing in site-specific conditions.
Baillie B.R., Hicks B.J., Hogg I.D., Van Den Heuvel M.R., Kimberley M.O. (2019). Debris dams as habitat for aquatic invertebrates in forested headwater streams: A large-scale field experiment. Marine and Freshwater Research, 70(5) 734-744.

To evaluate the effects of debris dams on aquatic invertebrate communities, we sampled benthic invertebrates in debris dams and riffles in three forested headwater streams in New Zealand. As part of a large-scale field experiment, debris dams were subsequently removed from three treatment sections in each of the streams to assess effects on invertebrate communities. Prior to debris dam removal, total invertebrate densities in debris dams were not significantly different from those in riffles. However, densities of Ephemeroptera, Plecoptera and Trichoptera taxa were significantly higher in debris dams than in riffles. Debris dams contained a higher number of less common taxa (defined as <1% of total catch) and significantly higher densities of shredders. Densities for Coleoptera, Diptera and Trichoptera taxa were significantly higher in the autumn than in the spring. Non-metric multidimensional scaling axis scores indicated that both habitat and season had a significant effect on aquatic invertebrate community composition. At the reach scale, the effects of debris dam removal on the aquatic invertebrate communities were not statistically detectable because debris dams comprised only a small proportion of total habitat. However, these data highlight the importance of debris dams in contributing to the diversity of aquatic invertebrates in forested headwater streams.
Benítez-Mondragón B.D., Aguilar-Betancourt C.M., González-Sansón G., Lucano-Ramírez G., Flores-Ortega J.R., Ruiz-Ramírez S., Kosonoy-Aceves D. (2019). Diet composition and its relation to the characteristics of the digestive tract of the blue sea catfish, ariopsis guatemalensis (Actinopterygii: Ariidae), in barra de navidad lagoon, jalisco, mexico. Ciencias Marinas, 45(4) 151-162.

Diet composition and the characteristics of the digestive tract of the blue sea catfish, Ariopsis guatemalensis, in a coastal lagoon in western Mexico were investigated. This species is consumed by locals and it has been used as a bioindicator of sewage pollution. This study aimed to determine if the feeding habits of this species were related to the macroscopic and microscopic morphological characteristics of the digestive tract. Specimens were captured in the Barra de Navidad Lagoon (Jalisco, Mexico) from 2011 to 2016. For every fish collected, total length (TL) was recorded and the esophagus, stomach, and intestine were extracted for histological analyses and identification of food items in their diet. The macroscopic and microscopic characteristics of the digestive tract and the stomach content analysis indicate A. guatemalensis is a carnivorous species with preference for goby fish. Crustaceans were the second most important food item and were dominated by portunid crabs and mud shrimps. The size and position of the mouth, the presence of dental plates on the vomer, palatines, premaxilla, and pharynx, and the presence of goblet cells in the digestive tract are characteristic of fishes that consume live hard-bodied prey and crush their food before it enters the esophagus. The relatively short intestine and the folds in the mucous membrane are characteristic of carnivorous fishes.
Boudreault M., Koiter A.J., Lobb D.A., Liu K., Benoy G., Owens P.N., Li S. (2019). Comparison of sampling designs for sediment source fingerprinting in an agricultural watershed in Atlantic Canada. Journal of Soils and Sediments, 19(9) 3302-3318.

Purpose: Sediment fingerprinting is increasingly being used to improve the understanding of sediment dynamics within the critical zone and provide information that can help guide management decisions at the watershed scale. The objectives of this study were to investigate both the implications of different sediment fingerprinting sampling designs and spatial scales on the characterization of sediment dynamics in a predominantly agricultural watershed in northwestern New Brunswick, Canada. Materials and methods: Color and radionuclide fingerprints were used to discriminate between three potential sediment sources: agricultural topsoil, agricultural streambanks, and forested areas (topsoil and streambanks). Suspended sediment was collected seasonally, between 2008 and 2014, at five sites with drainage areas ranging from 3.0 to 13.4 km2. Using the same source and sediment data set, multiple-, nested-, and local-location fingerprinting sampling designs were employed to investigate the influence of scale of observation, geomorphic connectivity, land use, and the heterogeneity of source fingerprints on apportionment results. Results and discussion: Sediment collected in the headwaters was primarily derived from forested areas while the sediment collected at the outlet of the watershed was primarily from agricultural topsoil. When comparing the multiple- and nested-location designs, it was found that accounting for the spatial variability in the fingerprint properties of each source had a small difference in the sediment apportionment results. Furthermore, the local-location design demonstrated that the sediment collected at each location was composed of predominately local sources as opposed to upstream sediment entering the local catchment. Conclusions: Assessment of the sources of sediment at a range of spatial scales better accounts for both geomorphic connectivity and differences in land use throughout the watershed. Overall, each of the three fingerprinting sampling designs provided different information that can be used to guide soil and water conservation management.
Bracewell S., Verdonschot R.C.M., Schäfer R.B., Bush A., Lapen D.R., Van den Brink P.J. (2019). Qualifying the effects of single and multiple stressors on the food web structure of Dutch drainage ditches using a literature review and conceptual models. Science of the Total Environment, 684 727-740.

In September 2017, a workshop was held at Wageningen University and Research to determine the current state of knowledge of multiple stressor effects on aquatic ecosystems and to assess how to improve prediction of these effects. We developed a theoretical framework that integrates species-level responses to stressors to predict how these effects propagate through higher levels of biological organisation. Here, we present the application of the framework for drainage ditch ecosystems in the Netherlands. We used food webs to assess single and multiple stressor effects of common stressors on ditch communities. We reviewed the literature for the effects of targeted stressors (nutrients, pesticides, dredging and mowing, salinization, and siltation) on each functional group present in the food web and qualitatively assessed the relative sensitivity of groups. Using this information, we created a stressor-response matrix of positive and negative direct effects of each stressor-functional group combination. Fungicides, salinization, and sedimentation were identified as particularly detrimental to most groups, although destructive management practices, such as dredging with almost complete community removal, would take precedence depending on frequency. Using the stressor-response matrix we built, first, a series of conceptual null models of single stressor effects on food web structure and, second, a series of additive null models to illustrate potential paired-stressor effects. We compared these additive null models with published studies of the same pairs of combined single stressors to explore more complex interactions. Our approach serves as a first-step to considering multiple stressor scenarios in systems that are understudied or data-poor and as a baseline from which more complex models that include indirect effects and quantitative data may be developed. We make specific suggestions for appropriate management strategies that could be taken to support the biodiversity of these systems for individual stressors and their combined impacts.
Brueckner-Irwin I., Armitage D., Courtenay S. (2019). Applying a social-ecological well-being approach to enhance opportunities for marine protected area governance. Ecology and Society, 24(3).

The design and implementation of ecologically effective marine protected areas (MPAs) are influenced by social acceptance and the impact of MPAs on communities. Integrative analyses of the social and ecological determinants of marine conservation efforts and MPA networks are lacking but are needed to achieve desired outcomes. We developed and applied a “social-ecological well-being” (SEWB) approach to critically examine the linkages between MPAs and well-being in Southwest New Brunswick (Bay of Fundy, Canada). SEWB is defined as a social-ecological system state in which ecological resilience is sustained, while human needs are met and the quality of life of individuals is maintained. We examined (1) how stakeholders perceive benefits and costs of MPAs in relation to SEWB, and (2) how well-being insights contribute to the effectiveness of MPA governance. Using a qualitative case study approach, we conducted 49 semistructured interviews and 4 focus groups with fishers and other key informants at an existing MPA, as well as at an ecologically and biologically significant area that is a candidate for a future MPA. We identified 15 attributes of SEWB that related to MPAs, such as fishery access, community relations, place identity, and natural capital. Three key governance insights for decision makers emerged from the identification of these attributes: (1) displacement attributable to MPAs has implications across material, relational, subjective, and ecological dimensions; (2) effective collaboration is critical for community support, but perspectives about what constitutes effective collaboration may vary across stakeholder groups; and (3) aspects of MPA design fit poorly with the local context because they do not take social and ecological dynamics into account. Our findings empirically demonstrate the applicability of the SEWB framework, suggest a need to focus more on governance processes and improving fit, and highlight barriers to aligning national and local conservation priorities.
Bush A., Catullo R., Mokany K., Harwood T., Hoskins A.J., Ferrier S. (2019). Incorporating existing thermal tolerance into projections of compositional turnover under climate change. Global Ecology and Biogeography, 28(6) 851-861.

Aim: Observed, realized niche space often underestimates species’ physiological tolerances due to interactions with other species, dispersal constraints, and because some combinations of influential environmental factors do not currently exist in the real world. Conversely, correlative ecological niche models rely on the assumption that the range of environmental conditions encompassed by a species’ geographic distribution accurately reflects their environmental tolerances, including community-level approaches like generalized dissimilarity modelling (GDM). We extend GDM to better understand what effect broader environmental tolerances could have on compositional turnover under climate change. Innovation: We show how GDM can be adjusted as a function of best-available estimates of the average ratio between realized and potential niche widths to modify projected temporal turnover. We demonstrate this approach by using the estimated niche ratios of Australian plant species (n = 7,184) relative to thermal extremes, and the rate at which this ratio varied with temperature. The modified GDMs showed existing thermal tolerance could reduce the turnover predicted by standard models under climate change by up to 11%. We further show how the reduction in expected turnover by 2090 will influence where a greater proportion of the current community will persist in a region. Main conclusions: We suggest that standard spatial GDMs and their modified versions represent the extremes of ecological niche perspectives (i.e., realized and potential) and the range of tolerance communities may have when responding to environmental change. GDM projections therefore identify the range of uncertainty associated with a critical model assumption, and as climate change continues, ongoing community monitoring could be used to validate the balance between the two possibilities.
Bush A., Compson Z.G., Monk W.A., Porter T.M., Steeves R., Emilson E., Gagne N., Hajibabaei M., Roy M., Baird D.J. (2019). Studying Ecosystems With DNA Metabarcoding: Lessons From Biomonitoring of Aquatic Macroinvertebrates. Frontiers in Ecology and Evolution, 7.

An ongoing challenge for ecological studies has been the collection of data with high precision and accuracy at a suitable scale to detect and manage critical global change processes. A major hurdle has been the time-consuming and challenging process of sorting and identification of organisms, but the rapid development of DNA metabarcoding as a biodiversity observation tool provides a potential solution. As high-throughput sequencing becomes more rapid and cost-effective, a “big data” revolution is anticipated, based on higher and more accurate taxonomic resolution, more efficient detection, and greater sample processing capacity. These advances have the potential to amplify the power of ecological studies to detect change and diagnose its cause, through a methodology termed “Biomonitoring 2.0.” Despite its promise, the unfamiliar terminology and pace of development in high-throughput sequencing technologies has contributed to a growing concern that an unproven technology is supplanting tried and tested approaches, lowering trust among potential users, and reducing uptake by ecologists and environmental management practitioners. While it is reasonable to exercise caution, we argue that any criticism of new methods must also acknowledge the shortcomings and lower capacity of current observation methods. Broader understanding of the statistical properties of metabarcoding data will help ecologists to design, test and review evidence for new hypotheses. We highlight the uncertainties and challenges underlying DNA metabarcoding and traditional methods for compositional analysis, specifically comparing the interpretation of otherwise identical bulk-community samples of freshwater benthic invertebrates. We explore how taxonomic resolution, sample similarity, taxon misidentification, and taxon abundance affect the statistical properties of these samples, but recognize these issues are relevant to applications across all ecosystem types. In conclusion, metabarcoding has the capacity to improve the quality and utility of ecological data, and consequently the quality of new research and efficacy of management responses.
Chaumel A.L.I., Armanini D.G., Schwindt J.A., Yates A.G. (2019). Interannual variation of benthic macroinvertebrate communities at long-term monitoring sites impacted by human activities: Implications for bioassessment. Diversity, 11(9) 1-19.

Bioassessment assumes that ecological conditions remain stable in the absence of environmental changes. Evidence suggests this assumption may hold for reference streams, but knowledge gaps remain for impacted streams. Our study quantified interannual variation of benthic macroinvertebrate communities, monitored for at least 14 years in eight impacted streams in the Upper Thames River watershed in Ontario, Canada. Benthic communities exhibited moderate interannual variation in relative abundance of EPT (Ephemeroptera, Plecoptera and Trichoptera) and Chironomidae taxa. Year-to-year changes were reflected in lower community persistence than that observed in studies of reference streams. In contrast, tolerance-based metrics showed minimal interannual variation, suggesting compositional changes were because of taxonomic substitutions, in which one tolerant taxon replaced another. Analyses indicated limited directionality in temporal variation for most bioassessment metrics. An exception was taxa richness, which increased at most sites, possibly because of changes in subsampling. However, no associations between calculated bioassessment metrics and measured environmental factors (stream flow and water chemistry) or sampling procedures were observed. We conclude interannual variation in ecological conditions can be substantial and may not be associated with deterministic factors routinely measured in stream assessments. We recommend increased sampling frequency and traits-based assessment as options for limiting effects of interannual variation on assessment results.
Coffin M.R.S., Courtenay S.C., Knysh K.M., Pater C.C., van den Heuvel M.R. (2019). Correction: Impacts of hypoxia on estuarine macroinvertebrate assemblages across a regional nutrient gradient (FACETS(2018)3 (23–44)Doi: 10.1139/facets-2017-0044). Facets, 4(1) 161.

Re: Coffin MRS, Courtenay SC, Knysh KM, Pater CC, and van den Heuvel MR. 2018. Impacts of hypoxia on estuarine macroinvertebrate assemblages across a regional nutrient gradient. FACETS 3: 23–44. doi:10.1139/facets-2017-0044 On page of 40 the originally published article, the title of the journal in the following reference was incorrectly cited as Pollution Bulletin. The correct title is Marine Pollution Bulletin. Coffin MRS, Courtenay SC, Pater CC, and van den Heuvel MR. Submitted. An empirical model using dissolved oxygen as a proxy for eutrophication at a regional scale. Pollution Bulletin. The corrected (and updated) reference is shown here: Coffin MRS, Courtenay SC, Pater CC, and van den Heuvel MR. 2018. An empirical model using dissolved oxygen as an indicator for eutrophication at a regional scale. Marine Pollution Bulletin, 133: 261–270. PMID: 30041313 DOI: 10.1016/j.marpolbul.2018.05.041 The article has been corrected accordingly.
Compson Z.G., Monk W.A., Hayden B., Bush A., O'Malley Z., Hajibabaei M., Porter T.M., Wright M.T.G., Baker C.J.O., Al Manir M.S., Curry R.A., Baird D.J. (2019). Network-Based Biomonitoring: Exploring Freshwater Food Webs With Stable Isotope Analysis and DNA Metabarcoding. Frontiers in Ecology and Evolution, 7.

Threatened freshwater ecosystems urgently require improved tools for effective management. Food web analysis is currently under-utilized, yet can be used to generate metrics to support biomonitoring assessments by measuring the stability and robustness of ecosystems. Using a previously developed analysis pipeline, we combined taxonomic outputs from DNA metabarcoding with a text-mining routine to extract trait information directly from the literature. This pipeline allowed us to generate heuristic food webs for sites within the lower Saint John/Wolastoq River and the Grand Lake Meadows (hereafter called the “GLM complex”), Atlantic Canada's largest freshwater wetland. While these food webs are derived from empirical traits and their structure has been shown to discriminate sites both spatially and temporally, the accuracy of their properties have not been assessed against other methods of trophic analysis. We explored two approaches to validate the utility of heuristic food webs. First, we qualitatively compared how well-trophic position derived from heuristic food webs recovered spatial and temporal differences across the GLM complex in comparison to traditional stable isotope approaches. Second, we explored how the trophic position of invertebrates, derived from heuristic food webs, predicted trophic position measured from δ15N values. In general, both heuristic food webs and stable isotopes were able to detect seasonal changes in maximum trophic position in the GLM complex. Samples from the entire GLM complex demonstrated that prey-averaged trophic position measured from heuristic food webs strongly predicted trophic position inferred from stable isotopes (R2 = 0.60), and even stronger relationships were observed for some individual models (R2 = 0.78 for best model). Beyond their areas of congruence, heuristic food web and stable isotope analyses also appear to complement one another, suggesting a surprising degree of independence between community trophic niche width (assessed from stable isotopes) and food web size and complexity (assessed from heuristic food webs). Collectively, these analyses indicate that trait-based networks have properties that correspond to those of actual food webs, supporting the routine adoption of food web metrics for ecosystem biomonitoring.
Culp J.M., Lento J., Allen Curry R., Luiker E., Halliwell D. (2019). Arctic biodiversity of stream macroinvertebrates declines in response to latitudinal change in the abiotic template. Freshwater Science, 38(3) 465-479.

We aimed to determine which processes drive patterns of a and b diversity in Arctic river benthic macrofauna across a broad latitudinal gradient spanning the low to high Arctic of eastern Canada (58 to 81oN). Further, we examined whether latitudinal differences in taxonomic composition resulted from species replacement with organisms better adapted to northerly conditions or from the loss of taxa unable to tolerate the harsh environments of higher latitudes. We used the bioclimatic envelope concept to provide a first approximation forecast of how climate warming may modify a and b diversity of Arctic rivers and to identify potential changes in environmental variables that will drive future assemblage structure. Benthic macroinvertebrates, environmental supporting variables, and geospatial catchment data were collected to assess drivers of ecological pattern. We compared a diversity (i.e., taxonomic richness) across latitudes and partitioned b diversity into components of nestedness and species turnover to assess their relative contributions to compositional differences. We found sharp declines in taxonomic richness along a latitudinal gradient. This a diversity pattern was not associated with a change in numerical abundance. b diversity was highest when the most distant latitudes were compared, and pairwise latitudinal comparisons indicated that nestedness (loss of species) was the dominant contributor to compositional differences. Biotic-abiotic associations reflected both large-scale climatic drivers, including air temperature and prevalence of vegetated tundra, and small-scale secondary abiotic drivers of assemblage composition (e.g., substrate composition, water chemistry). The importance of nestedness to b diversity across latitudes supports the physiological tolerance hypothesis that a change in environmental tolerance is a key driver of species richness declines with increasing latitude. Distinct taxonomic assemblages among low and high Arctic latitude sites were associated with large-scale, climate-related drivers (e.g., temperature trends, terrestrial vegetation), reflecting the primary structuring of assemblages by bioclimatic envelopes. The abiotic environment was the strongest driver of assemblage structure at high latitudes because of the extreme conditions. With continued warming, biodiversity differences along latitudinal gradients are expected to become less pronounced as temperatures and vegetation become more similar from south to north, with local-scale variables becoming dominant biotic drivers.
Dauphin G.J.R., Chaput G., Breau C., Cunjak R.A. (2019). Hierarchical model detects decadal changes in calibration relationships of single-pass electrofishing indices of abundance of atlantic salmon in two large canadian catchments. Canadian Journal of Fisheries and Aquatic Sciences, 76(4) 523-542.

Electrofishing is a commonly used technique to assess freshwater fish population abundance, and in many programs, there has been a shift in the sampling methodologies towards less laborious techniques. These new techniques usually only provide an index of abundance and require calibration with other sampling methods such as successive removal to be used for absolute abundance estimation. Using data for juvenile Atlantic salmon (Salmo salar) collected in 400 sites sampled over 21 years in two large Canadian river catchments with a single sampling protocol, we developed a hierarchical Bayesian model to account for effort, day of sampling, area of the site, and catchment effects on the relationship between the single-pass index of abundance and the fish densities, thereby illustrating the importance of carrying out a calibration exercise on a regular basis. Our work indicates that calibration relationships can change over time even with standardized sampling protocols and that these directional changes in important components of the sampling procedure can bias the estimate of population abundance and misinform the understanding of population dynamics.
Erdozain M., Freeman E.C., Ouellet Dallaire C., Teichert S., Nelson H.W., Creed I.F. (2019). Demand for provisioning ecosystem services as a driver of change in the Canadian boreal zone. Environmental Reviews, 27(2) 166-184.

The Canadian boreal zone provides extractive goods and services (provisioning ecosystem services (PrES)) to domestic and global markets and makes a significant contribution to the Canadian economy. The intensity and location of these extractive activities, however, may positively or negatively affect the availability of other benefits that the Canadian and global society receive from the boreal. Where PrES compete, managing these activities along with their impacts to boreal ecosystems becomes a balancing act between the need for resource extraction and the continued availability of the other benefits from ecosystems. Management measures and policies are more likely to succeed if they are designed with foresight, which means accounting for how demand, a key driver of change in the boreal, may change in the future. To help this process, we present three divergent, yet plausible future scenarios based on the analysis of: (i) the capacity of the boreal to provide wood products, fossil fuels, metals and minerals, and hydropower and other renewables; (ii) past trends (1985-2015) and key events in the demand for these PrES; (iii) the interaction of demand for PrES with other drivers of change to the boreal zone; and (iv) the synergies and trade-offs between PrES. We find that historically and currently the capacity of the boreal to provide these PrES exceeds the amount currently supplied. However, the capacity of different PrES and location of extractive activities are spatially dispersed creating a spatial and temporal patchwork of associated risks to local ecosystem integrity and the supply of non-PrES. In addition, these scenarios suggest that the future of boreal PrES is very uncertain and highly dependent on how other drivers of change (namely governance and geopolitics, societal values and climate change) play out in the future. Given the spatial complexity, we find that the cumulative effect of these drivers (e.g., climate change) will determine what paths unfold for different areas of the boreal, and we conclude that careful consideration and planning must be given to ensure that the balance between PrES and non-PrES is maintained.
Erdozain M., Kidd K., Kreutzweiser D., Sibley P. (2019). Increased reliance of stream macroinvertebrates on terrestrial food sources linked to forest management intensity. Ecological Applications, 29(4).

Our understanding of how forest management practices affect the relative importance of autochthonous vs. allochthonous resource use by headwater stream food webs is relatively poor. To address this, we used stable isotope (C, N, and H) analyses of food sources and macroinvertebrates from 15 streams in New Brunswick (Canada) and assessed how different catchment conditions arising from the gradient in forest management intensity affect the contribution of autochthonous resources to these food webs. Aquatic primary production contributed substantially to the biomass of invertebrates in these headwater streams, especially for scrapers and collector-gatherers (25–75%). However, the contribution of algae to food webs decreased as forest management intensity (road density and associated sediments, water cations/carbon, and dissolved organic matter humification) increased, and as canopy openness decreased. This trend was probably due to an increase in the delivery of organic and inorganic terrestrial materials (dissolved and in suspension) in areas of greater harvesting intensity and road density, which resulted in more heterotrophic biofilms. Overall, results suggest that, despite the presence of riparian buffers, forest management can affect stream food web structure via changes in energy flows, and that increased protection should be directed at minimizing ground disturbance in areas with direct hydrological connection to streams and at reducing dissolved and particulate matter inputs from roads and stream crossings in catchments with high degrees of management activity.
Erdozain M., Thompson D.G., Porter T.M., Kidd K.A., Kreutzweiser D.P., Sibley P.K., Swystun T., Chartrand D., Hajibabaei M. (2019). Metabarcoding of storage ethanol vs. conventional morphometric identification in relation to the use of stream macroinvertebrates as ecological indicators in forest management. Ecological Indicators, 101 173-184.

Aquatic macroinvertebrate communities are often used to assess the ecological integrity of streams. However, conventional methods involving morphometric identification of macroinvertebrates are usually costly and time-consuming. Here we compare stream macroinvertebrate community metrics based on conventional morphometrics vs. non-destructive DNA metabarcoding from storage ethanol to assess forest management impacts on headwater streams across a gradient of intensively managed forest catchments in eastern Canada. The two approaches demonstrated substantial congruence in the detection of taxa (81% and 69% at the family and genus level, respectively) and in the characterization of community composition and richness. However, DNA metabarcoding from preservative ethanol identified significantly fewer genera (3.3 on average, 15.9%) and families (2.0, 11.5%) than conventional morphometrics. Taxa missed by metabarcoding of storage ethanol were typically those low in proportional mass or poorly represented in the CO1 reference database. This led to some differences in the explanatory variables identified as being related to macroinvertebrate metrics, which could have implications on conclusions and management actions that might result therefrom. For example, the negative relationships between richness and reach-scale variables associated with forest management intensity were weaker when richness was based on metabarcoding as compared to conventional morphometrics. Discriminatory power was greater when data at the genus level were used. The congruence between functional feeding group results derived from morphometric (based on relative abundance) vs. metabarcoding (based on relative frequency and read abundance) identifications was group specific (r = 0.16–0.63), but low overall. We conclude that DNA metabarcoding of storage ethanol provides a promising approach for characterizing stream macroinvertebrate communities, but that its full deployment in biomonitoring projects requires developing more complete reference libraries and enhancing the sensitivity for detecting taxa with low sample biomass.
Flinders C.A., Ragsdale R.L., Ikoma J., Arthurs W.J., Kidd J. (2019). Spatial and temporal patterns of diatom assemblages, and their drivers, in four US streams: evidence from a long-term dataset. Hydrobiologia, 846(1) 159-179.

Bioassessment to evaluate stream integrity and determine changes related to point-source discharges is typically focused in wadeable streams, with limited understanding of seasonal and annual variation. We used a multi-year (n = 13), multi-site (n = 5–7), seasonally (spring and fall) sampled dataset to evaluate spatial and temporal patterns in diatom assemblages relative to measured environmental variables, land use, and pulp and paper mill discharges in a wadeable stream (Codorus Creek, PA) and three non-wadeable rivers (Leaf River, MS; McKenzie and Willamette rivers, OR). Analysis of variance (ANOVA) and permutational ANOVA (PERMANOVA) showed that significant spatial differences in commonly used diatom biotic integrity/diagnostic metrics and assemblage structure were common in the wadeable stream, but rare in the non-wadeable rivers. Season-specific diatom patterns were observed in all streams regardless of size, but annual variation was more prevalent in the non-wadeable rivers. Environmental variables explained 35–58% of the variability in diatoms in the spring and 33–50% in the fall, with physical habitat characteristics associated with stream morphology and seasonality more important than those associated with anthropogenic inputs such as land use and point sources. Findings from this study highlight the value of spatially and temporally comprehensive datasets in understanding and interpreting diatom assemblage patterns.
Garneau C., Duchesne S., St-Hilaire A. (2019). Comparison of modelling approaches to estimate trapping efficiency of sedimentation basins on peatlands used for peat extraction. Ecological Engineering, 133 60-68.

Peatlands on which there is vacuum peat harvesting must be drained to allow peat extraction. Peat erosion due to mechanical tilling, vacuum harvest and rain can generate large suspended sediment concentrations that must be reduced before reaching the receiving waters. In this study, six sedimentation basins were monitored over one or two ice-free seasons, resulting in seven basin-years time series, to estimate their trapping efficiency. Using these data, two modelling approaches were first applied to predict the seasonal trapping efficiency of the basins, namely the Brown equation and a multilinear regression model (MLR). Secondly, an additional approach based on the hydrodynamic model MOHID was used to compute the trapping efficiency of one of the basins for a single rain event. The Brown equation, used worldwide in agricultural sedimentation ponds, proved to be less efficient in predicting the trapping efficiency of the basins (r = 0.67, p = 0.1, leave-one-out RMSE = 47.2%) than a MLR model using the volume of the basin, the surface of the harvested catchment and the Von Post decomposition degree of the peat as predictors (r = 0.87, p = 0.01, leave-one-out RMSE = 31.6%). The deterministic MOHID model was capable of reproducing high flow suspended sediment concentration at the basin outlet, based on measured settling velocity distribution of the peat through ViCAs protocol, but requires a good description of the settling velocity distribution across multiple hydrological conditions to simulate the suspended sediment concentrations over a full season in order to compute trapping efficiency. The results presented here provide new insights on eroded peat modelling and could lead to better design formulas for basin conception.
Garzke J., Connor S.J., Sommer U., O’connor M.I. (2019). Trophic interactions modify the temperature dependence of community biomass and ecosystem function. Plos Biology, 17(6).

Aquatic ecosystems worldwide continue to experience unprecedented warming and ecological change. Warming increases metabolic rates of animals, plants, and microbes, accelerating their use of energy and materials, their population growth, and interaction rates. At a much larger biological scale, warming accelerates ecosystem-level processes, elevating fluxes of carbon and oxygen between biota and the atmosphere. Although these general effects of temperature at finer and broader biological scales are widely observed, they can lead to contradictory predictions for how warming affects the structure and function of ecological communities at the intermediate scale of biological organization. We experimentally tested the hypothesis that the presence of predators and their associated species interactions modify the temperature dependence of net ecosystem oxygen production and respiration. We tracked a series of independent freshwater ecosystems (370 L) over 9 weeks, and we found that at higher temperatures, cascading effects of predators on zooplankton prey and algae were stronger than at lower temperatures. When grazing was weak or absent, standing phytoplankton biomass declined by 85%–95% (<1-fold) over the temperature gradient (19–30 ˚C), and by 3-fold when grazers were present and lacked predators. These temperature-dependent species interactions and consequent community biomass shifts occurred without signs of species loss or community collapse, and only modestly affected the temperature dependence of net ecosystem oxygen fluxes. The exponential increases in net ecosystem oxygen production and consumption were relatively insensitive to differences in trophic interactions among ecosystems. Furthermore, monotonic declines in phytoplankton standing stock suggested no threshold effects of warming across systems. We conclude that local changes in community structure, including temperature-dependent trophic cascades, may be compatible with prevailing and predictable effects of temperature on ecosystem functions related to fundamental effects of temperature on metabolism.
Grace M., Butler K.E., Simpkin P., Yamazaki G. (2019). Imaging dam reservoir siltation with decimetre precision by acoustic and gpr profiling. Proceedings of the Symposium on the Application of Geophyics to Engineering and Environmental Problems Sageep, 2019-March 242.
Gray M.A., Walker E.M., Brooks C., deMarsh L. (2019). Analysis of Environmental Contaminants in Muskrat Root, Acorus americanus Raf.: A Traditional Indigenous Medicinal Plant. Bulletin of Environmental Contamination and Toxicology, 102(2) 275-279.

The diets of Indigenous people rely on food and medicinal plants harvested directly from the land and there is increasing concern from Indigenous knowledge holders over changes to the appearance and flavor of wild harvested food and medicinal plants. We collected samples of muskrat root, considered an important medicinal plant, at 11 traditional collection locations to quantify contaminants of concern. There were no spatial or temporal trends apparent and the risk via consumption was found to be very low. This study provides a “base” measure to which future samples may be compared, especially as development and other anthropogenic pressures increase. This study is also an example of how western science and Indigenous knowledge, can be merged for the benefit of both knowledge systems in what is known to Indigenous groups as etuaptmumk or ‘two-eyed seeing’.
Hajibabaei M., Porter T.M., Robinson C.V., Baird D.J., Shokralla S., Wright M.T.G. (2019). Watered-down biodiversity? A comparison of metabarcoding results from DNA extracted from matched water and bulk tissue biomonitoring samples. Plos One, 14(12).

Biomonitoring programs have evolved beyond the sole use of morphological identification to determine the composition of invertebrate species assemblages in an array of ecosystems. The application of DNA metabarcoding in freshwater systems for assessing benthic invertebrate communities is now being employed to generate biological information for environmental monitoring and assessment. A possible shift from the extraction of DNA from net-collected bulk benthic samples to its extraction directly from water samples for metabarcoding has generated considerable interest based on the assumption that taxon detectability is comparable when using either method. To test this, we studied paired water and benthos samples from a taxon-rich wetland complex, to investigate differences in the detection of arthropod taxa from each sample type. We demonstrate that metabarcoding of DNA extracted directly from water samples is a poor surrogate for DNA extracted from bulk benthic samples, focusing on key bioindicator groups. Our results continue to support the use of bulk benthic samples as a basis for metabarcoding-based biomonitoring, with nearly three times greater total richness in benthic samples compared to water samples. We also demonstrated that few arthropod taxa are shared between collection methods, with a notable lack of key bioindicator EPTO taxa in the water samples. Although species coverage in water could likely be improved through increased sample replication and/or increased sequencing depth, benthic samples remain the most representative, cost-effective method of generating aquatic compositional information via metabarcoding.
Haralampides K., Yamazaki G., Ndong M., Curry R.A. (2019). Modelling sediment movement for a multi-option large-scale hydroelectric dam removal project. 16th International Environmental Specialty Conference 2018 Held as Part of the Canadian Society for Civil Engineering Annual Conference 2018 177-186.

The Mactaquac Generating Station (MGS), a 672 MW run-of-the-river hydroelectric facility on the main stem of the Saint John River, New Brunswick, Canada was built in 1968 by New Brunswick Power. Since 2013, the Canadian Rivers Institute has been undertaking the Mactaquac Aquatic Ecosystem Study (MAES), a planned, whole-river multidisciplinary ecosystem study and manipulation of the MGS, in support of a decision-making process regarding the future of the aging facility. Future options under consideration range from in-situ refurbishment to full removal and river restoration. Prediction of the potential transport and fate (or long-term retention) of post-inundation sediment is a crucial aspect for decision-makers. Extensive bathymetric surveys, sediment surveys, core sampling, and laboratory studies were conducted to estimate the volume of sediment upstream, sediment bed composition, thickness, particle size diameter, erosion rate and threshold shear stress. These results were integrated into the hydrodynamic model Delft3d that was calibrated and validated using water level and flow data. The model results predicted the downstream fate of the sediments under various hydrodynamic regimes, including the case of complete removal of the hydraulic structure. Given drawdown scenarios were simulated, and sediment movement was quantified. The sediment transport studies have helped to identify areas of interest for future research focus, and have furthered the field and laboratory techniques undertaken by the team. The results of the MAES project will help to advance the science of dam renewal decision-making processes using a holistic, multidisciplinary approach.
Hards A.R., Gray M.A., Noël S.C., Cunjak R.A. (2019). Utility of condition indices as predictors of lipid content in slimy sculpin (Cottus cognatus). Diversity, 11(5).

Slimy sculpin (Cottus cognatus) are increasingly being used as indicator species. This has primarily entailed measuring their condition, the assumption being that condition can be used as a surrogate for lipid content. While there is evidence to suggest this assumption is applicable to some fish, it has yet to be validated for C. cognatus. Further, there are several means by which one may calculate condition, the most commonly employed of which are indirect measurements of lipid content (namely, Fulton's K, somatic K (Ks), and Le Cren's relative condition factor (Kn)). We compared the ability of each of these morphometric indices to predict whole-body lipid content in C. cognatus. There was a moderate degree of evidence that Fulton's K, Ks, and Kn are reliable predictors (Ks and Kn in particular). Of the latter we recommend Kn be used because, unlike Ks, it does not require that fish be killed. And while Fulton's K did not perform quite as well, we consider it a sufficient substitute if the data necessary to calculate Kn are unavailable.
Hayden B., Ferron M., Cunjak R.A., Samways K. (2019). Fruit of the forest - larval sea lamprey Petromyzon marinus are fuelled by allochthonous resources. Journal of Fish Biology, 95(3) 781-792.

We used stable isotopes of carbon, hydrogen and nitrogen to quantify the trophic position and resource use of larval sea lamprey Petromyzon marinus, four benthic macroinvertebrate functional feeding guilds (scraper, shredder, collector and predator) and other fishes in three rivers in eastern Canada. Larval lamprey and most invertebrate guilds foraged as primary consumers in all rivers whereas all other fishes predominantly foraged as secondary consumers. Larval lamprey obtained 75–85% of their resources from allochthonous derived material. This level exceeded all invertebrate guilds, which assimilated approximately 50% allochthonous and 50% autochthonous materials and fishes, which predominantly assimilated between 25% and 60% allochthonous material. Larval lamprey occupied a unique position within the river food webs analysed and show remarkable fidelity to a trophic niche specialising on terrestrially derived detritus.
Hayden B., Harrod C., Thomas S.M., Eloranta A.P., Myllykangas J.P., Siwertsson A., Præbel K., Knudsen R., Amundsen P.A., Kahilainen K.K. (2019). From clear lakes to murky waters – tracing the functional response of high-latitude lake communities to concurrent ‘greening’ and ‘browning’. Ecology Letters, 22(5) 807-816.

Climate change and the intensification of land use practices are causing widespread eutrophication of subarctic lakes. The implications of this rapid change for lake ecosystem function remain poorly understood. To assess how freshwater communities respond to such profound changes in their habitat and resource availability, we conducted a space-for-time analysis of food-web structure in 30 lakes situated across a temperature-productivity gradient equivalent to the predicted future climate of subarctic Europe (temperature +3°C, precipitation +30% and nutrient +45 μg L −1 total phosphorus). Along this gradient, we observed an increase in the assimilation of pelagic-derived carbon from 25 to 75% throughout primary, secondary and tertiary consumers. This shift was overwhelmingly driven by the consumption of pelagic detritus by benthic primary consumers and was not accompanied by increased pelagic foraging by higher trophic level consumers. Our data also revealed a convergence of the carbon isotope ratios of pelagic and benthic food web endmembers in the warmest, most productive lakes indicating that the incorporation of terrestrial derived carbon into aquatic food webs increases as land use intensifies. These results, reflecting changes along a gradient characteristic of the predicted future environment throughout the subarctic, indicate that climate and land use driven eutrophication and browning are radically altering the function and fuelling of aquatic food webs in this biome.
Hayden B., Palomares M.L.D., Smith B.E., Poelen J.H. (2019). Biological and environmental drivers of trophic ecology in marine fishes - a global perspective. Scientific Reports, 9(1).

Dietary niche width and trophic position are key functional traits describing a consumer’s trophic ecology and the role it plays in a community. However, our understanding of the environmental and biological drivers of both traits is predominantly derived from theory or geographically restricted studies and lacks a broad empirical evaluation. We calculated the dietary niche width and trophic position of 2,938 marine fishes and examined the relationship of both traits with species’ maximum length and geographic range, in addition to species richness, productivity, seasonality and water temperature within their geographic range. We used Generalized Additive Models to assess these relationships across seven distinct marine habitat types. Fishes in reef associated habitats typically had a smaller dietary niche width and foraged at a lower trophic position than those in pelagic or demersal regions. Species richness was negatively related to dietary niche width in each habitat. Species range and maximum length both displayed positive associations with dietary niche width. Trophic position was primarily related to species maximum length but also displayed a non-linear relationship with dietary niche width, whereby species of an intermediate trophic position (3–4) had a higher dietary niche width than obligate herbivores or piscivores. Our results indicate that trophic ecology of fishes is driven by several interlinked factors. Although size is a strong predictor of trophic position and the diversity of preys a species can consume, dietary niche width of fishes is also related to prey and competitor richness suggesting that, at a local level, consumer trophic ecology is determined by a trade-off between environmental drivers and biological traits.
Helminen J., Linnansaari T., Bruce M., Dolson-Edge R., Curry R.A. (2019). Accuracy and Precision of Low-Cost Echosounder and Automated Data Processing Software for Habitat Mapping in a Large River. Diversity, 11(7).

The development of consumer hydroacoustic systems continues to advance, enabling the use of low-cost methods for professional mapping purposes. Information describing habitat characteristics produced with a combination of low-cost commercial echosounder (Lowrance HDS) and a cloud-based automated data processing tool (BioBase EcoSound) was tested. The combination frequently underestimated water depth, with a mean absolute error of 0.17 ± 0.13 m (avg ± 1SD). The average EcoSound bottom hardness value was high (0.37–0.5) for all the substrate types found in the study area and could not be used to differentiate between the substrate size classes that varied from silt to bedrock. Overall, the bottom hardness value is not informative in an alluvial river bed setting where the majority of the substrate is composed of hard sands, gravels, and stones. EcoSound separated vegetation presence/absence with 85–100% accuracy and assigned vegetation height (EcoSound biovolume) correctly in 55% of instances but often overestimated it in other instances. It was most accurate when the vegetation canopy was ≤25% or >75% of the water column. Overall, as a low-cost, easy-to-use application EcoSound offers rapid data collection and allows users with no specialized skill requirements to make more detailed bathymetry and vegetation maps than those typically available for many rivers, lakes, and estuaries.
Henriksson P.J.G., Banks L.K., Suri S.K., Pratiwi T.Y., Fatan N.A., Troell M. (2019). Indonesian aquaculture futures-identifying interventions for reducing environmental impacts. Environmental Research Letters, 14(12).

Indonesia is the world's second largest producer and third largest consumer of seafood. Fish is therefore essential to the nation, both financially and nutritionally. Overfishing and the effects of climate change will, however, limit future landings of capture fisheries, so any increases in future seafood production will need to come from aquaculture. The ecological effects of aquaculture are dependent upon the choice of species, management, and where it is sited. In the present study we use life cycle assessment (LCA) to evaluate how possible interventions and innovations can mitigate environmental impacts related to the aquaculture sector's growth. The mitigation potential of six interventions were also quantified, namely (1) FCR reductions for whiteleg shrimp, carp, and tilapia; (2) sustainable intensification of milkfish and Asian tiger shrimp polyculture; (3) shifting groupers from whole fish diets to pellets; (4) favoring freshwater finfish over shrimp; (5) renewable electricity; and (6) reduced food waste and improved byproduct utilization. If all six interventions are implemented, we demonstrate that global warming, acidification, eutrophication, land occupation, freshwater use, and fossil energy use could be reduced by between 28% and 49% per unit of fish. The addition of many innovations that could not be quantified in the present study, including innovative feed ingredients, suggest that production could double within the current environmental footprint. This does not, however, satisfy the expected 3.25-fold increase under a business-as-usual scenario, neither does it satisfy the government's growth targets. We therefore also explore possible geographical areas across Indonesia where aquaculture expansions and ecological hotspots may conflict. Conclusively, we advocate more conservative production targets and investment in more sustainable farming practices. To accelerate the implementation of these improvements, it will be central to identify the most cost-effective aquaculture interventions.
Jardine T.D. (2019). Indigenous knowledge as a remedy for shifting baseline syndrome. Frontiers in Ecology and the Environment, 17(1) 13-14.
Jardine T.D., Doig L.E., Jones P.D., Bharadwaj L., Carr M., Tendler B., Lindenschmidt K.E. (2019). Vanadium and thallium exhibit biodilution in a northern river food web. Chemosphere, 233 381-386.

Trophic transfer of contaminants dictates concentrations and potential toxic effects in top predators, yet biomagnification behaviour of many trace elements is poorly understood. We examined concentrations of vanadium and thallium, two globally-distributed and anthropogenically-enriched elements, in a food web of the Slave River, Northwest Territories, Canada. We found that tissue concentrations of both elements declined with increasing trophic position as measured by δ15N. Slopes of log [element] versus δ15N regressions were both negative, with a steeper slope for V (−0.369) compared with Tl (−0.099). These slopes correspond to declines of 94% with each step in the food chain for V and 54% with each step in the food chain for Tl. This biodilution behaviour for both elements meant that concentrations in fish were well below values considered to be of concern for the health of fish-eating consumers. Further study of these elements in food webs is needed to allow a fuller understanding of biomagnification patterns across a range of species and systems.
Kahilainen K.K., Thomas S.M., Harrod C., Hayden B., Eloranta A.P. (2019). Trophic ecology of piscivorous Arctic charr (Salvelinus alpinus (L.)) in subarctic lakes with contrasting food-web structures. Hydrobiologia, 840(1) 227-243.

The trophic ecology of piscivorous Arctic charr (Salvelinus alpinus (L.); charr) in the food webs of large subarctic lakes is not well understood. We assessed charr diets, parasites, growth, maturity, and stable isotope ratios in Fennoscandian subarctic lakes dominated by monomorphic or polymorphic whitefish (Coregonus lavaretus (L.)) populations. Charr density was low in all lakes, except in profundal habitats. Charr shifted to piscivory at small size (16–25 cm total length) and consumed a range of prey-fish sizes (2–25 cm). Cannibalism was observed in a few individuals from one monomorphic whitefish lake. Charr matured at 37–51 cm (5–8 years old), grew to 52–74 cm maximum observed length and 47–83 cm asymptotic length. Charr increased total area of convex hull and core stable isotopic diversity area of the fish community by 51–98% and 44–51% in monomorphic whitefish lakes, but only 8–11% and 7–10% in polymorphic whitefish lakes. The difference was due to increasing food-chain length in monomorphic whitefish lakes, whereas reliance on littoral carbon did not change. Charr were the top piscivores in monomorphic whitefish lakes, but played a less important role in polymorphic whitefish lakes, which contained a more diverse predator fauna.
Keva O., Tang P., Käkelä R., Hayden B., Taipale S.J., Harrod C., Kahilainen K.K. (2019). Seasonal changes in European whitefish muscle and invertebrate prey fatty acid composition in a subarctic lake. Freshwater Biology, 64(11) 1908-1920.

Ambient light and temperature show extreme seasonal variation in subarctic lakes due to the midnight sun period in summer and cold polar night period in winter. These changes have clear impacts on fish feeding and reproduction cycles, potentially affecting the fatty acid (FA) composition of muscle. Despite extensive research into fish FA over recent decades, we know little about intra-annual changes of fish FA profile and content. We studied intra-annual changes in the FA profile (mol%) and content (mg g-1 dry weight) of sexually mature European whitefish (Coregonus lavaretus) muscle in a large and deep subarctic lake located in northern Fennoscandia. We collected fish, zooplankton, and benthic macroinvertebrate samples during 3 ice-covered months, including December (during whitefish spawning), and 3 open-water months. Fish size, age, sex, stomach content and fullness, and gonadosomatic index were also assessed as co-variates. Whitefish changed diet from benthic macroinvertebrates in winter to zooplankton in summer. Generally, whitefish somatic growth was slow and most energy was used for gonad growth. Zooplankton had higher total content and different profile of FA compared to benthic macroinvertebrates. Increased zooplanktivory in summer was detected with higher α-linolenic acid (ALA, 18:3n-3) and stearidonic acid (SDA, 18:4n-3) percentage and content as well as increased the ratio of polyunsaturated FAs (PUFAs) of n-3 and n-6 family (n-3/n-6 ratio) in fish muscle. Whitefish gonadal growth and development occur during the summer growing season and continue until the initiation of spawning in early winter. We found that the content of physiologically crucial PUFA, eicosapentaenoic acid (EPA, 20:5n-3), docosahexaenoic acid (DHA, 22:6n-3), and arachidonic acid (ARA, 20:4n-6) decreased by c. 60% between late summer and the spawning period in early winter. After spawning, total FA content of whitefish muscle increased rapidly, reaching the maximum recorded level in mid-summer. Intra-annual changes in whitefish muscle FA profiles and contents were modified both by available diet and reproductive phase; however, reproductive physiology was clearly a stronger driver of the changes in muscle FA composition. Results suggest marked changes in intra-annual FA composition of fish muscle, an important factor that should be considered in future studies and especially in long term monitoring programs. Future studies are needed to determine whether these inter-annual FA patterns revealed in this study can be extended to different regions and to e.g. adipose or spring spawning species.
Krynak E.M., Lindo Z., Yates A.G. (2019). Patterns and drivers of stream benthic macroinvertebrate beta diversity in an agricultural landscape. Hydrobiologia, 837(1) 61-75.

Knowledge of benthic macroinvertebrate β-diversity patterns and drivers in an agricultural landscape can inform and improve watershed management decisions. Our study used multi-site and pairwise measures to determine taxonomic and functional β-diversity and associated nestedness and turnover components for benthic macroinvertebrate communities in the agricultural landscape. Total taxonomic β-diversity was mostly due to turnover, whereas total functional β-diversity was composed of turnover and nestedness more equally. Variation partitioning showed that spatial and habitat variables explained the largest proportion of variation in the total and turnover component of both taxonomic and functional β-diversity. Variation in nestedness was associated with local-scale habitat. Agricultural land cover was not a driver of β-diversity; however, extensive agricultural land cover appeared to disrupt the habitat–functional β-diversity relationship. Our findings suggest that distance among benthic macroinvertebrate communities should be considered when making land management or conservation decisions. Moreover, apparent disruption of the habitat–functional β-diversity relationship with extensive agricultural cover suggests managers should strategically target restoration activities to upland or channel areas based on catchment conditions. Finally, differences between taxonomic and functional β-diversity suggest including both measures in monitoring programs may enhance regional biodiversity assessments.
Kurek J., MacKeigan P.W., Veinot S., Mercer A., Kidd K.A. (2019). Ecological legacy of DDT archived in lake sediments from eastern Canada. Environmental Science and Technology, 53(13) 7316-7325.

Historic forest management practices led to widespread aerial application of insecticides, such as dichlorodiphenyltrichloroethane (DDT), to North American conifer forests during ∼1950-1970. Lake basins thus may provide an important archive of inputs and aquatic responses to these organochlorines. We use dated sediment cores from five study lakes in multiple watersheds in New Brunswick (NB), Canada, to provide a regional paleo-ecotoxicological perspective on this potential legacy stressor in remote lake ecosystems. Peak sedimentary levels of p,p'- and o,p'-DDT (ΣDDT) and breakdown products ΣDDE (dichlorodiphenyldichloroethylene) and ΣDDD (dichlorodiphenyldichloroethane) generally occurred during the 1970s to 1980s. Sediments exceeded probable effect levels (PELs) by ∼450 times at the most impacted lake. Modern sediments in all study lakes still contained levels of DDT-related compounds that exceed PELs. For the first time, we show that aerial applications of DDT to eastern Canadian forests likely resulted in large shifts to primary consumers within several lake food webs, principally through lake-specific impacts on zooplankton community composition. Modern pelagic zooplankton communities are now much different compared to communities present before DDT use, suggesting that a regional organochlorine legacy may exist in the modern food webs of many remote NB lakes.
Lamb K.J., MacQuarrie K.T.B., Butler K.E., Danielescu S., Mott E., Grimmet M., Zebarth B.J. (2019). Hydrogeophysical monitoring reveals primarily vertical movement of an applied tracer across a shallow, sloping low-permeability till interface: Implications for agricultural nitrate transport. Journal of Hydrology, 573 616-630.

Intensive potato production is an important contributor to groundwater and surface water nitrate contamination in the province of Prince Edward Island (PEI), Canada. In PEI, the presence of a permeability contrast between soil and the underlying compact basal till at approximately 1 m depth is known to cause temporary perched water table conditions, but the implications for agricultural nitrate transport are not well understood. This study is the first detailed field investigation to examine the impact of the soil – compact basal till interface on vertical and lateral subsurface flow of water and solutes on a moderate hillslope in PEI. A surface-applied tracer test was conducted and a shallow drain-tile pipe system, with a tipping bucket gauge, was installed down-gradient of the tracer application to monitor lateral subsurface flow. In addition, three-dimensional electrical resistivity imaging (ERI) was employed to monitor the evolution of the applied tracer plume over a period of 1 year. A small scale, transient flow and transport model was used to simulate the tracer test and to investigate the sensitivity of tracer transport to selected parameters (primarily, the hydraulic conductivities of the soils and underlying compact basal till). Monitoring, conducted from October 2013 to June 2015, and numerical modeling showed a strong tendency for vertical flow of water and tracer through the soil – compact basal till interface as opposed to lateral down-slope subsurface flow. Water balance calculations estimated a total vertical flow of 94.5% of the infiltration for the October 2014 to January 2015 period. The preference for vertical over lateral flow and transport was consistent with electrical resistivity images for the same time period. These findings indicate that the fate of infiltrating water and dissolved nitrate is the deeper bedrock aquifer water table, and that intermittent perched water table conditions do not result in significant lateral flow toward nearby surface waters.
Lavery J.M., Cunjak R.A. (2019). The influence of abiotic incubation conditions on the winter mortality of wild salmonid embryos. Freshwater Biology, 64(6) 1098-1113.

Embryos of many valued salmonid species incubate in the hyporheic zone of boreal streams over winter. Influence of individual winter-related environmental variables on salmonid embryo success has been previously investigated. However, how multiple variables act together to influence embryo incubation remains poorly understood. Using a naturally spawning population of Atlantic salmon (Salmo salar) in the Miramichi River basin (New Brunswick, Canada), we related variation in the abiotic embryo incubation habitat in different streams (spatial) and over the course of two winters (temporal) to embryo mortality between fertilisation and hatch. Over two years (2013–2014 and 2014–2015), we introduced fertilised eggs to six simulated salmon redds in each of three riffles in each of five active spawning reaches (n<inf>redds</inf> = 90) with a range of hyporheic conditions. Embryo mortality was quantified at an early sampling event (March; pre-freshet and during late embryonic development) and a late sampling event (May; post-freshet and post-hatch). We extracted 22 abiotic predictor variables for statistical analyses from continuous records of hyporheic environmental conditions, collected for the duration of the incubation period in each study reach. Through partial least squares regression analyses, 37.6% of the total variation in mortality was explained by the predictor variables. Each group of predictor variables explained similar proportions of variation (water temperature: 8.4%, water level: 7.4%, dissolved oxygen: 7.1%, ice conditions: 7.2%, and substrate characteristics: 7.5%), which suggests that mortality is influenced by multiple interacting abiotic conditions, rather than a single variable in isolation, and that the factors contributing to ideal salmonid incubation habitats are complex and interconnected. Our research highlights the value of a multi-faceted research perspective and provides a baseline from which future changes in threatened salmonid populations can be measured and compared in an effort to identify relevant species- or population-specific differences.
Lento J., Gray M.A., Ferguson A.J., Allen Curry R. (2019). Establishing baseline biological conditions and monitoring metrics for stream benthic macroinvertebrates and fish in an area of potential shale gas development. Canadian Journal of Fisheries and Aquatic Sciences, 76(9) 1480-1494.

Potential for shale gas production is linked to regional geology, which influences water chemistry of freshwater systems. However, there has been little work to establish baseline ecological conditions of rivers within areas of shale gas development. In this study, water chemistry and monitoring metrics for fish and benthic macroinvertebrates were compared among varying-sized streams in New Brunswick, Canada, with different underlying geology. Water chemistry and biotic community structure differed strongly among geological age classes. Early Carboniferous stations, with highest potential for shale gas production, had the highest ions, invertebrate abundances, and richness of invertebrates and fish, with strongest differences between Early Carboniferous and Older Classes of bedrock. A reference condition model indicated numerous sites deviated from normal, but this was not specific to geological classes and reflected the lack of model reference site coverage. These results highlight the importance of selecting appropriate reference sites for bioassessment in areas of resource development to ensure that response to perturbation is differentiated from natural variability along environmental gradients in geology and resource-dependent variables that potentially influence aquatic ecosystem composition.
Lescord G.L., Clayden M.G., Kidd K.A., Kirk J.L., Wang X., O’Driscoll N.J., Muir D.C.G. (2019). Assessing the utility of sulfur isotope values for understanding mercury concentrations in water and biota from high arctic lakes. Arctic Science, 5(2) 90-106.

Methylmercury (MeHg) biomagnifies through aquatic food webs resulting in elevated concentrations in fish globally. Stable carbon and nitrogen isotopes are frequently used to determine dietary sources of MeHg and to model its biomagnification. However, given the strong links between MeHg and sulfur cycling, we investigated whether sulfur isotopes (δ34S) would improve our understanding of MeHg concentrations ([MeHg]) in Arctic lacustrine food webs. Delta34S values and total mercury (THg) or MeHg were measured in water, sediments, and biota from six lakes near Resolute Bay, NU, Canada. In two lakes impacted by historical eutrophication, aqueous sulfate δ34S was ∼8‰ more positive than sedimentary δ34S, suggestive of bacterial sulfate reduction in the sediment. In addition, aqueous δ34S showed a significant positive relationship with aqueous [MeHg] across lakes. Within taxa across lakes, [THg] in Arctic char muscle and [MeHg] in their main prey, chironomids, were positively related to their δ34S values across lakes, but inconsistent relationships were found across entire food webs among lakes. Across lakes, nitrogen isotopes were better predictors of biotic [THg] and [MeHg] than δ34S within this dataset. Our results suggest some linkages between Hg and S biogeochemistry in high Arctic lakes, which is an important consideration given anticipated climate-mediated changes in nutrient cycling.
Lucano-Ramírez G., De Jesús Gómez-García M., Ruiz-Ramírez S., González-Sansón G., Aguilar-Betancourt C., Flores-Ortega J.R. (2019). Reproductive characteristics of the sole Achirus mazatlanus (Pleuronectiformes: Achiridae) in the Barra de Navidad coastal lagoon, Jalisco, Mexico. Ciencias Marinas, 45(2) 47-58.

Achirus mazatlanus is one of the most widely distributed and abundant soles occurring on the Pacific coast of Mexico, yet most of its biological and reproductive characteristics are unknown. Weekly and monthly samples were collected in the Barra de Navidad coastal lagoon (Jalisco, Mexico) from February 2011 to August 2016 to assess the reproductive biology of this species. Observed total sex ratio (F1.00:M1.03) was not significantly different from the expected 1:1 ratio. Females were, on average, larger than males. The observed monthly gonadosomatic index, percentage of mature gonads, mean oocyte diameter, and ovarian-wall thickness suggest that the species reproduces year-round, with an important reproductive season lasting from April to August. Females were classified as partial spawners with asynchronous oocyte development, and males showed unrestricted spermatogonial testes. The presence of spawned individuals and hydrated oocytes in certain months indicates that the species could be spawning in the lagoon; however, the occurrence of eggs and larvae needs to be demonstrated to ascertain this statement. This was the first time length at sexual maturity was assessed for female (10.84 cm) and male (10.23 cm) A. mazatlanus.
Lucano-Ramírez G., Robles-Ravelero M., Ruiz-Ramírez S., González-Sansón G., Aguilar-Betancourt C., Perez-Toledo A. (2019). Reproductive biology of Mulloidichthys dentatus (Perciformes: Mullidae) in the mexican tropical pacific. Revista De Biologia Marina Y Oceanografia, 54(1) 118-128.

-Although Mulloidichthys dentatus is a commercially important species in this region of the Mexican Pacific, most aspects of its biological life cycle, including reproduction, are not known. The main goal of this study was the description of several reproductive traits of M. dentatus in the southern coast of Jalisco, Mexico. Monthly sampling was carried on from January 1998 to December 2008. Fish were caught using a set of gill nets with different mesh sizes. A total of 1,590 individual were sampled and total length (TL), total weight, sex and maturation stage were determined for each fish. Gonads were extracted and preserved for histological analyses. Minimum, mean and maximum TL of fish sampled were 16.5, 30.9 and 40.0 cm, respectively. A total of 899 females and 691 males were collected with the overall sex ratio equal to 1.3:1. Maximum values of gonadosomatic index (GSI) and mean oocyte diameter, as well as the percentages of gonads in advanced reproduction stages suggest that M. dentatus has three main reproductive periods in March, May-July and November. Significant correlation between both sexes was found for GSI and condition factor. Seven oocyte development phases were found in ripe ovaries, which suggest asynchronic oocyte development. Cell arrangement found in testis was of lobular type with an externally well-defined sperm duct. Maturation length was 25.4 cm for females and 24.5 cm for males. As these values are less than the mean lengths observed in catches (31.9 and 29.7 cm TL), it can be assumed that more than 50% of caught individuals have had a reproductive event (99% female and male).
Macnaughton C.J., Deslauriers D., Ipsen E.L., Corey E., Enders E.C. (2019). Using meta-analysis to derive a respiration model for atlantic salmon (Salmo salar) to assess bioenergetics requirements of juveniles in two canadian rivers. Canadian Journal of Fisheries and Aquatic Sciences, 76(12) 2225-2234.

Standard metabolic rates (SMRs) for Atlantic salmon (Salmo salar) have been calculated independently for different life stages and populations, but the absence of a comprehensive SMR model limits its application for modelling the energy use or life stage-specific growth. Atlantic salmon respiration data were compiled from a meta-analysis of 26 publications, and exponential or optimal relationships were fitted to the metadata to estimate respiration equation parameters and generate confidence intervals dependent on temperature and body mass. While model parameters were significant for both models, mass-corrected standard metabolic rates (g O<inf>2</inf>·day−1) increased as a function of water temperature (°C) and decreased beyond ~16 °C following an optimal relationship (AIC<inf>optimal</inf> = –9185.50 versus AIC<inf>exponential</inf> = –8948.95; ∆AIC = 236.55). Juvenile Atlantic salmon growth (cohorts 1 and 2) from bioenergetics simulations did not vary between Little Southwest Miramichi and Northwest Miramichi rivers; however, variation between simulations using the different respiration models (i.e., exponential versus optimal) led to differences in the way fish allocate energy throughout the year. Results from this analysis will inform conservation efforts for the species throughout its current range and predict the energetic requirements at juvenile life stages.
Marley G., Lawrence A.J., Phillip D.A.T., Hayden B. (2019). Mangrove and mudflat food webs are segregated across four trophic levels, yet connected by highly mobile top predators. Marine Ecology Progress Series, 632 13-25.

Seascape connectivity is crucial for healthy, resilient ecosystems and fisheries. Yet, our understanding of connectivity in turbid mangrove-lined estuaries-some of the world's most productive ecosystems-is limited to macrotidal systems, and rarely incorporates highly mobile top predators. We analysed δ13C and δ15N isotope values of 7 primary producers, 24 invertebrate taxa, 13 fishes, 4 birds and 1 reptile to reveal trophic interactions within and between a mangrove and adjacent mudflat in a microtidal system of the Gulf of Paria, Orinoco River estuary. Primary producers, invertebrates and fishes collected within the mangrove were significantly depleted in 13C and 15N compared to those collected on the mudflat. Stable isotope mixing models showed that mangrove-derived carbon was predominantly assimilated by invertebrates (78 ± 5% SE) and fishes (88 ± 11%) sampled in the mangrove. In contrast, invertebrates and fishes sampled in the mudflat derived <21% of their carbon from mangrove sources. Instead, microphytobenthos and phytoplankton underpinned the mudflat food web. Scarlet ibis Eudocimus ruber and yellow-crowned night heron Nyctanassa violacea were also highly associated with mangrove carbon sources. However, osprey Pandion haliaetus, snowy egret Egretta thula and spectacled caiman Caiman crocodilus obtained carbon from both mangrove and mudflat sources, effectively integrating the food webs. The present study demonstrates simultaneous aspects of food web segregation and connectivity, as well as the importance of surveying the entire food web across a range of tidal systems when investigating seascape connectivity.
Mokany K., Bush A., Ferrier S. (2019). Community assembly processes restrict the capacity for genetic adaptation under climate change. Ecography, 42(6) 1164-1174.

Given the magnitude and rate of ongoing climate change, the physiological capacity of species to tolerate extreme conditions will play a key role in influencing outcomes for biodiversity. It is also possible that species will respond to changes in climate by shifting their physiological tolerances, through genetic adaptation. How these processes influence biodiversity outcomes will be crucial in determining the most suitable management responses to retain diversity into the future. Here we assess how accounting for physiological tolerances, genetic adaptation and community assembly processes such as species replacement, influence projected climate change outcomes for the flora of Tasmania (all 2051 plant species). We incorporate these processes into the M-SET metacommunity model and compare four different assumptions of species niches: realized niches, broader physiological tolerances and low or high capacity for genetic adaptation. Accounting for physiological tolerances rather than realized niches had the largest impact on projected outcomes, with 358 fewer species extinctions in the hottest climate scenario (mean = 30 extinctions). In contrast, adding the capacity for species physiological tolerances to shift through genetic adaptation resulted in little additional benefits for biodiversity outcomes, even under an optimistic level of adaptive capacity. We find that this is due largely to community assembly processes such as species replacement restricting the ability of species to persist and adapt in situ, as has been suggested from theoretical metacommunity models applied in simple artificial settings. Our results highlight the importance of accounting for species physiological tolerances and community-level processes in biodiversity projections, while the potential role for genetic adaptation may be small, requiring further exploration in alternative contexts.
Monk W.A., Compson Z.G., Choung C.B., Korbel K.L., Rideout N.K., Baird D.J. (2019). Urbanisation of floodplain ecosystems: Weight-of-evidence and network meta-analysis elucidate multiple stressor pathways. Science of the Total Environment, 684 741-752.

Freshwater floodplains are dynamic, diverse ecosystems that represent important transition zones between terrestrial, riparian, subsurface and aquatic habitats. Given their historic importance in human development, floodplains have been exposed to a variety of pressures, which in combination have been instrumental in driving changes within these ecosystems. Here, we present an evidence-based framework to explore direct and indirect effects of pressures and stressors on floodplain ecosystems and test this structure within the urban landscape. Evidence was obtained from peer-reviewed scientific literature, focusing on effects of key pressures and stressors on receptors, including species composition (e.g., species presence-absence, diversity) and ecosystem function (e.g., biomass, decomposition). The strength of direct and indirect effects of individual and multiple stressors on biological receptors was quantified using two separate analyses: an evidence-weighted analysis and a quantitative network meta-analysis using data extracted from 131 studies. Results demonstrate the power of adopting a systematic framework to advance quantitative assessment of floodplain ecosystems affected by multiple stressors. While direct pathways were generally stronger and provided the core network skeleton, there were many more significant indirect pathways indicating evidence gaps in our mechanistic understanding of these processes. Indeed, the importance of indirect pathways (e.g. increase in impervious surface → increase in the accumulation rate of sediment nutrients) suggests that embracing complexity in network meta-analysis is a necessary step in revealing a more complete snapshot of the network. Results from the weight-of-evidence approach generally mirrored the direct pathway structure and demonstrated the strength of incorporating study quality alongside data sufficiency. Networks illustrated novel disturbance pathways (e.g., decrease in habitat structure → decrease in structure and function of aquatic and riparian assemblages) that can be used for hypothesis generation for future scientific enquiries. Our results highlight the broader applicability of adopting the proposed framework for assessing complex environments, such as floodplains.
Mudge J.F., Houlahan J.E. (2019). Wetland macrophyte community response to and recovery from direct application of glyphosate-based herbicides. Ecotoxicology and Environmental Safety, 183.

Community-scale impacts of glyphosate-based herbicides on wetland plant communities and the magnitude of those impacts that should be considered biologically relevant are poorly understood. We contrast three different thresholds for setting biologically meaningful critical effect sizes for complex ANOVA study designs. We use each of the of the critical effect sizes to determine optimal α levels for assessment of how different concentrations of glyphosate-based herbicides affect wetland plant communities over two years of herbicide application (alone and in combination with agricultural fertilizers) and two subsequent years without herbicide (or fertilizer) application. The application of glyphosate-based herbicides was found to result in a decrease in macrophyte species richness, an increase in macrophyte species evenness, a decrease in macrophyte cover and a reduction in community similarity. There was little evidence that nutrient additions directly or indirectly affected plant community endpoints. The glyphosate effects were evident in the first year of herbicide application in 2009, and became more pronounced in the second year of herbicide application in 2010. However, when herbicides were not applied in 2011, recovery was observed in most endpoints, with the exception being species evenness, for which partial recovery was not observed until 2012. Optimal α levels differed among the three critical effect sizes for each ANOVA term and endpoint combination, however regardless of differences in α levels, conclusions were generally consistent across all critical effect sizes.
Munkittrick K.R., Arciszewski T.J., Gray M.A. (2019). Principles and challenges for multi-stakeholder development of focused, tiered, and triggered, adaptive monitoring programs for aquatic environments. Diversity, 11(9).

In Canada, there is almost 30 years of experience in developing tiered and triggered adaptive monitoring programs focused on looking at whether environmental concerns remain when pulp and paper mills, or metal mines, are in compliance with their discharge limits. These environmental effects monitoring programs were based on nationally standardized designs. Many of the programs have been developed through multi-stakeholder working groups, and the evolution of the program faced repeated frictions and differing opinions on how to design environmental monitoring programs. This paper describes key guidance to work through the initial steps in program design, and includes scientific advice based on lessons learned fromthe development of the Canadian aquatic environmental effects monitoring program.
Nguyen H.Q., Curry R.A., Monk W.A., Culp J., Linnansaari T. (2019). Seasonal differences in plankton community structure are more pronounced than spatial patterns in the headpond and downstream portions of a large impounded river. Inland Waters, 9(3) 348-361.

Plankton community samples from a reservoir were compared to samples from a river downstream of a large hydroelectric generating station on the lower Saint John River, New Brunswick, Canada. The study focused on spatiotemporal variation of the plankton communities and their association with physicochemical parameters in the reservoir–downstream river system after almost 50 years of limnological evolution. The survey revealed 288 phytoplankton and 85 zooplankton taxa, dominated in abundance by rotifers and Cyanobacteria. The taxa richness was significantly greater than reports at the time of the reservoir creation. Spatial variability of the plankton community in the reservoir was statistically homogeneous among sites and the water layers across sites during its stratified period. The river plankton communities followed the same patterns as the reservoir, and river sites were always statistically similar to the reservoir community in terms of richness and abundance. The similarity of the communities across the reservoir and the river was highest during summer. Influential variables explaining seasonal differences in phytoplankton and zooplankton communities included physical, nutrient, and biotic factors. Our study demonstrates how a large, run-of-the-river hydroelectric generating station can regulate the plankton community up to 20 km downstream.
O'Sullivan A.M., Devito K.J., Curry R.A. (2019). The influence of landscape characteristics on the spatial variability of river temperatures. Catena, 177 70-83.

River temperature is well established as an important variable for aquatic denizens. Given its importance, researchers are attempting to disentangle complex interactions between landscapes and river temperatures. We investigated how landscape variables of geomorphology, geology, and vegetation can explain a large portion of the spatial variations amongst tributary temperatures in the large, Miramichi watershed, New Brunswick. We utilize thermal infrared imagery (TIR) to characterize river temperature and remote sensed data to delineate landscape variables. Partial Least Squares regression (PLS) models indicated that variability in river temperature was associated with landscape attributes, but these differed with physiography. For the Clearwater Brook and Burnthill Brook watersheds located on the Miramichi Highlands physiographic unit, solar radiation exposure, surficial geology deposit (comprising gravels, sands, and minor silt), geological contact zones, and maximum watershed slope were strongly and positively correlated with river temperature. We stipulate that the interaction of slope steepness and geologic contact zones can produce complex local and larger groundwater interactions influencing river temperatures in this physiographic region. In the lower elevation, and lower relief, Cains River watershed, located on the Maritime Plains physiographic unit, watershed elevation and wetlands were significant and positively correlated with river temperatures. Here the main stem was cooler in the downstream reaches, likely due to the semi-confined channel interaction with groundwater discharge originating from the surficial deposits and fractured underlying sandstone of the lowlands, and possibly hyporheic processes. These findings illustrate how physiography and geomorphology influence thermal processes in flowing waters at both the landscape and local scales, and the resultant implications for management and conservation efforts both in terms of land use and climate change.
O'Sullivan A.M., Linnansaari T., Curry R.A. (2019). Ice cover exists: A quick method to delineate groundwater inputs in running waters for cold and temperate regions. Hydrological Processes, 33(26) 3297-3309.

Groundwater can be important in regulating stream thermal regimes in cold, temperate regions, and as such, it can be a significant factor for aquatic biota habits and habitats. Groundwater typically remains at a constant temperature through time; that is, it is warmer than surface water in winter and cooler in summer. Further, small tributaries are often dominated by groundwater during low flows of winter and summer. We exploit these thermal patterns to identify and delineate tributary/groundwater inputs along a frozen river (ice-on) using publically available satellite data, and we tested the findings against airborne, thermal infrared (TIR) data. We utilize a supervised maximum likelihood classification (sMLC) to identify possible groundwater inputs while the river is in a frozen state (kappa coefficient of 96.77 when compared with visually delineated possible groundwater inputs). We then compare sMLC-identified possible groundwater inputs with TIR-classified groundwater inputs, which confirmed that there was no statistical difference (χ2 =.78), that is, confirming that groundwater inputs can be delineated in north temperate river systems using available satellite imagery of the system's frozen state. Our results also established the spatial extent and influence of possible groundwater inputs in two seasons. The thermal plumes were longer and narrower in winter; this is likely related to seasonal differences in dispersion regimes. We hypothesize that differences between summer and winter is related to either (a) tributaries that are modulated by shading in summer or (b) aquifer disconnection from the river in winter owing to frozen ground conditions and lack of aquifer recharge. This method of establishing tributary/groundwater inputs and contributions to surface water thermal regimes is relatively simple and can be useful for science and management as long as “ice cover exists”; that is, the system can achieve a frozen state.
Ouellet-Proulx S., St-Hilaire A., Boucher M.A. (2019). Implication of evaporative loss estimation methods in discharge and water temperature modelling in cool temperate climates. Hydrological Processes, 33(22) 2867-2884.

Evaporative flux is a key component of hydrological budgets. Water loss through evapotranspiration reduces volumes available for run-off. The transition from liquid to water vapour on open water surfaces requires heat. Consequently, evaporation act as a cooling mechanism during summer. Both river discharge and water temperature simulations are thus influenced by the methods used to model evaporation. In this paper, the impact of evapotranspiration estimation methods on simulated discharge is assessed using a semidistributed model on two Canadian watersheds. The impact of evaporation estimation methods on water temperature simulations is also evaluated. Finally, the validity of using the same formulation to simulate both of these processes is verified. Five well-known evapotranspiration models and five evaporation models with different wind functions were tested. Results show a large disparity (18–22% of mean annual total evapotranspiration) among the evapotranspiration methods, leading to important differences in simulated discharge (3–25% of observed discharge). Larger differences result from evaporation estimation methods with mean annual divergences of 34–48%. This translates into a difference in mean summer water temperature of 1–15%. Results also show that the choice of model parameter has less influence than the choice of evapotranspiration method in discharge simulations. However, the parameter values influence thermal simulations in the same order of magnitude as the choice of evaporation estimation method. Overall, the results of this study suggest that evapotranspiration and open water evaporation should be represented separately in a hydrological modelling framework, especially when water temperature simulations are required.
Pearson J.M.N., Kidd J.A., Knysh K.M., Van Den Heuvel M.R., Gagnon J.M., Courtenay S.C. (2019). Identification of native and non-native grass shrimps Palaemon spp. (Decapoda: Palaemonidae) by citizen science monitoring programs in Atlantic Canada. Journal of Crustacean Biology, 39(2) 189-192.

Grass shrimp collected by the Community Aquatic Monitoring Program (CAMP) in estuaries of the southern Gulf of St. Lawrence, Canada were previously assumed to be the native Palaemon vulgaris Say, 1818. Taxonomic identification of grass shrimps from CAMP estuaries revealed most individuals were P. vulgaris, but several from the Souris River and Trout River estuaries in Prince Edward Island (PEI) belong to the European species P. adspersus Rathke, 1837. We provide the first documented presence of P. adspersus in PEI estuaries, extending its known range in Atlantic Canada from coastal Newfoundland and the Magdalen Islands. Boat traffic was probably responsible for the introduction of P. adspersus. The results highlight the importance of community-based monitoring in coastal ecology.
Prestie K., Phillips I.D., Chivers D.P., Jardine T.D. (2019). Effects of ontogeny and invasive crayfish on feeding ecology and mercury concentrations of predatory fishes. Canadian Journal of Fisheries and Aquatic Sciences, 76(11) 1929-1939.

Lake food web structure dictates the flow of energy and contaminants to top predators, and addition of invasive species can shift these flows. We examined trophic position (TP), proportional reliance on the littoral zone (Prop<inf>littoral</inf>), and mercury (Hg) concentrations across the life-span of two predatory fishes, walleye (Sander vitreus) and northern pike (Esox lucius), in lakes with and without invasive virile crayfish (Faxonius virilis). The littoral zone was the dominant foraging zone for both species regardless of size, accounting for 59% and 80% of the diet of walleye and pike, respectively. Both species increased in TP and Hg with body size, as did crayfish. Walleye in crayfish-present lakes had lower Prop<inf>littoral</inf>, TP, and Hg concentrations compared with non-present lakes, but trophic magnification of Hg through the food web was consistent across all six lakes. These findings underscore a strong role for the littoral zone in channeling energy and contaminants to higher trophic levels and how invasive species can occupy new habitats at low abundance while altering food web structure and contaminant bioaccumulation.
Puncher G.N., Cariani A., Cilli E., Massari F., Leone A., Morales-Muñiz A., Onar V., Toker N.Y., Bernal Casasola D., Moens T., Tinti F. (2019). Comparison and optimization of genetic tools used for the identification of ancient fish remains recovered from archaeological excavations and museum collections in the Mediterranean region. International Journal of Osteoarchaeology, 29(3) 365-376.

Among the many fish species commercially exploited since prehistoric times, Atlantic bluefin tuna (Thunnus thynnus) is one of the most economically significant, having left an indelible imprint on several civilizations including the Phoenicians, Greeks, and Romans. Here, we describe our efforts to identify tuna specimens among the remains of 345 fish vertebrae and bones in several large collections from the Atlantic Ocean, Mediterranean Sea, and Black Sea, dating from the Late Iron Age (2nd century BCE) to the early 20th century (1911–1927). Unfortunately, ancient fish specimens are often mislabelled, which can cause a great deal of confusion among zoologists. Protocols were developed and optimized to overcome the unique challenges related to the compromised integrity of genetic material preserved in ancient bones. Three DNA isolation protocols were compared to maximize yields, and as reported for other faunal remains, a silica spin column-based method was proven most effective. Endogenous DNA was successfully extracted from the majority of bones and amplified using polymerase chain reactions (PCRs) and an assortment of four primer pairs targeting nuclear (internal transcribed spacer) and mitochondrial sequences (cytochrome oxidase subunit 1 and control region). Protocols targeting mitochondrial markers were more successful than those focused on nuclear targets. Due to the restricted length of the extracted DNA molecules, character-based keys containing diagnostic nucleotide substitutions were defined and used to identify 231 samples to genera, of which 171 were identified to species level. The success rate of assignment of specimens to species level varied between location and collection, reflecting variation in DNA preservation between different sites and environments. The methods detailed herein can be used to identify other ancient fish specimens and provide information about historical human diets, trade, species distribution, and biodiversity. The same tools can be applied to the analysis of processed food items with highly damaged DNA.
Puncher G.N., Rowe S., Rose G.A., Leblanc N.M., Parent G.J., Wang Y., Pavey S.A. (2019). Chromosomal inversions in the Atlantic cod genome: Implications for management of Canada's Northern cod stock. Fisheries Research, 216 29-40.

Following stock collapse and over twenty years of moratoria, the state of Canada's Northern Atlantic cod (Gadus morhua) remains precarious. To test if recent stock growth was of endogenous or exogenous origin, we performed a whole genome scan (ddRAD) on 135 adults captured in 2015 at three offshore spawning locations spanning the range of the offshore stock along the northeastern Newfoundland and Labrador shelf (Hawke Channel, Notre Dame Channel and Bonavista Corridor), with an additional 105 adults from three more southern locations (St. Anns Bank, Browns Bank and Bay of Fundy). Population structure analysis using 5,077 single nucleotide polymorphisms (SNPs) detected a distinct genetic break off the coast of Nova Scotia near 45 °N. Gene flow between groups north and south of this divide appears to be limited despite the presence of several northern-type and admixed individuals present in the southern area. North of the genetic divide, allele frequencies of neutral loci were indicative of a panmictic population. Several outlier SNPs were found to be associated with ecologically relevant physical characteristics (visual pigments, fin development, response to hypoxia, and various metabolic processes), which may be indicative of different ecological niches.
Simmons D.B.D., Cowie A.M., Koh J., Sherry J.P., Martyniuk C.J. (2019). Hepatic proteome network data in zebrafish (Danio rerio) liver following dieldrin exposure. Data in Brief, 25.

Dieldrin is an environmental contaminant that adversely affects aquatic organisms. The data presented in this study are proteomic data collected in liver of zebrafish that were exposed to the pesticide in a dietary exposure. For label free proteomics, data were collected with a quadrupole Time-of-Flight mass spectrometer and for iTRAQ proteomics, data were acquired using a hybrid quadrupole Orbitrap (Q Exactive) MS system. Using formic acid digestion and label free proteomics, 2,061 proteins were identified, and among those, 103 were differentially abundant (p < 0.05 in at least one dose). In addition, iTRAQ proteomics identified 722 proteins in the liver of zebrafish following dieldrin treatment. The label-free approach identified 21 proteins that followed a dose dependent response. Of the differentially abundant proteins identified by iTRAQ, there were 26 unique expression patterns for proteins based on the three doses of dieldrin. Proteins were queried for disease networks to learn more about adverse effects in the liver following dieldrin exposure. Differentially abundant proteins were related to metabolic disease, steatohepatitis and lipid metabolism disorders, drug-induced liver injury, neoplasms, tissue degeneration and liver metastasis. The proteomics data described here is associated with a research article, “Label-free and iTRAQ proteomics analysis in the liver of zebrafish (Danio rerio) following a dietary exposure to the organochlorine pesticide dieldrin” (Simmons et al. 2019). This investigation reveals new biomarkers of toxicity and will be of interest to those studying aquatic toxicology and pesticides.
Simmons D.B.D., Cowie A.M., Koh J., Sherry J.P., Martyniuk C.J. (2019). Label-free and iTRAQ proteomics analysis in the liver of zebrafish (Danio rerio) following dietary exposure to the organochlorine pesticide dieldrin. Journal of Proteomics, 202.

The organochlorine dieldrin (DLD) bioaccumulates in lipid-rich tissues and is associated with immunosuppression, altered metabolism, and cancer. The objective of this study was to determine the effect of DLD on the hepatic proteome in zebrafish following dietary treatment as the liver is central to metabolism. Females were fed a control dose or one of three doses of DLD-contaminated food pellets over 21 days. Both label-free and iTRAQ proteomics were conducted as two complementary methods to expand coverage of the proteome. Label-free proteomics quantified 1563 proteins: 6 proteins showed a linear dose-response with DLD. iTRAQ quantified >3500 proteins; 5 proteins were decreased and 34 proteins were increased in abundance within the liver with all three doses. Overall, DLD reduced the abundance of proteins associated with glucose and cholesterol metabolism, lipid oxidation, liver function, and immune-related processes. Few proteins were identified by both methods as being altered (~1%), suggesting that each method detected different subsets of proteins. Protein responses in the liver were largely dependent on dose, however proteins related to liver and organ function, centrosome separation, glucose/energy metabolism, and immune-related pathways were confirmed by each independent technique and were suppressed with DLD exposure. This study identifies proteomic responses that are associated with organochlorine-induced hepatotoxicity. Biological significance: Environmental contaminants cause hepatotoxicity because the liver is the major organ for detoxification. The legacy pesticide dieldrin significantly bioaccumulates in tissues, and can affect molecular processes that can lead to liver pathology. LC MS/MS proteomics identified protein networks related to tumors, energy homeostasis, and chromosomal separation as those affected by dietary exposure to dieldrin. We applied two orthogonal mass spectrometry-based methods to more completely survey the liver proteome, strengthening data interpretation. These data improve understanding as to the effects of organochlorine pesticide toxicity in the liver and the study identifies proteome networks that can contribute to adverse outcome pathways for pesticide exposure.
Sirabahenda Z., St-Hilaire A., Courtenay S.C., van den Heuvel M.R. (2019). Comparison of acoustic to optical backscatter continuous measurements of suspended sediment concentrations and their characterization in an agriculturally impacted river. Water Switzerland, 11(5).

The increased soil loss in an agricultural watershed raises challengers for river water quality and a reliable automated monitoring for suspended sediment concentrations (SSC) is crucial to evaluate sediment budgets variation in systems. The aims of this study were (1) to test if an acoustic doppler current profiler (ADCP) would give similar results to turbidity probe measurements as a high frequency monitoring tool for suspended sediment; and (2) to analyze the relationship between sediment drivers and SSC in a typical agricultural drainage basin. The acoustic and optical backscatter sensors were used to collect SSC data during the ice-free seasons of four consecutive years in the Dunk River (PEI, Canada). The slopes of the relationships between the two SSC indirect measurements were not significantly different than 1. Correlations between SSC and hydro-meteorological variables showed that the high SSC values were more associated with the streamflow and water velocity than precipitation. This study highlighted the great potential of ADCP for the continuous monitoring of suspended sediment in an agricultural watershed. For summer periods the prevalence of clockwise hysteresis (74.1% of measured rainstorm events with SSC > 25 mg L-1) appeared related to rainstorm behaviors.
Taylor L.J., Mann N.S., Daoud D., Clark K.F., van den Heuvel M.R., Greenwood S.J. (2019). Effects of Sublethal Chlorpyrifos Exposure on Postlarval American Lobster (Homarus americanus). Environmental Toxicology and Chemistry, 38(6) 1294-1301.

The organophosphate pesticide chlorpyrifos has been introduced to the marine environment via adsorption to agricultural soil runoff or as spray drift. Chlorpyrifos affects the survival of some larval decapod crustaceans, but no data exist on the impacts to the American lobster, Homarus americanus. The purpose of the present study was to assess the levels at which chlorpyrifos affects the survival of postlarval H. americanus. Using acute saltwater exposures, the 24- and 48-h median lethal concentrations were established for stage IV H. americanus (1.56 and 1.33 µg/L, respectively). Movement, acetylcholinesterase activity, intermoult period, specific growth rate, and moult increment were measured during exposure to sublethal concentrations. Movement patterns were assessed to establish a 48-h median inhibition concentration for cessation of normal movement (0.66 µg/L). Acetylcholinesterase activity was found to be inhibited immediately post-exposure to 0.50, 0.57, and 0.82 µg/L chlorpyrifos but could be recovered within a period (9–15 d) in clean seawater. Sublethal growth effects of increased intermoult period, decreased specific growth rate, and decreased moult increment were observed during exposure to an environmentally relevant concentration (0.82 µg/L). The present study suggests that H. americanus stage IV larvae were marginally less sensitive to chlorpyrifos compared with other decapods and that acute lethality of H. americanus postlarvae is not likely to occur with chlorpyrifos concentrations previously reported from aquatic environments. Environ Toxicol Chem 2019;38:1294–1301. © 2019 SETAC.
Thera J.C., Kidd K.A., Bertolo R.F., O'Driscoll N.J. (2019). Tissue content of thiol-containing amino acids predicts methylmercury in aquatic invertebrates. Science of the Total Environment, 688 567-573.

Aquatic invertebrates vary in methylmercury (MeHg) levels among systems which has been attributed, in part, to environmental conditions, but may also be linked to differences in their biochemical composition. As MeHg is known to bind to thiol-containing amino acids such as cysteine in proteins of fish, our objective was to determine if these amino acids explain MeHg variability among aquatic invertebrate taxa. Benthic macroinvertebrates from diverse functional feeding groups and bulk zooplankton were collected from six acidic lakes in Kejimkujik National Park, Nova Scotia, Canada, and analyzed for MeHg, cysteine (as cysteic acid), methionine (as methionine sulfone), and nitrogen (relative trophic level, δ15N) and carbon (carbon source, δ13C) isotopes. MeHg was significantly and positively related to cysteine or methionine in zooplankton, caddisfly and stonefly tissues (R2 from 0.24 to 0.57). In addition, methionine or cysteine in combination with δ15N and/or δ13C were better predictors of MeHg levels in stoneflies, mayflies, caddisflies and zooplankton among these lakes (R2 <inf>adj</inf> = 0.25–0.91). Overall, these novel findings suggest that the variability in MeHg of aquatic invertebrates can be explained, in part, by their tissue levels of thiol-containing amino acids.
Thomas S.M., Kainz M.J., Amundsen P.A., Hayden B., Taipale S.J., Kahilainen K.K. (2019). Resource polymorphism in European whitefish: Analysis of fatty acid profiles provides more detailed evidence than traditional methods alone. Plos One, 14(8).

Resource polymorphism—whereby ancestral generalist populations give rise to several specialised morphs along a resource gradient—is common where species colonise newly formed ecosystems. This phenomenon is particularly well documented in freshwater fish populations inhabiting postglacial lakes formed at the end of the last ice age. However, knowledge on how such differential exploitation of resources across contrasting habitats might be reflected in the biochemical compositions of diverging populations is still limited, though such patterns might be expected. Here, we aimed to assess how fatty acids (FA)—an important biochemical component of animal tissues—diverged across a polymorphic complex of European whitefish (Coregonus lavaretus) and their closely related monomorphic specialist congener vendace (Coregonus albula) inhabiting a series of six subarctic lakes in northern Fennoscandia. We also explored patterns of FA composition in whitefish’s predators and invertebrate prey to assess how divergence in trophic ecology between whitefish morphs would relate to biochemical profiles of their key food web associates. Lastly, we assessed how information on trophic divergence provided by differential FA composition compared to evidence of resource polymorphism retrieved from more classical stomach content and stable isotopic (δ13C, δ15N) information. Examination of stomach contents provided high-resolution information on recently consumed prey, whereas stable isotopes indicated broad-scale patterns of benthic-pelagic resource use differentiation at different trophic levels. Linear discriminant analysis based on FA composition was substantially more successful in identifying whitefish morphs and their congener vendace as distinct groupings when compared to the other two methods. Three major FA (myristic acid, stearic acid, and eicosadienoic acid) proved particularly informative, both in delineating coregonid groups, and identifying patterns of pelagic-benthic feeding throughout the wider food web. Myristic acid (14:0) content and δ13C ratios in muscle tissue were positively correlated across fish taxa, and together provided the clearest segregation of fishes exploiting contrasting pelagic and benthic niches. In general, our findings highlight the potential of FA analysis for identifying resource polymorphism in animal populations where this phenomenon occurs, and suggest that this technique may provide greater resolution than more traditional methods typically used for this purpose.
Van den Brink P.J., Bracewell S.A., Bush A., Chariton A., Choung C.B., Compson Z.G., Dafforn K.A., Korbel K., Lapen D.R., Mayer-Pinto M., Monk W.A., O'Brien A.L., Rideout N.K., Schäfer R.B., Sumon K.A., Verdonschot R.C.M., Baird D.J. (2019). Towards a general framework for the assessment of interactive effects of multiple stressors on aquatic ecosystems: Results from the Making Aquatic Ecosystems Great Again (MAEGA) workshop. Science of the Total Environment, 684 722-726.

A workshop was held in Wageningen, The Netherlands, in September 2017 to collate data and literature on three aquatic ecosystem types (agricultural drainage ditches, urban floodplains, and urban estuaries), and develop a general framework for the assessment of multiple stressors on the structure and functioning of these systems. An assessment framework considering multiple stressors is crucial for our understanding of ecosystem responses within a multiply stressed environment, and to inform appropriate environmental management strategies. The framework consists of two components: (i) problem identification and (ii) impact assessment. Both assessments together proceed through the following steps: 1) ecosystem selection; 2) identification of stressors and quantification of their intensity; 3) identification of receptors or sensitive groups for each stressor; 4) identification of stressor-response relationships and their potential interactions; 5) construction of an ecological model that includes relevant functional groups and endpoints; 6) prediction of impacts of multiple stressors, 7) confirmation of these predictions with experimental and monitoring data, and 8) potential adjustment of the ecological model. Steps 7 and 8 allow the assessment to be adaptive and can be repeated until a satisfactory match between model predictions and experimental and monitoring data has been obtained. This paper is the preface of the MAEGA (Making Aquatic Ecosystems Great Again) special section that includes three associated papers which are also published in this volume, which present applications of the framework for each of the three aquatic systems.
van den Heuvel M.R., Hitchcock J.K., Coffin M.R.S., Pater C.C., Courtenay S.C. (2019). Inorganic nitrogen has a dominant impact on estuarine eelgrass distribution in the Southern Gulf of St. Lawrence, Canada. Limnology and Oceanography, 64(6) 2313-2327.

Eelgrass (Zostera marina) coverage and height were evaluated in 16 estuaries in the Southern Gulf of St. Lawrence, Canada, using boat-based sonar surveys to determine the dominant factors in the decline of eelgrass in the region. Eelgrass coverage was modeled from the sonar surveys and quantified as the percentage of available habitat occupied—with habitat being defined by salinity limits (> 10 PSU) and depth (< 3 m). Estuaries showed a marked variation in eelgrass coverage ranging between 6% and 57% of available habitat, with eelgrass absent in the upper estuary of estuaries with the highest nitrate loading. The Dunk River estuary showed a decline in eelgrass coverage between 1967 and 2014, a period of increasing nitrogen loading. Measures of eelgrass height were not related to coverage endpoints, suggesting that height variables are not suitable endpoints for overall eelgrass health. Analysis of the influence of environmental factors showed that the factor that consistently correlated to eelgrass coverage was nitrate-N loading while the factor most influencing eelgrass height was light attenuation. A nonlinear logistic loading-effect model relating eelgrass coverage to nitrate-N loading indicated that 10%, 25%, 50%, 75%, and 90% decline in eelgrass would be expected to occur in response to estuarine nitrate-N loads of 1.3 kg ha−1 yr−1, 8.0 kg ha−1 yr−1, 50.0 kg ha−1 yr−1, 312 kg ha−1 yr−1, and 1947 kg ha−1 yr−1, respectively. These results suggest that inorganic nitrogen loading is the most significant factor to be addressed by environmental managers when addressing eelgrass declines in estuaries similar to those studied.
Webb J.R., Pearce N.J.T., Painter K.J., Yates A.G. (2019). Hierarchical variation in cellulose decomposition in least-disturbed reference streams: a multi-season study using the cotton strip assay. Landscape Ecology, 34(10) 2353-2369.

Context: Decomposition of organic matter dictates productivity of headwater streams in forested biomes. However, the hierarchical structure of stream ecosystems entails that research aimed at understanding patterns and drivers of decomposition incorporate multiple spatio-temporal scales. Objectives: We assessed spatio-temporal patterns of cellulose decomposition in least-disturbed streams and determined the relative distribution of variation associated with region, stream and habitat scales. We also established the environmental drivers associated with heterogeneity in cellulose decomposition. Methods: We applied a hierarchical design to assess spatio-temporal patterns of cellulose decomposition in least-disturbed streams of Ontario, Canada. Cotton strips were deployed in one pool and one riffle in each of 19 streams across three regions with distinct climates and physiography. Strips were deployed in spring, summer and autumn and assessed for rate of tensile strength loss. Results: Rates of tensile loss differed among regions regardless of season. Habitat differences were observed in two of three regions during the spring and summer. Season only explained a significant amount of variance when tensile loss rates were not corrected for stream temperatures. Region and stream scales were associated with twice the variance in tensile loss than habitat. Spatial variation in tensile loss was negatively associated with latitude, forest cover, nutrients and conductivity. Conclusions: Our findings demonstrate the importance of the regional landscape template in explaining spatio-temporal patterns of cellulose decomposition in streams. Moreover, our study suggests application of cellulose decomposition as a biomonitoring tool requires consideration of regional landscapes, habitat and season when developing sampling protocols and bioassessment models.
Wegscheider B., MacLean H.O., Linnansaari T., Curry R.A. (2019). Freshwater mussel abundance and species composition downstream of a large hydroelectric generating station. Hydrobiologia, 836(1) 207-218.

Freshwater mussels are a significant component of freshwater ecosystems and often make up the largest biomass within these systems. However, their habitat is often subject to impacts such as changes in water quality or hydraulic stressors related to dams. Using snorkelling surveys, this study identified the presence, relative abundance, and spatial distribution of freshwater mussels in the Saint John River downstream of the Mactaquac Generating Station. This study also characterizes, in a general sense, the different habitats supporting these mussel assemblages. The surveys found five of the 11 species that have been previously recorded in the whole Saint John River system. Additional surveys within the Saint John River watershed with increased search effort per site are needed to detect rare species. Species composition and relative abundance differed in surveyed reaches, which are characterized by discrete habitat conditions. No differences in species diversity were observed between surveyed reaches. Trends in species distribution are likely due to a changing substrate composition moving downstream from a sediment-starved reach in the tailrace area of the river, followed by a coarse/fine flow-sorted mixture in the island area to a nearly homogenous sandy substrate further downstream.
Wellband K., Mérot C., Linnansaari T., Elliott J.A.K., Curry R.A., Bernatchez L. (2019). Chromosomal fusion and life history-associated genomic variation contribute to within-river local adaptation of Atlantic salmon. Molecular Ecology, 28(6) 1439-1459.

Chromosomal inversions have been implicated in facilitating adaptation in the face of high levels of gene flow, but whether chromosomal fusions also have similar potential remains poorly understood. Atlantic salmon are usually characterized by population structure at multiple spatial scales; however, this is not the case for tributaries of the Miramichi River in North America. To resolve genetic relationships between populations in this system and the potential for known chromosomal fusions to contribute to adaptation, we genotyped 728 juvenile salmon using a 50 K SNP array. Consistent with previous work, we report extremely weak overall population structuring (Global F <inf>ST</inf> = 0.004) and failed to support hierarchical structure between the river's two main branches. We provide the first genomic characterization of a previously described polymorphic fusion between chromosomes 8 and 29. Fusion genomic characteristics included high LD, reduced heterozygosity in the fused homokaryotes, and strong divergence between the fused and the unfused rearrangement. Population structure based on fusion karyotype was five times stronger than neutral variation (F <inf>ST</inf> = 0.019), and the frequency of the fusion was associated with summer precipitation supporting a hypothesis that this rearrangement may contribute local adaptation despite weak neutral differentiation. Additionally, both outlier variation among populations and a polygenic framework for characterizing adaptive variation in relation to climate identified a 250-Kb region of chromosome 9, including the gene six6 that has previously been linked to age-at-maturity and run-timing for this species. Overall, our results indicate that adaptive processes, independent of major river branching, are more important than neutral processes for structuring these populations.
Yates A.G., Culp J.M., Armanini D.G., Baird D.J., Jardine T.D., Orlofske J.M. (2019). Enhancing bioassessment approaches: Development of a river services assessment framework. Freshwater Science, 38(1) 12-22.

There has been a trend toward increasing anthropocentrism in definitions of river health through the explicit inclusion of societal valuation of ecosystem services provided by rivers. New frameworks and associated indicators of river health are therefore required to centralize ecosystem services within river assessment and management activities. Here, we adopt an anthropocentric conceptualization of rivers to focus on a river’s ability to maintain ecological function and structure that support ecosystem services valued by society. We apply this approach to further existing conceptual models of river assessment by identifying how benthic indicators can be linked to valued ecosystem services in a river services assessment framework. This approach extends bioassessment from a focus on assessing departure from reference condition to also include the evaluation of rivers based on their delivery of ecosystem services. Indicators based on benthic processes and assemblages are widely used in river health assessments; thus, these are reviewed to identify those indicators most closely linked with the provision of river ecosystem services. Finally, we illustrate how our approach can be applied to management through contrasting watershed examples, including a highly modified agricultural region and relatively pristine Arctic watersheds. The proposed approach supports an explicit connection between valued ecosystem services and benthic indicators, providing more targeted assessment results for use in river management decision-making.
Zhang J., Knight R., Wang Y., Sawyer T.W., Martyniuk C.J., Langlois V.S. (2019). Hair follicle miRNAs: a novel biomarker for primary blast Induced-Mild traumatic brain injury. Biomarkers, 24(2) 166-179.

Context: Due to the wide use of improvised explosive devices during modern warfare, primary blast-derived mild traumatic brain injury (mTBI) has become a major medical condition in the military. With minimal visually identifiable symptoms, an effective molecular biomarker system is desirable. Objective: We assessed the potential of mammalian hair follicle miRNAs as an mTBI biomarker. Materials and methods: Due to their well-established roles in mTBI molecular pathology, the expression level of miR-183, miR-26a, miR-181c, miR-29a, miR-34a and miR-27b was determined using qRT-PCR in whisker hair follicles from rats subject to head-only exposure to a single-pulse shock wave. Based on established transcriptomics profiles, sub-network enrichment analysis (SNEA) was also conducted. Results: The results revealed that molecular networks involving miR-183, miR-26a and miR-181c were enriched in multiple treatments, whereas sub-networks of miR-29a, miR-34a and miR-27b were unique to individual exposure groups. Discussion: Our study showed that all six miRNAs were reflective of the mTBI signature involved in cellular responses. Noteworthy was that the decrease in the transcript levels of miR-181c was correlated with shockwave exposure severity. Conclusion: This study demonstrates for the first time that mammalian hair follicles are capable of housing miRNA biomarkers for TBI.
Ahonen S.A., Hayden B., Leppänen J.J., Kahilainen K.K. (2018). Climate and productivity affect total mercury concentration and bioaccumulation rate of fish along a spatial gradient of subarctic lakes. Science of the Total Environment, 637-638 1586-1596.

Climate change is resulting in increased temperatures and precipitation in subarctic regions of Europe. These changes are extending tree lines to higher altitudes and latitudes, and enhancing tree growth enabling intensification of forestry into previously inhospitable subarctic regions. The combined effects of climate change and land-use intensification extend the warm, open-water season in subarctic lakes and increase lake productivity and may also increase leaching and methylation activity of mercury within the lakes. To assess the joint effects of climate and productivity on total mercury (THg) bioaccumulation in fish, we conducted a space-for-time substitution study in 18 tributary lakes of a subarctic watercourse forming a gradient from cold pristine oligotrophic lakes in the northern headwaters to warmer and increasingly human-altered mesotrophic and eutrophic systems in the southern lower reaches. Increasing temperature, precipitation, and lake productivity were predicted to elevate length- and age-adjusted THg concentrations, as well as THg bioaccumulation rate (the rate of THg bioaccumulation relative to length or age) in muscle tissue of European whitefish (Coregonus lavaretus), vendace (Coregonus albula), perch (Perca fluviatilis), pike (Esox lucius), roach (Rutilus rutilus) and ruffe (Gymnocephalus cernua). A significant positive relationship was observed between age-adjusted THg concentration and lake climate-productivity in vendace (r2 = 0.50), perch (r2 = 0.51), pike (r2 = 0.55) and roach (r2 = 0.61). Higher climate-productivity values of the lakes also had a positive linear (pike; r2 = 0.40 and whitefish; r2 = 0.72) or u-shaped (perch; r2 = 0.64 and ruffe; r2 = 0.50) relationship with THg bioaccumulation rate. Our findings of increased adjusted THg concentrations in planktivores and piscivores reveal adverse effects of warming climate and increasing productivity on these subarctic fishes, whereas less distinct trends in THg bioaccumulation rate suggest more complex underlying processes. Joint environmental stressors such as climate and productivity should be considered in ongoing and future monitoring of mercury concentrations.
Andrews S.N., Wallace B., Gautreau M., Linnansaari T., Curry R.A. (2018). Seasonal movements of striped bass Morone saxatilis in a large tidal and hydropower regulated river. Environmental Biology of Fishes, 101(10) 1549-1558.

Following a failed spawning event in 1975 and the suspected absence of recent spawning by Striped Bass Morone saxatilis in the Saint John River, New Brunswick, the native Striped Bass population has been considered extirpated. Non-native migratory Striped Bass, however, still frequent the river, and a remnant, likely native, population may still exist. To characterize the movements and habitat use of adult Striped Bass still arriving to, and possibly residing within the Saint John River, Striped Bass (n = 40, size range, 40.5–90.9 cm FL) were captured throughout 2010–13 in the lower Saint John River, and surgically implanted with multi-year acoustic transmitters. Striped Bass were passively tracked using an array of 5–33 project specific receivers between 2010 and 14 and augmented by detections from the Ocean Tracking Network from 2011 to 13. Most tag detections recorded during the predicted spawning period occurred near locations suspected to have supported Striped Bass spawning historically. Only six tagged fish (15% of total) were detected outside of the river, five of which only left the river briefly during the spawning period and then returned. Tagged Striped Bass used four overwintering sites within the Saint John River to which individuals demonstrated annual fidelity. Our findings suggest the presence of a local, possibly reproducing Striped Bass population that exhibits multi-annual residency within the river; however, successful spawning remains to be confirmed.
Andrews S.N., Zelman K., Ellis T., Linnansaari T., Curry R.A. (2018). Diet of Striped Bass and Muskellunge Downstream of a Large Hydroelectric Dam: A Preliminary Investigation into Suspected Atlantic Salmon Smolt Predation. North American Journal of Fisheries Management, 38(3) 734-746.

Top predators, such as the Striped Bass Morone saxatilis and Muskellunge Esox masquinongy, can impact food webs and alter ecosystem structure through the regulation of prey populations. Within the Saint John River, New Brunswick, Canada, both predators have long been hypothesized to impart significant mortality on smolts of the endangered Atlantic Salmon Salmo salar. As a consequence, current management practices entail euthanizing Muskellunge (an introduced species) that enter fish passage facilities along the Saint John River. Furthermore, the recovery and protection of a native Striped Bass population have largely been ignored. To assess seasonal diet, gastric lavage was performed on Striped Bass (n = 244) and Muskellunge (n = 96) captured in the downstream proximity of the Mactaquac Dam from April to November 2016. Clupeids dominated the stomach contents by number (92% for Striped Bass; 49% for Muskellunge) and mass (71% for Striped Bass; 96% for Muskellunge). Other prey species included White Perch Morone americana, Yellow Perch Perca flavescens, American Shad Alosa sapidissima, and American Eels Anguilla rostrata. No Atlantic Salmon smolts or other regionally recognized recreational fish species were identified in any of the stomach samples (n = 340) examined. Concurrently, this study observed little temporal overlap between the smolt migratory period and the arrival of Striped Bass to the Mactaquac Dam. Some Striped Bass (n = 33) were observed to be in spawning condition, releasing eggs and milt when handled, although reproduction by this species in the Saint John River was thought to have ceased long ago.
Boudreault M., Koiter A.J., Lobb D.A., Liu K., Benoy G., Owens P.N., Danielescu S., Li S. (2018). Using colour, shape and radionuclide fingerprints to identify sources of sediment in an agricultural watershed in Atlantic Canada. Canadian Water Resources Journal, 43(3) 347-365.

Information on the sources of sediment is required both for the targeting, development and implementation of best management practices (BMPs) in agricultural regions and for understanding the nature of sediment dynamics within watersheds. Investigations have shown that a number of physical and biogeochemical sediment properties can be used as fingerprints to trace sediment back to its source. Three groups of fingerprints–spectral reflectance (colour), particle morphology (size and shape), and fallout radionuclides (137Cs)–were used to fingerprint the sources of sediment in a predominantly agricultural watershed (14.5 km2) in Atlantic Canada over a 7-year period. Both spectral reflectance and fallout radionuclides were successful in discriminating between sources of sediment identified within the watershed. In contrast, fingerprints based on particle morphology were not able to discriminate between any of the sources of sediment. A composite fingerprint including both spectral reflectance and radionuclide fingerprints was used to estimate the relative contributions from agricultural topsoil (i.e. rill and inter-rill erosion), agricultural subsurface (i.e. streambank and gully erosion) and forested areas. Sediment fingerprinting indicated that topsoil derived from agricultural land was the greatest contributor (77.2%; 95% credible interval (CI<inf>95%</inf>) [35.5, 92.5]) to suspended sediment collected at the outlet of the watershed. Streambanks and gullies within agricultural areas were also identified as important sources of sediment (17.4%; CI<inf>95%</inf> [3.1, 46.9]), while forested land was a minor source of sediment in the watershed (3.2%; CI<inf>95%</inf> [0.2, 18.9]). The fingerprinting results demonstrate that BMPs that target soil erosion in agricultural fields will result in the greatest reduction in the export of sediment from the watershed. This study also established that adjusting the spatial scale at which suspended sediment samples are collected would provide more detailed information on the location of the sources of sediment (i.e. identify sources at the sub-watershed level) and lead to better targeting of BMPs.
Bruce M., Linnansaari T., Allen Curry R. (2018). First record of Eurasian Water-milfoil, Myriophyllum spicatum, for the Saint John River, New Brunswick. Canadian Field Naturalist, 132(3) 231-237.

Eurasian Water-milfoil (Myriophyllum spicatum L.) is regarded by conservation practitioners as one of the most challenging invasive aquatic plants to manage. Owing to its broad tolerance to environmental conditions, vegetative propagation, and rapid establishment and growth, M. spicatum introductions have the potential to drastically alter macrophyte species assemblages via a loss of native species and their respective ecosystem functions. Following the discovery of a single specimen of M. spicatum in the Saint John River, near Fredericton, New Brunswick (Canada) we further investigated the localized distribution of this non-indigenous species. Thirteen areas were identified as potential M. spicatum habitat and were surveyed by wading or snorkeling. Specimens of M. spicatum were collected and morphological identifications were verified through genetic analyses (ITS2; rbcLa). The results of our investigation confirm the presence of M. spicatum at six different locations within the Saint John River. Here we discuss the implications of this discovery in the context of the contiguous aquatic habitats along a large river system.
Chin A.T.M., Linke J., Boudreau M., Thériault M.H., Courtenay S.C., Cormier R., Fortin M.J. (2018). Beta diversity changes in estuarine fish communities due to environmental change. Marine Ecology Progress Series, 603 161-173.

Estuarine ecosystems are intrinsically resilient to the dynamic fluctuations of environmental conditions. Yet, it is unknown how the changes in environmental variability associated with climate change will affect fish communities. We assessed how species turnover over space and time in estuaries is influenced by changes in environmental conditions over years. We used fish abundances and water quality sampled at 42 stations among 7 estuaries in New Brunswick (Canada) from 2005 to 2012 to estimate (1) spatial turnover between stations based on the local contribution to beta diversity (LCBD) index, and (2) temporal turnover from year to year based on the β-Sørensen index. We found that beta diversity was potentially structured (i) over space due to inherent within-year differences in each estuary and (ii) over time related to the environmental condition of the previous year which led to changes in salinity, dissolved oxygen, and water temperature at sampling stations. Species contribution to spatial beta diversity (SCBD) was attributed across all years to 4 key species which were sensitive to dissolved oxygen. The current environmental condition of dissolved oxygen, temperature, salinity, and eelgrass Zostera marina affected temporal year-to-year turnover. When each year is analyzed separately, the estuaries with the greatest annual summer temperature fluctuations within a station contribute the most to spatial beta diversity between estuaries. Understanding how fish community structure responds to changes in environmental conditions can help inform the management of estuarine resources in the face of a rapidly changing environment.
Coffin M.R.S., Courtenay S.C., Knysh K.M., Pater C.C., van den Heuvel M.R. (2018). Impacts of hypoxia on estuarine macroinvertebrate assemblages across a regional nutrient gradient. Facets, 3(1) 23-44.

In this study, we examined the effects of dissolved oxygen, via metrics based on hourly measurements, and other environmental variables on invertebrate assemblages in estuaries spanning a gradient of nutrient loading and geography in the southern Gulf of St. Lawrence, Canada. Upper areas (15–25 practical salinity units (PSU)) of 13 estuaries that were dominated by either seagrass (Zostera marina Linnaeus, 1753) or macroalgae (Ulva spp. Linnaeus, 1753) were sampled from June to September 2013. Macroinvertebrate assemblages from Z. marina were found to be distinct from Ulva assemblages for both epifauna and infauna. Small snails dominated each vegetation type, specifically cerithids in Z. marina and hydrobids in Ulva. Although Z. marina had higher species richness, approximately 70% of species were common to both habitats. Faunal communities differed among estuaries with large, within-estuary, temporal variance only observed at Ulva sites impacted by hypoxia and particularly at sites with long water residence time. Indeed, abundances varied by several orders of magnitude in Ulva ranging from zero to thousands of macroinvertebrates. There was a strong negative correlation between hypoxic or anoxic water, 48 h prior to sampling, with relative abundances of amphipods, and a positive correlation with the relative abundances of snails. As one of the first studies to use high-frequency oxygen monitoring, this study revealed probable impacts and the transient nature of hypoxia in eutrophication.
Coffin M.R.S., Courtenay S.C., Pater C.C., van den Heuvel M.R. (2018). An empirical model using dissolved oxygen as an indicator for eutrophication at a regional scale. Marine Pollution Bulletin, 133 261-270.

Simple empirical models can sometimes capture salient patterns without sacrificing predictive capacity when compared to more complex models. Herein we examine dissolved oxygen as an indicator of eutrophication status for shallow estuaries. Dissolved oxygen was measured hourly in the upper estuary of 15 watersheds along a nutrient-loading and geographic gradient. Metrics describing hypoxia and supersaturation were devised and then analyzed using multivariate statistics. Results revealed independent responses for hypoxia and supersaturation with hypoxia-related metrics correlating strongly with water residence. A metric integrating hypoxia and supersaturation effectively discriminated between seagrass and algae-dominated habitats and was significantly correlated with both water residence and nitrate-N loading. Chlorophyll, measured bi-weekly, was not correlated with our predictor variables likely because it does not account for benthic production. Over 70% of the variability in hypoxia was explained by water residence and nitrate-N loading indicating that this model can be of use for managers.
Compson Z.G., Hungate B.A., Whitham T.G., Koch G.W., Dijkstra P., Siders A.C., Wojtowicz T., Jacobs R., Rakestraw D.N., Allred K.E., Sayer C.K., Marks J.C. (2018). Linking tree genetics and stream consumers: isotopic tracers elucidate controls on carbon and nitrogen assimilation. Ecology, 99(8) 1759-1770.

Leaf litter provides an important nutrient subsidy to headwater streams, but little is known about how tree genetics influence energy pathways from litter to higher trophic levels. Despite the charge to quantify carbon (C) and nitrogen (N) pathways from decomposing litter, the relationship between litter decomposition and aquatic consumers remains unresolved. We measured litter preference (attachments to litter), C and N assimilation rates, and growth rates of a shredding caddisfly (Hesperophylax magnus, Limnephilidae) in response to leaf litter of different chemical and physical phenotypes using Populus cross types (P. fremontii, P. angustifolia, and F<inf>1</inf> hybrids) and genotypes within P. angustifolia. We combined laboratory mesocosm studies using litter from a common garden with a field study using doubly labeled litter (13C and 15N) grown in a greenhouse and incubated in Oak Creek, Arizona, USA. We found that, in the lab, shredders initially chose relatively labile (low lignin and condensed tannin concentrations, rapidly decomposing) cross type litter, but preference changed within 4 d to relatively recalcitrant (high lignin and condensed tannin concentrations, slowly decomposing) litter types. Additionally, in the lab, shredder growth rates were higher on relatively recalcitrant compared to labile cross type litter. Over the course of a three-week field experiment, shredders also assimilated more C and N from relatively recalcitrant compared to labile cross type litter. Finally, among P. angustifolia genotypes, N assimilation by shredders was positively related to litter lignin and C:N, but negatively related to condensed tannins and decomposition rate. C assimilation was likewise positively related to litter C:N, and also to litter %N. C assimilation was not associated with condensed tannins or lignin. Collectively, these findings suggest that relatively recalcitrant litter of Populus cross types provides more nutritional benefit, in terms of N fluxes and growth, than labile litter, but among P. angustifolia genotypes the specific trait of litter recalcitrance (lignin or tannins) determines effects on C or N assimilation. As shredders provide nutrients and energy to higher trophic levels, the influence of these genetically based plant decomposition pathways on shredder preference and performance may affect community and food web structure.
Compson Z.G., Monk W.A., Curry C.J., Gravel D., Bush A., Baker C.J.O., Al Manir M.S., Riazanov A., Hajibabaei M., Shokralla S., Gibson J.F., Stefani S., Wright M.T.G., Baird D.J. (2018). Linking DNA Metabarcoding and Text Mining to Create Network-Based Biomonitoring Tools: A Case Study on Boreal Wetland Macroinvertebrate Communities. Advances in Ecological Research, 59 33-74.

Ecological networks are powerful tools for visualizing biodiversity data and assessing ecosystem health and function. Constructing these networks requires considerable empirical efforts, and this remains highly challenging due to sampling limitations and the laborious and notoriously limited, error-prone process of traditional taxonomic identification. Recent advancements in high-throughput gene sequencing and high-performance computing provide new ways to address these challenges. DNA metabarcoding, a method of bulk taxonomic identification from DNA extracted from environmental samples, can generate detailed biodiversity information through a standardizable analytical pipeline for species detection. When this biodiversity information is annotated with prior knowledge on taxon interactions, body size, and trophic position, it is possible to generate trait-based networks, which we call “heuristic food webs”. Although curating trait matrices for constructing heuristic food webs is a laborious, often intractable process using manual literature surveys, it can be greatly accelerated via text mining, allowing knowledge of relevant traits to be gathered across large databases. To explore this possibility, we employed a General Architecture for Text Engineering (GATE) system to create a hybrid text-mining pipeline combining rule-based and machine-learning modules. This pipeline was then used to query online repositories of published papers for missing data on a key trait, body size, that could not be gathered from existing trophic link libraries of freshwater benthic macroinvertebrates. Combining text-mined body size information with feeding information from existing sources allowed us to generate a database of over 20,000 pairwise trophic interactions. Next, we developed a pipeline that uses taxa lists generated from DNA metabarcoding and annotates this matrix with trophic information from existing databases and text-mined body size data. In this way, we generated heuristic food webs for wetland sites within a large delta complex formed by the confluence of the Peace and Athabasca rivers in northern Alberta: the Peace–Athabasca delta. Finally, we used these putative food webs and their network properties to resolve spatial and temporal differences between the benthic subwebs of wetlands in the Peace and Athabasca sectors of the delta complex. Specifically, we asked two questions. (1) How do food web properties (e.g. number of links, linkage density, trophic height) differ between the wetlands of the Peace and Athabasca deltas? (2) How do food web properties change temporally in wetlands of the two deltas? We discuss using DNA-generated, trait-based food webs as a powerful tool for rapid bioassessment, assess the limitations of our current approach, and outline a path forward to make this powerful tool more widely available for land managers and conservation biologists.
Connor S.J., Alexander-Trusiak A.C., Baird D.J. (2018). Vulnerability of diatom communities in the Peace-Athabasca Delta to environmental change. Peerj, 2018(8).

Habitat degradation associated with resource development is a major ecological concern, particularly in Canada's boreal zone where limited information on biodiversity is available. Habitat degradation can lead to reductions in biodiversity and ecosystem function, especially when drivers of variability and diversity patterns have not been identified for a region of interest. In this study, the distribution of diatom genera in the Peace-Athabasca Delta in northeastern Alberta was examined in relation to seasonal, geographic, and alkalinity gradients. Grab samples of six abiotic variables (total dissolved nitrogen, total dissolved phosphorus, dissolved iron, turbidity, pH, and specific conductance (SPC)) were taken from 12 remote wetlands over three sampling periods, and regressed against an ordination of diatom community composition to identify key environmental drivers of diatom community variation. Indirect gradient analysis identified two major gradients among sites. First, separation of sites among sampling periods showed successional seasonal changes in diatom community composition. Second, separation of sites from the Peace sub-delta and Birch sub-delta showed a gradient of geographic separation. Direct gradient analysis failed to explain the underlying drivers of these two gradients, but did show that alkalinity is a key driver of diatom community composition in the Embarras sub-delta, and that these sites could be particularly vulnerable to community changes associated with acidification.
Creed I.F., Bergström A.K., Trick C.G., Grimm N.B., Hessen D.O., Karlsson J., Kidd K.A., Kritzberg E., McKnight D.M., Freeman E.C., Senar O.E., Andersson A., Ask J., Berggren M., Cherif M., Giesler R., Hotchkiss E.R., Kortelainen P., Palta M.M., Vrede T., Weyhenmeyer G.A. (2018). Global change-driven effects on dissolved organic matter composition: Implications for food webs of northern lakes. Global Change Biology, 24(8) 3692-3714.

Northern ecosystems are experiencing some of the most dramatic impacts of global change on Earth. Rising temperatures, hydrological intensification, changes in atmospheric acid deposition and associated acidification recovery, and changes in vegetative cover are resulting in fundamental changes in terrestrial–aquatic biogeochemical linkages. The effects of global change are readily observed in alterations in the supply of dissolved organic matter (DOM)—the messenger between terrestrial and lake ecosystems—with potentially profound effects on the structure and function of lakes. Northern terrestrial ecosystems contain substantial stores of organic matter and filter or funnel DOM, affecting the timing and magnitude of DOM delivery to surface waters. This terrestrial DOM is processed in streams, rivers, and lakes, ultimately shifting its composition, stoichiometry, and bioavailability. Here, we explore the potential consequences of these global change-driven effects for lake food webs at northern latitudes. Notably, we provide evidence that increased allochthonous DOM supply to lakes is overwhelming increased autochthonous DOM supply that potentially results from earlier ice-out and a longer growing season. Furthermore, we assess the potential implications of this shift for the nutritional quality of autotrophs in terms of their stoichiometry, fatty acid composition, toxin production, and methylmercury concentration, and therefore, contaminant transfer through the food web. We conclude that global change in northern regions leads not only to reduced primary productivity but also to nutritionally poorer lake food webs, with discernible consequences for the trophic web to fish and humans.
Curry C.J., Gibson J.F., Shokralla S., Hajibabaei M., Baird D.J. (2018). Identifying north American freshwater invertebrates using DNA barcodes: Are existing COI sequence libraries fit for purpose? Freshwater Science, 37(1) 178-189.

We reviewed the availability of cytochrome c oxidase subunit I (COI) sequences for 2534 North American freshwater invertebrate genera in public databases (GenBank and Barcode of Life Data Systems) and assessed representation of genera commonly encountered in the Canadian Aquatic Biomonitoring Network (CABIN) database. COI sequence records were available for 61.2% of North American genera and 72.4% of Insecta genera in public databases. Mollusca (73.9%) and Nematoda (15.4%) were the best and worst represented groups, respectively. In CABIN, 85.4% of genera had COI sequence records, and 95.2% of genera occurring in >1% of samples were represented. Genera absent from CABIN tended to be uncommon or members of groups not routinely used for biomonitoring purposes. On average, 94.1% of genera in well-identified samples had associated sequence data. To leverage the full potential of genomics approaches, we must expand DNA-barcode reference libraries for poorly described components of freshwater food webs. Some genera appear to be well represented (e.g., Eukiefferiella), but deposited sequences represent few sampling localities or few species and lead to underestimation of sequence diversity at the genus level and reduced confidence in identifications. Public COI libraries are sufficiently populated to permit routine application of genomics tools in biomonitoring, and ongoing quality assurance/quality control should include re-evaluation as new COI reference sequences are added or taxonomic hierarchies change. Next, we must understand whether and how established biomonitoring approaches can capitalize on high-throughput sequencing tools. Biomonitoring approaches that use genomics data to facilitate structural and functional assessments are fertile ground for future investigation and will benefit from continued improvement of publicly available sequence libraries.
Danielescu S., MacQuarrie K.T.B., Popa A. (2018). SEPHYDRO: A Customizable Online Tool for Hydrograph Separation. Groundwater, 56(4) 589-593.
Dansie A.P., Thomas D.S.G., Wiggs G.F.S., Munkittrick K.R. (2018). Spatial variability of ocean fertilizing nutrients in the dust-emitting ephemeral river catchments of Namibia. Earth Surface Processes and Landforms, 43(3) 563-578.

Research into global hot spots of dust emission has focused on exposed fine-grained sediments in palaeo- or ephemeral dryland lake basins including Etosha (Namibia) and Makgadikgadi (Botswana) in southern Africa. Namibia's western ephemeral river valleys are also known to produce dust but have remained largely overlooked as a regionally significant source. Nutrient enrichment of valley sediments and proximity to the South Atlantic suggests aeolian dust could play an important role in ocean fertilization. The fertility of valley dust is dependent on fluvial sediments originating in the upper catchments on the Southern African Central Plateau. In this study we investigate climate, geology, vegetation and land use variability and how these may influence the nitrogen, phosphorus and iron availability in the catchments. We intensely sampled the Huab, Kuiseb and Tsauchab river systems to map the spatial distribution of nutrients from upper catchments to river termini. Samples were analysed for the bioavailable fractions of iron, nitrogen and phosphorus as well as total nitrogen and phosphorus. Results show that the lower valley reaches are sources of aeolian dust enriched in nutrients. Nitrogen levels correlate with precipitation and vegetation levels and phosphorus levels with geology. However, differences in upper catchment sediment nutrient levels were not representative of downstream nutrient differences between valleys. Rather, it is the hydrological and geomorphological processes of the ephemeral river systems that are key for producing the enriched sediments in the lower reaches. We demonstrate that the ephemeral river valleys of western Namibia are an extensive and enriched source of mineral dust that could play a critical role in marine productivity of the southern Atlantic. © 2017 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.
Debertin A.J., Hanson J.M., Courtenay S.C. (2018). Linking zooplankton assemblages with oceanographic zones in an atlantic coastal ecosystem. Canadian Journal of Fisheries and Aquatic Sciences, 75(6) 868-882.

Shallow (5-35 m depth) coastal waters, with their proximity to human populations, are likely to experience greater changes to ecosystem structure and functions from climate change and human impacts than offshore waters. Concerns of declining fisheries landings and deteriorating habitat quality in Northumberland Strait led to an assessment by Fisheries and Oceans Canada of the state of the environment and biota including zooplankton during the summer. In this paper we describe spatial structure of zooplankton (three distinct assemblages) and determined that two oceanographic zones can explain the spatial variation. Using distance-based linear models, bottom water temperature and surface water salinity explained 16% to 25% of the variation in zooplankton composition for each year of the survey. We used retrospective analyses to estimate what the zooplankton assemblage may have resembled in the early 1990s from data of oceanographic conditions. Given the prediction of warming oceans by the Intergovernmental Panel on Climate Change, we provide a means of predicting zooplankton composition and their distribution, with implications for the planktivorous fishes that prey upon them.
DesRoches A.J., Butler K.E., MacQuarrie K.T.B. (2018). Surface self-potential patterns related to transmissive fracture trends during a water injection test. Geophysical Journal International, 212(3) 2047-2060.

Variations in self-potential (SP) signals were recorded over an electrode array during a constant head injection test in a fractured bedrock aquifer. Water was injected into a 2.2 m interval isolated between two inflatable packers at 44 m depth in a vertical well. Negative SP responses were recorded on surface corresponding to the start of the injection period with strongest magnitudes recorded in electrodes nearest the well. SP response decreased in magnitude at electrodes further from the well. Deflation of the packer system resulted in a strong reversal in the SP signal. Anomalous SP patterns observed at surface at steady state were found to be aligned with dominant fracture strike orientations found within the test interval. Numerical modelling of fluid and current flow within a simplified fracture network showed that azimuthal patterns in SP are mainly controlled by transmissive fracture orientations. The strongest SP gradients occur parallel to hydraulic gradients associated with water flowing out of the transmissive fractures into the tighter matrix and other less permeable cross-cutting fractures. Sensitivity studies indicate that increasing fracture frequency near the well increases the SP magnitude and enhances the SP anomaly parallel to the transmissive set. Decreasing the length of the transmissive fractures leads to more fluid flow into the matrix and into cross-cutting fractures proximal to the well, resulting in a more circular and higher magnitude SP anomaly. Results from the field experiment and modelling provide evidence that surface-based SP monitoring during constant head injection tests has the ability to identify groundwater flow pathways within a fractured bedrock aquifer.
Dugdale S.J., Allen Curry R., St-Hilaire A., Andrews S.N. (2018). Impact of Future Climate Change on Water Temperature and Thermal Habitat for Keystone Fishes in the Lower Saint John River, Canada. Water Resources Management, 32(15) 4853-4878.

Water temperature is a key determinant of biological processes in rivers. Temperature in northern latitude rivers is expected to increase under climate change, with potentially adverse consequences for cold water-adapted species. In Canada, little is currently known about the timescales or magnitude of river temperature change, particularly in large (≥104 km2) watersheds. However, because Canadian watersheds are home to a large number of temperature-sensitive organisms, there is a pressing need to understand the potential impacts of climate change on thermal habitats. This paper presents the results of a study to simulate the effects of climate change on the thermal regime of the lower Saint John River (SJR), a large, heavily impounded, socio-economically important watershed in eastern Canada. The CEQUEAU hydrological-water temperature model was calibrated against river temperature observations and driven using meteorological projections from a series of regional climate models. Changes in water temperature were assessed for three future periods (2030–2034, 2070–2074 and 2095–2099). Results show that mean water temperature in the SJR will increase by approximately ~1 °C by 2070–2074 and a further ~1 °C by 2095–2099, with similar findings for the maximum, minimum and standard deviation. We calculated a range of temperature metrics pertaining to the Atlantic Salmon and Striped Bass, key species within the SJR. Results show that while the SJR will become increasingly thermally-limiting for Atlantic Salmon, the Striped Bass growth season may actually lengthen under climate change. These results provide an insight into how climate change may affect thermal habitats for fish in eastern Canadian rivers.
Erdozain M., Kidd K., Kreutzweiser D., Sibley P. (2018). Linking stream ecosystem integrity to catchment and reach conditions in an intensively managed forest landscape. Ecosphere, 9(5).

Forests are vital to maintaining headwater stream integrity in forested biomes, which ensures the delivery of aquatic ecosystem services downstream. Forest harvesting, however, can alter land–water linkages and compromise stream integrity. Historically, the main effects of forestry on streams have been documented by studies that used relatively few (mainly abiotic) indicators and which focused on single harvesting events. However, forest management is expected to intensify in the future to meet increasing global wood demand and it is likely that our present understanding does not adequately capture the cumulative effects that streams will be subjected to under intensive forest management. To address this, we assessed the effects of varying forest management intensities on the integrity of 15 forest headwater streams in northwestern New Brunswick, Canada. We used a comprehensive approach to link multiple biotic and abiotic indicators of stream ecosystem integrity to reach- and catchment-level characteristics including forest management (e.g., cumulative harvesting over time, road density, forest condition). Most indicators detected the gradient in forest management intensity with abiotic indicators responding most strongly. Streams in catchments with highest management intensity (especially road density) tended to have higher fine inorganic sediment deposition and entrainment, water cations and carbon, dissolved organic matter humification, and water temperature. These abiotic differences were associated with higher biofilm biomass and shredder densities, but lower leaf decomposition. Evidence from our multi-indicator approach elucidated a potential effects pathway of higher inorganic sediment content in biofilms of organic matter potentially limiting or altering its use by microbial and benthic macroinvertebrate (BMI) communities and resulting in reduced leaf decomposition rates. Overall, this study shows that current best management practices in an intensively managed watershed (and legacy effects from past management such as older road systems) do not fully protect against an increased delivery of terrestrial materials to streams with resulting habitat and biotic changes, but that they are mostly effective at preventing the impairment of BMI communities.
Espejo W., Kitamura D., Kidd K.A., Celis J.E., Kashiwada S., Galbán-Malagón C., Barra R., Chiang G. (2018). Biomagnification of Tantalum through Diverse Aquatic Food Webs. Environmental Science and Technology Letters, 5(4) 196-201.

Tantalum (Ta) is a technology-critical element (TCE) that is growing in global demand because of its use in electronic and medical devices, capacitors, aircraft, and hybrid cars. Despite its economic relevance, little is known about its environmental concentrations and the trophodynamics of Ta in aquatic food webs have not been studied. Invertebrates and fishes from coastal marine food webs representing different climatic zones in northwestern Chile, western Chilean Patagonia, and the Antarctic Peninsula were sampled and analyzed for Ta. The trophic level (TL) of species was assessed with nitrogen stable isotopes (δ15N), and carbon stable isotopes (δ13C) were used to trace energy flow in the food webs. Levels of Ta varied among taxa and sites, with the highest values found in fishes (0.53-44.48 ng g-1dry weight) and the lowest values found in invertebrates (0.11-7.80 n ng g-1dry weight). The values of δ13C ranged from -11.79 to -25.66 ‰. Ta biomagnified in all four aquatic food webs, with slopes of log Ta versus TL ranging from 0.16 to 0.60. This has important implications as little is known about its potential toxicity and there may be increased demand for TCEs such as Ta in the future.
Espejo W., Padilha J.d.A., Kidd K.A., Dorneles P.R., Barra R., Malm O., Chiang G., Celis J.E. (2018). Trophic transfer of cadmium in marine food webs from Western Chilean Patagonia and Antarctica. Marine Pollution Bulletin, 137 246-251.

In aquatic environments, Cd contamination is a great concern because this non-essential metal presents risks both for wildlife and human health. Data about the concentration and transfer of Cd in Patagonian and Antarctic aquatic food webs are crucial for assessing the impacts of this element in pristine ecosystems. Consequently, the concentration of Cd was measured in thirty-two species collected in the 2014 austral summer from two locations of the Western Patagonia and two locations of the Antarctic Peninsula. The main objective of this work was to assess the relationship between Cd concentration and trophic level determined by δ15N. In the studied trophic positions, Cd showed a positive relationship between concentration and trophic level, which suggests biomagnification of this element in macroinvertebrates. However, there was a significant dilution when higher trophic organisms were considered.
Gaillard M., Pavey S.A., Bernatchez L., Audet C. (2018). River-Specific Gene Expression Patterns Associated with Habitat Selection for Key Hormone-Coding Genes in Glass Eel-Stage American Eels. Transactions of the American Fisheries Society, 147(5) 855-868.

The glass eel stage of the American Eel Anguilla rostrata marks the onset of the catadromous migration into estuarine or freshwater habitats, and the endocrine mechanisms underlying this habitat selection are still not well understood. Using a candidate genes approach, the aim of this study was to test for different patterns of gene expression related to (1) salinity preferences and/or (2) capture site to predict physiological differences between migratory behaviors. We performed analyses revealing the expression of genes coding for key hormonal factors or their receptors on glass eel-stage American Eels collected at the mouths of three rivers on the east coast of Canada (Grande-Rivière-Blanche, St. Lawrence estuary; Rivière-Saint-Jean, Gaspé Peninsula; and the Mersey River, Nova Scotia); eels from the three systems displayed different salinity preferences (brackish water/salt water/freshwater) under laboratory conditions. Transcripts from genes coding for prolactin (PRL), thyroid-stimulating hormone β subunit, type-2 iodothyronine deiodinase (DIO-2), thyroid hormone receptors α<inf>a</inf> and α<inf>b</inf> (THRα<inf>a</inf> and THRα<inf>b</inf>), growth hormone (GH), insulin-like growth factor 1 (IGF-1), and their respective receptors (GH-R<inf>1</inf> and IGF-1R) were all detected in glass eels. No differences in the expression patterns were detected pertaining to salinity preference, but strong differences were found among rivers. Rivière-Saint-Jean glass eels, which were the longest and the least pigmented among the three rivers, were characterized by the highest expression of PRL, DIO-2, and THRα<inf>b</inf>. Those from Grande-Rivière-Blanche showed an increase in IGF-1R. Glass eels captured from these two rivers also exhibited the highest expression of GH and GH-R<inf>1</inf>. Overall, these results confirm gene × environment interactions at the gene expression level when glass eels settle into their continental habitat. As such, our results also support the concept of the presence of different ecotypes in the Atlantic Canadian coast and in the estuary and Gulf of St. Lawrence.
Gibson C.A., Koch B.J., Compson Z.G., Hungate B.A., Marks J.C. (2018). Ecosystem responses to restored flow in a travertine river. Freshwater Science, 37(1) 169-177.

Disruptions of natural flow impair rivers and streams worldwide. Those conducting restoration efforts have rarely explored how and when stream ecosystems can recover after reinstating natural flows. We quantified responses of ecosystem metabolism and N dynamics to the decommissioning and removal of a 100-y-old diversion dam in a desert stream, Fossil Creek, Arizona. Fossil Creek is a travertine river, meaning that CaCO<inf>3</inf> concentrations in water in the springs that feed Fossil Creek are high enough to precipitate out of the water to form travertine terraces and deep pools. The majority of flow was diverted for power generation, so travertine deposition rates were significantly reduced and travertine terraces were smaller and less frequent compared to pre-dam historical records. Flow restoration enabled the recovery of the geochemical process of travertine deposition and increased gross primary production and N uptake to rates comparable to those measured in an upstream, reference reach. Reinstating a river's natural flow regime can result in rapid and near-complete recovery of fundamental ecosystem processes that reshape the aquatic food web.
González-Sansón G., Aguilar-Betancourt C.M., Kosonoy-Aceves D. (2018). Influence of sediment granulometry and salinity on the composition of an estuarine fish assemblage in the Mexican Tropical Pacific. Revista De Biologia Tropical, 66(3) 1065-1077.

Barra de Navidad lagoon (BNL) is one of the main coastal wetlands in the coast of the State of Jalisco, Mexico. It is a Ramsar site (wetland of international importance) and has been included among the 81 mangrove sites with biological relevance and ecological rehabilitation needs in Mexico. Although fish fauna composition is well known in BNL, little evidence exists that support seasonal and spatial changes of fish assemblages’ structure. The hypothesis tested in this study was that there are significant seasonal and spatial changes in BNL fish assemblages’ composition which can be explained, at least partially, by changes in salinity, water temperature and sediment’s granulometry. Fish assemblages were sampled monthly from October 2012 to September 2013 at four zones of BNL, using gill nets (7.62 mm stretched mesh). A sample was taken every month in a randomly selected area of each zone. Prior to each sampling operation, water salinity and temperature were measured using an YSI-30 probe. Samples of sediment were collected with a Van Veen grab sampler in three randomly selected points of each zone for granulometry and organic matter analyses. A total of 2 026 individuals belonging to 48 species were collected. Slightly more than 90% of all caught fish belonged to nine species: Peruvian mojarra (Diapterus brevirostris), Pacific crevalle-jack (Caranx caninus), White mullet (Mugil curema), Blue sea-catfish (Ariopsis guatemalensis), Oval flounder (Syacium ovale), Pacific lined sole (Achirus mazatlanus), Yellowfin mojarra (Gerres simillimus), Pacific bumper (Chloroscombrus orqueta) and Freckled porcupinefish (Diodon holocanthus). Generalized linear models yielded significant differences among zones for the mean abundance of each of these nine species, but only in two cases seasonal differences were significant (D. brevisrostris and C. caninus). Permutational multivariate analysis of variance yielded also significant differences among zones and between seasons for the composition of the fish assemblage. Redundancy analysis using salinity, temperature, and percentage mud in sediment as environmental variables showed that fish assemblage’s composition varies along two main gradients defined by mud fraction of sediments in a small spatial scale (~ 3 km) and salinity in a seasonal scale. Percentage of variation explained by canonical axes was less than 25%, indicating that other factors could be influencing changes in assemblage composition. As most species appear as juveniles in the lagoon, fluctuations in their abundances could be linked, at least partially, with recruitment events.
Gray M.A., Allen Curry R., Arciszewski T.J., Munkittrick K.R., Brasfield S.M. (2018). The biology and ecology of slimy sculpin: A recipe for effective environmental monitoring. Facets, 3(1) 103-127.

Recently, the use of small-bodied fish in environmental monitoring has increased, particularly within the Canadian environmental effects monitoring (EEM) and other adaptive programs. Although it is possible to measure changes with many small-bodied species, interpretation is often complicated by the absence of information on the biology and ecology of fish not of commercial, recreational, or traditional interest. Knowing and understanding the basic biology of these fishes aids in the sensitivity of study designs (i.e., ability to detect change) and the interpretation of all biological levels of responses (e.g., cellular to community). The increased use of slimy sculpin (Cottus cognatus Richardson, 1836) in impact assessment studies in North America provides a considerable amount of information on life history aspects. The slimy sculpin has the most ubiquitous North American distribution among cottids but yet has a very small home range, thus integrating environmental conditions of localized areas. This paper describes aspects of slimy sculpin life cycle that affect collection efficiency and timing, and describes and provides data collected over more than 10 years of studies at more than 20 reference study sites. This overview provides a functional and informative compilation to support adaptive environmental monitoring and provide a baseline for comparative ecological study.
Grimstead J.P., Krynak E.M., Yates A.G. (2018). Scale-specific land cover thresholds for conservation of stream invertebrate communities in agricultural landscapes. Landscape Ecology, 33(12) 2239-2252.

Context: In agricultural landscapes, riparian forests are used as a management tool to protect stream ecosystems from agricultural activities. However, the ability of managers to target stream protection actions is limited by incomplete knowledge of scale-specific effects of agriculture in riparian corridor and catchment areas. Objectives: We evaluated scale-specific effects of agricultural cover in riparian corridor and catchment areas on stream benthic macroinvertebrate (BMI) communities to develop cover targets for agricultural landscapes. Methods: Sixty-eight streams assigned to three experimental treatments (Forested Riparian, Agricultural Riparian, Agricultural Catchment) were sampled for BMIs. Ordination and segmented regression were used to assess impacts of agriculture on BMI communities and detect thresholds for BMI community metrics. Results: BMI communities were not associated with catchment agricultural cover where the riparian corridor was forested, but were associated with variation in catchment agriculture where riparian forests had been converted to agriculture. Trait-based metrics showed threshold responses at greater than 70% agricultural cover in the catchment. Increasing agriculture in the riparian corridor was associated with less diverse and more tolerant BMI communities. Eight metrics exhibited threshold responses ranging from 45 to 75% agriculture in the riparian corridor. Conclusions: Riparian forest effectively buffered streams from agricultural activity even where catchment agriculture exceeds 80%. We recommend managers prioritize protection of forested riparian corridors and that restore riparian corridors where agricultural cover is near identified thresholds be a secondary priority. Adoption of catchment management actions should be effective where the riparian corridor has been converted to agriculture.
Ho E. (2018). Criteria-based ranking (CBR): A comprehensive process for selecting and prioritizing monitoring indicators. Methodsx, 5 1324-1329.

Resources allocated to natural resource management often fluctuate, requiring the types and numbers of parameters used in monitoring programs (e.g., indicators of ecosystem health) to be frequently reassessed. Conventional approaches to selecting monitoring indicators are often biased and non-inclusive. A new Criteria-based Ranking (CBR) process for selecting and/or prioritizing indicators was tested in the Muskoka River Watershed (Ontario, Canada). The CBR process is based on two environmental assessment tools, Simple Weighted and Leopold matrices. It incorporates environmental components and criteria for assessing each indicator, which generate a score per indicator. The process tested in this study was concluded to be an effective way to prioritize and/or select environmental monitoring indicators. A different set of indicators emerged when a common set of criteria was used to assess monitoring indicators. Benefits of the CBR process include: • Standardization of indicator selection process with less bias and lower cost (e.g., time and human resources).• Indicators that are representative of the community and more relevant for decision-making (e.g., more resilient to socio-political change).• Adaptability: (1) to other goals, e.g., selecting from a list of Valued Ecosystem Components (VECs), and (2) to any context through localized scoring criteria. Easily integrated into existing practice.
Ho E., Eger S., Courtenay S.C. (2018). Assessing current monitoring indicators and reporting for cumulative effects integration: A case study in Muskoka, Ontario, Canada. Ecological Indicators, 95 862-876.

Climate is changing at an unprecedented rate with impacts being felt in social and ecological systems around the world. Opportunities for building climate resilience of the social-ecological system surrounding freshwater areas are assessed using the aquatic monitoring and reporting programs of Muskoka River Watershed (Ontario, Canada) as a case study. A three-step study design was used: establishment of a knowledge baseline (i.e., what has been done), confirmation of the baseline to ensure perspectives that emerged were inclusive of multiple stakeholders (i.e., broadly applicable) and an exploratory workshop to disseminate recommendations and discuss implementation with key stakeholders. Two themes are discussed: the strengthening of watershed-scale monitoring approaches, and improved communication with stakeholders (e.g., through ‘state of the watershed’ reporting). This study offers an evaluation of watershed-scale aquatic monitoring and reporting and provides concrete examples from the case study. We test a new process for refining, selecting, or prioritizing indicators for aquatic monitoring. Cumulative effects assessment and monitoring (CEAM) is considered as the suggested monitoring approach at a watershed-scale. Recommendations for developing CEAM in the Muskoka River Watershed include considerations for selection of monitoring indicators, consistent communication of indicators, and implementing a metadatabase. Ways to enhance education of, and engagement with, local stakeholders through improved ‘state of the watershed’ report cards are highlighted. Resilience is strengthened by addressing two goals in the case study: engaging with the community and improving knowledge of stressor-effect relationships in the watershed via stronger aquatic monitoring.
Hogan N.S., Thorpe K.L., van den Heuvel M.R. (2018). Opportunistic disease in yellow perch in response to decadal changes in the chemistry of oil sands-affected waters. Environmental Pollution, 234 769-778.

Oil sands-affected water from mining must eventually be incorporated into the reclaimed landscape or treated and released. However, this material contains petrogenic organic compounds, such as naphthenic acids and traces of polycyclic aromatic hydrocarbons. This has raised concerns for impacts of oil sands process-affected waters on the heath of wildlife and humans downstream of receiving environments. The objective of this study was to evaluate the temporal association of disease states in fish with water chemistry of oil sands-affected waters over more than a decade and determine the pathogens associated with disease pathologies. Yellow perch (Perca flavescens) captured from nearby lakes were stocked into two experimental ponds during 1995–1997 and 2008–2010. South Bison Pond is a drainage basin that has received unextracted oil sands-contaminated material. Demonstration Pond is a constructed pond containing mature fine tailings capped with fresh water. Two disease pathologies, fin erosion for which a suspected bacterial pathogen (Acinetobacter Iwoffi) is identified, and lymphocystis (confirmed using a real-time PCR) were associated with oil sands-affected water exposure. From 1995 to 1997 pathologies were most prevalent in the South Bison Pond; however, from 2008 to 2009, disease was more frequently observed in the Demonstration Pond. CYP1A activity was 3–16 fold higher in fish from experimental ponds as compared to reference populations and this pattern was consistent across all sampling years. Bile fluorescence displayed a gradient of exposure with experimental ponds being elevated over local perch populations. Naphthenic acids decreased in the Bison Pond from approximately 12 mg/L to <4 mg/L while naphthenic acids increased in the Demonstration Pond from 6 mg/L to 12 mg/L due to tailings densification. Temporal changes in naphthenic acid levels, CYP1A activity and bile fluorescent metabolites correlate positively with incidence of disease pathologies whereas all inorganic water quality changes (major ions, pH, metals) were not associated with disease responses.
Izral N.M., Brua R.B., Culp J.M., Yates A.G. (2018). Developing metabolomics-based bioassessment: crayfish metabolome sensitivity to food and dissolved oxygen stress. Environmental Science and Pollution Research, 25(36) 36184-36193.

There is a need to develop bioassessment tools that can diagnose the effects of individual stressors that can have multiple ecological effects. Using nuclear magnetic resonance (NMR)-based metabolomics, our experiments aimed to identify the sensitivity of metabolites to changes in food availability and dissolved oxygen (DO) concentrations, and compare these results to identify metabolites that may differentiate between the effects of these two stressors. Forty-eight, laboratory-raised, red swamp crayfish (Procambarus clarkii) were randomly assigned and exposed to one of three food availability or DO treatment levels (high, normal, low). Starved crayfish had lower amounts of amino acids than fed crayfish, suggesting catabolic effects of starvation on tail muscle tissue for energy requirements. In contrast, crayfish exposed to hypoxic conditions experienced changes in abundance of metabolites primarily associated with energy metabolism. Tail muscle was the only tissue sensitive to food and DO stress, suggesting the need to select tissues for monitoring appropriately. Our evaluation of environmental metabolomics as a tool for bioassessment indicates that several identified metabolites in crayfish tail muscle may be able to diagnose food and oxygen stress. Further study is required to determine if these metabolic effects are linked with changes of individual fitness and higher levels of biological organization, such as population size.
Krynak E.M., Yates A.G. (2018). Benthic invertebrate taxonomic and trait associations with land use in an intensively managed watershed: Implications for indicator identification. Ecological Indicators, 93 1050-1059.

Expansion and intensification of human land uses has resulted in the loss of all but remnant areas of natural cover over increasingly vast areas of land. Effective stream assessment in these regions thus requires indicators sensitive to ecosystem change in systems that are already highly stressed. The goal of this study was to determine if benthic macroinvertebrate communities in streams exposed to extensive anthropogenic stress are associated with land-use variables and demonstrate potential to be used as bioindicators for assessment of further land use modification. Using the Grand River in southern Ontario as our model, we sampled for benthic macroinvertebrates in 70 small (3–20 km2) sub-watersheds that comprised a gradient of intensive land use (65–100% developed). Redundancy analysis and variance partitioning results indicated that macroinvertebrate taxonomy and traits were only weakly associated with environmental gradients with the strongest associations occurring at the reach scale. With strong anthropogenic filters present across the watershed, it is likely that the majority of benthic macroinvertebrate communities in the Grand River have experienced a homogenization towards tolerant taxa and traits that respond more to local habitat variables. Threshold Indicator Taxa Analysis (TITAN) revealed 19 valid taxa indicators and 32 valid trait indicators for one or more of six environmental variables (percent sub-watershed agriculture, percent buffer agriculture, pool substrate, sediment reduction, natural channel, and riparian width). However, individual taxon and community change points exhibited broad quantile scores indicating a gradual or random response to environmental variables. Comparison of traits and taxonomic associations with environmental variables showed minimal difference suggesting traits may not offer increased sensitivity to land-use stress. However, several traits did show potential to serve as diagnostic indicators for specific stressors associated with agricultural land use. Our ability to identify even a few indicators in a region with intensive human activity is promising for land managers charged with detecting biotic alterations in this stressed system. Further research developing indicators sensitive to intensification of anthropogenic stress in extensively developed landscapes is critical to ensuring managers have the tools needed to protect and enhance aquatic resources.
Landsman S.J., McLellan N., Platts J., van den Heuvel M.R. (2018). Nonsalmonid versus Salmonid Passage at Nature-Like and Pool-and-Weir Fishways in Atlantic Canada, with Special Attention to Rainbow Smelt. Transactions of the American Fisheries Society, 147(1) 94-110.

In recent years, fish passage efforts have begun shifting away from targeting salmonids and instead toward passing entire fish communities, including nonsalmonids. The objectives of this study were to evaluate the performance of a nature-like fishway and a pool-and-weir fishway at passing Rainbow Smelt Osmerus mordax (2014 and 2016) and Brook Trout Salvelinus fontinalis (2015 and 2016). Both fishways are located at the same dam on the Glenfinnan River, Prince Edward Island, Canada. Fish were PIT-tagged, and their movements were tracked using stationary PIT antennas. Results indicated that passage efficiency at the pool-and-weir fishway was 0% for Rainbow Smelt in both years. In contrast, 100% and 99.2% of Brook Trout passed the pool-and-weir fishway in 2015 and 2016, respectively. At the nature-like fishway, the highest passage efficiency measured for Rainbow Smelt was 28.6% (2016) and was not significantly different between years. In comparison, 100% and 91.7% of Brook Trout passed the nature-like fishway in 2015 and 2016, respectively. Additionally, attempts to improve attraction efficiency at the nature-like fishway by directing more water toward the fishway's entrance and removing instream debris were made in 2015, but attraction efficiency did not differ between 2014 and 2016. Finally, Rainbow Smelt were also observed spawning throughout the nature-like fishway. This study adds to the growing evidence that fishways designed specifically for salmonids can be inappropriate for nonsalmonids. Data indicate that although some passage of Rainbow Smelt was noted at the nature-like fishway relative to the pool-and-weir fishway, overall passage was low. Future efforts directed at improving passage should focus on adjusting the entrance location of the nature-like fishway. Despite low overall passage for Rainbow Smelt, the presence of spawning adults within the nature-like fishway suggests that the fishway itself provides suitable spawning habitat and that fishway performance evaluation should take this into consideration.
Landsman S.J., Samways K.M., Hayden B., Knysh K.M., Van Den Heuvel M.R. (2018). Assimilation of marine-derived nutrients from anadromous Rainbow Smelt in an eastern North American riverine food web: evidence from stable-isotope and fatty acid analysis. Freshwater Science, 37(4) 747-759.

Movement of anadromous fishes from marine to freshwater habitats provides a seasonal pulse of marine-derived nutrients (MDNs) to freshwater biota. In northeastern North America, iteroparous, anadromous Rainbow Smelt (Osmerus mordax Mitchell, 1814) migrate in high densities to freshwater spawning grounds in early spring. To assess whether 1) MDNs from migratory Rainbow Smelt were incorporated into multiple trophic levels and 2) total fatty acid (FA) compositions of Brook Trout changed during the Rainbow Smelt migration, we compared stable13C and15N isotope values and FA profiles of biota in the Pisquid River, Prince Edward Island, Canada. We sampled periphyton, benthic macroinvertebrates, and stream-resident Brook Trout (Salvelinus fontinalis Mitchell, 1814) at a downstream site encompassing Rainbow Smelt spawning grounds and an upstream site inaccessible to Rainbow Smelt. During the Rainbow Smelt migration at the downstream site, predatory caddisflies (Rhyacophilidae) and Brook Trout displayed a 3.1 and 1.3 increase in d13C and d15N, respectively, relative to isotope levels before the migration. Less consistent evidence of MDN assimilation was found in periphyton and nonpredatory macroinvertebrates (Heptageniidae, Elmidae). Increases in d13C values for Rhyacophilidae and Brook Trout indicated direct consumption of tissue, most probably eggs based on limited stomach content analysis in Brook Trout. FA composition differed between Rainbow Smelt and Brook Trout sampled down- and upstream. Transfer of marine x-3 FAs was evidenced by statistically similar amounts of eicosapentaenoic and docosahexaenoic acid between Rainbow Smelt and Brook Trout sampled on spawning grounds. We found connections between Rainbow Smelt-based MDNs and stream food webs and a nutritional benefit to Brook Trout.
Larabi S., St-Hilaire A., Chebana F. (2018). A new concept to calibrate and evaluate a hydrological model based on functional data analysis. Journal of Water Management Modeling, 2018.

Performance measures are widely used in hydrological modeling to provide objective evaluation of the match between simulated and observed system output (i.e. discharge). Each performance measure emphasises a particular aspect of a hydrograph, and the use of a particular performance measure on a specific metric typically means discounting one aspect at the expense of another (e.g. high flows vs low flows). This is mainly because most performance measures reflect the adequacy of simulations using one calculated value based on residuals between daily or hourly series of simulated and observed streamflows. However, it would be more practical to conserve the temporal flow variability of the entire annual hydrograph than to focus merely on flood peaks, for instance. Functional data analysis is a mathematical tool that allows the comparison of such data. In this paper, a methodology for model calibration and evaluation that considers an annual hydrograph as a single observation instead of 365 daily observations, based on functional data analysis, is proposed. The model is evaluated on its ability to reproduce the same shape and variability as the observed hydrographs. The functional statistics, defined for each time step, are used to construct the objective function for model calibration as well as for further model evaluation. A case study is presented to evaluate the hydrological CEQUEAU model on the Lac St-Jean drainage basin. The concept that we describe is general and can be used with any calibration scheme or model evaluation.
Larranaga N., Valdimarsson S.K., Linnansaari T., Steingrímsson S. (2018). Diel activity and foraging mode of juvenile Arctic charr in fluctuating water flow. River Research and Applications, 34(4) 348-356.

Streams fluctuate in water flow because of natural (e.g., rain) and human-induced events (e.g., hydropeaking). Magnitude, frequency, and predictability of these events can have drastic consequences for fish populations. We studied how rapid modifications of water flow affect diel activity and foraging mode of juvenile Arctic charr Salvelinus alpinus in stream enclosures exposed to either stable (intermediate) or fluctuating (low vs. high) water flow. Under stable conditions, Arctic charr showed limited activity (9.4%). In fluctuating water flow, charr increased activity during low flow periods, especially during the first hours after the flow decreased, but ceased activity almost completely at high flow. Charr were mostly nocturnal, and more nocturnal at low than intermediate water flow. Fish were more mobile and swam faster during prey search and attacked prey at longer distances at low water flow. Activity and foraging mode differed between the first and second day after reduced water flow, suggesting that Arctic charr require time to adjust their foraging behaviour. This study demonstrates the importance of behavioural flexibility for population ecology in fluctuating environments such as regulated rivers.
Leblanc N.M., Andrews S.N., Avery T.S., Puncher G.N., Gahagan B.I., Whiteley A.R., Curry R.A., Pavey S.A. (2018). Evidence of a Genetically Distinct Population of Striped Bass within the Saint John River, New Brunswick, Canada. North American Journal of Fisheries Management, 38(6) 1339-1349.

Sound management of a species requires, among other things, careful consideration of their distribution and genetic structure throughout their range. Historically, there were three spawning populations of Striped Bass Morone saxatilis occurring within the Bay of Fundy, Canada (Shubenacadie River, Annapolis River, and Saint John River), but today the only known spawning population is found in the Shubenacadie River, Nova Scotia. The last spawning event recorded (albeit unsuccessful) in the Saint John River was in 1975 shortly after the completion of the Mactaquac Dam in 1968. Adult Striped Bass from other rivers frequent the Saint John River during much of the year, making the presence of adults uninformative about the status of spawning. In the absence of direct indicators of spawning, such as eggs and larvae, genomic tools can provide insight into the genetic origin of the juvenile Striped Bass in the Saint John River. Tissue samples were taken from Striped Bass (ages 1–3; 12.2–35.0 cm TL) captured in the Saint John River and compared with samples from the Shubenacadie River, Hudson River, and Chesapeake Bay. A double-digest RAD-seq technique was used to identify 4,700 single nucleotide polymorphisms, and population structure was assessed using population differentiation statistics (F<inf>ST</inf>) and genetic clustering algorithms. The F<inf>ST</inf> analysis found significant differences among all sample sites, albeit weak differences between Hudson River and Chesapeake Bay samples, and a global F<inf>ST</inf> of 0.101. Genetic clustering analyses and discriminant analysis of principle components both grouped samples into three clusters: the Shubenacadie River, the U.S. populations, and the Saint John River juveniles. Based on these findings and the current understanding of Striped Bass juvenile dispersal, there is strong evidence of a genetically distinct population of Striped Bass within the Saint John River.
Levenstein B., Culp J.M., Lento J. (2018). Sediment inputs from retrogressive thaw slumps drive algal biomass accumulation but not decomposition in Arctic streams, NWT. Freshwater Biology, 63(10) 1300-1315.

Increasing rates of precipitation and higher air temperatures have increased the size and frequency of retrogressive thaw slumps—large depressions of thawed permafrost that form on the landscape—in north-western Canada. Many of these thaw slumps flow into nearby stream systems, leading to increased sediment, solute and nutrient loads. We evaluated the impacts of retrogressive thaw slumps on measurements of algal biomass accumulation and decomposition of organic materials in streams in the Peel Plateau, Northwest Territories. We predicted that increased sediment loads from thaw slumps would decrease algal standing stock and decomposition in thaw slump-impacted streams, overriding the potential positive effects of increased nutrient concentrations. Chl-a measurements were obtained as a proxy for algal standing stock from sites upstream and downstream of thaw slumps by performing algae scrapes and deploying artificial substrates in 2014. Cotton strips were deployed at upstream and downstream sites in 2013 and 2014, and tensile strength was measured to assess breakdown. Grab water samples were taken to measure physical and chemical parameters at each site. Thaw slumps increased total suspended solids, but not dissolved nutrients at downstream sites. Our results indicated a significant negative relationship between Chl-a and total suspended solids. Decomposition indicated a negative relationship with total suspended solids, but displayed much stronger positive relationships with temperature, pH and dissolved phosphorus. Our findings indicated that total suspended solids were a stronger driver of change in thaw slump-impacted stream reaches than nutrients, although nutrients may be more influential during the initiation of thaw slump disturbances. Algal biomass accumulation was found to be more sensitive to thaw slump impacts than decomposition, which may lead to a functional and structural shift in favour of allochthonous-based food webs over autochthonous ones at thaw slump-impacted stream reaches.
Loughery J.R., Kidd K.A., Mercer A., Martyniuk C.J. (2018). Part A: Temporal and dose-dependent transcriptional responses in the liver of fathead minnows following short term exposure to the polycyclic aromatic hydrocarbon phenanthrene. Aquatic Toxicology, 199 90-102.

Phenanthrene is a low molecular weight polycyclic aromatic hydrocarbon (PAH) that is composed of three fused benzene rings. PAHs are formed naturally through incomplete combustion of organic materials, and are environmental contaminants due to anthropogenic activities (e.g. oil extraction and refining, industrial and municipal effluents, fossil fuel burning). Fish exposed to PAHs such as phenanthrene have been reported to exhibit altered reproductive axis endpoints, however the mechanisms that underlie these responses are not fully characterized. To better understand effects at the mechanistic level, we applied transcriptomics to identify molecular pathways altered after acute exposure to phenanthrene on both a dose and temporal scale. Female fathead minnow (Pimephales promelas) were exposed to an average measured concentration of either 0, 29.8, 389 or 943 μg phenanthrene/L for 24, 48, and 72 h in a static-renewal bioassay. Ovaries were assessed for oocyte distribution as well as in vitro 17β-estradiol production and gene expression for transcripts related to steroidogenesis and estrogen signalling. In addition, the liver transcriptome was measured as this tissue is the primary source of the egg yolk precursor protein vitellogenin. Exposure to 29.8 μg phenanthrene/L increased proportions of the cortical alveolar stage in the ovaries after 48 h while the proportion of cortical alveolar oocyte were decreased in fish exposed to 943 μg phenanthrene/L for 48 h. Phenanthrene did not affect 17β-estradiol production at any time or dose, and did not affect transcripts associated with hormone synthesis nor signalling pathways. In the liver, the transcriptome showed fewer genes in common across time when compared to those transcripts affected by concentration at a single time point. Cholesterol metabolism was the only pathway perturbed in the liver following all comparisons in both the dose and time course experiments. Our data suggest that transcriptome networks associated with hepatic lipid metabolism are rapidly affected by phenanthrene, and this may indirectly reduce resources available for reproductive efforts.
Loughery J.R., Kidd K.A., Mercer A., Martyniuk C.J. (2018). Part B: Morphometric and transcriptomic responses to sub-chronic exposure to the polycyclic aromatic hydrocarbon phenanthrene in the fathead minnow (Pimephales promelas). Aquatic Toxicology, 199 77-89.

Phenanthrene is a tricyclic polycyclic aromatic hydrocarbon and environmental contaminant found in high concentrations around urban catchments and in the vicinity of oil extraction activities. Fish exposed to phenanthrene can exhibit altered reproductive hormone profiles and/or differences within gonadosomatic index and altered gamete proportions, but the mechanisms underlying these changes are not fully understood. In this study, we conducted a sub-chronic bioassay and measured transcriptional responses in the liver, the major tissue involved in generating lipids for oocyte growth. Adult male and female fathead minnow (Pimephales promelas) were exposed to an average measured concentration of 202 μg phenanthrene/L for a 7 week period. Condition factor was reduced in both males and females, while female fish also showed decreased gonadosomatic index relative to control females. In females exposed to phenanthrene, perinucleolar proportions were increased ∼1.9-fold relative to the control group whereas the proportions of vitellogenic oocytes decreased ∼8.8 fold. In males exposed to phenanthrene, spermatogonia proportions were increased ∼2.3 fold in testicular tissues compared to control fish. Thus, gametes were at an earlier stage of maturation in phenanthrene-treated fish compared to controls. However, no differences were detected in the production of 17β-estradiol or testosterone from the gonad in either sex. Catalase activity was also assessed in the liver as a measure of oxidative stress and this biomarker did not change in activity in either sex. In addition to endpoints in the ovary, the female hepatic transcriptome was measured, as this tissue produces lipids for oocyte maturation. Transcriptomic responses to phenanthrene exposure suggested a reduction in vitellogenin mRNA, and lipid metabolism and immune system pathways. Comparisons of hepatic transcriptome responses with Part A (72 h phenanthrene exposure) showed that energy homeostasis pathways were consistently altered following phenanthrene exposure over multiple durations and concentrations. We suggest that altered energy homeostasis may be adversely affecting reproductive efforts, as impaired reproduction has been observed in other studies investigating polycyclic aromatic hydrocarbons.
Marjan P., Van Der Kraak G.J., MacLatchy D.L., Fuzzen M.L.M., Bragg L.M., McMaster M.E., Tetreault G.R., Servos M.R. (2018). Assessing recovery of in vitro steroid production in male rainbow darter (Etheostoma caeruleum) in response to municipal wastewater treatment plant infrastructure changes. Environmental Toxicology and Chemistry, 37(2) 501-514.

The present study examined in vitro 11-ketotestosterone and testosterone production by the testes of rainbow darter (Etheostoma caeruleum) collected from selected reference sites and downstream of 2 municipal wastewater treatment plants (MWWTPs; Waterloo and Kitchener) on the central Grand River (Ontario, Canada), over a 6-yr period (2011–2016). The main objective was to investigate if infrastructure upgrades at the Kitchener MWWTP in 2012 resulted in a recovery of this response in the post-upgrade period (2013–2016). Two supporting studies showed that the fall season is appropriate for measuring in vitro sex steroid production because it provides stable detection of steroid patterns, and that the sample handling practiced in the present study did not introduce a bias. Infrastructure upgrades of the Kitchener MWWTP resulted in significant reductions in ammonia and estrogenicity. After the upgrades, 11-ketotestosterone production by MWWTP-exposed fish increased in 2013 and it continued to recover throughout the study period of 2014 through 2016, returning to levels measured in reference fish. Testosterone production was less sensitive and it lacked consistency. The Waterloo MWWTP underwent some minor upgrades but the level of ammonia and estrogenicity remained variable over time. The production of 11-ketotestosterone and testosterone in rainbow darter below the Waterloo MWWTP was variable and without a clear recovery pattern over the course of the present study. The results of the present study demonstrated that measuring production of sex steroids (especially 11-ketotestosterone) over multiple years can be relevant for assessing responses in fish to environmental changes such as those resulting from major infrastructure upgrades. Environ Toxicol Chem 2018;37:501–514. © 2017 SETAC.
McBriarty G.J., Kidd K.A., Burridge L.E. (2018). Short-Term Effects of the Anti-sea Lice Therapeutant Emamectin Benzoate on Clam Worms (Nereis virens). Archives of Environmental Contamination and Toxicology, 74(4) 539-545.

The polychaete Nereis virens occurs commonly in marine sediments, is widely distributed, and is a popular bait species, as well as a potential replacement for wild-caught fish in commercial fish feed preparations. It is being considered as a potential co-extractive species for culture in integrated multi-trophic aquaculture operations. However, it is not known whether pesticides or drugs used to treat sea lice on farmed salmon, such as emamectin benzoate (EB), would adversely affect cultured or wild worms, because these compounds may persist in the environment. To determine the potential effects of EB to N. virens, bioassays were performed wherein worms were exposed in sand for 30 days to a concentration of 400 µg/kg dw (nominal). While no treatment-related mortality occurred, significant decreases in worm mass and marked behavioral changes (lack of burrowing) were observed in EB-treated sand compared with controls. These lab-based observations suggest a potential hazard to worms at sites where EB treatments have occurred.
Mocq J., St-Hilaire A., Cunjak R.A. (2018). Do habitat measurements in the vicinity of Atlantic salmon (Salmo salar) parr matter? Fisheries Management and Ecology, 25(1) 22-30.

Atlantic salmon, Salmo salar L., parr habitat characterisation is usually performed by in situ measures of key environmental variables taken at the exact fish location if the fishing gear allows precise pinpointing of this location, or in large sampling sections covering a river reach or mesohabitat, often ignoring variability in the immediate vicinity around individual fish. These data may be critically important in the development and validation of habitat preference models. The influences of seven increasing distances of measures, the variation of the number of considered measures and the depth of velocity measurement (bottom or 0.6 of the depth) in the calculations of HSI (Habitat Suitability Index) from a multiple-experts fuzzy model of Atlantic salmon parr habitat were tested. When a parr was present, six measures collected in a 50-cm radius around the fish to provide an average measure as input data and velocity measured at 60% of the depth gave the highest HSI values. These results show some potential for the use of an intermediate study scale, between micro- and mesohabitat, and questions how fish habitat conditions are currently measured.
Monk W.A., Compson Z.G., Armanini D.G., Orlofske J.M., Curry C.J., Peters D.L., Crocker J.B., Baird D.J. (2018). Flow velocity–ecology thresholds in Canadian rivers: A comparison of trait and taxonomy-based approaches. Freshwater Biology, 63(8) 891-905.

Understanding the physical and biological mechanisms contributing to flow velocity–ecology relationships is crucial for successful river management. The application of an ecological traits-based approach offers the potential to explore mechanistic linkages between aquatic communities and a hydrological gradient. To date, however, studies focused on identifying these relationships have been limited by a lack of large-scale, long-term biological data. To address this gap at a scale relevant for water policy management, we employed data from a large-scale standardised benthic monitoring program—the Canadian Aquatic Biomonitoring Network—obtained from wadeable river sites across Canada. We applied the Threshold Indicator Taxa ANalysis method to quantify the response of the macroinvertebrate community, expressed as traditional taxonomic information and also as ecological traits, along a flow velocity gradient in reference and potential reference sites. Five key findings emerged: (1) using taxa and trait modalities revealed different flow velocity thresholds, (2) trait flow velocity indicators were less variable than taxon indicators, especially for positively responding trait modalities, (3) labile and non-labile trait modalities demonstrated highly similar patterns along the flow velocity gradient, (4) taxa from 12 different orders responded negatively to flow velocity, while only EPT taxa and some dipterans responded positively to flow velocity, and (5) traits related to mobility and ecology (e.g. climber and swimmer habits, preference of cold-cool eurythermal water and ability to survive desiccation) tended to respond positively to flow velocity, while traits related to morphology, life history and ecology (e.g. sprawler and burrower habits, preference for warm eurythermal water and inability to survive desiccation) tended to respond negatively to flow velocity. Providing ecologically based flow management targets can improve management plans, anticipate ecosystem consequences of anthropogenic change and support the development of policies to mitigate anthropogenic flow alteration. While our taxon and trait modality flow indicators were developed for Canadian watersheds, our methods to develop flow indicators and thresholds are transferrable to other systems where long-term biomonitoring programs are being developed, underscoring the need for long-term biomonitoring programs to support better ecosystem management.
Nielsen J.M., Clare E.L., Hayden B., Brett M.T., Kratina P. (2018). Diet tracing in ecology: Method comparison and selection. Methods in Ecology and Evolution, 9(2) 278-291.

Determining diet is a key prerequisite for understanding species interactions, food web structure and ecological dynamics. In recent years, there has been considerable development in both the methodology and application of novel and more traditional dietary tracing methods, yet there is no comprehensive synthesis that systematically and quantitatively compares the different approaches. Here we conceptualise diet tracing in ecology, provide recommendations for method selection, and illustrate the advantages of method integration. We summarise empirical evidence on how different methods quantify diet mixtures, by contrasting estimates of dietary proportions from multiple methods applied to the same consumer-resource datasets, or from experimental studies with known diet compositions. Our data synthesis revealed an urgent need for more experiential comparisons among the dietary methods. The comparison of diet quantifications from field observations showed that different techniques aligned well in cases with less than six diet items, but diverged considerably when applied to more complex diet mixtures. Efforts are ongoing to further advance dietary estimation, including how reliably compound specific stable isotope analyses and fatty acid profiles can quantify more prey items than bulk stable isotope analyses. Similarly, DNA analyses, which can depict trophic interactions at a higher resolution than any other method, are generating new ways to better quantify diets and differentiate among life-stages of prey. Such efforts, combined with more empirical testing of each dietary method and establishment of open data repositories for dietary data, promise to greatly advance community and ecosystem ecology.
Paris J.R., Sherman K.D., Bell E., Boulenger C., Delord C., El-Mahdi M.B.M., Fairfield E.A., Griffiths A.M., Gutmann Roberts C., Hedger R.D., Holman L.E., Hooper L.H., Humphries N.E., Katsiadaki I., King R.A., Lemopoulos A., Payne C.J., Peirson G., Richter K.K., Taylor M.I., Trueman C.N., Hayden B., Stevens J.R. (2018). Understanding and managing fish populations: keeping the toolbox fit for purpose. Journal of Fish Biology, 92(3) 727-751.

Wild fish populations are currently experiencing unprecedented pressures, which are projected to intensify in the coming decades. Developing a thorough understanding of the influences of both biotic and abiotic factors on fish populations is a salient issue in contemporary fish conservation and management. During the 50th Anniversary Symposium of The Fisheries Society of the British Isles at the University of Exeter, UK, in July 2017, scientists from diverse research backgrounds gathered to discuss key topics under the broad umbrella of ‘Understanding Fish Populations’. Below, the output of one such discussion group is detailed, focusing on tools used to investigate natural fish populations. Five main groups of approaches were identified: tagging and telemetry; molecular tools; survey tools; statistical and modelling tools; tissue analyses. The appraisal covered current challenges and potential solutions for each of these topics. In addition, three key themes were identified as applicable across all tool-based applications. These included data management, public engagement, and fisheries policy and governance. The continued innovation of tools and capacity to integrate interdisciplinary approaches into the future assessment and management of fish populations is highlighted as an important focus for the next 50 years of fisheries research.
Patricia G.D., Gaspar G.S., Betancourt C.A., Alvarez Fernández S., Pérez O.P., Fernández L.H., Rodríguez V.M.F., Caballero Y.C., Armenteros M., De La Guardia Llanso E. (2018). Status of Cuban coral reefs. Bulletin of Marine Science, 94(2) 229-247.

Cuban coral reefs have been called the “crown jewels of the Caribbean Sea,” but there are few comparative data to validate this claim. Here, we provide an overview of Cuban coral reefs based on surveys carried out between 2010 and 2016 on seven of the main Cuban coral reef systems: Havana, Artemisa, Los Colorados, Punta Francés, Los Canarreos Archipelago, Península Ancón, and Jardines de la Reina. Ecological indicators were evaluated for each of these areas at the community level. Results suggest differences among benthic communities (corals, sponges, and gorgonians) that are most evident for reefs that develop near highly urbanized areas, such as Havana, than for those far from the coast and less accessible. Offshore reefs along the south-central coast at Jardines de la Reina and Península Ancón exhibited high coral density and diversity. Acropora cervicornis (Lamarck, 1816) and the Orbicella complex corals were uncommon, possibly indicating losses prior to our study due to coral diseases or competition with macroalgae. Siderastrea siderea (Ellis and Solander, 1786) was the most consistently-abundant species at all reef sites. The ecological condition at Jardines de la Reina and Península Ancón is comparatively healthy. Our study supports claims that some Cuban coral reef systems are probably among the best preserved in the Caribbean basin, but other highly impacted areas exhibit many of the degradation patterns that are common to the rest of the Caribbean region. Strong conservation strategies are required with regard to subsistence fisheries and pollution at highly-impacted reefs to stop further degradation, and reefs that appear healthy need protection to avoid degradation and maintain resilience.
Páez Y.C., Aguilar-Betancourt C.M., González-Sansón G., Rodríguez F.N., Gray M. (2018). Sediment granulometry and salinity drive spatial and seasonal variability of an estuarine demersal fish assemblage dominated by juvenile fish. Estuarine Coastal and Shelf Science, 212 241-252.

Abiotic factors are known to structure estuarine fish communities; however, their effects on the ichthyofauna are not yet clear. The objective of this study was to evaluate abundance and composition, by species and size, of the demersal ichthyofauna in a Mexican Central Pacific lagoon, and correlate its spatial and seasonal variations with selected abiotic factors. Eight sampling campaigns were conducted in representative months of the dry and rainy seasons between April 2015 and February 2017. Salinity, temperature and sediment granulometry were recorded. A total of 10 093 individuals of 64 species were collected and measured for total length. Of the 22 most abundant species, 19 were mainly juveniles (>50%). Diapterus brevirostris, Achirus mazatlanus, Centropomus robalito and Lutjanus argentiventris comprised more than 80% of the total collection. PERMANOVA yielded significant differences in fish community composition between sites and months, and post hoc tests resulted in four homogenous, significantly different groups of sites based on fish assemblage composition. These groups of sites lie well ordered along a west-east axis inside the lagoon. Two well separated seasonal groups of months were defined, namely dry season (February, April) and rainy season (July, October). The spatial changes in abundance and composition of the fish fauna were primarily explained by the Site factor in a spatial scale, while the Month factor influenced to a lesser degree the community structure on a seasonal scale. Redundancy analysis showed the type of sediment, the bottom salinity and the organic matter content were highly correlated with the composition and abundance of ichthyofauna in the lagoon. One species group (dominated by D. brevirostris, C. robalito and A. mazatlanus) was found to be highly positively correlated with percentage of mud and organic matter but negatively correlated with bottom salinity. Another species group (dominated by Diodon holocanthus, Eucinostomus dowii, Sphoeroides annulatus and Chaetodon humeralis) was highly correlated with percentage of sand and bottom salinity. A high number of juveniles in the catches also validates the Barra de Navidad lagoon as a probable nursery area.
Quezada-Romegialli C., Jackson A.L., Hayden B., Kahilainen K.K., Lopes C., Harrod C. (2018). tRophicPosition, an r package for the Bayesian estimation of trophic position from consumer stable isotope ratios. Methods in Ecology and Evolution, 9(6) 1592-1599.

Stable isotope analysis provides a powerful tool to identify the energy sources which fuel consumers, to understand trophic interactions and to infer consumer trophic position (TP), an important concept that describes the ecological role of consumers in food webs. However, current methods for estimating TP using stable isotopes are limited and do not fulfil the complete potential of the isotopic approach. For instance, researchers typically use point estimates for key parameters including trophic discrimination factors and isotopic baselines, and do not explicitly include variance associated with these parameters when calculating TP. We present “tRophicPosition,” an r package incorporating a Bayesian model for the calculation of consumer TP at the population level using stable isotopes, with one or two baselines. It combines Markov Chain Monte Carlo simulations through JAGS and statistical and graphical analyses using R. We model consumer and baseline observations using relevant statistical distributions, allowing them to be treated as random variables. The calculation of TP—a random parameter—for one baseline follows standard equations linking 15N enrichment per trophic level and the trophic position of the baseline (e.g. a primary producer or primary consumer). In the case of two baselines, a simple mixing model incorporating δ13C allows for the differentiation between two distinct sources of nitrogen, thus including heterogeneity derived from alternatives sources of δ15N. Methods currently implemented in “tRophicPosition” include loading, plotting and summarizing stable isotope data either from multiple sites and/or communities or a local assemblage; loading trophic discrimination factors from an internal database or generating them; defining and initializing a Bayesian model of TP; sampling posterior parameters; analysing, comparing and plotting posterior estimates of TP and other parameters; and calculating a parametric (non-Bayesian) TP estimate. Additionally, full documentation including examples, multiple vignettes and code are available for download.
Reinhart B.L., Kidd K.A., Curry R.A., O'Driscoll N.J., Pavey S.A. (2018). Mercury bioaccumulation in aquatic biota along a salinity gradient in the Saint John River estuary. Journal of Environmental Sciences China, 68 41-54.

Although estuaries are critical habitats for many aquatic species, the spatial trends of toxic methylmercury (MeHg) in biota from fresh to marine waters are poorly understood. Our objective was to determine if MeHg concentrations in biota changed along a salinity gradient in an estuary. Fourspine Stickleback (Apeltes quadracus), invertebrates (snails, amphipods, and chironomids), sediments, and water were collected from ten sites along the Saint John River estuary, New Brunswick, Canada in 2015 and 2016, with salinities ranging from 0.06 to 6.96. Total mercury (proxy for MeHg) was measured in whole fish and MeHg was measured in a subset of fish, pooled invertebrates, sediments, and water. Stable sulfur (δ34S), carbon (δ13C), and nitrogen (δ15N) isotope values were measured to assess energy sources (S, C) and relative trophic level (N). There were increases in biotic δ13C and δ34S from fresh to more saline sites and these measures were correlated with salinity. Though aqueous MeHg was higher at the freshwater than more saline sites, only chironomid MeHg increased significantly with salinity. In the Saint John River estuary, there was little evidence that MeHg and its associated risks increased along a salinity gradient.
Rojas D.C., Schmitter-Soto J.J., Aguilar-Perera A., Aguilar Betancourt C.M., Ruiz-Zárate M., Sansón G.G., Chevalier Monteagudo P.P., Rodríguez A.G., Pavón R.H., Valderrama S.P., Aragón H.C., de la Guardia E. (2018). Diversity of native reef fish communities in two protected areas in the Caribbean Sea and its relationship to the invasive lionfish. Revista De Biologia Tropical, 66(1) 189-203.

Lionfish (Pterois volitans) invaded the Caribbean region with the potential to alter the composition and structure of native coral reef fish communities. The objective of this study was to analyze the diversity indices of these fish communities potentially affected by lionfish predation and to compare with pre-invasion data. The study was undertaken in two Caribbean marine protected areas (MPAs): Guanahacabibes National Park (PNG) in W Cuba and Xcalak Reefs National Park (PNAX) in S Quintana Roo. We carried out visual censuses of fish species in reef habitats during the dry and rainy seasons of the period 2013-2015. For this, nine sites were defined and evaluated using stationary counts. Our results showed higher species richness (43.47 ± 5.14) and mean abundance (0.76 ± 1.25) in PNG than in PNAX (40.22 ± 4.96, 0.19 ± 0.46, respectively). Diversity decreased after the arrival of lionfish in a single site of PNG and in two sites of the PNAX, but apparently, these results are more related to the fishing activity effect than to the lionfish presence. Based on the results and assuming that changes in the native fish communities by lionfish may not yet be detected, we recommend to continue the monitoring community descriptions in order to detect future changes in native fish communities.
Roldán-Wong N.T., Kidd K.A., Marmolejo-Rodríguez A.J., Ceballos-Vázquez B.P., Shumilin E., Arellano-Martínez M. (2018). Bioaccumulation and biomagnification of potentially toxic elements in the octopus Octopus hubbsorum from the Gulf of California. Marine Pollution Bulletin, 129(2) 458-468.

The concentrations of 21 potentially toxic elements (PTEs) were determined in the tissues of Octopus hubbsorum from three locations along the Gulf of California coast: two near Santa Rosalia (SR), a site with historical metal contamination, and one in La Paz Bay, a reference site. Concentrations of Cd, Co, Cr, Mn, Ni, Pb, and Zn in octopus from the two SR sites were higher than those from the reference site, reflecting the higher sediment concentrations at the mining-impacted locations. The highest bioaccumulation and biomagnification of elements was found in digestive gland and branchial hearts, while the lowest was observed in the mantle, where the mean concentration of PTEs did not exceed international standards for human consumption of octopus. This study found elevated PTEs in octopus from sites with high metal contamination, and presents the first data on these elements in octopus from the Gulf of California.
Roloson S.D., Knysh K.M., Coffin M.R.S., Gormley K.L., Pater C.C., van den Heuvel M.R. (2018). Rainbow trout (Oncorhynchus mykiss) habitat overlap with wild Atlantic salmon (Salmo salar) and brook trout (Salvelinus fontinalis) in natural streams: Do habitat and landscape factors override competitive interactions? Canadian Journal of Fisheries and Aquatic Sciences, 75(11) 1949-1959.

The purpose of this study was to update rainbow trout (Oncorhynchus mykiss) invasion status, delineate factors that increase the invasion probability, and quantify habitat overlap between invasive rainbow trout and native Atlantic salmon (Salmo salar) and brook trout (Salvelinus fontinalis) on Prince Edward Island, Canada. Analysis of landscape-level variables in 26 watersheds (14 with and 12 without rainbow trout) demonstrated that watershed slope, percent agricultural land use, and distance to the nearest rainbow trout population significantly increased the probability of rainbow trout establishment. Two independent reach-level fish community surveys were conducted by electrofishing in combination with habitat surveys. Reaches with rainbow trout had higher stream slope, Atlantic salmon were found in wider reaches with larger substrate, and brook trout were typically dominant in headwater reaches with finer substrate. Findings at multiple ecological scales illustrated that rainbow trout invasion success is positively influenced by the presence of high-slope habitat. Habitat separation of the three salmonid species indicates that competition with introduced rainbow trout may not be the most significant threat to native salmonid populations.
Rundle K.I., Sharaf M.S., Stevens D., Kamunde C., Van Den Heuvel M.R. (2018). Oil Sands Derived Naphthenic Acids Are Oxidative Uncouplers and Impair Electron Transport in Isolated Mitochondria. Environmental Science and Technology, 52(18) 10803-10811.

Naphthenic acids (NAs) are predominant compounds in oil sands influenced waters. These acids cause numerous acute and chronic effects in fishes. However, the mechanism of toxicity underlying these effects has not been fully elucidated. Due to their carboxylic acid moiety and the reported disruption of cellular bioenergetics by similar structures, we hypothesized that NAs would uncouple mitochondrial respiration with the resultant production of reactive oxygen species (ROS). Naphthenic acids were extracted and purified from 17-year-old oil sands tailings waters yielding an extract of 99% carboxylic acids with 90% fitting the classical O<inf>2</inf>-NA definition. Mitochondria were isolated from rainbow trout liver and exposed to different concentrations of NAs. Mitochondrial respiration, membrane potential, and ROS emission were measured using the Oroboros fluorespirometry system. Additionally, mitochondrial ROS emission and membrane potential were evaluated with real-time flow cytometry. Results showed NAs uncoupled oxidative phosphorylation, inhibited respiration, and increased ROS emission. The effective concentration (EC<inf>50</inf>) and inhibition concentration (IC<inf>50</inf>) values for the end points measured ranged from 21.0 to 157.8 mg/L, concentrations similar to tailings waters. For the same end points, EC<inf>10</inf>/IC<inf>10</inf> values ranged from 11.8 to 66.7 mg/L, approaching concentrations found in the environment. These data unveil mechanisms underlying effects of NAs that may contribute to adverse effects on organisms in the environment.
Samson-Dô M., St-Hilaire A. (2018). Characterizing and modelling the trapping efficiency of sedimentation basins downstream of harvested peat bog. Canadian Journal of Civil Engineering, 45(6) 478-488.

Peat moss harvesting is an important industry in Canada. To harvest peat, the water table of the peatland must be lowered to allow the surficial peat layer to dry and be harvested. Drainage water can contain suspended sediments, so at most harvesting sites, the water is routed through sedimentation basins. This work focuses on characterizing and modelling their trapping efficiency. Eight basins with different volume/watershed area ratios (705 to 4170m3/km2) were studied in three Quebec regions. Suspended sediment concentration and discharge were monitored up- and downstream of each basin during the ice-free season. Basins with high ratios of volume/drainage area, multiple basin configurations (i.e., two basins in series or in parallel), and those equipped with a flow regulation structure were more efficient than regular basins. Moreover, the nature of sediments (size, decomposition level, and organic content) influences loads, but not the trapping efficiency. Finally, two empirical models developed to predict trapping efficiency of municipal sedimentation basins were tested and adapted for basins that capture peat sediments.
Samways K.M., Soto D.X., Cunjak R.A. (2018). Aquatic food-web dynamics following incorporation of nutrients derived from Atlantic anadromous fishes. Journal of Fish Biology, 92(2) 399-419.

Changes in the isotopic composition (δ13C and δ15N) in biofilm, macro-invertebrates and resident salmonids were used to characterize temporal dynamics of marine derived nutrients (MDNs) incorporation between stream reaches with and without MDN inputs. Five Atlantic rivers were chosen to represent contrasting MDN subsidies: four rivers with considerable numbers of anadromous fishes; one river with little MDN input. Rainbow smelt Osmerus mordax, alewife Alosa pseudoharengus, sea lamprey Petromyzon marinus and Atlantic salmon Salmo salar, were the primary anadromous species for the sampled rivers. Regardless of the spatial resolution or the pathway of incorporation, annual nutrient pulses from spawning anadromous fishes had a positive effect on isotopic enrichment at all trophic levels (biofilm, 1·2–5·4‰; macro-invertebrates, 0·0–6·8‰; fish, 1·2–2·6‰). Community-wide niche space shifted toward the marine-nutrient source, but the total ecological niche space did not always increase with MDN inputs. The time-integrated marine-nutrient resource contribution to the diet of S. salar parr and brook trout Salvelinus fontinalis ranged between 16·3 and 36·0% during anadromous fish-spawning periods. The high degree of spatio-temporal heterogeneity in marine-nutrient subsidies from anadromous fishes lead to both direct and indirect pathways of MDN incorporation into stream food webs. This suggests that organisms at many trophic levels derive a substantial proportion of their energy from marine resources when present. The current trend of declining anadromous fish populations means fewer nutrient-rich marine subsidies being delivered to rivers, diminishing the ability to sustain elevated riverine productivity.
Siders A.C., Compson Z.G., Hungate B.A., Dijkstra P., Koch G.W., Wymore A.S., Grandy A.S., Marks J.C. (2018). Litter identity affects assimilation of carbon and nitrogen by a shredding caddisfly. Ecosphere, 9(7).

Ecologists often equate litter quality with decomposition rate. In soil and sediments, litter that is rapidly decomposed by microbes often has low concentrations of tannin and lignin and low C:N ratios. Do these same traits also favor element transfer to higher trophic levels in streams, where many insects depend on litter as their primary food source? We test the hypothesis that slow decomposition rates promote element transfer from litter to insects, whereas rapid decomposition favors microbes. We measured carbon and nitrogen fluxes from four plant species to a leaf-shredding caddisfly using isotopically labeled litter. Caddisflies assimilated a higher percentage of litter carbon and nitrogen lost from slowly decomposing litters (Platanus wrightii and Quercus gambelii). In contrast, rapidly decomposing litters (Fraxinus velutina and Populus fremontii) supported higher microbial biomass. These results challenge the view that rapidly decomposing litter is higher quality by demonstrating that slowly decomposing litters provide a critical resource for insects.
Soto D.X., Trueman C.N., Samways K.M., Dadswell M.J., Cunjak R.A. (2018). Ocean warming cannot explain synchronous declines in North American Atlantic salmon populations. Marine Ecology Progress Series, 601 203-213.

Atlantic salmon Salmo salar populations have suffered global, synchronous declines over the past decades. These declines are coincident with improvements in river habitats and reductions in high seas fisheries, implying higher rates of natural marine mortality that have been widely linked to increasing ocean temperatures in the North Atlantic. The mechanisms linking temperature to marine mortality in Atlantic salmon, however, are unclear. During the period 1980−2010, populations of S. salar returning to the St. John River, New Brunswick, Canada, after spending either 1 or multiple winters at sea have shown similar patterns of decline, coincident with recent ocean warming in the North Atlantic Ocean. Here we used stable isotope data from historic scale collections to investigate the relationship between foraging location, experienced ocean temperature and population trends for S. salar returning to the St. John River. We show that salmon spending either 1 or multiple winters at sea before returning to the St. John River consistently fed in different regions of the North Atlantic and experienced different ocean warming trends. However, both cohorts show synchronous progressive population declines over the study period. We therefore suggest that ocean warming cannot be the principal cause of increased marine mortality for salmon returning to the St. John River. Both cohorts experience similar conditions during the initial post-smolt period, and increased post-smolt mortality could underpin population declines. Our results support concentrating management and conservation efforts to reduce mortality in the post-smolt phase of salmon lifecycles.
St-Hilaire A., Boyer C., Bergeron N., Daigle A. (2018). Water temperature monitoring in eastern Canada: A case study for network optimization. Wit Transactions on Ecology and the Environment, 228 269-275.

Water temperature is a key variable affecting important water quality parameters such as dissolved oxygen. In Eastern Canada, iconic fish species such as Atlantic salmon (Salmo salar) can be affected by increase in temperature associated with climate change. A major endeavour is underway to establish and optimize a water temperature monitoring network in this region. This network, called RivTemp, includes temperature data from over 600 stations in 277 streams or rivers. These data are being used to develop/adapt methods network optimization, temperature interpolation and modelling/forecasting. Different approaches to interpolate water temperature at ungauged sites using data from monitoring stations are being compared. More recently, two regression approaches that are often used when collinearity is present among predictors, the ridge regression and the LASSO regression were compared. Results show that the LASSO regression is more parsimonious than the ridge regression and provides adequate estimates of daily average water temperature.
Standen K.M., Chambers P.A., Culp J.M. (2018). Arrowhead (Sagittaria cuneata) as a bioindicator of nitrogen and phosphorus for prairie streams and wetlands. Wetlands Ecology and Management, 26(3) 331-343.

The emergent aquatic plant, Sagittaria cuneata, is an easily-identified and commonly-found species in the Great Plains region of North America and has the potential to be a bioindicator of nitrogen (N) and phosphorus (P) because of its previously-identified leaf plasticity in response to nutrient conditions. To identify associations between leaf morphology and soil and water nutrients, we conducted: (1) a 10-week controlled experiment in which plants were grown in nutrient-enriched sediment, nutrient-enriched water, or unamended control trials, and (2) a field study where emergent leaves were collected from 15 streams of varying nutrient concentrations. Plants grown in experimentally enriched sediment were more productive than those grown in enriched water or control conditions: they produced more emergent leaves and tubers, had a larger final biomass and height, and developed emergent leaves that showed a consistent increase in size and unique change in shape over time. Emergent leaves collected from field plants also showed significant variability of leaf traits; however, this variability occurred at all scales of replication (leaf, plant, quadrat, and site), with linear mixed effects modelling indicating that random chance was likely driving this variability. Although sediment nutrients were crucial to successful growth of S. cuneata under controlled conditions, the high variability in leaf morphology under field conditions (likely due to large natural variability at the species, population, and individual scale) make leaf plasticity of S. cuneata unsuitable as a bioindicator. Our results emphasize the need to quantify within and among plant variation in leaf morphology (and to clarify sampling methods) for the many taxa of aquatic macrophytes that are phenotypically plastic and notoriously difficult to classify.
Thera J.C., Kidd K.A., Nosworthy M.G., Bertolo R.F. (2018). Evaluation of a performic acid oxidation method for quantifying amino acids in freshwater species. Limnology and Oceanography Methods, 16(12) 803-813.

Thiol amino acids in proteins store metals like mercury, but established methods for their quantitation in freshwater species have had limited application and evaluation. As such, literature on the amino acid composition of aquatic species often lacks the thiols cysteine and methionine. Here, we evaluated a performic acid (PFA) oxidation method to determine its suitability to measure cysteine and methionine, as well as 15 other amino acids, in novel matrices (zooplankton, benthic invertebrates, fishes, and algae). Protein-bound amino acids were oxidized with PFA, hydrolyzed in hydrochloric acid, derivatized with AccQ·Tag<inf>ultra</inf> (Waters), and separated by ultra-high performance liquid chromatography with fluorescence detection. PFA oxidation was successful in determining precise results for 15 amino acids, including the sulfur amino acids, with the complete loss of tyrosine (TYR) and poor precision of phenylalanine (PHE). The overall variability of the method was 11% (excluding TYR and PHE), or 6% when reported as relative percentages, comparable to methods without PFA oxidation in other matrices. Except for TYR and thiols, PFA oxidation did not affect the amino acid composition of these biota. Overall, the findings were reproducible and comparable to other approaches and suggest this is a rigorous method for measuring sulfur amino acids and the overall amino acid composition for aquatic biota, both of which are rare in the literature.
Thomas K.E., Lazor R., Chambers P.A., Yates A.G. (2018). Land-use practices influence nutrient concentrations of southwestern Ontario streams. Canadian Water Resources Journal, 43(1) 2-17.

Human activities have transformed the landscape and altered geochemical pathways through intensive land uses such as agriculture and urbanization. This study quantified the individual and cumulative influence of land-use drivers on nutrient concentrations for 29 Ontario tributaries flowing to Lake Erie and Lake Huron. For each watershed, measures of agriculture, urbanization and population served by municipal sewage treatment plants were quantified at multiple spatial scales; stream-water nutrients (nitrogen, N, and phosphorus, P) were sampled on 10 occasions between May and November 2012, and were also compiled from government records for concurrent (2012) and prior (2007, 2008, 2011) years. Application of ordinary least squares regression analysis showed that in 2012, concentrations of N and P (total as well as dissolved forms) were primarily driven by sewage treatment and urban activity, with agricultural activity as a secondary influence on variability. Evaluation of model predictive performance under scenarios of varying climate (wet, dry and ‘normal’ conditions) and spatial coverage (i.e. broader than the original sampling sites) showed that stream nitrogen concentrations could be predicted, on average, 36–85% of the time; phosphorus forms were, however, not successfully predicted, likely due to differences in sampling frequency relative to runoff events. The finding that both urban and agricultural land-use activities influence nutrient concentrations in Canadian tributaries to lakes Erie and Huron underscores the need to reduce both point and non-point inputs in order to mitigate eutrophication of downstream lakes.
Yates A.G., Brua R.B., Culp J.M., Young R.G., Chambers P.A. (2018). Variation in stream metabolism and benthic invertebrate composition along longitudinal profiles of two contrasting river systems. Canadian Journal of Fisheries and Aquatic Sciences, 75(4) 549-559.

Our study aimed to determine drivers of longitudinal variation in stream metabolism and benthic macroinvertebrate (BMI) composition and assess concordance of these ecological measures for two Canadian rivers (Rat River and Tobacco Creek). Gross primary production was associated with longitudinal position in both rivers but also with the percentage of the watershed used for agriculture and hydrogeomorphic zone. However, within- and among-zone differences in stream metabolism indicated that longitudinal variation followed a staircase pattern rather than a clinal pattern. BMI composition was associated with network position in both rivers, but hydrogeomorphic zones were only important in Tobacco Creek. Among-zone differences in BMI communities in Tobacco Creek depended on season. Concordance between stream metabolism and BMI composition was not observed within either river despite metabolism and BMI composition being associated with longitudinal position. For these rivers, segment-scale hydrogeomorphic conditions appear to be important modifiers of longitudinal patterns observed at the whole river scale. The lack of concordance between stream metabolism and BMI composition suggests reach-scale processes are driving ecological differences within sampling sites.
Zhang J., Knight R., Wang Y., Sawyer T.W., Martyniuk C.J., Langlois V.S. (2018). Comprehensive assessment of shockwave intensity: Transcriptomic biomarker discovery for primary blast-induced mild traumatic brain injury using the mammalian hair follicle. Brain Injury, 32(1) 123-134.

Objective: Primary blast-induced mild traumatic brain injury (mTBI) is an injury experienced during modern warfare due to exposure to the pressure waves produced by the detonation of explosives. With virtually no apparent physical damage or symptoms presented, there is a need for more objective and accessible mTBI biomarkers posing minimal invasiveness risk. Methods: We measured the transcriptomic sensitivity of the hair follicles in relation to the severity of primary blast-derived TBI. An Advanced Blast Simulator system was used to expose male rats to single pulse shock waves (intensities ranging from 15 to 30 psi) in a head-only fashion. Gene differential expression (DE) and gene set (GS) analyses were conducted in the rat whisker hair follicles and the whole blood samples. Results: While shared cellular function, themes were found across the exposure groups, some gene sets under such themes were unique to the exposure conditions. Intensity-specific pathway enrichment patterns within shared GS themes were also identified. Furthermore, while exhibited shared pathways, the blood transcriptome showed substantially fewer enriched gene sets compared with the hair follicles across all exposure conditions. Conclusions: Accordingly, we demonstrate the potential of mammalian hair follicles serving as an additional source for biomarker discovery and for diagnosing mTBI with high accessibility.
Aguilar-Betancourt C.M., González-Sansón G., Flores-Ortega J.R., Kosonoy-Aceves D., Lucano-Ramírez G., Ruiz-Ramírez S., Padilla-Gutierrez S.C., Curry R.A. (2017). Comparative analysis of diet composition and its relation to morphological characteristics in juvenile fish of three lutjanid species in a Mexican pacific coastal lagoon. Neotropical Ichthyology, 15(4).

The main goal of this research was to investigate the differences in diet composition among three species of the genus Lutjanus inhabiting a coastal lagoon as juveniles. The working hypothesis was that these species feed on a common base of food resources and therefore, some niche overlap is present in terms of general diet composition. However, changes in the trophic niche with size and differences in some morphological traits among species explain observed differences in diet. Fish were collected during 42 sampling trips conducted regularly from February 2011 to January 2012 using several types of fishing gear. Total number of analyzed stomachs was 288 for Lutjanus argentiventris from 2.3 to 19.9 cm total length (TL); 178 for Lutjanus colorado ranging from 2.4 to 30.1 cm TL; and 183 for Lutjanus novemfasciatus with 1.2 to 20.0 cm TL. Results indicate that juveniles of all three lutjanid species share a general diet based on decapods and fishes. However, L. novemfasciatus has a more piscivorous habit, which can be explained by a more slender body shape and larger teeth, characteristics, which increase fish catching performance. Larger fish of all three species eat larger prey, which is consistent with the optimum foraging theory.
Alexander A.C., Chambers P.A., Jeffries D.S. (2017). Episodic acidification of 5 rivers in Canada's oil sands during snowmelt: A 25-year record. Science of the Total Environment, 599-600 739-749.

Episodic acidification during snowmelt is a natural phenomenon that can be intensified by acidic deposition from heavy industry. In Canada's oil sands region, acid deposition is estimated to be as much as 5% of the Canadian total and large tracks of northeastern Alberta are considered acid-sensitive because of extensive peatland habitats with poorly weathered soils. To identify the frequency, duration and severity of acidification episodes during snowmelt (the predominant hydrological period for delivery of priority pollutants from atmospheric oil sands emissions to surface waters), a 25-year record (1989 to 2014) of automated water quality data (pH, temperature, conductivity) was assembled for 3 rivers along with a shorter record (2012–2014) for another 2 rivers. Acidic episodes (pH < 7, ANC < 0) were recorded during 39% of all 83 snowmelt events. The severity (duration x magnitude) of episodic acidification increased exponentially over the study period (r2 = 0.56, P < 0.01) and was strongly correlated (P < 0.01) with increasing maximum air temperature and weakly correlated with regional land development (P = 0.06). Concentrations of aluminum and 11 priority pollutants (Sb, As, Be, Cd, Cr, Cu, Pb, Se, Ag, Tl and Zn) were greatest (P < 0.01) during low (< 6.5) pH episodes, particularly when coincident with high discharge, such that aluminum and copper concentrations were at times high enough to pose a risk to juvenile rainbow trout (Oncorhynchus mykiss). Although low pH (pH < 6.5) was observed during only 8% of 32 acidification episodes, when present, low pH typically lasted 10 days. Episodic surface water acidification during snowmelt, and its potential effects on aquatic biota, is therefore an important consideration in the design of long-term monitoring of these typically alkaline (pH = 7.72 ± 0.05) rivers.
Andrews S.N., Linnansaari T., Curry R.A., Dadswell M.J. (2017). The Misunderstood Striped Bass of the Saint John River, New Brunswick: Past, Present, and Future. North American Journal of Fisheries Management, 37(1) 235-254.

The Striped Bass Morone saxatilis of the Saint John River, New Brunswick, is an enigma, having now existed in a state of uncertain species status for more than four decades. Despite a well-established historical record of adult occurrence in large numbers, the available literature, historical accounts, and status reports contain no evidence for the persistence of a native, reproducing Striped Bass population. In 2012, the Committee on the Status of Endangered Wildlife in Canada listed the Saint John River Striped Bass as endangered as part of the Bay of Fundy designatable unit. This listing lacked current peer-reviewed literature and based its conclusions predominately on restatements of findings and opinions from the 1970s and 1980s. After the apparent failure of Striped Bass spawning in the 1975, the decline of native Saint John River Striped Bass was accredited to many factors ranging from chemical pollutants to overfishing to the installation of a sizeable hydropower facility. Modest attempts to locate eggs and juveniles of the native species have been taken; however, the results have been inconclusive due to ineffective, infrequent, and poorly timed sampling. Here we reviewed all available information, literature, reports, and data to effectively describe the Saint John River Striped Bass population in an effort to help manage and recover (if required) this apparently missing population. Received March 8, 2016; accepted September 14, 2016Published online January 24, 2017
Arens C.J., Arens J.C., Hogan N.S., Kavanagh R.J., Berrue F., Van Der Kraak G.J., van den Heuvel M.R. (2017). Population impacts in white sucker (Catostomus commersonii) exposed to oil sands–derived contaminants in the Athabasca River. Environmental Toxicology and Chemistry, 36(8) 2058-2067.

Two hypotheses were exmained, one is that water samples collected downstream of oil sands developments would contain a greater proportion of naphthenic acids associated with oil sands process-affected water than water samples collected upstream of development. Second, that white sucker (Catastomus commersonii) collected from the Athabasca oil sands deposti would show signs of hydrocarbon exposure compared with fish collected upstream White sucker showed increased exposure to polycyclic aromatic hydrocarbons as indicated by hepatic cytochrome P4501A activity and fluorescent bile metabolites, as well as higher concentrations of naphthenic acids in bile. Ca, Cu, Ni, and Se were also elevated in white sucker liver tissue compared with the reference location. Based on the exposure profile and response pattern observed, effects on energy storage and utilization in white sucker from the Athabasca River most likely resulted from exposure to polycyclic aromatic hydrocarbons derived from petrogenic and pyrolytic sources.
Babin C., Gagnaire P.A., Pavey S.A., Bernatchez L. (2017). RAD-Seq reveals patterns of additive polygenic variation caused by spatially-Varying selection in the American eel (Anguilla rostrata). Genome Biology and Evolution, 9(11) 2974-2986.

The American Eel (Anguilla rostrata) has an exceptional life cycle characterized by panmictic reproduction at the species scale, random dispersal, and selection in a highly heterogeneous habitat extending from subtropical to subarctic latitudes. The genetic consequences of spatially-varying selection in this species have been investigated for decades, revealing subtle clines in allele frequency at a few loci that contrast with complete panmixia on the vast majority of the genome. Because reproduction homogenizes allele frequencies every generation, sampling size, and genomic coverage are critical to reach sufficient power to detect selected loci in this context. Here, we used a total of 710 individuals from 12 sites and 12,098 high-quality single nucleotide polymorphisms to re-evaluate the extent to which local selection affects the spatial distribution of genetic diversity in this species. We used environmental association methods to identify markers under spatially-varying selection, which indicated that selection affects 1.5% of the genome. We then evaluated the extent to which candidate markers collectively vary with environmental factors using additive polygenic scores. We found significant correlations between polygenic scores and latitude, longitude and temperature which are consistent with polygenic selection acting against maladapted genotypes in different habitats occupied by eels throughout their range of distribution. Gene functions associated with outlier markers were significantly enriched for the insulin signaling pathway, indicating that the trade-offs inherent to occupying such a large distribution range involve the regulation of metabolism. Overall, this study highlights the potential of the additive polygenic scores approach in detecting selective effects in a complex environment.
Brin L.D., Giblin A.E., Rich J.J. (2017). Similar temperature responses suggest future climate warming will not alter partitioning between denitrification and anammox in temperate marine sediments. Global Change Biology, 23(1) 331-340.

Removal of biologically available nitrogen (N) by the microbially mediated processes denitrification and anaerobic ammonium oxidation (anammox) affects ecosystem N availability. Although few studies have examined temperature responses of denitrification and anammox, previous work suggests that denitrification could become more important than anammox in response to climate warming. To test this hypothesis, we determined whether temperature responses of denitrification and anammox differed in shelf and estuarine sediments from coastal Rhode Island over a seasonal cycle. The influence of temperature and organic C availability was further assessed in a 12-week laboratory microcosm experiment. Temperature responses, as characterized by thermal optima (T<inf>opt</inf>) and apparent activation energy (E<inf>a</inf>), were determined by measuring potential rates of denitrification and anammox at 31 discrete temperatures ranging from 3 to 59 °C. With a few exceptions, T<inf>opt</inf> and E<inf>a</inf> of denitrification and anammox did not differ in Rhode Island sediments over the seasonal cycle. In microcosm sediments, E<inf>a</inf> was somewhat lower for anammox compared to denitrification across all treatments. However, T<inf>opt</inf> did not differ between processes, and neither E<inf>a</inf> nor T<inf>opt</inf> changed with warming or carbon addition. Thus, the two processes behaved similarly in terms of temperature responses, and these responses were not influenced by warming. This led us to reject the hypothesis that anammox is more cold-adapted than denitrification in our study system. Overall, our study suggests that temperature responses of both processes can be accurately modeled for temperate regions in the future using a single set of parameters, which are likely not to change over the next century as a result of predicted climate warming. We further conclude that climate warming will not directly alter the partitioning of N flow through anammox and denitrification.
Briones A., Aguilar C.M., González-Sansón G. (2017). Shrimp trawling bycatch of ray hypanus americanus (Elasmobranchii) in the southeastern region of cuba. Latin American Journal of Aquatic Research, 45(4) 840-845.

Shrimp trawl fisheries have a high incidence of bycatch due to the low selectivity of the fishing gear. In Cuba shrimp trawling is permitted by four state fishing enterprises that operate in the south east region of the country. The objective of this work is to estimate sizes, proportion of sexes and fecundity of Hypanus americanus in the shrimp trawl fishery and its possible relation to designated fishing zones. The study was carried out between January 2015 and February 2016 with 300 specimens examined. The catches were 61% female and 39% male, with disc widths between 21.5-135 cm and 20-137 cm respectively. Forty-one pregnant females were identified with fecundity of 1 to 5 embryos; also a correlation between the disc width and the number of embryos was established. This is the first study that has been carried out on this topic in the country; therefore the results provide new information for the fishing region.
Bush A., Hoskins A.J. (2017). Does dispersal capacity matter for freshwater biodiversity under climate change? Freshwater Biology, 62(2) 382-396.

Freshwater ecosystems appear to be sensitive to even minor climatic shifts, and the dendritic nature of rivers as well as patchy distribution of habitats within the terrestrial landscape could limit the ability of species to track suitable climate conditions. Although the importance of dispersal is recognised in theory, there is great uncertainty when quantifying the capacity of species to shift their distributions in response to climate change. The influence of dispersal capacity on species’ vulnerability to climate change was assessed, using the modelled projections of 527 freshwater species in New South Wales (NSW), Australia. Species’ future ranges were calculated by iteratively identifying colonisation of accessible habitats and loss of suitable habitats within network models. The accessibility of new habitats was based on a given dispersal mode (aquatic, semi-terrestrial and aerial). The relative impact of dispersal parameters on projected range were evaluated alongside other known sources of uncertainty (climate and emissions scenarios, modelling algorithm and biological group), analysed collectively in a generalised additive mixed-model, and spatially to locate regions of NSW where projections are associated with the most uncertainty. Our simulations (1.4 million scenario combinations) suggest at least a third of species will lose more than half their range under climate change. Nevertheless, we emphasise the broad uncertainty that any average encapsulates. Dispersal capacity only had a minor impact on projected range shifts relative to other modelling assumptions but the network-pathways and maps of uncertainty have value for conservation planning at large scales. Projected range losses initially decreased rapidly as dispersal rates increased but the benefits are reduced above 2–3 km year−1. Taxa restricted to dispersal within the stream network (aquatic) were more vulnerable to climate change than taxa with semi-terrestrial or aerial dispersal and maps of variation due to dispersal mode and rate indicate where habitat connectivity would be most beneficial. This study demonstrates the breadth of uncertainties that challenge plans for improving ecosystem adaptation under climate change and highlights where in the landscape those differences were consistent. We emphasise the need for freshwater conservation studies to be ecologically representative, to focus on broad-scale connectivity for taxa that can move between catchments, and an accessible network of refugia for taxa with more limited dispersal.
Bush A., Sollmann R., Wilting A., Bohmann K., Cole B., Balzter H., Martius C., Zlinszky A., Calvignac-Spencer S., Cobbold C.A., Dawson T.P., Emerson B.C., Ferrier S., Gilbert M.T.P., Herold M., Jones L., Leendertz F.H., Matthews L., Millington J.D.A., Olson J.R., Ovaskainen O., Raffaelli D., Reeve R., Rödel M.O., Rodgers T.W., Snape S., Visseren-Hamakers I., Vogler A.P., White P.C.L., Wooster M.J., Yu D.W. (2017). Connecting Earth observation to high-throughput biodiversity data. Nature Ecology and Evolution, 1(7).

Understandably, given the fast pace of biodiversity loss, there is much interest in using Earth observation technology to track biodiversity, ecosystem functions and ecosystem services. However, because most biodiversity is invisible to Earth observation, indicators based on Earth observation could be misleading and reduce the effectiveness of nature conservation and even unintentionally decrease conservation effort. We describe an approach that combines automated recording devices, high-throughput DNA sequencing and modern ecological modelling to extract much more of the information available in Earth observation data. This approach is achievable now, offering efficient and near-real-time monitoring of management impacts on biodiversity and its functions and services.
Cabrera-Páez Y., Aguilar-Betancourt C., González-Sansón G., Hernández-Hernández I. (2017). Embryonic development stages description in gambusia puncticulata (Pisces: Poeciliidae) from almendares river, Cuba. Latin American Journal of Aquatic Research, 45(4) 858-863.

This research’s main goal is the description of the embryonic developmental stages of Gambusia puncticulata. It also provides an analysis of the embryonic mean developmental stage, and mean weight in relation to the mother’s carcass weight. The fish were caught monthly from July 2006 to June 2007 throughout Almendares River, North of Havana, Cuba. The embryonic mean stage values (F<inf>4,600</inf> = 14.79, P < 0.001), and mean weight values (F<inf>4,395</inf> = 7.09, P < 0.001), increased with mother’s size increment. This research describes, for the first time, seven embryonic developmental stages in G. puncticulata. The applied macroscopic classification of the embryos showed great consistency, due to the large number of examined specimens. The criteria used to define the stages are accurate, and allow to distinguish the stages easily, quickly and with high reliability. These criteria could be applied to other species of the Gambusia genus.
Chase J.W., Benoy G.A., Culp J.M. (2017). Combined effects of nutrient enrichment and inorganic sedimentation on benthic biota in an experimental stream system. Water Quality Research Journal, 52(3) 151-165.

Sedimentation and nutrient loading are among the most prevalent threats to fluvial ecosystem integrity. This study employed artificial streams (mesocosms) to simulate individual and combined impacts of nutrient enrichment and deposited fine sediment on benthic biota. Ninety-six circular mesocosms were used in a 21-day crossed experiment that measured the impact of three substrate compositions (0, 25, and 50% fines <2 mm) and four nitrogen concentrations (17, 22, 43, and 94 µg L-1 (soluble inorganic nitrogen)) on periphyton and benthic macroinvertebrate assemblages. Permutational multivariate analysis of variance (PERMANOVA) of macroinvertebrate assemblages indicated substantial shifts in structural composition, while univariate models for Lepidostomatidae and total Ephemeroptera, Plecoptera and Trichoptera revealed that nutrient and sediment subsidies related to single factors were suppressed by an additional stressor. Stressor mechanism overlap was evident at higher treatment levels, as moderate nutrient enrichment increased nutritional resources but high nitrogen concentrations lead to substrate smothering by periphyton, contributing to habitat degradation originating from inorganic sedimentation. Our study is consistent with research showing that nutrient loading and sedimentation interact to deteriorate lotic systems beyond levels attributable to either individual stressor. Management practices and pollution standards need to incorporate relationships between stressors tightly co-vary in natural settings.
Clayden M.G., Lescord G.L., Kidd K.A., Wang X., Muir D.C.G., O'Driscoll N.J. (2017). Using sulfur stable isotopes to assess mercury bioaccumulation and biomagnification in temperate lake food webs. Environmental Toxicology and Chemistry, 36(3) 661-670.

Nitrogen and carbon stable isotopes (δ15N, δ13C) are commonly used to understand mercury (Hg) bioaccumulation and biomagnification in freshwater food webs. Though sulfur isotopes (δ34S) can distinguish between energy sources from the water column (aqueous sulfate) and from sediments to freshwater organisms, little is known about whether δ34S can help interpret variable Hg concentrations in aquatic species or food webs. Seven acidic lakes in Kejimkujik National Park (Nova Scotia, Canada) were sampled for biota, water, and sediments in 2009 and 2010. Fishes, zooplankton, and macroinvertebrates were analyzed for δ34S, δ15N, δ13C, and Hg (methyl Hg in invertebrates, total Hg in fishes); aqueous sulfate and profundal sediments were analyzed for δ34S. Within lakes, mean δ34S values in sediments and sulfate differed between 0.53‰ and 1.98‰, limiting their use as tracers of energy sources to the food webs. However, log-Hg and δ34S values were negatively related (slopes –0.14 to –0.35, R2 0.20–0.39, p < 0.001–0.01) through each food web, and slopes were significantly different among lakes (analysis of covariance, lake × δ34S interaction term p = 0.04). Despite these relationships, multiple regression analyses within each taxon showed that biotic Hg concentrations were generally better predicted by δ15N and/or δ13C. The results indicate that δ34S values are predictive of Hg concentrations in these food webs, although the mechanisms underlying these relationships warrant further study. Environ Toxicol Chem 2017;36:661–670. © 2016 SETAC.
Coffin M.R.S., Knysh K.M., Theriault E.F., Pater C.C., Courtenay S.C., van den Heuvel M.R. (2017). Are floating algal mats a refuge from hypoxia for estuarine invertebrates? Peerj, 2017(3).

Eutrophic aquatic habitats are characterized by the proliferation of vegetation leading to a large standing biomass that upon decomposition may create hypoxic (low-oxygen) conditions. This is indeed the case in nutrient impacted estuaries of Prince Edward Island, Canada, where macroalgae, from the genus Ulva, form submerged ephemeral mats. Hydrological forces and gases released from photosynthesis and decomposition lead to these mats occasionally floating to the water's surface, henceforth termed floating mats. Here, we explore the hypothesis that floating mats are refugia during periods of sustained hypoxia/anoxia and examine how the invertebrate community responds to it. Floating mats were not always present, so in the first year (2013) sampling was attempted monthly and limited to when both floating and submerged mats occurred. In the subsequent year sampling was weekly, but at only one estuary due to logistical constraints from increased sampling frequency, and was not limited to when both mat types occurred. Water temperature, salinity, and pH were monitored bi-weekly with dissolved oxygen concentration measured hourly. The floating and submerged assemblages shared many of the same taxa but were statistically distinct communities; submerged mats tended to have a greater proportion of benthic animals and floating mats had more mobile invertebrates and insects. In 2014, sampling happened to occur in the weeks before the onset of anoxia, during 113 consecutive hours of sustained anoxia, and for four weeks after normoxic conditions returned. The invertebrate community on floating mats appeared to be unaffected by anoxia, indicating that these mats may be refugia during times of oxygen stress. Conversely, there was a dramatic decrease in animal abundances that remained depressed on submerged mats for two weeks. Cluster analysis revealed that the submerged mat communities from before the onset of anoxia and four weeks after anoxia were highly similar to each other, indicating recovery. When mobile animals were considered alone, there was an exponential relationship between the percentage of animals on floating mats, relative to the total number on both mat types, and hypoxia. The occupation of floating mats by invertebrates at all times, and their dominance there during hypoxia/anoxia, provides support for the hypothesis that floating mats are refugia.
Corey E., Linnansaari T., Cunjak R.A., Currie S. (2017). Physiological eﬀects of environmentally relevant, multi-day thermal stress on wild juvenile Atlantic salmon (Salmo salar). Conservation Physiology, 5(1).

The frequency of extreme thermal events in temperate freshwater systems is expected to increase alongside global surface temperature. The Miramichi River, located in eastern Canada, is a prominent Atlantic salmon (Salmo salar) river where water temperatures can exceed the proposed upper thermal limit for the species (~27°C). Current legislation closes the river to recreational angling when water temperatures exceed 20°C for two consecutive nights. We aimed to examine how natural thermal variation, representative of extreme high thermal events, aﬀected the thermal tolerance and physiology of wild, juvenile Atlantic salmon. We acclimated ﬁsh to four thermal cycles, characteristic of real-world thermal conditions while varying daily thermal minima (16°C, 18°C, 20°C or 22°C) and diel thermal ﬂuctuation (e.g. Δ5°C-Δ9°C). In each cycling condition, we assessed the role that thermal minima played on the acute thermal tolerance (critical thermal maximum, (CTMax)), physiological (e.g. heat shock protein 70 (HSP70), ubiquitin) and energetic (e.g. hepatic glycogen, blood glucose and lactate) status of juvenile Atlantic salmon throughout repeated thermal cycles. Exposure to 16-21°C signiﬁcantly increased CTMax (+0.9°C) compared to a stable acclimation temperature (16°C), as did exposure to diel thermal ﬂuctuations of 18-27°C, 20-27°C and 22-27°C, yet repeated exposure provided no further increases in acute thermal tolerance. In comparison to the reference condition (16-21°C), consecutive days of high temperature cycling with diﬀerent thermal minima resulted in signiﬁcant increases in HSP70 and ubiquitin, a signiﬁcant decrease in liver glycogen, and no signiﬁcant cumulative eﬀect on either blood glucose or lactate. However, comparison between thermally taxed treatments suggested the diel thermal minima had little inﬂuence on the physiological or energetic response of juvenile salmon, despite the variable thermal cycling condition. Our results suggest that relatively cooler night temperatures in the summer months may play a limited role in mitigating physiological stress throughout warm diel cycle events.
Cowie A.M., Sarty K.I., Mercer A., Koh J., Kidd K.A., Martyniuk C.J. (2017). Molecular networks related to the immune system and mitochondria are targets for the pesticide dieldrin in the zebrafish (Danio rerio) central nervous system. Journal of Proteomics, 157 71-82.

The objectives of this study were to determine the behavioral and molecular responses in the adult zebrafish (Danio rerio) central nervous system (CNS) following a dietary exposure to the pesticide dieldrin. Zebrafish were fed pellets spiked with 0.03, 0.15, or 1.8 μg/g dieldrin for 21 days. Behavioral analysis revealed no difference in exploratory behaviors or those related to anxiety. Transcriptional networks for T-cell aggregation and selection were decreased in expression suggesting an immunosuppressive effect of dieldrin, consistent with other studies investigating organochlorine pesticides. Processes related to oxidative phosphorylation were also differentially affected by dieldrin. Quantitative proteomics (iTRAQ) using a hybrid quadrupole-Orbitrap identified 226 proteins that were different following one or more doses. These proteins included ATP synthase subunits (mitochondrial) and hypoxia up-regulated protein 1 which were decreased and NADH dehydrogenases (mitochondrial) and signal recognition particle 9 which were up-regulated. Thus, proteins affected were functionally associated with the mitochondria and a protein network analysis implicated Parkinson's disease (PD) and Huntington's disease as diseases associated with altered proteins. Molecular networks related to mitochondrial dysfunction and T-cell regulation are hypothesized to underlie the association between dieldrin and PD. These data contribute to a comprehensive transcriptomic and proteomic biomarker framework for pesticide exposures and neurodegenerative diseases. Biological significance Dieldrin is a persistent organochlorine pesticide that has been associated with human neurodegenerative disease such as Parkinson's disease. Dieldrin is ranked 18th on the 2015 U.S. Agency for Toxic Substances and Disease Registry and continues to be a pesticide of concern for human health. Transcriptomics and quantitative proteomics (ITRAQ) were employed to characterize the molecular networks in the central nervous system that are altered with dietary exposure to dieldrin. We found that transcriptional and protein networks related to the immune system, mitochondria, and Parkinson's disease were preferentially affected by dieldrin. The study provides new insight into the mechanisms of dieldrin neurotoxicity that may explain, in part, the association between this pesticide and increased risks to neurodegeneration. These data contribute in a significant way to developing a molecular framework for pesticide induced neurotoxicity.
Cowie A.M., Sarty K.I., Mercer A., Koh J., Kidd K.A., Martyniuk C.J. (2017). The pesticide dieldrin disrupts proteins related to oxidative respiration and mitochondrial stress in the central nervous system. Data in Brief, 11 628-633.

Quantitative proteins analysis was carried out in the hypothalamus of zebrafish following dietary exposure to the legacy pesticide dieldrin. Data were collected using iTRAQ labeling methodology and data were acquired using a hybrid quadrupole Orbitrap (Q Exactive) MS system (Thermo Fisher Scientific, Bremen, Germany). There were 3941 proteins identified in the hypothalamus of zebrafish, and these proteins comprised 23 unique expression patterns for proteins based on the three doses of dieldrin. There were 226 proteins that were regulated in one or more doses of dieldrin and 3715 proteins that were not affected. Thus, 5.7% of the proteins detected responded to the treatment. Many proteins that were differentially expressed were those found in, or associated with, the mitochondria. The proteomics data described in this article is associated with a research article, “Transcriptomic and proteomic analysis implicates the immune system and mitochondria as molecular targets of dieldrin in the zebrafish (Danio rerio) central nervous system” (A.M. Cowie, K.I. Sarty, A. Mercer, J. Koh, K.A. Kidd, C.J. Martyniuk, submitted) [1], and serves as a resource for researchers working in the field of pesticide exposures and protein biomarkers.
Crawford S.E., Cofalla C.B.n., Aumeier B., Brinkmann M., Classen E., Esser V., Ganal C., Kaip E., Häussling R., Lehmkuhl F., Letmathe P., Müller A.K., Rabinovitch I., Reicherter K., Schwarzbauer J., Schmitt M., Stauch G., Wessling M., Yüce S., Hecker M., Kidd K.A., Altenburger R., Brack W., Schüttrumpf H., Hollert H. (2017). Project house water: a novel interdisciplinary framework to assess the environmental and socioeconomic consequences of flood-related impacts. Environmental Sciences Europe, 29(1).

Protecting our water resources in terms of quality and quantity is considered one of the big challenges of the twenty-first century, which requires global and multidisciplinary solutions. A specific threat to water resources, in particular, is the increased occurrence and frequency of flood events due to climate change which has significant environmental and socioeconomic impacts. In addition to climate change, flooding (or subsequent erosion and run-off) may be exacerbated by, or result from, land use activities, obstruction of waterways, or urbanization of floodplains, as well as mining and other anthropogenic activities that alter natural flow regimes. Climate change and other anthropogenic induced flood events threaten the quantity of water as well as the quality of ecosystems and associated aquatic life. The quality of water can be significantly reduced through the unintentional distribution of pollutants, damage of infrastructure, and distribution of sediments and suspended materials during flood events. To understand and predict how flood events and associated distribution of pollutants may impact ecosystem and human health, as well as infrastructure, large-scale interdisciplinary collaborative efforts are required, which involve ecotoxicologists, hydrologists, chemists, geoscientists, water engineers, and socioeconomists. The research network “project house water” consists of a number of experts from a wide range of disciplines and was established to improve our current understanding of flood events and associated societal and environmental impacts. The concept of project house and similar seed fund and boost fund projects was established by the RWTH Aachen University within the framework of the German excellence initiative with support of the German research foundation (DFG) to promote and fund interdisciplinary research projects and provide a platform for scientists to collaborate on innovative, challenging research. Project house water consists of six proof-of-concept studies in very diverse and interdisciplinary areas of research (ecotoxicology, water, and chemical process engineering, geography, sociology, economy). The goal is to promote and foster high-quality research in the areas of water research and flood-risk assessments that combine and build off-laboratory experiments with modeling, monitoring, and surveys, as well as the use of applied methods and techniques across a variety of disciplines.
Crispo E., Tunna H.R., Hussain N., Rodriguez S.S., Pavey S.A., Jackson L.J., Rogers S.M. (2017). The evolution of the major histocompatibility complex in upstream versus downstream river populations of the longnose dace. Ecology and Evolution, 7(10) 3297-3311.

Populations in upstream versus downstream river locations can be exposed to vastly different environmental and ecological conditions and can thus harbor different genetic resources due to selection and neutral processes. An interesting question is how upstream–downstream directionality in rivers affects the evolution of immune response genes. We used next-generation amplicon sequencing to identify eight alleles of the major histocompatibility complex (MHC) class II β exon 2 in the cyprinid longnose dace (Rhinichthys cataractae) from three rivers in Alberta, upstream and downstream of municipal and agricultural areas along contaminant gradients. We used these data to test for directional and balancing selection on the MHC. We also genotyped microsatellite loci to examine neutral population processes in this system. We found evidence for balancing selection on the MHC in the form of increased nonsynonymous variation relative to neutral expectations, and selection occurred at more amino acid residues upstream than downstream in two rivers. We found this pattern despite no population structure or isolation by distance, based on microsatellite data, at these sites. Overall, our results suggest that MHC evolution is driven by upstream–downstream directionality in fish inhabiting this system.
Culp J.M., Yates A.G., Armanini D.G., Baird D.J. (2017). Establishing Cause-Effect Relationships in Multistressor Environments. Methods in Stream Ecology Third Edition, 2 335-351.

In this chapter, we present a combination of methodologies for investigating multiple stressor effects of effluent discharge on river ecosystems. We focus on the integration of laboratory, field, and experimental manipulation studies that help identify cause-and-effect relationships and generate weight-of-evidence ecological risk assessments for rivers. The chapter (1) outlines a basic methodology for assessing the biological responses to an effluent discharge (i.e., a point source); (2) demonstrates how nutrient diffusing substrate bioassays can be used to evaluate the effect of effluents on nutrient limitation of algal biomass; (3) illustrates the usefulness of field-based toxicity bioassays to determine contaminant effects of effluents; and (4) introduces the use of stream mesocosms as an approach to establish causality between stressors and biological effects. Together, the different methods provide a process through which key stressors are identified, ecological effects are measured, and subsequent investigations into the cause of effects are conducted.
Dadswell M.J., Ceapa C., Spares A.D., Stewart N.D., Curry R.A., Bradford R.G., Stokesbury M.J.W. (2017). Population Characteristics of Adult Atlantic Sturgeon Captured by the Commercial Fishery in the Saint John River Estuary, New Brunswick. Transactions of the American Fisheries Society, 146(2) 318-330.

The commercial fishery for Atlantic Sturgeon Acipenser oxyrinchus in the Saint John River, New Brunswick, began in 1880. The early fishery was unregulated, and the adult stock was depleted by 1886 after landings of 712 metric tons. After a 10-year closure the fishery was reopened in 1897 with management regulations, and landings varied from 6 to 20 metric tons/year until 2010. In 2011 an annual quota of 350 adults was established and landings are now stable at 11.3 ± 1.7 (mean ± SD) metric tons/year. Since 2009, fishers have collected biological statistics from adults taken in the fishery and 14–60% of captured individuals have been marked and released each year. During 2009–2015, annual mean values of total length and dressed weight of landed adults were stable, the male : female sex ratio was 1.2:1.0, and mean age of males and females was 27.2 and 34.0 years, respectively. Estimates of instantaneous total mortality ranged from 0.08 to 0.11, and mean annual survival was 90.9%. Of 1,396 marked adults released, 147 were recaptured in the estuary in subsequent years. Tag returns indicated that the modal spawning periodicity of males was 2 years and that of females was 4 years. Valid, modified Schnabel and Jolly–Seber mean annual population estimates for 2013–2015 were 18,179 and 20,798 adults, respectively. The quota in relation to these estimated adult populations represented annual exploitation rates of 1.9% and 1.7%, which are below F<inf>50</inf> and would maintain present stock size. The virgin adult population was determined using 1880–1886 total landings and a mean weight range for adults of 50–30 kg. Estimated range of the 1880 virgin population size was 14,240–23,733 adults. These data suggest that the fishery is sustainable at its current annual yield and that the population is near the carrying capacity of the Saint John River. Received July 12, 2016; accepted November 17, 2016 Published online February 21, 2017
Dauphin G.J.R., Brugel C., Legrand M., Prévost E. (2017). Separating wild versus stocking components in fish recruitment without identification data: A hierarchical modelling approach. Canadian Journal of Fisheries and Aquatic Sciences, 74(7) 1111-1124.

Salmonid juvenile stocking programs are often poorly monitored due to the lack of identification between stocked and wild fish. In this study, a hierarchical Bayesian model is developed to take advantage of spatiotemporal variations of stocking and wild recruitment for estimating these two components despite the absence of identification data. It is first tested by means of simulated data and then applied to the 37 year abundance data set of the Atlantic salmon (Salmo salar) population of the Allier catchment (France). Despite the absence of identification data, juvenile densities could be estimated and split into wild and stocked components. We found that the stocked juveniles contributed significantly to the total juvenile production, while the wild reproduction continued to provide an important contribution. This approach is encouraging and promising from a management advice perspective. It is flexible enough to accommodate for case study specificities and shows that long-term monitoring abundances can be useful to assess the impact of stocking programs even in the absence of direct means of identifying stocked versus wild fish.
Dugdale S.J., St-Hilaire A., Curry R.A. (2017). Automating drainage direction and physiographic inputs to the CEQUEAU hydrological model: Sensitivity testing on the lower Saint John River watershed, Canada. Journal of Hydroinformatics, 19(3) 469-492.

CEQUEAU is a process-based hydrological model capable of simulating river flows and temperatures. Despite an active user base, no facility yet exists for the automatic assembly and input of watershed data required for flow simulations. CEQUEAU can therefore be time-consuming to implement, particularly on large (≥104 km2) watersheds. We detail a new MATLAB toolbox designed to remove this key limitation by automatically computing CEQUEAU's key drainage direction and physiographic inputs from geographic information system (GIS) data. With the toolbox, model implementation can now be achieved extremely quickly (<1.5 hr) given suitable inputs. This time saving enabled us to assess CEQUEAU's sensitivity to changes in grid size by implementing the model on a large (14,990 km2) watershed at successively decreasing resolution (2.5 km to 112 km), using a fixed calibration parameter set. Results of this analysis showed that despite some model strength fluctuations linked to variability in computed basin size/land-use, only a minor decrease in model strength (mean Nash-Sutcliffe efficiency (NSE) reduction = 0.03) was observed at relatively fine resolutions (2.5 km to 20 km). Although results might change if the model was recalibrated at each resolution step, findings indicate that CEQUEAU is able to provide realistic flow simulations at a wide range of resolutions.
Elvidge C.K., Cooke E.L.L., Cunjak R.A., Cooke S.J. (2017). Social cues may advertise habitat quality to refuge-seeking conspecifics. Canadian Journal of Zoology, 95(1) 1-5.

Individuals travelling through landscapes may use the presence of conspecifics to evaluate habitat quality. Juvenile Atlantic salmon (Salmo salar L., 1758) are usually territorial and exhibit some degree of density-dependent regulation in wild populations. They are also vulnerable to heat stress and may need to locate a thermal refuge to offset metabolic costs above certain temperature thresholds. During July 2010, a heat wave resulted in water temperatures in the Miramichi River system exceeding 30 °C. During this period, salmon parr were observed aggregating in cold-water refugia at densities several orders of magnitude greater than usual. We tested whether groups of wild-caught salmon parr held at high densities (160 parr/m2) would have an attractant effect on free-swimming parr at three sites differing in temperature between 16.5 and 24 °C. Although neither temperature nor site influenced the number of parr that we observed, there were significantly more parr in close proximity (<1 m) to the artificial aggregations than to the controls. These results suggest that social cues from high-density aggregations of conspecifics during extreme temperature events may advertise the location of thermal refugia to others. Understanding how heat-stressed salmon locate refugia may prove valuable to ongoing conservation efforts given the likelihood of increasingly frequent and extreme high-temperature events.
Gerwing T.G., Hamilton D.J., Barbeau M.A., Haralampides K., Yamazaki G. (2017). Short-Term Response of a Downstream Marine System to the Partial Opening of a Tidal-River Causeway. Estuaries and Coasts, 40(3) 717-725.

The spillway gates of the Petitcodiac Causeway, a hydraulic structure ~35 km upstream of the mouth of the Petitcodiac River in New Brunswick, Canada, were permanently opened in April 2010. The short-term effect opening the spillway gates had on downstream intertidal mudflats of the upper Bay of Fundy was investigated. Specifically, a multivariate before-after-control-impact design was used to determine if opening the spillway gates affected the invertebrate community (crustaceans, polychaetes, and molluscs), abiotic sediment conditions (sediment water content, mean particle size, penetrability, and depth of the apparent redox potential discontinuity), or resource availability (sediment chlorophyll a concentration and organic matter content) of five intertidal mudflats (two impacted sites, three reference sites) spanning Chignecto Bay, the northern arm of the upper Bay of Fundy, up to 5 months post-opening. No biologically or statistically meaningful differences were detected between impacted and reference sites for any of the measured variables. This suggests that opening the causeway did not have a quantifiable impact on these intertidal mudflats, at least within half a year of the opening. This is likely a result of the macrotidal nature of the Bay of Fundy that overwhelmed any immediate changes to hydrodynamics that occurred after the opening of the causeway gates.
Graves S.D., Kidd K.A., Batchelar K.L., Cowie A.M., O'Driscoll N.J., Martyniuk C.J. (2017). Response of oxidative stress transcripts in the brain of wild yellow perch (Perca flavescens) exposed to an environmental gradient of methylmercury. Comparative Biochemistry and Physiology Part C Toxicology and Pharmacology, 192 50-58.

Methylmercury (MeHg) exposure and adverse health effects in fishes have been documented, but the molecular mechanisms involved in toxicity have not been fully characterized. The objectives of the current study were to (1) determine whether total Hg (THg) in the muscle was predictive of MeHg concentrations in the brain of wild female yellow perch (Perca flavescens) collected from four lakes in Kejimkujik National Park, a known biological mercury (Hg) hotspot in Nova Scotia, Canada and (2) to determine whether transcripts involved in the oxidative stress response were altered in abundance in fish collected across five lakes representing a MeHg gradient. In female yellow perch, MeHg in whole brain (0.38 to 2.00 μg/g wet weight) was positively associated with THg in muscle (0.18 to 2.13 μg/g wet weight) (R2 = 0.61, p < 0.01), suggesting that muscle THg may be useful for predicting MeHg concentrations in the brain. Catalase (cat) mRNA levels were significantly lower in brains of perch collected from lakes with high Hg when compared to those individuals from lakes with relatively lower Hg (p = 0.02). Other transcripts (cytochrome c oxidase, glutathione peroxidase, glutathione-s-transferase, heat shock protein 70, protein disulfide isomerase, and superoxide dismutase) did not show differential expression in the brain over the gradient. These findings suggest that MeHg may be inversely associated with catalase mRNA abundance in the central nervous system of wild fishes.
Hayden B., Myllykangas J.P., Rolls R.J., Kahilainen K.K. (2017). Climate and productivity shape fish and invertebrate community structure in subarctic lakes. Freshwater Biology, 62(6) 990-1003.

Climate change and land-use intensification are increasing productivity in subarctic lakes. Simultaneously, fish and invertebrate species adapted to temperate conditions are expanding their range northwards into subarctic habitats. Community level studies are required to predict long-term effects of these dual stressors on subarctic freshwater ecosystems. We conducted a space-for-time study examining the fish, benthic invertebrate and pelagic zooplankton communities in littoral, profundal and pelagic habitats in 19 subarctic lakes situated on a temperature, land-use and productivity gradient in northern Europe. Fish density (ranging between 0.5 and 150.5 fish per net series h−1) and biomass (range between 92 and 5,147 g per net series h−1) increased significantly with increasing lake temperature and productivity. This was associated with significantly decreasing body size (26 to 12 cm total length; 174 to 19 g body mass) and a shift in fish community structure from salmonid (Arctic charr Salvelinus alpinus, whitefish Coregonus lavaretus), to percid (ruffe Gymnocephalus cernua, perch Perca fluviatilis) and ultimately cyprinid (roach Rutilus rutilus, bleak Alburnus alburnus) dominance. Changes in fish community composition were most apparent in littoral and pelagic zones. Benthic macroinvertebrate density peaked in mesotrophic lakes, zooplankton density was highest at either end of the gradient, indicating habitat specific differences in predation pressure and top-down control. Body size of zooplankton and benthic macroinvertebrates was negatively related to temperature and productivity. These results suggest that climate change and intensification of land-use practices are gradually turning subarctic lakes into warmer, less transparent and more productive systems harbouring abundant, small-sized and warmer adapted communities.
Hayden B., Tongnunui S., Beamish F.W.H., Nithirojpakdee P., Cunjak R.A. (2017). Variation in stable-isotope ratios between fin and muscle tissues can alter assessment of resource use in tropical river fishes. Journal of Fish Biology, 91(2) 574-586.

Carbon and nitrogen stable-isotope ratios were compared of fin and muscle tissue from 15 fish species collected from seven headwater rivers in eastern and western Thailand. In addition, two-source stable-isotope mixing models were used to derive estimates of each fish's reliance on allochthonous and autochthonous energy based on fin and muscle tissues. Across the dataset, fish fin was enriched in 13C relative to muscle by c. 1·5‰. Variation in δ15N between tissues was below statistically significant levels. Estimates of autochthonous resource use calculated from fin tissue were on average 15% greater than those calculated from muscle. Linear mixed-effects models indicated that inter-tissue variation in estimates of resource use was predominantly related to inter-tissue variation in δ13C. Fish fin is a credible and desirable alternative to tissues such as muscle or liver which require destructive sampling of fishes. Care must be taken, however, when estimating resource use or interpreting previous estimates of resource use derived from different tissues.
Kahilainen K.K., Thomas S.M., Nystedt E.K.M., Keva O., Malinen T., Hayden B. (2017). Ecomorphological divergence drives differential mercury bioaccumulation in polymorphic European whitefish (Coregonus lavaretus) populations of subarctic lakes. Science of the Total Environment, 599-600 1768-1778.

Resource polymorphism, whereby ancestral trophic generalists undergo divergence into multiple specialist morphs, is common in salmonid fish populations inhabiting subarctic lakes. However, the extent to which such resource specialization into the three principal lake habitats (littoral, profundal, and pelagic) affects patterns of contaminant bioaccumulation remains largely unexplored. We assessed total mercury concentrations (THg) of European whitefish (Coregonus lavaretus (L.)) and their invertebrate prey in relation to potential explanatory variables across 6 subarctic lakes, of which three are inhabited by polymorphic (comprised of four morphs) and three by monomorphic populations. Among invertebrate prey, the highest THg concentrations were observed in profundal benthic macroinvertebrates, followed by pelagic zooplankton, with concentrations lowest in littoral benthic macroinvertebrates in both lake types. Broadly similar patterns were apparent in whitefish in polymorphic systems, where average age-corrected THg concentrations and bioaccumulation rates were the highest in pelagic morphs, intermediate in the profundal morph, and the lowest in the littoral morph. In monomorphic systems, age-corrected THg concentrations were generally lower, and showed pronounced lake-specific variation. In the polymorphic systems, we found significant relationships between whitefish muscle tissue THg concentration and gill raker count, resource use, lipid content and maximum length, whilst no such relationships were apparent in the monomorphic systems. Across all polymorphic lakes, the major variables explaining THg in whitefish were gill raker count and age, whereas in monomorphic systems, the factors were lake-specific. Whitefish resource polymorphism across the three main lake habitats therefore appears to have profound impacts on THg concentration and bioaccumulation rate. This highlights the importance of recognizing such intraspecific diversity in both future scientific studies and mercury monitoring programs.
Keva O., Hayden B., Harrod C., Kahilainen K.K. (2017). Total mercury concentrations in liver and muscle of European whitefish (Coregonus lavaretus (L.)) in a subarctic lake - Assessing the factors driving year-round variation. Environmental Pollution, 231 1518-1528.

Subarctic lakes are characterised by extreme seasonal variation in light and temperature which influences growth, maturation, condition and resource use of fishes. However, our understanding of how seasonal changes affect mercury concentrations of fishes is limited. We conducted a year-round study (3 ice-covered months, 3 open-water months) with open-water inter-annual aspect (3 years: samples from August/September), focusing on total mercury (THg) concentrations and ecological characteristics of a common freshwater fish, European whitefish (Coregonus lavaretus (L.)) from a subarctic lake. We measured THg concentrations from tissues with fast (liver, n = 164) and moderate (muscle, n = 225) turnover rates, providing information on THg dynamics over different temporal scales. In both tissues, lipid-corrected THg concentrations were highest in winter (liver: 1.70 ± 0.88 μg/g, muscle: 0.24 ± 0.05 μg/g) and lowest in summer (liver: 0.87 ± 0.72 μg/g, muscle: 0.19 ± 0.04 μg/g). THg concentrations increased in winter following the summer-autumn dietary shift to pelagic zooplankton and starvation after spawning. Whitefish THg concentrations decreased towards summer, and were associated with consumption of benthic macroinvertebrates and subsequent growth dilution. Mercury bioaccumulated in both tissues with age, both showing the strongest regression slopes in winter and lowest in summer. THg concentrations in liver and muscle tissue were correlated throughout the year, however the correlation was lowest in summer, indicating high metabolism during somatic growing season in summer and growth dilution. Multiple linear regression models explained 50% and 55% of the THg variation in liver and muscle both models dominated by seasonally-variable factors i.e. sexual maturity, δ13C, and condition factor. Seasonally varying bioaccumulation slopes and the higher level of intra-annual variation (21%) in whitefish THg concentration in muscle than the inter-annual accumulation (8%) highlight the importance of including seasonal factors in future THg studies. Capsule Strong seasonal variation was observed in THg concentrations and bioaccumulation slopes in muscle and liver tissues, suggesting that the temporal component of sampling should be considered in future THg monitoring and risk assessment programmes.
Laanaya F., St-Hilaire A., Gloaguen E. (2017). Water temperature modelling: comparison between the generalized additive model, logistic, residuals regression and linear regression models. Hydrological Sciences Journal, 62(7) 1078-1093.

Water temperature has a significant influence on aquatic organisms, including stenotherm fish such as salmonids. It is thus of prime importance to build reliable tools to forecast water temperature. This study evaluated a statistical scheme to model average water temperature based on daily average air temperature and average discharge at the Sainte-Marguerite River, Northern Canada. The aim was to test a non-parametric water temperature generalized additive model (GAM) and to compare its performance to three previously developed approaches: the logistic, residuals regression and linear regression models. Due to its flexibility, the GAM was able to capture some of the nonlinear response between water temperature and the two explanatory variables (air temperature and flow). The shape of these effects was determined by the trends shown in the collected data. The four models were evaluated annually using a cross-validation technique. Three comparison criteria were calculated: the root mean square error (RMSE), the bias error and the Nash-Sutcliffe coefficient of efficiency (NSC). The goodness of fit of the four models was also compared graphically. The GAM was the best among the four models (RMSE = 1.44°C, bias = −0.04 and NSC = 0.94).
Landsman S.J., Wilson A.D.M., Cooke S.J., van den Heuvel M.R. (2017). Fishway passage success for migratory rainbow smelt Osmerus mordax is not dictated by behavioural type. River Research and Applications, 33(8) 1257-1267.

Recent research has demonstrated that an individual's behavioural decisions can have a profound impact on an animal's fitness. For anadromous fishes requiring access to spawning habitat above obstructions, successful passage at fishways may at least in part be a function of an individual's behavioural type. The objectives of this study were to determine whether distinct behavioural types—bold and shy—could be distinguished within a population of anadromous rainbow smelt (Osmerus mordax) and, if so, whether passage success at a nature-like fishway varied relative to behavioural type. Field-caught rainbow smelt were tested for individual differences in boldness (i.e., willingness to engage in risk-taking behaviour) using the metrics of exploratory behaviour, general activity, and response to a simulated predator. After testing, 276 rainbow smelt were implanted with a passive integrated transponder tag, released below the fishway, and their movements monitored via a stationary antenna array. The results of our behavioural assays indicated the presence of a behavioural syndrome among rainbow smelt, and that behaviour was partially repeatable. In total, 41.7% of fish entering the fishway passed successfully, but contrary to our initial prediction, boldness was not a significant predictor of successful passage. Instead, increasing water temperature and decreasing river discharge were consistent predictors of successful passage and greater distances moved through the fishway. Our findings indicate that the nature-like fishway did not select for a particular behavioural type and that individuals representing the spectrum of bold–shy behavioural types could pass.
Lin H.Y., Bush A., Linke S., Possingham H.P., Brown C.J. (2017). Climate change decouples marine and freshwater habitats of a threatened migratory fish. Diversity and Distributions, 23(7) 751-760.

Aim: To assess how climate change may decouple the ecosystems used by a migratory fish, and how decoupling influences priorities for stream restoration. Location: Australia. Methods: We modelled changes in habitat suitability under climate change in both riverine and marine habitats for a threatened diadromous species, the Australian Grayling Prototroctes maraena, using niche models. The loss of riverine habitats for Grayling was compared with or without considering the impact of climate change on adjacent marine habitats. We also asked whether considering marine climate change changed the locations where removing dams had the greatest benefit for Grayling conservation. Results: Climate change is expected to cause local extinction in both marine and river habitats regardless of whether dams are retained or removed at the trailing edge of the Grayling's range (north-eastern). Decoupling of habitats was most apparent in the eastern and south-eastern portion of the Grayling's range, where ocean warming may cause a decline in the suitability of marine habitats for larvae, while many freshwater habitats retained suitable habitat for adults. Removing dams to restore connectivity between ocean and freshwater habitats was predicted to have the greatest benefit for Grayling in southern portions of their range. Under climate change, the priorities for barrier removal gradually shift towards dams at higher elevation because of increasing suitability of freshwater habitats at higher elevations. Main conclusions: Our study highlights the importance of assessing climate range shifts in multiple ecosystems for migratory species and can help inform priorities for stream restoration under a changing climate.
Linke J., Fortin M.J., Courtenay S., Cormier R. (2017). High-resolution global maps of 21st-century annual forest loss: Independent accuracy assessment and application in a temperate forest region of Atlantic Canada. Remote Sensing of Environment, 188 164-176.

Monitoring forest ecosystems requires accurate and up-to-date information on the type and extent of forest depletions, which may exist but are not always open and transparent. The ever growing, freely accessible Landsat archive provides data to derive such information; however, the manipulation of raw imagery can constitute a barrier to those lacking remote sensing expertise. The Landsat-based, global dataset of annual forest loss (version 1.0, Hansen et al., 2013) makes such information readily available. While the accuracy of this dataset has been assessed at the global scale, its applicability for reliable local monitoring of forest harvesting has not yet been validated. Here we undertake such an exercise in a temperate forest in Atlantic Canada. We used a census, polygon-based approach to comprehensively assess thematic, temporal and structural accuracy. We vectorized Hansen's forest loss raster for the 8,520 km2 of public lands in the Miramichi River basin (13,496 km2), which yielded 9299 polygons of 1 ha minimum size. Then we used the provincial forest harvest inventory as reference. User's and producer's accuracies were 81% and 82% based on area, and 86% and 85% based on polygon counts. Detection probability decreased with decreasing cutblock size and harvest intensity. From all Hansen polygons, 85% had the correct harvest year and 88% structurally matched one or more reference polygons either alone or together with other Hansen polygons. After the validation, we used the Hansen dataset to derive trends for the entire basin. Mean annual harvest rate was 0.92 ha/km2/year between 2000 and 2012. Most of the catchments around the western headwaters of the Miramichi River underwent intensive harvesting, underscoring the need of further monitoring. Our results indicate that the Hansen dataset could be used as a surrogate harvest layer for temperate forests where clear-cutting is common and fire is rare.
Liu X.J.A., Sun J., Mau R.L., Finley B.K., Compson Z.G., van Gestel N., Brown J.R., Schwartz E., Dijkstra P., Hungate B.A. (2017). Labile carbon input determines the direction and magnitude of the priming effect. Applied Soil Ecology, 109 7-13.

Labile carbon (C) input to soil can accelerate or slow the decomposition of soil organic matter, a phenomenon called priming. However, priming is difficult to predict, making its relationship with C input elusive. To assess this relationship, we added 13C-glucose at five levels (8 to 1606 μg C g−1 week−1) to the soil from four different ecosystems for seven weeks. We observed a positive linear relationship between C input and priming in all soils: priming increased from negative or no priming at low C input to strong positive priming at high C input. However, the sensitivity of priming to C input varied among soils and between ways of expressing C input, and decreased with elevation. Positive substrate thresholds were detected in three soils (56 to 242 μg C g−1 week−1), suggesting the minimum C input required to trigger positive priming. Carbon input expressed as a fraction of microbial biomass explained 16.5% less variation in priming than did C input expressed as a fraction of dry soil mass, indicating that priming is not strongly related to the size of the soil microbial biomass. We conclude that priming increases with the rate of labile C input, once that rate exceeds a threshold, but the magnitude of increase varies among soils. Further research on mechanisms causing the variation of priming sensitivity to increasing labile C input might help promote a quantitative understanding of how such phenomenon impacts soil C cycling, offering the potential to improve earth system models.
Marlatt V.L., Martyniuk C.J. (2017). Biological responses to phenylurea herbicides in fish and amphibians: New directions for characterizing mechanisms of toxicity. Comparative Biochemistry and Physiology Part C Toxicology and Pharmacology, 194 9-21.

Urea-based herbicides are applied in agriculture to control broadleaf and grassy weeds, acting to either inhibit photosynthesis at photosystem II (phenylureas) or to inhibit acetolactate synthase acetohydroxyacid synthase (sulfonylureas). While there are different chemical formulas for urea-based herbicides, the phenylureas are a widely used class in North America and have been detected in aquatic environments due to agricultural run-off. Here, we summarize the current state of the literature, synthesizing data on phenylureas and their biological effects in two non-target animals, fish and amphibians, with a primary focus on diuron and linuron. In fish, although the acutely lethal effects of diuron in early life stages appear to be > 1 mg/L, recent studies measuring sub-lethal behavioural and developmental endpoints suggest that diuron causes adverse effects at lower concentrations (i.e. < 0.1 mg/L). Considerably less toxicity data exist for amphibians, and this is a knowledge gap in the literature. In terms of sub-lethal effects and mode of action (MOA), linuron is well documented to have anti-androgenic effects in vertebrates, including fish. However, there are other MOAs that are not adequately assessed in toxicology studies. In order to identify additional potential MOAs, we conducted in silico analyses for linuron and diuron that were based upon transcriptome studies and chemical structure-function relationships (i.e. ToxCast™, Prediction of Activity Spectra of Substances). Based upon these analyses, we suggest that steroid biosynthesis, cholesterol metabolism and pregnane X receptor activation are common targets, and offer some new endpoints for future investigations of phenylurea herbicides in non-target animals.
Martel P.H., O'Connor B.I., Kovacs T.G., Van Den Heuvel M.R., Parrott J.L., McMaster M.E., MacLatchy D.L., Van Der Kraak G.J., Hewitt L.M. (2017). The Relationship between Organic Loading and Effects on Fish Reproduction for Pulp Mill Effluents across Canada. Environmental Science and Technology, 51(6) 3499-3507.

This study builds upon the work of a multiagency consortium tasked with determining cost-effective solutions for the effects of pulp mill effluents on fish reproduction. A laboratory fathead minnow egg production test and chemical characterization tools were used to benchmark 81 effluents from 20 mills across Canada, representing the major pulping, bleaching, and effluent treatment technologies. For Kraft and mechanical pulp mills, effluents containing less than 20 mg/L BOD<inf>5</inf> were found to have the greatest probability of having no effects. Organic loading, expressed as the total detected solvent-extractable components by gas chromatography/mass spectrometry (GC/MS), also correlated with decreased egg laying. Exceptions were found for specific Kraft, mechanical, and sulfite mills, suggesting yet unidentified causative agents are involved. Recycled fiber mill effluents, tested for the first time, were found to have little potential for reproductive effects despite large variations in BOD<inf>5</inf> and GC/MS profiles. Effluent treatment systems across all production types were generally efficient, achieving a combined 82-98% BOD<inf>5</inf> removal. Further reductions of final effluent organic loadings toward the target of less than 20 mg/L are recommended and can be realized through biotreatment optimization, the reduction of organic losses associated with production upsets and selecting best available technologies that reduce organic loadings to biotreatment. (Figure Presented).
McHugh T.A., Compson Z., Gestel N.v., Hayer M., Ballard L., Haverty M., Hines J., Irvine N., Krassner D., Lyons T., Musta E.J., Schiff M., Zint P., Schwartz E. (2017). Climate controls prokaryotic community composition in desert soils of the southwestern United States. FEMS Microbiology Ecology, 93(10).

Aridisols are the dominant soil type in drylands, which occupy one-third of Earth's terrestrial surface. We examined controls on biogeographical patterns of Aridisol prokaryotic (bacterial and archaeal) communities at a regional scale by comparing communities from 100 Aridisols throughout the southwestern United States using high-throughput sequencing of the 16S rRNA gene. We found that microbial communities differed among global biomes and deserts of the Southwest. Differences among biomes were driven by differences in taxonomic identities, whereas differences among deserts of the Southwest were driven by differences in relative sequence abundance. Desert communities were dominated by Actinobacteria, Proteobacteria and Crenarchaeota, supporting the notion of a core set of abundant taxa in desert soils. Our findings contrast with studies showing little taxonomic overlap at the OTU level (97% sequence similarity) across large spatial scales, as we found ~90% of taxa in at least two of the three deserts. Geographic distance structured prokaryotic communities indirectly through the influence of climate and soil properties. Structural equation modeling suggests that climate exerts a stronger influence than soil properties in shaping the composition of Aridisol microbial communities, with annual heat moisture index (an aridity metric) being the strongest climate driver. Annual heat moisture index was associated with decreased microbial diversity and richness. If the Desert Southwest becomes hotter and drier as predicted, these findings suggest that prokaryotic diversity and richness in Aridisols will decline.
Morton S.M., MacQuarrie K.T.B., Connor D., Kurylyk B.L. (2017). Monitoring changes in near-well hydraulic conditions as a means to assess aquifer clogging. Journal of Hydrologic Engineering, 22(2).

To better understand and monitor the hydraulic effects caused by clogging near groundwater production wells, a study was conducted in the unconfined sand aquifer used by the City of North Battleford, Saskatchewan, Canada. Detailed investigations were carried out near one production well between the spring of 2007 and the fall of 2008. Results from four pumping tests conducted over this time period indicated no significant temporal changes in hydraulic conductivity within approximately 2 m of the pumping well. In contrast, long-term monitoring of hydraulic head differentials did reveal increases with time, and suggested that clogging began to accelerate within a radius of 1 m of the well after about one year of continuous pumping. Continuous monitoring of hydraulic head in pumping wells and nearby piezometers, combined with breakpoint analyses of head differentials and specific capacity tests, will be more effective than standard pumping tests for detecting temporal and spatial trends in aquifer and well screen clogging.
Mudge J.F., Martyniuk C.J., Houlahan J.E. (2017). Optimal alpha reduces error rates in gene expression studies: A meta-analysis approach. BMC Bioinformatics, 18(1).

Background: Transcriptomic approaches (microarray and RNA-seq) have been a tremendous advance for molecular science in all disciplines, but they have made interpretation of hypothesis testing more difficult because of the large number of comparisons that are done within an experiment. The result has been a proliferation of techniques aimed at solving the multiple comparisons problem, techniques that have focused primarily on minimizing Type I error with little or no concern about concomitant increases in Type II errors. We have previously proposed a novel approach for setting statistical thresholds with applications for high throughput omics-data, optimal α, which minimizes the probability of making either error (i.e. Type I or II) and eliminates the need for post-hoc adjustments. Results: A meta-analysis of 242 microarray studies extracted from the peer-reviewed literature found that current practices for setting statistical thresholds led to very high Type II error rates. Further, we demonstrate that applying the optimal α approach results in error rates as low or lower than error rates obtained when using (i) no post-hoc adjustment, (ii) a Bonferroni adjustment and (iii) a false discovery rate (FDR) adjustment which is widely used in transcriptome studies. Conclusions: We conclude that optimal α can reduce error rates associated with transcripts in both microarray and RNA-seq experiments, but point out that improved statistical techniques alone cannot solve the problems associated with high throughput datasets - these approaches need to be coupled with improved experimental design that considers larger sample sizes and/or greater study replication.
Nafziger J., She Y., Hicks F., Cunjak R.A. (2017). Anchor ice formation and release in small regulated and unregulated streams. Cold Regions Science and Technology, 141 66-77.

Anchor ice is a type of river ice that occurs on river beds in supercooled, turbulent water. Its formation and release can affect the water level, discharge, bed roughness, and morphology of rivers in cold regions. Despite these important effects, the number of anchor ice events documented in the literature has historically remained small because of the ephemeral nature of anchor ice. The purpose of this study was to determine the hydrometeorological factors that control anchor ice formation, release, and morphology, as well as to determine the impact of hydropower regulation on the anchor ice regime of small streams. In total, 161 anchor ice formation and release events were examined in 2 regulated streams and 1 unregulated stream in north-central New Brunswick, Canada, using hourly or half-hourly ice observations and near-continuously measured environmental variables. The day after formation, anchor ice accumulations either completely released, stayed in place to form multi-day accumulations, or were incorporated into the surface ice cover of the stream. 98% of anchor ice accumulations completely released on days when there was a net heat gain to the water surface and the air temperature was >− 15 °C, indicating a strong thermal control on anchor ice release. The release of one accumulation could not be attributed to either thermal effects or to the ‘plucking’ of the substrate, suggesting the need for further study of the strength of ice-pebble bonds. Finally, the regulated and unregulated streams had different ice regimes: the regulated stream experienced a greater number of anchor ice events, which occurred with a different seasonal pattern compared to the unregulated streams.
Ndong M., Bird D., Nguyen Quang T., Kahawita R., Hamilton D., de Boutray M.L., Prévost M., Dorner S. (2017). A novel Eulerian approach for modelling cyanobacteria movement: Thin layer formation and recurrent risk to drinking water intakes. Water Research, 127 191-203.

Toxic cyanobacteria (CB) blooms are being reported in an increasing number of water bodies worldwide. As drinking water (DW) treatment can be disrupted by CB, in addition to long term management plans, short term operational decision-making tools are needed that enable an understanding of the temporal variability of CB movement in relation to drinking water intakes. In this paper, we propose a novel conservative model based on a Eulerian framework and compare results with data from CB blooms in Missisquoi Bay (Québec, Canada). The hydrodynamic model considered the effects of wind and light intensity, demonstrated that current understanding of cell buoyancy in relation to light intensity in full-scale systems is incomplete and some factors are yet to be fully characterized. Factors affecting CB buoyancy play a major role in the formation of a thin surface layer that could be of ecological importance with regards to cell concentrations and toxin production. Depending on velocities, wind contributes either to the accumulation or to the dispersion of CB. Lake recirculation effects have a tendency to create zones of low CB concentrations in a water body. Monitoring efforts and future research should focus on short-term variations of CB throughout the water column and the characterization of factors other than light intensity that affect cell buoyancy. These factors are critical for understanding the risk of breakthrough into treatment plants as well as the formation of surface scums and subsequent toxin production.
Newbury R.W., Bates D.J. (2017). Dynamics of Flowing Water. Methods in Stream Ecology Third Edition, 1 71-87.

Aquatic habitats within and adjacent to the boundary of flowing water possess unique hydraulic characteristics that vary from slow-flowing to rapidly circulating and turbulent eddies. In these natural streams the dynamics of hydraulic characteristics have been studied and described by understanding empirical relationships from open channel hydraulics. At the reach scale, mesohabitats described as pools, riffles, and glides consist of nonuniform-flow patterns that can be predicted, and in some cases recreated, by understanding hydraulic and channel relationships. At the microhabitat scale, individual streamflow lines and states of flow can be delineated and partially analyzed with nonuniform-flow equations. Aquatic organisms have adapted to these varying hydraulic conditions (see also Chapters 15 and 16Chapter 15Chapter 16). This chapter provides an introduction to the dynamics and hydraulics of flowing water. It provides the student with the basics for understanding the complex nature of flowing water that help form aquatic habitats and features directly affecting aquatic organisms.
Olsen J.B., Wenburg J.K., Pavey S.A., Miller J.L., Hamon T.R. (2017). The time of origin and genetic diversity of three isolated kokanee populations in southwest Alaska. Transactions of the American Fisheries Society, 146(6) 1212-1222.

We examined the time of origin and genetic diversity of native kokanee, the nonanadromous ecotype of Sockeye Salmon Oncorhynchus nerka, from three isolated lakes in the Katmai National Park and Preserve in southwest Alaska. These kokanee evolved independently from Sockeye Salmon when migration barriers arose, blocking ocean access.We used information about the relative age of each barrier to hypothesize the relative time of origin for kokanee in each lake. In addition, we used data from 13 microsatellite loci to test our time of origin hypotheses and assess genetic diversity of kokanee from these three lakes and proximate Sockeye Salmon populations. Coalescent-based estimates of the time of origin for kokanee in Jo-Jo Lake (170 years before present [ybp]) and Devil’s Cove Lake (6,583 ybp) were consistent with the relative age of barriers isolating each lake.However, data from Dakavak Lake (1,379 ybp) suggested that the barrier was older than hypothesized. Indices of intrapopulation diversity were lower for kokanee than for Sockeye Salmon. Estimates for kokanee population divergence (R<inf>ST</inf>; the F<inf>ST</inf> analog for microsatellites) among the three lakes were consistent with time of origin estimates. Furthermore, the most recently isolated kokanee (Jo-Jo Lake population) were most closely related to neighboring Sockeye Salmon. Only the kokanee from Jo-Jo Lake exhibited a relatively low historical effective population size (N<inf>e</inf> ≈ 107) and evidence of a genetic bottleneck.Taken together, the results of this study show that although rare, kokanee in Alaska are not ephemeral and can persist in isolation for hundreds of generations despite the colder temperatures and shorter growing season, that are thought to limit their sustainability in Alaska.
Ouellet-Proulx S., St-Hilaire A., Boucher M.A. (2017). Water temperature ensemble forecasts: Implementation using the CEQUEAU model on two contrasted river systems. Water Switzerland, 9(7).

In some hydrological systems, mitigation strategies are applied based on short-range water temperature forecasts to reduce stress caused to aquatic organisms. While various uncertainty sources are known to affect thermal modeling, their impact on water temperature forecasts remain poorly understood. The objective of this paper is to characterize uncertainty induced to water temperature forecasts by meteorological inputs in two hydrological contexts. Daily ensemble water temperature forecasts were produced using the CEQUEAU model for the Nechako (regulated) and Southwest Miramichi (natural) Rivers for 1-5-day horizons. The results demonstrate that a larger uncertainty is propagated to the thermal forecast in the unregulated river (0.92-3.14 °C) than on the regulated river (0.73-2.29 °C). Better performances were observed on the Nechako with a mean continuous ranked probability score (MCRPS) < 0.85 °C for all horizons compared to the Southwest Miramichi (MCRPS ≈ 1 °C). While informing the end-user on future thermal conditions, the ensemble forecasts provide an assessment of the associated uncertainty and offer an additional tool to river managers for decision-making.
Pavey S.A., Laporte M., Normandeau E., Gaudin J., Letourneau L., Boisvert S., Corbeil J., Audet C., Bernatchez L. (2017). Draft genome of the American Eel (Anguilla rostrata). Molecular Ecology Resources, 17(4) 806-811.

Freshwater eels (Anguilla sp.) have large economic, cultural, ecological and aesthetic importance worldwide, but they suffered more than 90% decline in global stocks over the past few decades. Proper genetic resources, such as sequenced, assembled and annotated genomes, are essential to help plan sustainable recoveries by identifying physiological, biochemical and genetic mechanisms that caused the declines or that may lead to recoveries. Here, we present the first sequenced genome of the American eel. This genome contained 305 043 contigs (N50 = 7397) and 79 209 scaffolds (N50 = 86 641) for a total size of 1.41 Gb, which is in the middle of the range of previous estimations for this species. In addition, protein-coding regions, including introns and flanking regions, are very well represented in the genome, as 95.2% of the 458 core eukaryotic genes and 98.8% of the 248 ultra-conserved subset were represented in the assembly and a total of 26 564 genes were annotated for future functional genomics studies. We performed a candidate gene analysis to compare three genes among all three freshwater eel species and, congruent with the phylogenetic relationships, Japanese eel (A. japanica) exhibited the most divergence. Overall, the sequenced genome presented in this study is a crucial addition to the presently available genetic tools to help guide future conservation efforts of freshwater eels.
Pearce N.J.T., Yates A.G. (2017). Intra-annual variation of the association between agricultural best management practices and stream nutrient concentrations. Science of the Total Environment, 586 1124-1134.

Temporal variation may influence the ability of best management practices (BMPs) to mitigate the loss of agricultural pollutants to streams. Our goal was to assess variation in mitigation effects of BMPs by examining the associations between instream nutrient concentrations and the abundance and location of four structural BMPs over a hydrologic year. Water samples were collected monthly (Nov. 2013–Oct. 2014) in 15 headwater streams representing a gradient of BMP use in Southern Ontario, Canada. Partial least squares (PLS) regression models were used to associate two groups of collinear nutrient forms with the abundance and location of BMPs, antecedent precipitation and time of year. BMP metrics in PLS models were associated with instream concentrations of major phosphorus forms and ammonium throughout the year. In contrast, total nitrogen and nitrate-nitrite were only associated with BMPs during snowmelt. BMP metrics associated with reductions of phosphorus and ammonium included greater abundances of riparian buffers and manure storage structures, but not livestock restriction fences. Likewise, the abundance and location riparian vegetation in areas capturing more surface runoff were associated with decreased stream nitrogen concentrations during snowmelt. However, the amount of tile drainage was associated with increased nitrogen concentrations following snowmelt, as well as with greater phosphorus and ammonium concentrations throughout the year. Overall, our findings indicate that increasing the abundance of riparian buffers and manure storage structures may decrease instream nutrient concentrations in agricultural areas. Additionally, the implementation of these structural BMPs appear to be an effective year-round strategy to assist management objectives in reducing phosphorus concentrations in small agricultural streams and thus loadings to downstream tributaries. Further mitigation measures, such as managerial BMPs and controlled tile drainage, may be required to further reduce instream nutrient concentrations during baseflow periods and snowmelt events.
Phalen L.J., Köllner B., Hogan N.S., van den Heuvel M.R. (2017). Transcriptional response in rainbow trout (Oncorhynchus mykiss) B cells and thrombocytes following in vivo exposure to benzo[a]pyrene. Environmental Toxicology and Pharmacology, 53 212-218.

Immune toxicity of polycyclic aromatic hydrocarbons (PAHs) in fishes has been frequently reported but the reasons for differential cell toxicity remains unclear. Rainbow trout were exposed in vivo with a single intraperitoneal injection of corn oil or 100 mg/kg of the immunotoxic PAH benzo[a]pyrene (B[a]P) in corn oil. Leukocytes were harvested from head kidney, spleen and blood after 14 days, the optimal time for B cell depletion found in a previous study. The mRNA expression of five cytochrome P450 (CYP) enzymes, the aryl hydrocarbon receptor (AhR), and an intrinsic pathway apoptosis checkpoint (p53) in B cells and thrombocytes were examined. Transcript levels were measured in immunomagnetically-isolated B cells and thrombocytes from those tissues as well as in liver as B cells had been previously shown to be responsive the BaP whereas thrombocytes were not. There was induction of CYP1A1 in liver, blood B cells, and blood and spleen thrombocytes; CYP1B1 in blood B cells, blood and spleen thrombocytes; CYP1A3 in liver, blood and spleen B cells, and blood thrombocytes; CYP1C1 in liver; and AhR in liver and spleen thrombocytes. There was no change in CYP1C2, or p53 mRNA levels across tissues or cell type. Induction in mRNA was observed 14 d after exposure, indicating a prolonged physiological effect of a single B[a]P injection. CYP1A1 and CYP1A3 were the most abundantly expressed CYP genes and CYP1B1 was generally least abundant. B[a]P-induced thrombocytes had a significantly different pattern of CYP expression than either liver or B cells. Given the importance of metabolites in the toxicity of PAHs, differences in CYP expression between tissues may explain differences in toxicity previously observed between B cells and thrombocytes.
Plummer R., Baird J., Krievins K., Fresque-Baxter J., Imhof J., Mitchell S.J. (2017). Shifting Perspectives in an Era of Complexity and Change: Incorporating Resilience into the Water Governance of Canadian Drainage Basins. Global Issues in Water Policy, 17 419-433.

Governance has emerged as a central issue in addressing contemporary and future water challenges. Many shortcomings of past approaches to water policy in Canada are revealed in this volume as they relate to conservation (Changing Currents: A Case Study in the Evolution of Water Law in Western Canada and Patchy resources for the governance of Canada’s resource patches: How hydraulic fracturing is illuminating the need to improve water governance in Canada) and health (Public Health at the Watershed Scale). A fundamental shift in the prevailing mindset of government control of the hydrological cycle for human use is necessary. Resilience offers a radical departure from dominant approaches of the past and conceptual developments inform the future of water governance in an era of complexity and change. Incorporating resilience thinking into the governance of drainage basins is critical in this context. Four cases from Canada are presented to illustrate how resilience is emerging in policy and practice. Taken together, resilience thinking and resilience practice, provide a fertile ground for re-envisioning water resources and their governance.
Rattan K.J., Corriveau J.C., Brua R.B., Culp J.M., Yates A.G., Chambers P.A. (2017). Quantifying seasonal variation in total phosphorus and nitrogen from prairie streams in the Red River Basin, Manitoba Canada. Science of the Total Environment, 575 649-659.

A three-year study (2010, 2013 and 2014) was conducted to identify temporal and spatial patterns in phosphorus (P) and nitrogen (N) concentrations and loads in 11 sub-watersheds of the Red River Valley, Manitoba, Canada in relation to human activity on the landscape. Discharge exhibited a strong seasonal pattern in all sub-watersheds with high discharge during snowmelt, generally lower discharge with rainfall-induced peaks during spring, summer and fall, and low or no discharge during winter. Consistent with the hydrologic pattern, nutrient concentrations were highest during snowmelt such that 62% of the annual TP load and 67% of the annual TN load were delivered during the 12–18 day snowmelt period. Partial least squares regression analysis indicated that land use activities such as fertilizer application, livestock density and sewage were critical factors influencing TP and TN concentrations. In contrast, physical aspects such as water temperature and discharge were the primary determinants of TP and TN loads. The finding that stream water nutrients concentrations are associated with human activity on the landscape whereas nutrient loads are largely influenced by hydrologic events suggests that different types of beneficial management practices are needed for protection of instream ecological processes negatively affected by high nutrient levels versus reduction of nutrient export to downstream receiving bodies such as Lake Winnipeg.
Rolls R.J., Hayden B., Kahilainen K.K. (2017). Conceptualising the interactive effects of climate change and biological invasions on subarctic freshwater fish. Ecology and Evolution, 7(12) 4109-4128.

Climate change and species invasions represent key threats to global biodiversity. Subarctic freshwaters are sentinels for understanding both stressors because the effects of climate change are disproportionately strong at high latitudes and invasion of temperate species is prevalent. Here, we summarize the environmental effects of climate change and illustrate the ecological responses of freshwater fishes to these effects, spanning individual, population, community and ecosystem levels. Climate change is modifying hydrological cycles across atmospheric, terrestrial and aquatic components of subarctic ecosystems, causing increases in ambient water temperature and nutrient availability. These changes affect the individual behavior, habitat use, growth and metabolism, alter population spawning and recruitment dynamics, leading to changes in species abundance and distribution, modify food web structure, trophic interactions and energy flow within communities and change the sources, quantity and quality of energy and nutrients in ecosystems. Increases in temperature and its variability in aquatic environments underpin many ecological responses; however, altered hydrological regimes, increasing nutrient inputs and shortened ice cover are also important drivers of climate change effects and likely contribute to context-dependent responses. Species invasions are a complex aspect of the ecology of climate change because the phenomena of invasion are both an effect and a driver of the ecological consequences of climate change. Using subarctic freshwaters as an example, we illustrate how climate change can alter three distinct aspects of species invasions: (1) the vulnerability of ecosystems to be invaded, (2) the potential for species to spread and invade new habitats, and (3) the subsequent ecological effects of invaders. We identify three fundamental knowledge gaps focused on the need to determine (1) how environmental and landscape characteristics influence the ecological impact of climate change, (2) the separate and combined effects of climate and non-native invading species and (3) the underlying ecological processes or mechanisms responsible for changes in patterns of biodiversity.
Samways K.M., Blair T.J., Charest M.A., Cunjak R.A. (2017). Effects of spawning Atlantic salmon (Salmo salar) on total lipid content and fatty acid composition of river food webs. Ecosphere, 8(6).

Returning Atlantic salmon subsidize rivers with marine-derived nutrients (MDNs), potentially altering food web dynamics, shifting to reliance on marine-derived resources. Stream channels designed to simulate natural river systems, one with MDNs from spawning Atlantic salmon (Salmo salar) and one without marine-nutrient subsidies (control), were used to determine whether fatty acids (FAs) delivered to rivers and streams by spawning Atlantic salmon are incorporated by freshwater biota. Changes in FA profiles between stream channels with and without MDN inputs for biofilm, macroinvertebrates, and Atlantic salmon parr were used to characterize temporal dynamics of MDN incorporation during pre-spawning, spawning, and post-spawning periods. There were no differences between control and treatment stream channels prior to the addition of Atlantic salmon. Spawning Atlantic salmon had a positive effect on total lipid content in all trophic levels (biofilm, 4.33%; macroinvertebrates, 7.54%; salmon parr, 2.59%), relative to controls. Fatty acid profiles between the MDN treatment and control stream channels were similar for each biotic group prior to the introduction of adult Atlantic salmon; however, following adult salmon introductions, the FA profiles of the biofilm, invertebrates, and salmon parr differed by as much as 36.7%, 30.3%, and 22.9%, respectively, between the MDN treatment stream channels and the controls. Fatty acid profiles of the invertebrates and salmon parr from the MDN treatment stream channels tracked the FA profile of the salmon eggs. Proportions of docosahexaenoic acid and eicosapentaenoic acid varied with diet in a predictable manner related to dietary FA proportions. These responses demonstrate a change in the food web structure resulting from the establishment of this new, marine-based, basal resource. The positive effects of MDNs increasing freshwater productivity are complimented by marine-based lipids that represent surplus energy and an increase in the quality of resources, thereby contributing to the diversity and health of freshwater ecosystems.
Sarty K.I., Cowie A., Martyniuk C.J. (2017). The legacy pesticide dieldrin acts as a teratogen and alters the expression of dopamine transporter and dopamine receptor 2a in zebrafish (Danio rerio) embryos. Comparative Biochemistry and Physiology Part C Toxicology and Pharmacology, 194 37-47.

Dieldrin (DLD) is a lipophilic pesticide that shows environmental persistence. The objectives were to determine the effects of DLD on GABAergic and dopaminergic systems in developing zebrafish. Both chorionated and dechorionated embryos (~ 24 h post-hatch) were exposed to a single concentration of DLD (0.347–3470 μM) for 48 h. Following exposure, a subset of larvae was placed into clean water for 6 days (i.e. depuration phase). Chorionated embryos showed < 15% mortality while dechorionated embryos showed higher mortality (> 30%), suggesting that the chorion protected the embryos. Over a 6 day depuration phase, there was a dose dependent effect observed in both the “dechorionated and chorionated embryo” treatments for larval mortality (> 60%). At the end of depuration, there was no detectable change in neuro-morphological endpoints that included the ratio of notochord length to body length (%) and the ratio of head area to body area (%). However, DLD did induce cardiac edema, skeletal deformities, and tremors. GABA-related transcripts were not affected in abundance by DLD. Conversely, the relative mRNA levels of dopamine transporter (dat1) and dopamine receptor drd2a mRNA were decreased in dechorionated, but not chorionated, embryos. These data suggest that DLD can alter the expression of transcripts related to dopaminergic signaling. Lastly, GABA<inf>A</inf> receptor subunits gabrB1 and gabrB2, as well as dopamine receptors drd1 and drd2a, were inherently higher in abundance in dechorionated embryos compared to chorionated embryos. This is an important consideration when incorporating transcriptomics into embryo testing as expression levels can change with removal of the chorion prior to exposure.
Sirabahenda Z., St-Hilaire A., Courtenay S.C., Alberto A., Van Den Heuvel M.R. (2017). A modelling approach for estimating suspended sediment concentrations for multiple rivers influenced by agriculture. Hydrological Sciences Journal, 62(13) 2209-2221.

A data-driven model based on an adaptive neuro-fuzzy inference system (ANFIS) was tested for the estimation of suspended sediment concentrations within watersheds influenced by agriculture. ANFIS models were developed using different combinations of inputs such as precipitation, streamflow, surface runoff and the watershed vulnerability index. A multi-watershed ANFIS model was also developed combining the datasets from all studied watersheds. The best results were obtained from a combination of precipitation, streamflow and watershed vulnerability index as input variables. Nash-Sutcliffe coefficients were improved for the multi-watershed ANFIS compared to watershed-specific ANFIS models. The introduction of the erosion vulnerability index significantly improved the ability of the ANFIS model to estimate suspended sediment concentrations within the watersheds. Furthermore, the inclusion of this index opens the possibility of using the ANFIS model to investigate the impact of land-use changes on sediment delivery.
Spaak J.W., Baert J.M., Baird D.J., Eisenhauer N., Maltby L., Pomati F., Radchuk V., Rohr J.R., Van den Brink P.J., De Laender F. (2017). Shifts of community composition and population density substantially affect ecosystem function despite invariant richness. Ecology Letters, 20(10) 1315-1324.

There has been considerable focus on the impacts of environmental change on ecosystem function arising from changes in species richness. However, environmental change may affect ecosystem function without affecting richness, most notably by affecting population densities and community composition. Using a theoretical model, we find that, despite invariant richness, (1) small environmental effects may already lead to a collapse of function; (2) competitive strength may be a less important determinant of ecosystem function change than the selectivity of the environmental change driver and (3) effects on ecosystem function increase when effects on composition are larger. We also present a complementary statistical analysis of 13 data sets of phytoplankton and periphyton communities exposed to chemical stressors and show that effects on primary production under invariant richness ranged from −75% to +10%. We conclude that environmental protection goals relying on measures of richness could underestimate ecological impacts of environmental change.
Thera J.C., Kidd K.A., Dodge-Lynch M.E., Bertolo R.F. (2017). Quantification of sulphur amino acids by ultra-high performance liquid chromatography in aquatic invertebrates. Analytical Biochemistry, 539 158-161.

We examined the performance of an ultra-high performance liquid chromatography method to quantify protein-bound sulphur amino acids in zooplankton. Both cysteic acid and methionine sulfone were linear from 5 to 250 pmol (r2 = 0.99), with a method detection limit of 13 pmol and 9 pmol, respectively. Although there was no matrix effect on linearity, adjacent peaks and co-eluting noise from the invertebrate proteins increased the detection limits when compared to common standards. Overall, performance characteristics were reproducible and accurate, and provide a means for quantifying sulphur amino acids in aquatic invertebrates, an understudied group.
Thomas S.M., Harrod C., Hayden B., Malinen T., Kahilainen K.K. (2017). Ecological speciation in a generalist consumer expands the trophic niche of a dominant predator. Scientific Reports, 7(1).

Ecological speciation - whereby an ancestral founder species diversifies to fill vacant niches - is a phenomenon characteristic of newly formed ecosystems. Despite such ubiquity, ecosystem-level effects of such divergence remain poorly understood. Here, we compared the trophic niche of European whitefish (Coregonus lavaretus) and their predators in a series of contrasting subarctic lakes where this species had either diversified into four ecomorphologically distinct morphs or instead formed monomorphic populations. We found that the trophic niche of whitefish was almost three times larger in the polymorphic than in the monomorphic lakes, due to an increase in intraspecific specialisation. This trophic niche expansion was mirrored in brown trout (Salmo trutta), a major predator of whitefish. This represents amongst the first evidence for ecological speciation directly altering the trophic niche of a predator. We suggest such mechanisms may be a common and important - though presently overlooked - factor regulating trophic interactions in diverse ecosystems globally.
Tomie J.P.N., Cairns D.K., Hobbs R.S., Desjardins M., Fletcher G.L., Courtenay S.C. (2017). American eel (Anguilla rostrata) substrate selection for daytime refuge and winter thermal sanctuary. Marine and Freshwater Research, 68(1) 95-105.

We addressed hypotheses that anguillid eels use mud as a substrate refuge only in the absence of substrate cavities, and that the winter distribution of eels in coastal bay and estuarine habitat is limited to waters warmer than the freezing point of fish tissue (∼-0.7°C). In the seasonally ice-covered southern Gulf of St Lawrence, Canada, locations of summer fyke and winter spear fisheries indicate that American eels (Anguilla rostrata) are widely distributed in both summer and winter in shallow soft-bottomed bay and estuarine habitat. Captive eels in fresh water preferred mud substrates during summer, during pre-winter cooling and during post-winter warming periods, but in winter chose mud and cobble substrates at approximately equal frequencies. Plasma antifreeze was not detected in blood sampled from eels speared in mud under winter ice. Winter bottom water temperatures in an eel wintering site were below the approximate freezing point of fish tissue 29.9% of the time. Mud of eel wintering grounds is warmer than overlying water and appears to serve as a thermal sanctuary that allows eels to safely overwinter under ice-covered waters. American eels in the southern Gulf of St Lawrence spend ∼67% of their annual cycle within the substrate.
Turak E., Dudgeon D., Harrison I.J., Freyhof J., De Wever A., Revenga C., Garcia-Moreno J., Abell R., Culp J.M., Lento J., Mora B., Hilarides L., Flink S. (2017). Observations of Inland Water Biodiversity: Progress, Needs and Priorities. GEO Handbook on Biodiversity Observation Networks 165-186.

This chapter aims to assist biodiversity observation networks across the world in coordinating comprehensive freshwater biodiversity observations at national, regional or continental scales. We highlight special considerations for freshwater biodiversity and methods and tools available for monitoring. We also discuss options for storing, accessing, evaluating and reporting freshwater biodiversity data and for ensuring their use in making decisions about the conservation and sustainable management of freshwater biodiversity and provision of ecosystem services.
Wallace B.G., Curry R.A. (2017). Assessing the outcomes of stocking hatchery-reared juveniles in the presence of wild Atlantic salmon. Environmental Biology of Fishes, 100(7) 877-887.

Stocking of hatchery-reared juvenile Atlantic Salmon Salmo salar is a common enhancement and recovery strategy across jurisdictions, yet its impact remains uncertain. We investigate the potential effectiveness of stocking in the Miramichi River system where approximately 150,000 first-feeding fry are stocked annually in reaches where wild juveniles are present. Local site and landscape level characteristics were used to fit predictive models for wild parr densities measured as Percent Habitat Saturation (PHS) using Partial Least Squares Regression (PLSR). The observed PHS of stocked sites was found to be significantly lower than predicted, suggesting stocking has not been effective in increasing the PHS in the studied stocked sites. The results suggest that habitat and other density dependent effects limit productive capacity in this system, and consequently, may limit the effectiveness of stocking in other systems with natural production.
Wellman S., Kidd K.A., Podemski C.L., Blanchfield P.J., Paterson M.J. (2017). Incorporation of wastes by native species during and after an experimental aquaculture operation. Freshwater Science, 36(2) 387-401.

Freshwater aquaculture increases dissolved and particulate nutrients near fish cages, but the degree to which they are incorporated into tissues of native animals is uncertain. At the Experimental Lakes Area in northwestern Ontario, Canada, a cage culture of Rainbow Trout was operated seasonally for 5 y, and invertebrates and fishes were collected before, during, and after culturing from the experimental lake and a reference lake to assess changes in stable isotopes of C and N in their tissues. The feed contained marine fishmeal and was higher in C and N isotope values (δ13C and δ15N) than lake biota by ≥4‰(all taxa) and 3 ñ(all invertebrates), respectively. During the aquaculture operation, δ15N of littoral and pelagic invertebrates, profundal chironomids, minnows, and Lake Trout (Salvelinus namaycush) increased by 2 to 5‰ relative to before aquaculture values. In the 1st and 2nd years after aquaculture, δ15N of several invertebrate taxa and all fishes continued to increase 1 to 2‰/y. In contrast, during aquaculture, only minnows and trout had significant increases (up to 3) in δ13C. In the period after aquaculture, the δ13C of fishes, plankton, and profundal chironomids declined to below values measured before or during aquaculture. Isotopic analysis of native biota can be used to monitor assimilation of cage culture wastes in freshwater ecosystems.
Yee-Duarte J.A., Ceballos-Vázquez B.P., Shumilin E., Kidd K., Arellano-Martínez M. (2017). Evidence of health impairment of Megapitaria squalida (Bivalvia: Veneridae) near the "hot spot" of a mining port, Gulf of California. Hidrobiologica, 27(3) 391-398.

Background. It is known that organisms inhabiting polluted marine habitats may experience adverse physiological effects. The port of Santa Rosalía, Gulf of California, is characterized by high concentrations of heavy metals in sediments, particularly Cu, Zn, Co, Mn, Pb, and U, which are potentially toxic to the marine biota. In addition, this port receives urban wastewater that contributes mostly organic pollutants to the coastal zone. Goals. The main objective of this work was to determine whether clams in the mining region showed adverse effects because of the contamination. Methods. Through the analysis of biometric parameters, condition index, and weight-length relationship, the overall health of the chocolate clam Megapitaria squalida was evaluated in the coastal zone of the Santa Rosalía port and compared with data for clams from four mining-free areas. Results. Our findings revealed that clams from Santa Rosalía showed poor health, evidenced by their smaller size, inferior condition, and negative allometric growth compared to clams from all other sites, including San Lucas, a site located a few kilometers away from the pollution hot-spot and where the conditions of temperature and food availability are similar to those in the port area. Conclusions. All of the above suggests negative physiological effects in this species possibly caused by contamination from metals and/or organic pollutants from urban discharges. Particularly, it is likely that M. squalida at the mining site allocates more energy towards depurating or storing metals, in turn leading to poorer condition and deficient growth.
Yee-Duarte J.A., Ceballos-Vázquez B.P., Shumilin E., Kidd K.A., Arellano-Martínez M. (2017). Parasitic castration of chocolate clam megapitaria squalida (Sowerby, 1835) caused by trematode larvae. Journal of Shellfish Research, 36(3) 593-599.

The prevalence of parasites in gonads of the clam Megapitaria squalida (Sowerby, 1835) was investigated at Santa Rosalía mining port in the Gulf of California. A total of 696 gonads were histologically analyzed, observing an unusual parasitic castration caused by the development of trematode larvae within follicles. Trematode sporocysts within follicles containing germinal balls and developing cercariae were observed and associated with an inflammatory response, as evidenced by a heavy hemocytic infiltration and the formation of granulocytomas surrounding the parasite structures. Some metacercariae were observed within ovarian connective tissues suggesting that M. squalida could also act as a second intermediate host for digenean trematodes. Infection was age specific as juvenile clams (1-4-cm shell length) did not contain parasites and prevalence in the adult clams increased with size. Unlike males, which presented four levels of infection density, all the parasitized ovaries of females showed very high infection densities. The prevalence was significantly (χ2 = 6.99; df = 1; P = 0.001) higher in females (30.2%) than in males (17%). The highest prevalence of parasitized clams was in the ripe stage during the summer (43.7%) when seawater temperatures were highest, whereas the lowest prevalences were observed in winter. It is possible that the polluted environment of Santa Rosalía could increase the occurrence and high infection density by trematode larvae in M. squalida.
Aguilar-Betancourt C.M., González-Sansón G., Kidd K.A., Munkittrick K.R., Curry R.A., Kosonoy-Aceves D., Lucano-Ramírez G., Ruiz-Ramírez S., Flores-Ortega J.R. (2016). Fishes as indicators of untreated sewage contamination in a Mexican coastal lagoon. Marine Pollution Bulletin, 113(1-2) 100-109.

Lagoons are important nursery habitats for fishes but are often sites of intense human activity including wastewater discharges. The goal of this research was to compare stable nitrogen (δ15N) and carbon (δ13C) isotopes, total mercury (THg) and other metal levels in four selected fish species among sites with different levels of untreated sewage discharge inside Barra de Navidad coastal lagoon in the Mexican Pacific. Three species from sites heavily impacted by sewage showed higher δ15N and δ13C compared to those from non-impacted sites. In addition, the highest concentrations of THg were present in fish of two species (Sciades guatemalensis and Diapterus brevirostris) collected at the two most impacted sites, and exceeded the 0.2 μg/g ww threshold believed to be protective of adult and juvenile fish. No individuals of Achirus mazatlanus and Mugil curema exceeded this threshold, and liver somatic index and condition did not distinguish high from low impacted sites for all species. In general, the metal levels differed among species but not sites, and were lower than what has been measured in fishes elsewhere. The study also provides the first information on several fish species for coastal areas of Mexico, suggests that THg and isotopes can distinguish sewage-impacted sites, and can serve as a baseline for future studies.
Alberto A., St-Hilaire A., Courtenay S.C., van den Heuvel M.R. (2016). Monitoring stream sediment loads in response to agriculture in Prince Edward Island, Canada. Environmental Monitoring and Assessment, 188(7).

Increased agricultural land use leads to accelerated erosion and deposition of fine sediment in surface water. Monitoring of suspended sediment yields has proven challenging due to the spatial and temporal variability of sediment loading. Reliable sediment yield calculations depend on accurate monitoring of these highly episodic sediment loading events. This study aims to quantify precipitation-induced loading of suspended sediments on Prince Edward Island, Canada. Turbidity is considered to be a reasonably accurate proxy for suspended sediment data. In this study, turbidity was used to monitor suspended sediment concentration (SSC) and was measured for 2 years (December 2012–2014) in three subwatersheds with varying degrees of agricultural land use ranging from 10 to 69 %. Comparison of three turbidity meter calibration methods, two using suspended streambed sediment and one using automated sampling during rainfall events, revealed that the use of SSC samples constructed from streambed sediment was not an accurate replacement for water column sampling during rainfall events for calibration. Different particle size distributions in the three rivers produced significant impacts on the calibration methods demonstrating the need for river-specific calibration. Rainfall-induced sediment loading was significantly greater in the most agriculturally impacted site only when the load per rainfall event was corrected for runoff volume (total flow minus baseflow), flow increase intensity (the slope between the start of a runoff event and the peak of the hydrograph), and season. Monitoring turbidity, in combination with sediment modeling, may offer the best option for management purposes.
Alexander A.C., Chambers P.A. (2016). Assessment of seven Canadian rivers in relation to stages in oil sands industrial development, 1972-2010. Environmental Reviews, 24(4) 484-494.

We compiled a 38 year dataset (1972 to 2010) to evaluate changes in water chemistry over time in relation to oil sands mining activities. We examined patterns in three focal elements (dissolved selenium, dissolved arsenic, total vanadium) at 96 sites along seven tributaries of the Athabasca and Clearwater Rivers. Concentrations of the three focal elements did not differ between sites sampled upstream versus downstream of future development, between sites upstream versus downstream of the primary bitumen-bearing geologic formation, or at an upstream site over a 33 year period on the Muskeg River (1976-2009). Hence, longitudinal patterns observed in water chemistry following mine development cannot be attributed to natural background variation. In contrast, concentrations and loads of the three focal elements were greater post-development compared to reference values (p ≤ 0.01), and were typically greatest during the early exploration and land clearing stage of mine development (p < 0.01). Positive correlations between our three focal elements and 17 other variables either associated with bitumen or considered priority pollutants (r ≥ 0.13, p ≤ 0.04) suggest that the historical impacts of oil sands development on water quality extend beyond our three focal parameters. These results indicate that erosion and subsequent runoff associated with land clearing, construction, and early operational activities have affected water quality in the oil sands region.
Alexander A.C., Culp J.M., Baird D.J., Cessna A.J. (2016). Nutrient–insecticide interactions decouple density-dependent predation pressure in aquatic insects. Freshwater Biology, 61(12) 2090-2101.

Subsidy-stress responses can decouple density-dependent relationships between taxa within a community by increasing resources for some taxa while removing sensitive species. In this study, we examined the effects of a triad of subsidy-stress responses on predator-prey relationships in a benthic macroinvertebrate community under the action of insecticides, nutrients and predation pressure all at environmentally relevant doses. We stocked 72 outdoor artificial streams with benthic invertebrates to establish a fully factorial experiment to investigate the interactive effects of two anthropogenic factors: (i) three levels of nutrient enrichment (low, moderate and high); and (ii) three doses of imidacloprid, a common agricultural insecticide, at control, low (LOEC) and lethal doses (LC<inf>50</inf>). These factors were crossed with (iii) another, biotic stressor by stocking half of the streams with a predaceous perlid stonefly at near-natural densities. Fifty percent of the community-level responses were driven by the combined effect of nutrients and the insecticide. An additional 27% of the community variation was best explained by predation pressure, which we estimated as the gape width × density of Agnetina capitata at the end of the experiment. No negative effect of imidacloprid on A. capitata was detected (P = 0.62). By the end of the 3-week experiment, the overall gape width and predation pressure of A. capitata had more than doubled (2.1–3.7x) in all moderate nutrient streams (P < 0.01). Increased size and predation pressure of A. capitata covaried with the depressed density of all macroinvertebrate taxa as well as EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa and the mayfly Baetis in particular. Structural equation models (SEM) highlighted that nutrient enrichment was the main driver of individual and community responses in the artificial streams. Additionally, SEM showed that density but not body size of Baetis was severely hampered by A. capitata predation, suggesting that these stoneflies selectively foraged on other species in the first 10 days of the experiment. Our findings highlight the difficulties of assessing the risk of contaminants in aquatic communities where interacting species respond differently to subsidies and stresses.
Bahamonde P.A., Feswick A., Isaacs M.A., Munkittrick K.R., Martyniuk C.J. (2016). Defining the role of omics in assessing ecosystem health: Perspectives from the Canadian environmental monitoring program. Environmental Toxicology and Chemistry, 35(1) 20-35.

Scientific reviews and studies continue to describe omics technologies as the next generation of tools for environmental monitoring, while cautioning that there are limitations and obstacles to overcome. However, omics has not yet transitioned into national environmental monitoring programs designed to assess ecosystem health. Using the example of the Canadian Environmental Effects Monitoring (EEM) program, the authors describe the steps that would be required for omics technologies to be included in such an established program. These steps include baseline collection of omics endpoints across different species and sites to generate a range of what is biologically normal within a particular ecosystem. Natural individual variability in the omes is not adequately characterized and is often not measured in the field, but is a key component to an environmental monitoring program, to determine the critical effect size or action threshold for management. Omics endpoints must develop a level of standardization, consistency, and rigor that will allow interpretation of the relevance of changes across broader scales. To date, population-level consequences of routinely measured endpoints such as reduced gonad size or intersex in fish is not entirely clear, and the significance of genome-wide molecular, proteome, or metabolic changes on organism or population health is further removed from the levels of ecological change traditionally managed. The present review is not intended to dismiss the idea that omics will play a future role in large-scale environmental monitoring studies, but rather outlines the necessary actions for its inclusion in regulatory monitoring programs focused on assessing ecosystem health.
Bahamonde P.A., McMaster M.E., Servos M.R., Martyniuk C.J., Munkittrick K.R. (2016). Characterizing transcriptional networks in male rainbow darter (Etheostoma caeruleum) that regulate testis development over a complete reproductive cycle. Plos One, 11(11).

Intersex is a condition that has been associated with exposure to sewage effluents in male rainbow darter (Etheostoma caeruleum). To better understand changes in the transcriptome that are associated with intersex, we characterized annual changes in the testis transcriptome in wild, unexposed fish. Rainbow darter males were collected from the Grand River (Ontario, Canada) in May (spawning), August (post-spawning), October (recrudescence), January (developing) and March (pre-spawning). Histology was used to determine the proportion of spermatogenic cell types that were present during each period of testicular maturation. Regression analysis determined that the proportion of spermatozoa versus spermatocytes in all stages of development (R2 ≥ 0.58) were inversely related; however this was not the case when males were in the post-spawning period. Gene networks that were specific to the transition from developing to pre-spawning stages included nitric oxide biosynthesis, response to wounding, sperm cell function, and stem cell maintenance. The prespawning to spawning transition included gene networks related to amino acid import, glycogenesis, Sertoli cell proliferation, sperm capacitation, and sperm motility. The spawning to post-spawning transition included unique gene networks associated with chromosome condensation, ribosome biogenesis and assembly, and mitotic spindle assembly. Lastly, the transition from post-spawning to recrudescence included gene networks associated with egg activation, epithelial to mesenchymal transition, membrane fluidity, and sperm cell adhesion. Noteworthy was that there were a significant number of gene networks related to immune system function that were differentially expressed throughout reproduction, suggesting that immune network signalling has a prominent role in the male testis. Transcripts in the testis of post-spawning individuals showed patterns of expression that were most different for the majority of transcripts investigated when compared to the other stages Interestingly, many transcripts associated with female sex differentiation (i.e. esr1, sox9, cdca8 and survivin) were significantly higher in the testis during the post-spawning season compared to other testis stages. At post-spawning, there were higher levels of estrogen and androgen receptors (esr1, esr2, ar) in the testis, while there was a decrease in the levels of sperm associated antigen 1 (spag1) and spermatogenesis associated 4 (spata4) mRNA. Cyp17a was more abundant in the testis of fish in the pre-spawning, spawning, and postspawning seasons compared to those individuals that were recrudescent while aromatase (cyp19a) did not vary in expression over the year. This study identifies cell process related to testis development in a seasonally spawning species and improves our understanding regarding the molecular signaling events that underlie testicular growth. This is significant because, while there are a number of studies characterizing molecular pathways in the ovary, there are comparatively less describing transcriptomic patterns in the testis in wild fish.
Baird D.J., Van Den Brink P.J., Chariton A.A., Dafforn K.A., Johnston E.L. (2016). New diagnostics for multiply stressed marine and freshwater ecosystems: Integrating models, ecoinformatics and big data. Marine and Freshwater Research, 67(4) 391-392.
Baker D.G.L., Eddy T.D., McIver R., Schmidt A.L., Thériault M.H., Boudreau M., Courtenay S.C., Lotze H.K. (2016). Comparative analysis of different survey methods for monitoring fish assemblages in coastal habitats. Peerj, 2016(3).

Coastal ecosystems are among the most productive yet increasingly threatened marine ecosystems worldwide. Particularly vegetated habitats, such as eelgrass (Zostera marina) beds, play important roles in providing key spawning, nursery and foraging habitats for a wide range of fauna. To properly assess changes in coastal ecosystems and manage these critical habitats, it is essential to develop sound monitoring programs for foundation species and associated assemblages. Several survey methods exist, thus understanding how different methods perform is important for survey selection. We compared two common methods for surveying macrofaunal assemblages: beach seine netting and underwater visual census (UVC). We also tested whether assemblages in shallow nearshore habitats commonly sampled by beach seines are similar to those of nearby eelgrass beds often sampled by UVC. Among five estuaries along the Southern Gulf of St. Lawrence, Canada, our results suggest that the two survey methods yield comparable results for species richness, diversity and evenness, yet beach seines yield significantly higher abundance and different species composition. However, sampling nearshore assemblages does not represent those in eelgrass beds despite considerable overlap and close proximity. These results have important implications for how and where macrofaunal assemblages are monitored in coastal ecosystems. Ideally, multiple survey methods and locations should be combined to complement each other in assessing the entire assemblage and full range of changes in coastal ecosystems, thereby better informing coastal zone management.
Baker L.F., Mudge J.F., Thompson D.G., Houlahan J.E., Kidd K.A. (2016). The combined influence of two agricultural contaminants on natural communities of phytoplankton and zooplankton. Ecotoxicology, 25(5) 1021-1032.

Concentrations of glyphosate observed in the environment are generally lower than those found to exert toxicity on aquatic organisms in the laboratory. Toxicity is often tested in the absence of other expected co-occurring contaminants. By examining changes in the phytoplankton and zooplankton communities of shallow, partitioned wetlands over a 5 month period, we assessed the potential for direct and indirect effects of the glyphosate-based herbicide, Roundup WeatherMax© applied at the maximum label rate, both in isolation and in a mixture with nutrients (from fertilizers). The co-application of herbicide and nutrients resulted in an immediate but transient decline in dietary quality of phytoplankton (8.3 % decline in edible carbon content/L) and zooplankton community similarity (27 % decline in similarity and loss of three taxa), whereas these effects were not evident in wetlands treated only with the herbicide. Thus, even at a worst-case exposure, this herbicide in isolation, did not produce the acutely toxic effects on plankton communities suggested by laboratory or mesocosm studies. Indirect effects of the herbicide-nutrient mixture were evident in mid-summer, when glyphosate residues were no longer detectable in surface water. Zooplankton abundance tripled, and zooplankton taxa richness increased by an average of four taxa in the herbicide and nutrient treated wetlands. The lack of significant toxicity of Roundup WeatherMax alone, as well as the observation of delayed interactive or indirect effects of the mixture of herbicide and nutrients attest to the value of manipulative field experiments as part of a comprehensive, tiered approach to risk assessments in ecotoxicology.
Bosker T., Munkittrick K.R., Lister A., Maclatchy D.L. (2016). Mummichog (Fundulus heteroclitus) continue to successfully produce eggs after exposure to high levels of 17α-ethinylestradiol. Environmental Toxicology and Chemistry, 35(5) 1107-1112.

17α-Ethinylestradiol (EE2) is a potent estrogen used in birth-control pills. Previous laboratory and field studies have shown negative impacts in a variety of fish species after exposure to low levels of EE2, most notably a nearly complete shutdown of egg production. The present study demonstrates that mummichog (Fundulus heteroclitus), a small-bodied estuarine species, is able to continue to produce eggs after exposure for 28 d to 100ng of EE2/L. No effect of EE2 on egg production was observed, whereas a >35-fold increase in vitellogenin (vtg 1) gene expression in males was found. The lack of response in egg production in fish exposed to high levels of EE2 warrants further investigations on species-specific responses to estrogens and endocrine disruptors in general. Environ Toxicol Chem 2016;35:1107-1112.
Chantigny M.H., Rochette P., Angers D.A., Goyer C., Brin L.D., Bertrand N. (2016). Nongrowing season N2O and CO2 emissions — temporal dynamics and influence of soil texture and fall-applied manure. Canadian Journal of Soil Science, 97(3) 452-464.

Nongrowing season (NGS) greenhouse gas (GHG) emissions may be significant in cold agricultural regions, but the influence of winter conditions, soil type, and fall manuring must be better documented. We monitored NGS N<inf>2</inf>O and CO<inf>2</inf> fluxes and soil atmosphere composition from 2009 to 2013, on sandy loam and silty clay soils, with and without fall-applied pig slurry. Early-winter emission peaks indicated that soil respiration and biogenic N<inf>2</inf> O production were stimulated during active soil freezing. Soil atmosphere GHG concentrations increased throughout winter, whereas O<inf>2</inf> concentration declined, especially when surface fluxes were low. Therefore, soil respiration and denitrification were not stopped by cold temperatures, and low surface fluxes were mainly due to restriction of gas diffusion. Nitrous oxide emissions varied from 0.4 to 8.5 kg N ha−1 and were generally greater in the presence of pig slurry. Emissions were of similar magnitude between soil types, likely because O<inf>2</inf> restrictions on denitrification typically found in sandy soils during the growing season were eliminated by high soil moisture content in the NGS. This multiyear assessment highlights the need to include NGS GHG emissions to properly estimate yearly emissions and refine inventories in cold regions, particularly for sandy soils.
Chase J.W., Benoy G.A., Hann S.W.R., Culp J.M. (2016). Small differences in riparian vegetation significantly reduce land use impacts on stream flow and water quality in small agricultural watersheds. Journal of Soil and Water Conservation, 71(3) 194-205.

Fluvial ecosystem integrity is intimately tied to agricultural intensity in most rural landscapes. Row crop agriculture in particular can elicit a range of deleterious effects on hydrology, surface water quality, and fluvial ecology. Riparian vegetation represents a critical defence of stream systems against environmental perturbations. Vegetation filters surface runoff and encourages infiltration. Furthermore, riparian forests shade streams and are thus able to stabilize in-stream temperature and dissolved oxygen (O). In northwest New Brunswick's potato (Solanum tuberosum L.) growing region, once densely forested riparian corridors now often contain only scattered, irregular patches of residual vegetation, and national water quality standards for streams are regularly exceeded. The objective of this study was to ascertain whether relatively small differences in riparian forest cover are of any significant benefit to stream environments. Specifically, we assessed the capacity of riparian forests to reduce the effects of row crop agriculture on stream flow, water quality, and benthic macroinvertebrate communities of streams draining small subwatersheds near Grand Falls, New Brunswick. The subwatersheds ranged in agricultural intensity from 0.5% to 97% crop cover, which predominantly consisted of potato. Riparian cover and agricultural intensity were highly collinear; hence, riparian forest cover was converted to a binomial categorical predictor (i.e., high and low), with agricultural intensity treated as a continuous covariate. Higher intensity of rowcrop agriculture in small subwatersheds corresponded to base flow decline; greater flow pulse frequency; higher dissolved nitrate-nitrogen (NO3-N), conductivity, pH, and temperature; lower dissolved O; and prevalence of pollution-tolerant macroinvertebrate taxa and grazers. With less than 20% increase in riparian forest cover relative to agricultural intensity, we observed reduced severity of summer low flow periods, significantly lower dissolved phosphate (PO4) concentrations, lower temperatures, and higher dissolved O. Macroinvertebrate assemblage structure of the riparian cover categories diverged with increasing agriculture, demonstrating the value of even minor amounts of riparian vegetation to benthic community condition. Our results conclusively show that relatively small increases in riparian forest cover will lead to statistically detectable and ecologically meaningful improvements to stream health.
Chin K.S., Lento J., Culp J.M., Lacelle D., Kokelj S.V. (2016). Permafrost thaw and intense thermokarst activity decreases abundance of stream benthic macroinvertebrates. Global Change Biology, 22(8) 2715-2728.

Intensification of permafrost thaw has increased the frequency and magnitude of large permafrost slope disturbances (mega slumps) in glaciated terrain of northwestern Canada. Individual thermokarst disturbances up to 40 ha in area have made large volumes of previously frozen sediments available for leaching and transport to adjacent streams, significantly increasing sediment and solute loads in these systems. To test the effects of this climate-sensitive disturbance regime on the ecology of Arctic streams, we explored the relationship between physical and chemical variables and benthic macroinvertebrate communities in disturbed and undisturbed stream reaches in the Peel Plateau, Northwest Territories, Canada. Highly disturbed and undisturbed stream reaches differed with respect to taxonomic composition and invertebrate abundance. Minimally disturbed reaches were not differentiated by these variables but rather were distributed along a disturbance gradient between highly disturbed and undisturbed sites. In particular, there was evidence of a strong negative relationship between macroinvertebrate abundance and total suspended solids, and a positive relationship between abundance and the distance from the disturbance. Increases in both sediments and nutrients appear to be the proximate cause of community differences in highly disturbed streams. Declines in macroinvertebrate abundance in response to slump activity have implications for the food webs of these systems, potentially leading to negative impacts on higher trophic levels, such as fish. Furthermore, the disturbance impacts on stream health can be expected to intensify as climate change increases the frequency and magnitude of thermokarst.
Compson Z.G., Hungate B.A., Whitham T.G., Meneses N., Busby P.E., Wojtowicz T., Ford A.C., Adams K.J., Marks J.C. (2016). Plant genotype influences aquatic-terrestrial ecosystem linkages through timing and composition of insect emergence. Ecosphere, 7(5).

Terrestrial leaf litter provides aquatic insects with an energy source and habitat structure, and species differences in litter can influence aquatic insect emergence. Emerging insects also provide energy to riparian predators. We hypothesized that plant genetics would influence the composition and timing of emerging insect communities among individual genotypes of Populus angustifolia varying in litter traits. We also compared the composition and timing of emerging insect communities on litter from mixed genotypes of three cross types of a hybridizing cottonwood complex: P. angustifolia, P. fremontii, and their F<inf>1</inf> hybrids. Using litter harvested from an experimental common garden, we measured emerging insect community composition, abundance, and production for 12 weeks in large litter packs affixed with emergence traps. Five major findings emerged. (1) In support of the genetic similarity hypothesis, we found that, among P. angustifolia tree genotypes, litter from more closely related genotypes had more similar litter thickness, nitrogen concentrations, decomposition rates, and emerging insect communities. (2) Genetic similarity was not correlated with other litter traits, although the litter fungal community was a strong predictor of emerging insect communities. (3) Litter decomposition rate, which was the strongest predictor of emerging aquatic insect communities, was influenced by litter thickness, litter N, and the litter fungal community. (4) In contrast to strong community composition differences among P. angustifolia genotypes, differences in community composition between P. fremontii and P. angustifolia were only marginally significant, and communities on F<inf>1</inf> hybrids were indistinguishable from P. angustifolia despite genetic and litter trait differences. (5) Mixed litter packs muted the genetic effects observed in litter packs consisting of single genotypes. These results demonstrate that the genetic structure of riparian forests can affect the composition and timing of aquatic insect emergence. Because many riparian trees are clonal, including P. angustifolia, large clone size is likely to result in patches of genetically structured leaf litter that may influence the timing and composition of insect emergence within watersheds. Riparian restoration efforts incorporating different tree genotypes could also influence the biodiversity of emerging aquatic insects. Our work illustrates the importance of plant genes for community and ecosystem processes in riparian corridors.
Dafforn K.A., Johnston E.L., Ferguson A., Humphrey C.L., Monk W., Nichols S.J., Simpson S.L., Tulbure M.G., Baird D.J. (2016). Big data opportunities and challenges for assessing multiple stressors across scales in aquatic ecosystems. Marine and Freshwater Research, 67(4) 393-413.

Aquatic ecosystems are under threat from multiple stressors, which vary in distribution and intensity across temporal and spatial scales. Monitoring and assessment of these ecosystems have historically focussed on collection of physical and chemical information and increasingly include associated observations on biological condition. However, ecosystem assessment is often lacking because the scale and quality of biological observations frequently fail to match those available from physical and chemical measurements. The advent of high-performance computing, coupled with new earth observation platforms, has accelerated the adoption of molecular and remote sensing tools in ecosystem assessment. To assess how emerging science and tools can be applied to study multiple stressors on a large (ecosystem) scale and to facilitate greater integration of approaches among different scientific disciplines, a workshop was held on 10-12 September 2014 at the Sydney Institute of Marine Sciences, Australia. Here we introduce a conceptual framework for assessing multiple stressors across ecosystems using emerging sources of big data and critique a range of available big-data types that could support models for multiple stressors. We define big data as any set or series of data, which is either so large or complex, it becomes difficult to analyse using traditional data analysis methods.
De Laender F., Rohr J.R., Ashauer R., Baird D.J., Berger U., Eisenhauer N., Grimm V., Hommen U., Maltby L., Meliàn C.J., Pomati F., Roessink I., Radchuk V., Van den Brink P.J. (2016). Reintroducing Environmental Change Drivers in Biodiversity–Ecosystem Functioning Research. Trends in Ecology and Evolution, 31(12) 905-915.

For the past 20 years, research on biodiversity and ecosystem functioning (B-EF) has only implicitly considered the underlying role of environmental change. We illustrate that explicitly reintroducing environmental change drivers in B-EF research is needed to predict the functioning of ecosystems facing changes in biodiversity. Next we show how this reintroduction improves experimental control over community composition and structure, which helps to provide mechanistic insight on how multiple aspects of biodiversity relate to function and how biodiversity and function relate in food webs. We also highlight challenges for the proposed reintroduction and suggest analyses and experiments to better understand how random biodiversity changes, as studied by classic approaches in B-EF research, contribute to the shifts in function that follow environmental change.
Dreier D.A., Loughery J.R., Denslow N.D., Martyniuk C.J. (2016). The influence of breeding strategy, reproductive stage, and tissue type on transcript variability in fish. Comparative Biochemistry and Physiology Part D Genomics and Proteomics, 19 151-158.

Characterizing factors that contribute to transcript variability is necessary before molecular endpoints are widely adopted as biomarkers for environmental monitoring programs and risk assessment. Here, we employed a meta-analysis approach to understand how reproductive stage, breeding strategy, and tissue type influence transcript variability in multiple fish species. Transcript abundance from the scientific literature was examined by method of quantification (qPCR or microarray), and the extracted data were used to calculate the coefficient of variation (CoV) for each transcript. Based on qPCR data, variability in the abundance of estrogen receptor 1 and hydroxysteroid dehydrogenase 3b was dependent upon reproductive stage and/or breeding strategy in the female ovaries. The variability of other transcripts in the steroid biosynthesis pathway as well as other steroid receptors did not depend upon sex, breeding strategy, or reproductive stage. Variability estimates were used to determine sample size requirements for detecting specific critical effects in molecular endpoints. It was estimated that only 37.8% of published studies used in the qPCR meta-analysis had sufficient experimental power (0.8) to detect a 2-fold expression difference in a transcript. To build upon these analyses, microarray data were used to measure overall variability of the transcriptome, and it was determined that the vitellogenic reproductive stage had the lowest transcriptomic variability compared to other reproductive stages. This variability was lower in a single-spawning species (largemouth bass) compared to a multiple-spawner (fathead minnow). Following this, a meta-analysis of 777 microarrays for multiple fish species was performed to determine the influence of breeding strategy and tissue type on transcriptomic variability. In this analysis, single-spawning fish showed lower gonadal and hepatic transcriptome variability compared to multiple-spawning species. Thus, these species may be more appropriate for sampling molecular endpoints in monitoring programs. Transcript variability was lowest in the brain, followed by the gonads and liver, which may reflect fewer morphological changes relative to these tissues. The results of this study should be used in conjunction with other experimental and sampling recommendations to optimize the use of molecular endpoints in regulatory ecotoxicology and environmental monitoring programs.
Dugdale S.J. (2016). A practitioner's guide to thermal infrared remote sensing of rivers and streams: recent advances, precautions and considerations. Wiley Interdisciplinary Reviews Water, 3(2) 251-268.

Stream temperature is a key habitat variable controlling all physical and biological river processes. In light of the threat of climate change to fluvial environments, growing importance is being placed on the need to gain a better understanding of stream temperature dynamics. However, many current or historic stream temperature datasets are of very low spatial resolution. Such in situ measurements are often unable to provide the fine scale information on longitudinal or lateral temperature patterns necessary for understanding links between thermal heterogeneity and fluvial processes. In recent years, attention has therefore turned to the use of thermal infrared (TIR) remote sensing in order to acquire 2D stream temperature data at ecologically meaningful scales. While TIR remote sensing is a relatively mature technology in its own right, its application in fluvial environments is accompanied by a range of limitations and considerations that must be respected in order to ensure the acquisition of reasonable quality data. It is only in recent years that researchers have been started to shift from detailing the technical aspects of TIR imaging of river environments toward describing its application for river management and fundamental fluvial science. We critically review this recent research, demonstrating the utility of TIR for applied river temperature research. We also provide a detailed guide to the practical use of TIR in river environments with a view to further stimulating its use for advancing stream temperature science. WIREs Water 2016, 3:251–268. doi: 10.1002/wat2.1135. This article is categorized under: Water and Life > Nature of Freshwater Ecosystems Science of Water > Hydrological Processes Science of Water > Water Quality.
Dugdale S.J., Franssen J., Corey E., Bergeron N.E., Lapointe M., Cunjak R.A. (2016). Main stem movement of Atlantic salmon parr in response to high river temperature. Ecology of Freshwater Fish, 25(3) 429-445.

Atlantic salmon become thermally stressed when water temperatures exceed 23 °C. To alleviate this stress, they behaviourally thermoregulate by moving to patches of cold water, often forming large aggregations. These patches are known as thermal refuges. Given the consensus that climate change will increase temperatures in Atlantic salmon catchments, thermal refuges will become increasingly important in minimising summer mortalities. While the behaviour of salmonids within thermal refuges is fairly well understood, less is known about their main stem movement in search of thermal refuges or its thermal and temporal cues. We detail the results of a PIT telemetry study to investigate the main stem movement behaviour of thermally stressed Atlantic salmon parr in a temperature-impacted river. PIT antennas placed around two thermal refuges and at the upstream and downstream limits of their surrounding reach were used to record the movement of salmonids during a heatwave. We observed parr movement at the upstream and downstream antennas 135 min prior to the occurrence of the midpoint of aggregations in the thermal refuges, indicating that Atlantic salmon parr make reach-scale movements in search of cool water prior to aggregating. Logistic regression showed that the number of degree hours >28 °C predicted the occurrence of main stem movement with a good degree of accuracy, indicating that this temperature represents a fundamental threshold causing Atlantic salmon parr to move towards cool water. Such data could be instrumental in allowing river managers to place limits on human activity within rivers, allowing salmon populations time to recover following heat stress events.
Fahner N.A., Shokralla S., Baird D.J., Hajibabaei M. (2016). Large-scale monitoring of plants through environmental DNA metabarcoding of soil: Recovery, resolution, and annotation of four DNA markers. Plos One, 11(6).

In a rapidly changing world we need methods to efficiently assess biodiversity in order to monitor ecosystem trends. Ecological monitoring often uses plant community composition to infer quality of sites but conventional aboveground surveys only capture a snapshot of the actively growing plant diversity. Environmental DNA (eDNA) extracted from soil samples, however, can include taxa represented by both active and dormant tissues, seeds, pollen, and detritus. Analysis of this eDNA through DNA metabarcoding provides a more comprehensive view of plant diversity at a site from a single assessment but it is not clear which DNA markers are best used to capture this diversity. Sequence recovery, annotation, and sequence resolution among taxa were evaluated for four established DNA markers (matK, rbcL, ITS2, and the trnL P6 loop) in silico using database sequences and in situ using high throughput sequencing of 35 soil samples from a remote boreal wetland. Overall, ITS2 and rbcL are recommended for DNA metabarcoding of vascular plants from eDNA when not using customized or geographically restricted reference databases. We describe a new framework for evaluating DNA metabarcodes and, contrary to existing assumptions, we found that full length DNA barcode regions could outperform shorter markers for surveying plant diversity from soil samples. By using current DNA barcoding markers rbcL and ITS2 for plant metabarcoding, we can take advantage of existing resources such as the growing DNA barcode database. Our work establishes the value of standard DNA barcodes for soil plant eDNA analysis in ecological investigations and biomonitoring programs and supports the collaborative development of DNA barcoding and metabarcoding.Copyright:
Feswick A., Loughery J.R., Isaacs M.A., Munkittrick K.R., Martyniuk C.J. (2016). Molecular initiating events of the intersex phenotype: Low-dose exposure to 17α-ethinylestradiol rapidly regulates molecular networks associated with gonad differentiation in the adult fathead minnow testis. Aquatic Toxicology, 181 46-56.

Intersex, or the presence of oocytes in the testes, has been documented in fish following exposure to wastewater effluent and estrogenic compounds. However, the molecular networks underlying the intersex condition are not completely known. To address this, we exposed male fathead minnows to a low, environmentally-relevant concentration of 17alpha-ethinylestradiol (EE2) (15 ng/μl) and measured the transcriptome response in the testis after 96 h to identify early molecular initiating events that may proceed the intersex condition. The short-term exposure to EE2 did not affect gonadosomatic index and proportion of gametes within the testes. However, the production of 11-ketotestosterone and testosterone from the testis in vitro was decreased relative to controls. Expression profiling using a 8 × 60 K fathead minnow microarray identified 10 transcripts that were differentially expressed in the testes, the most dramatic change being that of coagulation factor XIII A chain (20-fold increase). Transcripts that included guanine nucleotide binding protein (Beta Polypeptide 2), peroxisome proliferator-activated receptor delta, and WNK lysine deficient protein kinase 1a, were down-regulated by EE2. Subnetwork enrichment analysis revealed that EE2 suppressed transcriptional networks associated with steroid metabolism, hormone biosynthesis, and sperm mobility. Most interesting was that gene networks associated with doublesex and mab-3 related transcription factor 1 (dmrt1) were suppressed in the adult testis, despite the fact that dmrt1 itself was not different in expression from control males. Transcriptional networks involving forkhead box L2 (foxl2) (transcript involved in ovarian follicle development) were increased in expression in the testis. Noteworthy was that a gene network associated to granulosa cell development was increased over 100%, suggesting that this transcriptome network may be important for monitoring estrogenic exposures. Other cell processes rapidly downregulated by EE2 at the transcript level included glucose homeostasis, response to heavy metal, amino acid catabolism, and the cyclooxygenase pathway. Conversely, lymphocyte chemotaxis, intermediate filament polymerization, glucocorticoid metabolism, carbohydrate utilization, and anterior/posterior axis specification were increased. These data provide new insight into the transcriptional responses that are perturbed prior to gonadal remodeling and intersex following exposure to estrogens. These data demonstrate that low concentrations of EE2 (1) rapidly suppresses male hormone production, (2) down-regulate molecular networks related to male sex differentiation, and (3) induce transcriptional networks related to granulosa cell development in the adult testis. These responses are hypothesized to be key molecular initiating events that occur prior to the development of the intersex phenotype following estrogenic exposures.
Finley M.L.D., Kidd K.A., Curry R.A., Lescord G.L., Clayden M.G., O'Driscoll N.J. (2016). A comparison of mercury biomagnification through lacustrine food webs supporting Brook Trout (Salvelinus fontinalis) and other salmonid fishes. Frontiers in Environmental Science, 4(APR).

Methylmercury (MeHg) bioaccumulation in lower-trophic-level organisms and its subsequent biomagnification through food webs differs in magnitude among lakes and results in intraspecific variability of MeHg in top predator fishes. Understanding these differences is critical given the reproductive and neurotoxic effects of MeHg on fishes and their predators, including humans. In this study we characterized the food webs of five lakes in New Brunswick, Canada, supporting Brook Trout (Salvelinus fontinalis) using measures of relative trophic position (δ 15 N) and carbon sources (δ 13 C), determined the concentrations of MeHg in invertebrates and total Hg (THg) in fishes, and quantified MeHg biomagnification from primary to tertiary consumers. Methyl Hg and THg concentrations were highest in biota from lakes with lower pH. The trophic magnification slopes (TMS; log Hg vs. δ 15 N) varied significantly among lakes (0.13-0.20; ANCOVA, p = 0.031). When combined with data from other salmonid lakes in temperate and Arctic Canada (n = 36), among-system variability in TMS was best, but weakly, positively predicted by aqueous total phosphorous (p = 0.028, Radj2= 0.109). These results suggest that lake productivity directly or indirectly influences the biomagnification of MeHg through diverse food webs supporting salmonids.
Fuzzen M.L.M., Bragg L.M., Tetreault G.R., Bahamonde P.A., Tanna R.N., Bennett C.J., McMaster M.E., Servos M.R. (2016). An assessment of the spatial and temporal variability of biological responses to municipal wastewater effluent in rainbow darter (Etheostoma caeruleum) collected along an urban gradient. Plos One, 11(10).

Municipal wastewater effluent (MWWE) and its constituents, such as chemicals of emerging concern, pose a potential threat to the sustainability of fish populations by disrupting key endocrine functions in aquatic organisms. While studies have demonstrated changes in biological markers of exposure of aquatic organisms to groups of chemicals of emerging concern, the variability of these markers over time has not been sufficiently described in wild fish species. The aim of this study was to assess the spatial and temporal variability of biological markers in response to MWWE exposure and to test the consistency of these responses between seasons and among years. Rainbow darter (Etheostoma caeruleum) were collected in spring and fall seasons over a 5-year period in the Grand River, Ontario, Canada. In addition to surface water chemistry (nutrients and selected pharmaceuticals), measures were taken across levels of biological organization in rainbow darter. The measurements of hormone production, gonad development, and intersex severity were temporally consistent and suggested impaired reproduction in male fish collected downstream of MWWE outfalls. In contrast, ovarian development and hormone production in females appeared to be influenced more by urbanization than MWWE. Measures of gene expression and somatic indices were highly variable between sites and years, respectively, and were inconclusive in terms of the impacts of MWWE overall. Robust biomonitoring programs must consider these factors in both the design and interpretation of results, especially when spatial and temporal sampling of biological endpoints is limited. Assessing the effects of contaminants and other stressors on fish in watersheds would be greatly enhanced by an approach that considers natural variability in the endpoints being measured.
Gehrels H., Knysh K.M., Boudreau M., Thériault M.H., Courtenay S.C., Cox R., Quijón P.A. (2016). Hide and seek: habitat-mediated interactions between European green crabs and native mud crabs in Atlantic Canada. Marine Biology, 163(7).

The non-indigenous European green crab (Carcinus maenas) has well-documented impacts on many native species. In the Atlantic Canada region, the green crab distribution is increasingly overlapping with the distribution of mud crabs (primarily Dyspanopeus sayi), a prominent native species. Despite the potential for antagonistic interactions, the relationship between the two species has not been examined, particularly in the context of the diversity of habitats available in the region. This study used observational beach seine data collected between 2009 and 2013 from the southern Gulf of St. Lawrence to explore the temporal and spatial relationships between mud crabs and green crabs, and detected a negative relationship between these species. Twenty-four-hour laboratory experiments examined their predator–prey interactions and assessed the influence of habitat complexity on the outcomes of these interactions. Mud crabs and similar-sized green crabs collected during July and August of 2010 and 2011 were used as prey for large green crab. These predators consumed almost twice as many mud crab compared with juvenile green crab in the two less structured habitats (no substrate or sandy substrate), but predation rates were statistically similar in oyster bed habitat. In that particular habitat, mud crab mortality dropped by ~65 %, whereas the generally lower mortality affecting juvenile green crabs was unaffected by habitat. These results suggest that complex habitats mediate predator–prey interactions and dampen the effect of green crab prey preference. As green crab continues to invade areas dominated by mud crabs, they may threaten the sustainability of this native species.
González-Sansón G., Aguilar-Betancourt C., Kosonoy-Aceves D., Lucano-Ramírez G., Ruiz-Ramírez S., Flores-Ortega J.R. (2016). Spatial and temporal variations of juvenile fish abundance in barra de navidad coastal lagoon, jalisco, méxico: Effects of hurricane jova. Revista De Biologia Marina Y Oceanografia, 51(1) 123-136.

Seasonal and spatial variations of nearshore juvenile fish assemblages were assessed inside the coastal lagoon of Barra de Navidad, Jalisco, Mexico. Sampling was carried out during 2 different periods: March 2011 to February 2012 in site 1 and October 2012 to November 2013 in sites 1 and 2. During the first sampling period, the hurricane Jova (October 2011) hits the study area and introduced an unpredicted environmental impact. Samples of fish assemblages were taken using a beach purse seine. Water salinity, temperature and sediment granulometry were measured. A total of 36,897 individuals of 61 species were collected and their total lengths were measured. 90% of the species and 96% of the individuals were classified as juvenile. Four taxa (Anchoa spp., Eucinostomus currani, Diapterus peruvianus and Mugil spp.) made more than 80 percent of catches in number. Significant differences were found in fish assemblage composition between sampling periods and between seasons for site 1, while significant differences were found between sites and between seasons for the second sampling period. A significant difference was found in the composition of fish assemblages before and after the hurricane Jova at site 1 during the first sampling period. Strong seasonal changes in salinity are most probably the cause of changes found in fish assemblages along the year, while differences in sediment granulometry and organic matter percentages could explain differences between sampling sites.
Hajibabaei M., Baird D.J., Fahner N.A., Beiko R., Brian Golding G. (2016). A new way to contemplate darwin’s tangled bank: How DNA barcodes are reconnecting biodiversity science and biomonitoring. Philosophical Transactions of the Royal Society B Biological Sciences, 371(1702).

Encompassing the breadth of biodiversity in biomonitoring programmes has been frustrated by an inability to simultaneously identify large numbers of species accurately and in a timely fashion. Biomonitoring infers the state of an ecosystem from samples collected and identified using the best available taxonomic knowledge. The advent of DNA barcoding has now given way to the extraction of bulk DNA from mixed samples of organisms in environmental samples through the development of high-throughput sequencing (HTS). This DNA metabarcoding approach allows an unprecedented view of the true breadth and depth of biodiversity, but its adoption poses two important challenges. First, bioinformatics techniques must simultaneously perform complex analyses of large datasets and translate the results of these analyses to a range of users. Second, the insights gained from HTS need to be amalgamated with concepts such as Linnaean taxonomy and indicator species, which are less comprehensive but more intuitive. It is clear that we are moving beyond proof-of-concept studies to address the challenge of implementation of this new approach for environmental monitoring and regulation. Interpreting Darwin’s ‘tangled bank’ through a DNA lens is now a reality, but the question remains: how can this information be generated and used reliably, and how does it relate to accepted norms in ecosystem study?.
Hayden B., McWilliam-Hughes S.M., Cunjak R.A. (2016). Evidence for limited trophic transfer of allochthonous energy in temperate river food webs. Freshwater Science, 35(2) 544-558.

The River Continuum Concept (RCC) predicts that riverine food webs shift from a reliance on allochthonous energy in headwaters to autochthonous production in lower reaches. However, estimates of resource reliance often fail to account for resource segregation within the food web. Stable-isotope biomarkers can be used to estimate the relative importance of allochthonous and autochthonous material to specific groups and within the food web. δ13C and δ15N isotope ratios were calculated for allochthonous (conditioned leaf litter) and autochthonous (biofilm and bryophytes) basal energy sources, macroinvertebrate functional feeding groups (shredder, grazer, collector-filterer, collector-gatherer, predator), and resident fish species at 17 locations spanning the headwaters to lower reaches of 2 river systems in eastern Canada. Stable-isotope mixing models and correlations were used to identify longitudinal trends in the food webs of both rivers. In headwater streams, allochthonous material was the predominant resource for shredders, whereas all other primary, secondary, and tertiary consumers predominantly used autochthonous basal resources. Stable-isotope ratios of allochthonous material varied minimally between sites. Both autochthonous basal sources were significantly 13C-enriched and 15N-depleted in lower-reach relative to headwater sites. Shredders displayed minimal variation across sites, whereas longitudinal variation in all other primary consumers, macroinvertebrate predators, and fishes was closely correlated with autochthonous basal sources. These results highlight the role of resource segregation within river food webs and indicate that the RCC may not predict energy pathways in all temperate river systems.
Holmes R., Armanini D.G., Yates A.G. (2016). Effects of Best Management Practice on Ecological Condition: Does Location Matter? Environmental Management, 57(5) 1062-1076.

Best management practices (BMPs) are increasingly being promoted as a solution to the potentially adverse effects agriculture can have on aquatic systems. However, the ability of BMPs to improve riverine systems continues to be questioned due to equivocal empirical evidence linking BMP use with improved stream conditions, particularly in regard to ecological conditions. Explicitly viewing BMP location in relation to hydrological pathways may, however, assist in establishing stronger ecological linkages. The goal of this study was to assess the association between water chemistry, benthic macroinvertebrate community structure, and the number and location of agricultural BMPs in a catchment. Macroinvertebrate and water samples were collected in 30 small (<12 km2) catchments exhibiting gradients of BMP use and location in the Grand River Watershed, Southern Ontario, Canada. Stepwise regression analysis revealed that concentrations of most stream nutrients declined in association with greater numbers of BMPs and particularly when BMPs were located in hydrologically connected areas. However, BMPs were significantly associated with only one metric (%EPT) describing macroinvertebrate community structure. Furthermore, variance partitioning analysis indicated that less than 5 % of the among site variation in the macroinvertebrate community could be attributed to BMPs. Overall, the implemented BMPs appear to be achieving water quality improvement goals but spatial targeting of specific BMP types may allow management agencies to attain further water quality improvements more efficiently. Mitigation and rehabilitation measures beyond the BMPs assessed in this study may be required to meet goals of enhanced ecological condition.
Kahilainen K.K., Thomas S.M., Keva O., Hayden B., Knudsen R., Eloranta A.P., Tuohiluoto K., Amundsen P.A., Malinen T., Järvinen A. (2016). Seasonal dietary shift to zooplankton influences stable isotope ratios and total mercury concentrations in Arctic charr (Salvelinus alpinus (L.)). Hydrobiologia, 783(1) 47-63.

Seasonal dietary shifts by Arctic charr (Salvelinus alpinus (L.)) are common in subarctic lakes, but less is known about how the shift to pelagic zooplankton feeding during the growing season affects stable isotope ratios and mercury concentrations. We sampled Arctic charr, zooplankton and benthic macroinvertebrates from oligotrophic Lake Galggojavri, northern Norway, in June, August and September. Stomach content, age, total length, weight, condition and sex were recorded for all individuals, and liver and muscle tissues were sampled for stable isotope (δ13C, δ15N) and total mercury analyses. We predicted that a dietary shift to zooplankton would lead to depleted 13C and increased mercury levels in charr. Arctic charr consumed benthic prey in June, but shifted to zooplankton feeding in August–September. Stable isotope mixing models revealed increased pelagic reliance towards September. Mercury content in liver increased from June to September, whereas muscle showed opposite trend. In stepwise multiple regression analyses, mercury content in muscle was explained by fish length, month and δ13C (R2 = 0.46), whereas in liver month, δ13C and δ15N were the main explaining factors (R2 = 0.69). Seasonal dietary shifts appeared to have an effect on total mercury content in charr, and thus sampling month should be considered when designing future monitoring programmes.
Karami A., Goh Y.M., Jahromi M.F., Lazorchak J.M., Abdullah M., Courtenay S.C. (2016). Diploid and triploid African catfish (Clarias gariepinus) differ in biomarker responses to the pesticide chlorpyrifos. Science of the Total Environment, 557-558 204-211.

The impacts of environmental stressors on polyploid organisms are largely unknown. This study investigated changes in morphometric, molecular, and biochemical parameters in full-sibling diploid and triploid African catfish (Clarias gariepinus) in response to chlorpyrifos (CPF) exposures. Juvenile fish were exposed to three concentrations of CPF (mean measured μg/L (SD): 9.71 (2.27), 15.7 (3.69), 31.21 (5.04)) under a static-renewal condition for 21 days. Diploid control groups had higher hepatosomatic index (HSI), plasma testosterone (T), and brain GnRH and cyp19a2 expression levels than triploids. In CPF-exposed groups, changes in HSI, total weight and length were different between the diploid and triploid fish. In contrast, condition factor did not alter in any of the treatments, while visceral-somatic index (VSI) changed only in diploids. In diploid fish, exposure to CPF did not change brain 11β-hsd2, ftz-f1, foxl2, GnRH or cyp19a2 mRNA levels, while reduced tph2 transcript levels compared to the control group. In contrast, 11β-hsd2 and foxl2 expression levels were changed in triploids following CPF exposures. In diploids, plasma T levels showed a linear dose-response reduction across CPF treatments correlating with liver weight and plasma total cholesterol concentrations. In contrast, no changes in plasma cholesterol and T concentrations were observed in triploids. Plasma cortisol and 17-β estradiol (E<inf>2</inf>) showed no response to CPF exposure in either ploidy. Results of this first comparison of biomarker responses to pesticide exposure in diploid and polyploid animals showed substantial differences between diploid and triploid C. gariepinus.
Karami A., Karbalaei S., Zad Bagher F., Ismail A., Simpson S.L., Courtenay S.C. (2016). Alterations in juvenile diploid and triploid African catfish skin gelatin yield and amino acid composition: Effects of chlorpyrifos and butachlor exposures. Environmental Pollution, 215 170-177.

Skin is a major by-product of the fisheries and aquaculture industries and is a valuable source of gelatin. This study examined the effect of triploidization on gelatin yield and proximate composition of the skin of African catfish (Clarias gariepinus). We further investigated the effects of two commonly used pesticides, chlorpyrifos (CPF) and butachlor (BUC), on the skin gelatin yield and amino acid composition in juvenile full-sibling diploid and triploid African catfish. In two separate experiments, diploid and triploid C. gariepinus were exposed for 21 days to graded CPF [mean measured: 10, 16, or 31 μg/L] or BUC concentrations [Mean measured: 22, 44, or 60 μg/L]. No differences in skin gelatin yield, amino acid or proximate compositions were observed between diploid and triploid control groups. None of the pesticide treatments affected the measured parameters in diploid fish. In triploids, however, gelatin yield was affected by CPF treatments while amino acid composition remained unchanged. Butachlor treatments did not alter any of the measured variables in triploid fish. To our knowledge, this study is the first to investigate changes in the skin gelatin yield and amino acid composition in any animal as a response to polyploidization and/or contaminant exposure.
Karami A., Omar D., Lazorchak J.M., Yap C.K., Hashim Z., Courtenay S.C. (2016). A comparison of biomarker responses in juvenile diploid and triploid African catfish, Clarias gariepinus, exposed to the pesticide butachlor. Environmental Research, 151 313-320.

Influence of waterborne butachlor (BUC), a commonly used pesticide, on morphometric, biochemical, and molecular biomarkers was evaluated in juvenile, full sibling, diploid and triploid African catfish (Clarias gariepinus). Fish were exposed for 21 days to one of three concentrations of BUC [mean measured µg/L: 22, 44 or 60]. Unexposed (control) triploids were heavier and longer and had higher visceral-somatic index (VSI) than diploids. Also, they had lighter liver weight (HSI) and showed lower transcript levels of brain gonadotropin-releasing hormone (GnRH), aromatase (cyp191b) and fushi tarazu-factor (ftz-f1), and plasma testosterone levels than diploids. Butachlor treatments had no effects, in either diploid or triploid fish, on VSI, HSI, weight or length changes, condition factor (CF), levels of plasma testosterone, 17-β estradiol (E2), cortisol, cholesterol, or mRNA levels of brain tryptophan hydroxylase (tph2), forkhead box L2 (foxl2), and 11 β-hydroxysteroid dehydrogenase type 2 (11β-hsd2). Expressions of cyp191b and ftz-f1 in triploids were upregulated by the two highest concentrations of BUC. In diploid fish, however, exposures to all BUC concentrations decreased GnRH transcription and the medium BUC concentration decreased ftz-f1 transcription. Substantial differences between ploidies in basal biomarker responses are consistent with the reported impaired reproductive axis in triploid C. gariepinus. Furthermore, the present study showed the low impact of short term exposure to BUC on reproductive axis in C. gariepinus.
Knight R., Marlatt V.L., Baker J.A., Lo B.P., deBruyn A.M.H., Elphick J.R., Martyniuk C.J. (2016). Dietary selenium disrupts hepatic triglyceride stores and transcriptional networks associated with growth and Notch signaling in juvenile rainbow trout. Aquatic Toxicology, 180 103-114.

Dietary Se has been shown to adversely affect adult fish by altering growth rates and metabolism. To determine the underlying mechanisms associated with these observations, we measured biochemical and transcriptomic endpoints in rainbow trout following dietary Se exposures. Treatment groups of juvenile rainbow trout were fed either control Lumbriculus variegatus worms or worms cultured on selenized yeast. Selenized yeast was cultured at four nominal doses of 5, 10, 20 or 40 mg/kg Se dry weight (measured dose in the worms of 7.1, 10.7, 19.5, and 31.8 mg/kg Se dw respectively) and fish were fed for 60 days. At 60 d, hepatic triglycerides, glycogen, total glutathione, 8-isoprostane and the transcriptome response in the liver (n = 8/group) were measured. Fish fed the nominal dose of 20 and 40 mg/kg Se dry weight had lower body weight and a shorter length, as well as lower triglyceride in the liver compared to controls. Evidence was lacking for an oxidative stress response and there was no change in total glutathione, 8-isoprostane levels, nor relative mRNA levels for glutathione peroxidase isoforms among groups. Microarray analysis revealed that molecular networks for long-chain fatty acid transport, lipid transport, and low density lipid oxidation were increased in the liver of fish fed 40 mg/kg, and this is hypothesized to be associated with the lower triglyceride levels in these fish. In addition, up-regulated gene networks in the liver of 40 mg/kg Se treated fish included epidermal growth factor receptor signaling, growth hormone receptor, and insulin growth factor receptor 1 signaling pathways. These molecular changes are hypothesized to be compensatory and related to impaired growth. A gene network related to Notch signaling, which is involved in cell–cell communication and gene transcription regulation, was also increased in the liver following dietary treatments with both 20 and 40 mg/kg Se. Transcriptomic data support the hypothesis that dietary Se increases the expression of networks for growth-related signaling cascades in addition to those related to fatty acid synthesis and metabolism. We propose that the disruption of metabolites related to triglyceride processing and storage, as well as gene networks for epidermal growth factor and Notch signaling in the liver, represent key molecular initiating events for adverse outcomes related to growth and Se toxicity in fish.
Knysh K.M., Giberson D.J., van den Heuvel M.R. (2016). The influence of agricultural land-use on plant and macroinvertebrate communities in springs. Limnology and Oceanography, 61(2) 518-530.

Many freshwater cool springs can be characterized by nearly constant temperatures and chemical composition. Agricultural activities may leach nutrients to the groundwater, add sediment and nutrients from overland flow, and change the cover of the riparian area surrounding springs, all factors that influence aquatic invertebrate and plant communities. Twenty limnocrene springs in Prince Edward Island, Canada (10 surrounded by and within 20 m of agricultural land, and 10 located in forested areas with<5% agriculture within 1 km) were studied to determine effects of agricultural activities on invertebrate and plant community structure. Chemical, flow, sediment, and cover variables were examined in all 20 springs, and invertebrates and macrophytes were evaluated in a subset of four agricultural and four forested springs. Although nutrients (particularly nitrate) were higher in agricultural springs than in forested ones, and plant communities differed between springs in the two land use types, light level (relating to the riparian canopy in the two land-use types) was a stronger predictor of aquatic plant community composition than nutrients. Plant diversity was highest in open agricultural sites. Overall invertebrate richness and abundance were higher in forested sites than agricultural sites, but invertebrate community composition differed between the two land-use types, and was primarily related to aquatic plant composition. Few taxa responded directly to elevated nutrients. The composition of the riparian area may be more important than direct inputs of nutrients and sedimentation when assessing agricultural impacts on springs.
Kohn J., Soto D.X., Iwanyshyn M., Olson B., Kalischuk A., Lorenz K., Hendry M.J. (2016). Groundwater nitrate and chloride trends in an agriculture-intensive area in southern Alberta, Canada. Water Quality Research Journal of Canada, 51(1) 47-59.

The potential effect of manure management from livestock production on groundwater quality is an issue of concern. Groundwater sampling from a regional transect in southern Alberta, Canada, was conducted to determine changes in groundwater quality with time. The study area has extensive irrigation and a high density of confined feeding operations. Nitrate-N (NO<inf>3</inf>−-N) and chloride (Cl−) concentration data from 23 groundwater-study wells were evaluated from 1994 to 2014. Twelve of these wells were water-table wells and 11 were piezometers. Of the 23 wells, 14 had significant temporal trends (increasing or decreasing) for NO<inf>3</inf>−-N and/or Cl− concentrations. On a regional basis, NO<inf>3</inf>−-N increased slightly with time while Cl− changed very little, suggesting that the effects of agricultural activities on regional groundwater quality have generally remained constant. However, concentration changes occurred on a smaller scale. Shallow groundwater in coarse-textured soils is at a relatively higher risk of contamination than groundwater in fine-textured soils, especially in locations where intensive agricultural activities occur.
Kurylyk B.L., Moore R.D., Macquarrie K.T.B. (2016). Scientific briefing: Quantifying streambed heat advection associated with groundwater-surface water interactions. Hydrological Processes, 30(6) 987-992.

Stream thermal regimes are controlled by the interactions of external and internal energy fluxes with the water in the channel. Solar radiation is typically the dominant driver of stream water temperature, but streambed heat fluxes can be important in forested headwater streams. Past studies have presented seemingly disparate formulae for quantifying streambed heat advection from upwelling groundwater. This note details the sources of the differences in these alternative formulations. The equations illustrate the difficulties of attempting to isolate the thermal influence of groundwater-surface water interactions and highlight future research opportunities.
Lavery M. (2016). Winner: Winter: The Forgotten Study Season. Fisheries, 41(1) 6-7.
Maheu A., Poff N.L., St-Hilaire A. (2016). A Classification of Stream Water Temperature Regimes in the Conterminous USA. River Research and Applications, 32(5) 896-906.

Temporal variability in water temperature plays an important role in aquatic ecosystems, yet the thermal regime of streams has mainly been described in terms of mean or extreme conditions. In this study, annual and diel variability in stream water temperature was described at 135 unregulated, gauged streams across the USA. Based on magnitude, amplitude and timing characteristics of daily water temperature records ranging from 5 to 33 years, we classified thermal regimes into six distinct types. This classification underlined the importance of including characteristics of variability (amplitude and timing) in addition to aspects of magnitude to discriminate thermal regimes at the continental scale. We used a classification tree to predict thermal regime membership of the six classes and found that the annual mean and range in the long-term air temperature average along with spring flows were important variables defining the thermal regime types at the continental scale. This research provides a framework for a comprehensive characterization of the thermal regimes of streams that could provide a basis for future assessment of changes in water temperature caused by anthropogenic activities such as dams, land use changes and climate change. Copyright © 2015 John Wiley & Sons, Ltd.
Maheu A., St-Hilaire A., Caissie D., El-Jabi N. (2016). Understanding the Thermal Regime of Rivers Influenced by Small and Medium Size Dams in Eastern Canada. River Research and Applications, 32(10) 2032-2044.

Although small and medium-size dams are prevalent in North America, few studies have described their year-round impacts on the thermal regime of rivers. The objective of this study was to quantify the impacts of two types of dams (run-of-river, storage with shallow reservoirs) on the thermal regime of rivers in eastern Canada. Thermal impacts of dams were assessed (i) for the open water period by evaluating their influence on the annual cycle in daily mean water temperature and residual variability and (ii) for the ice-covered winter period by evaluating their influence on water temperature duration curves. Overall, results showed that the run-of-river dam (with limited storage capacity) did not have a significant effect on the thermal regime of the regulated river. At the two rivers regulated by storage dams with shallow reservoirs (mean depth < 6 m), the annual cycle in daily mean water temperature was significantly modified which led to warmer water temperatures in summer and autumn. From August to October, the monthly mean water temperature at rivers regulated by storage dams was 1.4 to 3.9°C warmer than at their respective reference sites. During the open water period, the two storage dams also reduced water temperature variability at a daily timescale while increased variability was observed in regulated rivers during the winter. Storage dams also had a warming effect during the winter and the winter median water temperature ranged between 1.0 and 2.1°C downstream of the two storage dams whereas water temperature remained stable and close to 0°C in unregulated rivers. The biological implications of the altered thermal regimes at rivers regulated by storage dams are discussed, in particular for salmonids. Copyright © 2016 John Wiley & Sons, Ltd.
Maheu A., St-Hilaire A., Caissie D., El-Jabi N., Bourque G., Boisclair D. (2016). A regional analysis of the impact of dams on water temperature in medium-size rivers in eastern Canada. Canadian Journal of Fisheries and Aquatic Sciences, 73(12) 1885-1897.

Various studies have helped gain a better understanding of the thermal impacts of dams on a site-specific basis, but very few studies have compared the thermal impacts of varying types of dams within the same region. In this study, we conducted a regional-scale assessment of the impacts of dams on the thermal regime of 13 medium-size rivers in eastern Canada. The objectives of this study were to identify features of the thermal regime of rivers that are predominantly impacted by dams and to compare the impacts associated with different types of regulation (run-of-river, storage, peaking). The thermal regime of regulated and unregulated rivers was characterized using 15 metrics that described the magnitude, frequency, duration, timing, and rate of change of water temperature. Results indicate that storage and peaking dams impounding at least 10% of the median annual runoff generally (i) reduced the magnitude of water temperature variation at seasonal, daily, and subdaily timescales and (ii) increased the monthly mean water temperature in September. This regional assessment offers important insight regarding a generalized pattern of thermal alteration by dams, and this information could be used to guide biological monitoring efforts in regulated rivers.
Marlatt V.L., Sherrard R., Kennedy C.J., Elphick J.R., Martyniuk C.J. (2016). Application of molecular endpoints in early life stage salmonid environmental biomonitoring. Aquatic Toxicology, 173 178-191.

Molecular endpoints can enhance existing whole animal bioassays by more fully characterizing the biological impacts of aquatic pollutants. Laboratory and field studies were used to examine the utility of adopting molecular endpoints for a well-developed in situ early life stage (eyed embryo to onset of swim-up fry) salmonid bioassay to improve diagnostic assessments of water quality in the field. Coastal cutthroat trout (Oncorhynchus clarki clarki) were exposed in the laboratory to the model metal (zinc, 40 μg/L) and the polycyclic aromatic hydrocarbon (pyrene, 100 μg/L) in water to examine the resulting early life stage salmonid responses. In situ field exposures and bioassays were conducted in parallel to evaluate the water quality of three urban streams in British Columbia (two sites with anthropogenic inputs and one reference site). The endpoints measured in swim-up fry included survival, deformities, growth (weight and length), vitellogenin (vtg) and metallothionein (Mt) protein levels, and hepatic gene expression (e.g., metallothioneins [mta and mtb], endocrine biomarkers [vtg and estrogen receptors, esr] and xenobiotic-metabolizing enzymes [cytochrome P450 1A3, cyp1a3 and glutathione transferases, gstk]). No effects were observed in the zinc treatment, however exposure of swim-up fry to pyrene resulted in decreased survival, deformities and increased estrogen receptor alpha (er1) mRNA levels. In the field exposures, xenobiotic-metabolizing enzymes (cyp1a3, gstk) and zinc transporter (zntBigM103) mRNA were significantly increased in swim-up fry deployed at the sites with more anthropogenic inputs compared to the reference site. Cluster analysis revealed that gene expression profiles in individuals from the streams receiving anthropogenic inputs were more similar to each other than to the reference site. Collectively, the results obtained in this study suggest that molecular endpoints may be useful, and potentially more sensitive, indicators of site-specific contamination in real-world, complex exposure scenarios in addition to whole body morphometric and physiological measures.
Mathieu-Denoncourt J., Martyniuk C.J., Loughery J.R., Yargeau V., de Solla S.R., Langlois V.S. (2016). Lethal and sublethal effects of phthalate diesters in Silurana tropicalis larvae. Environmental Toxicology and Chemistry, 35(10) 2511-2522.

Phthalates are compounds used in polymers to increase their flexibility and are now ubiquitous in the environment as a result of widespread use. Because few studies have focused on the adverse effects of these chemicals in aquatic species, the present study aimed to determine the effects of phthalate diesters in amphibians. Western clawed frog (Silurana tropicalis) tadpoles were acutely exposed to water spiked with monomethyl phthalate (MMP; 1.3–1595.5 mg/L), dimethyl phthalate (DMP; 0.03–924.0 mg/L), or dicyclohexyl phthalate (DCHP; 0.3–99.3 mg/L). Because few studies have addressed the toxicity of these specific phthalates in most organisms, the present study used higher concentrations of these chemicals to determine their toxicity pathways in amphibians and at the same time investigate a suite of genes known to be altered by the well-studied phthalates. Both DMP and DCHP increased larval mortality (9.1–924.0 mg/L DMP and 4.1–99.3 mg/L DCHP), increased frequency of malformations in tadpoles (0.1–34.1 mg/L DMP and 4.1–19.0 mg/L DCHP), and up-regulated cellular stress-related messenger-RNA (mRNA) levels (4.1 mg/L DCHP). To characterize the molecular toxicity pathway of these phthalates in tadpoles, transcriptome analysis was conducted using a custom microarray. Parametric analysis of gene set enrichment revealed important changes in the expression of genes related to drug metabolism and transport, liver metabolism, xenobiotic clearance, and xenobiotic metabolism after DMP and DCHP treatments, although these responses were less pronounced with MMP (the metabolite of DMP). The present study is one of the few studies that demonstrated complementarity between gene expression analysis and organismal effects. Environ Toxicol Chem 2016;35:2511–2522. © 2016 SETAC.
Mendoza-Morales A.J., González-Sansón G., Aguilar-Betancourt C. (2016). Spatial and temporal mangrove litter production in Barra de Navidad lagoon, Jalisco, México. Revista De Biologia Tropical, 64(1) 259-273.

Barra de Navidad lagoon is a coastal wetland of international importance (Ramsar site) and it is included among the 81 Mexican mangrove priority sites. One of the most valued characteristics of this lagoon is the presence of mangrove forest in a good conservation state. The goal of our research was the measurement of mangrove litter production and environmental factors influencing its dynamics. The mangrove area was divided into seven zones and litterfall was monthly sampled from November 2011 to October 2012 using 0.25 m2 square collectors made with mosquito mesh (1 mm) and positioned at 1.3 m above the ground. Abiotic variables of the interstitial water were measured simultaneously at each zone in permanent plots using a multi-parameter probe, YSI-556-M. Total mean value of litterfall production, weighted by zone surface, was 19.12 ± 1.23 gPS/m2.mo (2.29 t/ha.year). This low productivity is a consequence of the region’s dry climate and low tide range. The species Avicennia germinans and Laguncularia racemosa produced more than 80 % of total litterfall, while Rhizophora mangle contributed only 16 % and Conocarpus erectus < 4 %. A significant correlation between litterfall production and abiotic variables was found (e.g. salinity and interstitial water depth). We concluded that there are significant spatial variations in soil abiotic variables which are correlated with differences in mangrove species composition, and produce, together with the life cycles stages of those species, significant variations in the quantity and composition of litterfall. Future research will be focused on quantifying spatial variations in forest structure and their relationship with litterfall production.
Namayandeh A., Culp J.M. (2016). Chironomidae larvae from the lower athabasca river, AB, Canada and its tributaries including macroscopic subfamily and tribe keys, indices for environmental tolerance and trait-based information for biomonitoring. Journal of Entomological and Acarological Research, 48(2) 201-232.

Since 2011 the Joint Oil Sands Monitoring (JOSM) program has been conducted in the lower Athabasca River by the Governments of Canada and Alberta to assess the freshwater health in areas associated with oil sands development. The majority of the benthic invertebrate assemblage of the Athabasca River and its tributaries are Chironomidae larvae. Assessments of such benthic assemblages are made difficult because the identification of Chironomidae larvae is costly and time consuming. To facilitate this identification process, we aimed to develop a simple taxonomic key for Chironomidae larvae of this region. This taxonomic reference and identification key makes use of the known taxonomic details on these Chironomidae species. Moreover, we provide details on their geographical distribution, ecology, habitats, environmental tolerance values for species, and trait-based morphological characters. Our main goal was to make this inforinformation readily available to both non-specialists and specialists so that biomonitoring programs can more readily utilize these organisms in biomonitoring.
Namayandeh A., Heard K.S., Luiker E.A., Culp J.M. (2016). Chironomidae (Insecta: Diptera) from the eastern Canadian arctic and subarctic with descriptions of new life stages, a possible new genus, and new geographical records. Journal of Entomological and Acarological Research, 48(2) 53-83.

Chironomidae larvae constituted the largest proportion of benthic invertebrates collected from 99 rivers stretching from northern Labrador (latitude 58°N) to northern parts of Ellesmere Island (82°N). We describe 92 species of Chironomidae (mainly larval forms) providing new descriptions, a revision for the adult female of Parametriocnemus boreoalpinus Gowin et Thienemann, a possible new genus (larval form only), and 9 larval forms that may represent a new species. In addition, new geographical distribution records are specified for 1 Nearctic species, 6 species in Canada, 10 for Labrador, and 17 for Nunavut. This work contributes to Environment Canadas International Polar Year output (2007-2009).
Noel L., Bärlocher F., Culp J.M., Seena S. (2016). Nutrient enrichment and flow regulation impair structure and function of a large river as revealed by aquatic hyphomycete species richness, biomass, and decomposition rates. Freshwater Science, 35(4) 1148-1163.

Diversity, sporulation rates, and biomass of aquatic hyphomycetes (Kingdom Fungi) on leaf litter were examined to assess the effects of nutrient enrichment and flow regulation on the ecological integrity of the Saint John River, New Brunswick, Canada. Leaf decomposition rate was used as an indicator of ecological function, whereas fungal abundance and diversity were chosen as structural indicators. Leaf-litter bags of yellow birch (Betula alleghaniensis) were deployed at 8 sites, periodically retrieved, and analyzed during 2 consecutive years in unregulated and regulated reaches. The interaction between nutrient enrichment and flow regulation regime significantly affected leaf decomposition rate and fungal sporulation during summer and autumn and fungal diversity during autumn. Flow regulation regime was the primary driver for fungal diversity during summer. In contrast, nutrient enrichment significantly affected fungal biomass. In general, this large 7th-order river responded to flow regulation and nutrient enrichment in the same manner as smaller rivers. Both factors increased decomposition rates, but only nutrient enrichment increased fungal biomass, diversity, and sporulation. Within the regulated reach, leaves in constantly covered litter bags had faster decomposition rates and more aquatic hyphomycete species, spore release, and biomass than in intermittently covered litter bags. Nutrient enrichment, flow regulation, and their interactions decreased ecosystem integrity by altering diversity and biomass of aquatic hyphomycetes and their function in the Saint John River.
Ornostay A., Marr J., Loughery J.R., Martyniuk C.J. (2016). Transcriptional networks associated with 5-alpha-dihydrotestosterone in the fathead minnow (Pimephales promelas) ovary. General and Comparative Endocrinology, 225 23-32.

Androgens play a significant role in regulating oogenesis in teleost fishes. The androgen dihydrotestosterone (DHT) is a potent non-aromatizable androgen involved in sexual differentiation in mammals; however, its actions are not well understood in teleost fish. To better characterize the physiological role of DHT in the fathead minnow (FHM) ovary on a temporal scale, in vitro assays for 17β-estradiol (E<inf>2</inf>) production were conducted in parallel with microarray analysis. Ovarian explants were incubated at different concentrations of DHT (10-6, 10-7, and 10-8M DHT) in three separate experiments conducted at 6, 9, and 12h. DHT treatment resulted in a rapid and consistent increase in E<inf>2</inf> production from the ovary at all three time points. Therefore, DHT may act to shift the balance of metabolites in the steroidogenic pathway within the ovary. Major biological themes affected by DHT in the ovary in one or more of the time points included those related to blood (e.g. vasodilation, blood vessel contraction, clotting), lipids (e.g. lipid storage, cholesterol metabolism, lipid degradation) and reproduction (e.g. hormone and steroid metabolism). Gene networks related to immune responses and calcium signaling were also affected by DHT, suggesting that this androgen may play a role in regulating these processes in the ovary. This study detected no change in mRNA levels of steroidogenic enzymes (cyp19a1, star, 11βhsd, 17βhsd, srd5a isoforms), suggesting that the observed increase in E<inf>2</inf> production is likely more dependent on the pre-existing gene or protein complement in the ovary rather than the de novo expression of transcripts. This study increases knowledge regarding the roles of DHT and androgens in general in the teleost ovary and identifies molecular signaling pathways that may be associated with increased E<inf>2</inf> production.
Ouellet-Proulx S., St-Hilaire A., Courtenay S.C., Haralampides K.A. (2016). Estimation of suspended sediment concentration in the Saint John River using rating curves and a machine learning approach. Hydrological Sciences Journal, 61(10) 1847-1860.

Sedimentation in navigable waterways and harbours is of concern for many water and port managers. One potential source of variability in sedimentation is the annual sediment load of the river that empties in the harbour. The main objective of this study was to use some of the regularly monitored hydro-meteorological variables to compare estimates of hourly suspended sediment concentration in the Saint John River using a sediment rating curve and a model tree (M5ʹ) with different combinations of predictors. Estimated suspended sediment concentrations were multiplied by measured flows to estimate suspended sediment loads. Best results were obtained using M5ʹ with four predictors, returning an R2 of 0.72 on calibration data and an R2 of 0.46 on validation data. Total load was underestimated by 1.41% for the calibration period and overestimated by 2.38% for the validation period. Overall, the model tree approach is suggested for its relative ease of implementation and constant performance. EDITOR M.C. Acreman; ASSOCIATE EDITOR B. Touaibia
Peters D.L., Caissie D., Monk W.A., Rood S.B., St-Hilaire A. (2016). An ecological perspective on floods in Canada. Canadian Water Resources Journal, 41(1-2) 288-306.

This review presents a summary of the influences of floods on river ecology, both instream and on the adjacent floodplain, mostly in a Canadian context. It emphasizes that ecological impacts and benefits can be highly dependent on flood-generation processes and their magnitude and timing. In Canada, floods can occur under open-water or ice-influenced river conditions. The ecological impacts of floods generated from ice jamming are particularly relevant in Canadian ecosystems due to the potentially higher water levels produced and suspended sediment concentrations that can be detrimental to instream aquatic habitat, but beneficial to floodplains. Large floods provide a major source of physical disturbance. Moderate floods with shorter return periods can be beneficial to aquatic habitats by providing woody debris that contributes to habitat complexity and diversity, by flushing fine sediments and by providing important food sources from terrestrial origins. Floods also influence water-quality variables such as sediment loads, metals and pH, which further influence river ecology. This review points out important links between floods and habitat connectivity and refugia, and the ability of aquatic resources to recover from flood disturbances. The floodplain vegetation also influences bank erosion and channel configuration, as well as many processes contributing to the river ecology, such as allochthonous inputs of carbon, preventing bank erosion, food-web dynamics and other effects. Many species of riparian trees are dependent on floods for reproduction, and floods can limit competitive encroachment of upland vegetation. Floods play a critical role in deltaic environments where high flows provide nutrient supplies and overflows maintain water balances within these environments. Two substantial factors that will likely influence future flood regimes in Canada are climate change and flow regulation. Future research should focus on enhancing our understanding of how floods affect river ecology, including under winter conditions, to better manage important natural resources.
Pippy B.A., Kidd K.A., Munkittrick K.R., Mercer A., Hunt H. (2016). Use of the Atlantic nut clam (Nucula proxima) and catworm (Nephtys incisa) in a sentinel species approach for monitoring the health of Bay of Fundy estuaries. Marine Pollution Bulletin, 106(1-2) 225-235.

Designing an effective environmental monitoring system for population responses requires knowledge of the biology of appropriate sentinel species and baseline information on the area's physical and chemical characteristics. This study collected information in Saint John Harbor, NB, Canada, for two abundant marine benthic invertebrates, the Atlantic nut clam (Nucula proxima) and the catworm (Nephtys incisa) to characterize their seasonal and spatial variability, determine the ideal sampling time and methods, and develop baseline data for future studies. We also evaluated whether contamination is impacting invertebrates by comparing sediment metal concentrations to responses of benthic infauna. Metals were generally below sediment quality guidelines except for nickel and arsenic. Clam densities were variable between sites but not seasons, whereas catworm densities were not significantly different between sites or seasons. Overall, these species show potential for environmental monitoring, although investigation at more contaminated sites is warranted to assess their sensitivity.
Porter T.M., Shokralla S., Baird D., Brian Golding G., Hajibabaei M. (2016). Ribosomal DNA and plastid markers used to sample fungal and plant communities from wetland soils reveals complementary biotas. Plos One, 11(1).

Though the use of metagenomic methods to sample below-ground fungal communities is common, the use of similar methods to sample plants from their underground structures is not. In this study we use high throughput sequencing of the ribulose-bisphosphate carboxylase large subunit (rbcL) plastid marker to study the plant community as well as the internal transcribed spacer and large subunit ribosomal DNA (rDNA) markers to investigate the fungal community from two wetland sites. Observed community richness and composition varied by marker. The two rDNA markers detected complementary sets of fungal taxa and total fungal composition clustered according to primer rather than by site. The composition of the most abundant plants, however, clustered according to sites as expected.We suggest that future studies consider using multiple genetic markers, ideally generated from different primer sets, to detect a more taxonomically diverse suite of taxa compared with what can be detected by any single marker alone. Conclusions drawn from the presence of even the most frequently observed taxa should be made with caution without corroborating lines of evidence.
Rommel R.E., Crump P.S., Packard J.M. (2016). Leaping from Awareness to Action: Impacts of an Amphibian Educator Workshop. Journal of Herpetology, 50(1) 12-16.

Where endangered species occur, recommendations call for conservation education programs that engage local educators; however, few studies have measured the effectiveness of implemented programs. We conducted a multipartner educator workshop for the endangered Houston Toad, Anaxyrus houstonensis, as one local example illustrating the broader issue of globally declining amphibians. We measured the effect of the workshop on participants' (n = 50) awareness/knowledge, values, beliefs, emotions, and intent to take action. We observed significant increases in awareness/knowledge and values regarding general amphibian declines and the focal species. The workshop significantly increased participants' belief that they had necessary resources to teach about the Houston Toad. Ninety-nine percent of participants agreed that they cared more about wild toads after meeting live ambassador toads. Postworkshop, we observed a 33% increase in use of amphibians or Houston Toads in participant learning settings. We recommend that educator workshops include biologist-educator teams, identify and address incentives and barriers to action, develop ecological knowledge, and incorporate experiential programming focused on native species and habitats.
Rudolph I., Chiang G., Galbán-Malagón C., Mendoza R., Martinez M., Gonzalez C., Becerra J., Servos M.R., Munkittrick K.R., Barra R. (2016). Persistent organic pollutants and porphyrins biomarkers in penguin faeces from Kopaitic Island and Antarctic Peninsula. Science of the Total Environment, 573 1390-1396.

Polychlorinated biphenyl (PCB) levels were determined in the faeces of three Antarctic Peninsula penguin species to assess viability as a non-invasive approach for sampling PCBs in Antarctic biota. These determinations were complemented with stable isotope and porphyrins assessments, and together this methodology determined the role of diet and metabolic disruption in penguins. Up to 60% of the collected faecal samples evidenced low molecular weight PCBs, of which, the more volatile compounds were predominant, in agreement with previous results. The highest PCB levels were reported in the gentoo penguin (Pygoscelis papua; 35.3 ng g− 1 wet weight average), followed by the chinstrap (Pygoscelis antarctica; 6.4 ng g− 1 wet weight average) and Adélie penguins (Pygoscelis adeliae; 12.9 ng g− 1 wet weight average). Stable isotope analyses (δ15N and δ13C) demonstrated that gentoo feeding and foraging habits differed from those of Adélie and chinstrap penguins. A strong positive correlation was found between PCB concentrations and δ15N, indicating the role of diet on the observed pollutant levels. Porphyrins metabolite levels were also directly correlated with PCB concentrations. These results suggest that PCB levels impair the health of Antarctic penguins.
Soto D.X., Benito J., Gacia E., García-Berthou E., Catalan J. (2016). Trace metal accumulation as complementary dietary information for the isotopic analysis of complex food webs. Methods in Ecology and Evolution, 7(8) 910-918.

Food web structure is a fundamental feature of ecosystems. Stable isotopes (δ15N and δ13C) are used to estimate the relative contribution of food sources to consumer's diets (e.g. mixing models). In complex food webs, the use of δ15N and δ13C measurements cannot always solve trophic interactions and distinguish among aquatic organisms with different feeding habits if little intra- and interspecific isotopic differentiation occurs. We have developed a method to characterize trophic relationships using Bayesian stable isotope mixing models in combination with trace metal data as prior information. Trace metal information is useful because of the high correspondence between trace metal profiles in consumers and their food sources, as we show here in an example of concentrations of fish and their expected dietary items. Trace metal concentration allows a more accurate estimation of relative contributions of food sources to consumer species compared to estimates based only on stable isotope values. We show the improvement of the procedure using four freshwater fish species with well-known feeding habits. The method provides a better estimation of the inter- and intraspecific dietary variability and correspondence with the feeding habits of these species. The approach described shows a considerable potential as a tool to assess trophic links in situations in which stable isotope methods are not conclusive. The method can be applied using other compounds that bioaccumulate in consumers (e.g. persistent organic pollutants).
St-Hilaire A., Duchesne S., Rousseau A.N. (2016). Floods and water quality in Canada: A review of the interactions with urbanization, agriculture and forestry. Canadian Water Resources Journal, 41(1-2) 273-287.

Water quality remains a major issue in Canada. This paper reviews recent research on the impacts of urbanization, agriculture and forestry on water quality in Canada. Specific water quality issues such as mining, sewage treatment and waste treatment are not included in this paper. For each land use, a brief summary of the dominant processes linking runoff to water quality is provided and recent findings are summarized. With respect to urbanized watersheds, the relatively large proportion of impervious areas, lower vegetation cover and the presence of high-density drainage systems alter surface water routing and timing of peak flows. High concentrations of heavy metals are considered to be the most important water quality problem in urban runoff, but nutrients, pathogens, concentration of pharmaceuticals and water temperature also often contribute. In watersheds dominated by agricultural activities, overland flow is an important vector of pollutants, but subsurface flow such as macropore and tile-drain flows also play a role in the alteration of water quality during or after high runoff events. Nutrients, pesticides, pathogens and sediments remain important topics of research in agricultural watersheds, and the modelling effort has significantly increased in the last few decades. Beneficial management practices (BMPs) are being tested and applied at a local scale, mostly on experimental watersheds. Forestry-related activities also affect water quality. In forested watersheds, studies have been ongoing for many decades, but have decreased in intensity in the last 15 years. Sediment delivery and water temperature can be strongly affected in watersheds with significant clear-cut logging and riparian buffer strips and sylviculture remain the main mitigation BMPs. There is a need for an increase in the monitoring effort for most water quality variables in Canada. The authors recommend that flow-dependent monitoring frameworks should be further developed and implemented in the future.
Sánchez Garayzar A.B., Bahamonde P.A., Martyniuk C.J., Betancourt M., Munkittrick K.R. (2016). Hepatic gene expression profiling in zebrafish (Danio rerio) exposed to the fungicide chlorothalonil. Comparative Biochemistry and Physiology Part D Genomics and Proteomics, 19 102-111.

Chlorothalonil (tetrachloroisophtalonitrile) is a fungicide that is widely used on agricultural crops around the world and as such, it is a ubiquitous aquatic contaminant. Despite high usage, the effects of this fungicide on non-target aquatic organisms have not been fully investigated. The aim of the present study was to (1) determine the effects of chlorothalonil toxicity on adult male zebrafish (Danio rerio) and (2) characterize the effects of chlorothalonil on gene expression patterns in the liver using two different concentrations of the fungicide, 0.007 mg/L (environmentally-relevant) and 0.035 mg/L (sublethal). These concentrations were selected from range-finding experiments that showed that zebrafish survival was significantly different from control animals at concentrations higher than 0.035 mg/L but not below. Male zebrafish in both treatments of chlorothalonil showed a decrease in liversomatic index. A commercial D. rerio microarray (4 × 44 K) was used to determine gene expression profiles in male zebrafish liver following a 96 h toxicological assay. Microarray analysis revealed that males exposed to both 0.007 mg/L or 0.035 mg/L of chlorothalonil showed increased transcriptional sub-networks related to cell division and DNA damage and decreased expression of gene networks associated with reproduction, immunity, and xenobiotic clearance. This study improves knowledge regarding whole animal exposures to chlorothalonil and identifies molecular signaling cascades that are sensitive to this fungicide in the fish liver.
Vandenberg L.N., Ågerstrand M., Beronius A., Beausoleil C., Bergman Å., Bero L.A., Bornehag C.G., Boyer C.S., Cooper G.S., Cotgreave I., Gee D., Grandjean P., Guyton K.Z., Hass U., Heindel J.J., Jobling S., Kidd K.A., Kortenkamp A., Macleod M.R., Martin O.V., Norinder U., Scheringer M., Thayer K.A., Toppari J., Whaley P., Woodruff T.J., Rudén C. (2016). A proposed framework for the systematic review and integrated assessment (SYRINA) of endocrine disrupting chemicals. Environmental Health A Global Access Science Source, 15(1).

Background: The issue of endocrine disrupting chemicals (EDCs) is receiving wide attention from both the scientific and regulatory communities. Recent analyses of the EDC literature have been criticized for failing to use transparent and objective approaches to draw conclusions about the strength of evidence linking EDC exposures to adverse health or environmental outcomes. Systematic review methodologies are ideal for addressing this issue as they provide transparent and consistent approaches to study selection and evaluation. Objective methods are needed for integrating the multiple streams of evidence (epidemiology, wildlife, laboratory animal, in vitro, and in silico data) that are relevant in assessing EDCs. Methods: We have developed a framework for the systematic review and integrated assessment (SYRINA) of EDC studies. The framework was designed for use with the International Program on Chemical Safety (IPCS) and World Health Organization (WHO) definition of an EDC, which requires appraisal of evidence regarding 1) association between exposure and an adverse effect, 2) association between exposure and endocrine disrupting activity, and 3) a plausible link between the adverse effect and the endocrine disrupting activity. Results: Building from existing methodologies for evaluating and synthesizing evidence, the SYRINA framework includes seven steps: 1) Formulate the problem; 2) Develop the review protocol; 3) Identify relevant evidence; 4) Evaluate evidence from individual studies; 5) Summarize and evaluate each stream of evidence; 6) Integrate evidence across all streams; 7) Draw conclusions, make recommendations, and evaluate uncertainties. The proposed method is tailored to the IPCS/WHO definition of an EDC but offers flexibility for use in the context of other definitions of EDCs. Conclusions: When using the SYRINA framework, the overall objective is to provide the evidence base needed to support decision making, including any action to avoid/minimise potential adverse effects of exposures. This framework allows for the evaluation and synthesis of evidence from multiple evidence streams. Finally, a decision regarding regulatory action is not only dependent on the strength of evidence, but also the consequences of action/inaction, e.g. limited or weak evidence may be sufficient to justify action if consequences are serious or irreversible.
Van Den Brink P.J., Choung C.B., Landis W., Mayer-Pinto M., Pettigrove V., Scanes P., Smith R., Stauber J. (2016). New approaches to the ecological risk assessment of multiple stressors. Marine and Freshwater Research, 67(4) 429-439.

So as to assess how emerging science and new tools can be applied to study multiple stressors at a large (ecosystem) scale and to facilitate greater integration of approaches among different scientific disciplines, a workshop was organised on 10-12 September 2014 at the Sydney Institute of Marine Sciences, Sydney, Australia. The present paper discusses the limitations of the current risk-assessment approaches and how multiple stressors at large scales can be better evaluated in ecological risk assessments to inform the development of more efficient and preventive management policies based on adaptive management in the future. A future risk-assessment paradigm that overcomes these limitations is presented. This paradigm includes cultural and ecological protection goals, the development of ecological scenarios, the establishment of the relevant interactions among species, potential sources of stressors, their interactions and the development of cause-effect models. It is envisaged that this will be achievable through a greater integration of approaches among different scientific disciplines and through the application of new and emerging tools such as 'big data', ecological modelling and the incorporation of ecosystem service endpoints.
Walters D.M., Jardine T.D., Cade B.S., Kidd K.A., Muir D.C.G., Leipzig-Scott P. (2016). Trophic Magnification of Organic Chemicals: A Global Synthesis. Environmental Science and Technology, 50(9) 4650-4658.

Production of organic chemicals (OCs) is increasing exponentially, and some OCs biomagnify through food webs to potentially toxic levels. Biomagnification under field conditions is best described by trophic magnification factors (TMFs; per trophic level change in log-concentration of a chemical) which have been measured for more than two decades. Syntheses of TMF behavior relative to chemical traits and ecosystem properties are lacking. We analyzed >1500 TMFs to identify OCs predisposed to biomagnify and to assess ecosystem vulnerability. The highest TMFs were for OCs that are slowly metabolized by animals (metabolic rate k<inf>M</inf> < 0.01 day-1) and are moderately hydrophobic (log K<inf>OW</inf> 6-8). TMFs were more variable in marine than freshwaters, unrelated to latitude, and highest in food webs containing endotherms. We modeled the probability that any OC would biomagnify as a combined function of K<inf>OW</inf> and k<inf>M</inf>. Probability is greatest (∼100%) for slowly metabolized compounds, regardless of K<inf>OW</inf>, and lowest for chemicals with rapid transformation rates (k<inf>M</inf> > 0.2 day-1). This probabilistic model provides a new global tool for screening existing and new OCs for their biomagnification potential.
Wood R.K., Crowley E., Martyniuk C.J. (2016). Developmental profiles and expression of the DNA methyltransferase genes in the fathead minnow (Pimephales promelas) following exposure to di-2-ethylhexyl phthalate. Fish Physiology and Biochemistry, 42(1) 7-18.

DNA methylation is an epigenetic regulator of gene expression, and this process has been shown to be disrupted by environmental contaminants. Di-2-(ethylhexyl) phthalate (DEHP) and related phthalate esters have been shown to affect development in early life stages of fish and can alter genomic methylation patterns in vertebrates. The objectives of this study were the following: (1) Describe the expression patterns of the DNA methyltransferase (dnmt) genes during early fathead minnow (FHM) development. These genes are critical for methylation and imprinting during development. (2) Determine the effects of DEHP on the development of FHM larvae [1 and 14 days post-hatch (dph)]. (3) Determine the effect of DEHP on dnmt expression and global methylation status in larval FHM. FHMs were first collected over a developmental time course [1, 3, 5, 6, and 14 days post-fertilization (dpf)] to investigate the expression patterns of five dnmt isoforms. The expression of dnmt1 and dnmt7 was relatively high in embryos at 1 dpf but was variable in expression, and these transcripts were later expressed at a lower level (>3 dpf); dnmt3 was significantly higher in embryos at 1 dpf compared to those at 3 dpf. Dnmt6 showed more of a constitutive pattern of expression during the first 2 weeks of development, and the mRNA levels of dnmt8 were higher in embryos at 5 and 6 dpf compared to those at 1 and 3 dpf, corresponding to the hatching period of the embryos. A waterborne exposure to three concentrations of DEHP (1, 10 and 100 µg/L) was conducted on 1-day FHM embryos for 24 h and on larval fish for 2 weeks, ending at 14 dpf. DEHP did not negatively affect survival, hatch rate, or the expression of dnmt isoforms in FHMs. There were no differences in global cytosine methylation following DEHP treatments in 14 dpf larvae, suggesting that environmentally relevant levels of DEHP may not affect global methylation at this stage of FHM development. However, additional targeted methylome studies are required to determine whether specific gene promoters are differently methylated following exposure to DEHP. This study offers new insight into the roles of the dnmt enzymes during FHM development.
Wrona F.J., Johansson M., Culp J.M., Jenkins A., Mård J., Myers-Smith I.H., Prowse T.D., Vincent W.F., Wookey P.A. (2016). Transitions in Arctic ecosystems: Ecological implications of a changing hydrological regime. Journal of Geophysical Research Biogeosciences, 121(3) 650-674.

Numerous international scientific assessments and related articles have, during the last decade, described the observed and potential impacts of climate change as well as other related environmental stressors on Arctic ecosystems. There is increasing recognition that observed and projected changes in freshwater sources, fluxes, and storage will have profound implications for the physical, biogeochemical, biological, and ecological processes and properties of Arctic terrestrial and freshwater ecosystems. However, a significant level of uncertainty remains in relation to forecasting the impacts of an intensified hydrological regime and related cryospheric change on ecosystem structure and function. As the terrestrial and freshwater ecology component of the Arctic Freshwater Synthesis, we review these uncertainties and recommend enhanced coordinated circumpolar research and monitoring efforts to improve quantification and prediction of how an altered hydrological regime influences local, regional, and circumpolar-level responses in terrestrial and freshwater systems. Specifically, we evaluate (i) changes in ecosystem productivity; (ii) alterations in ecosystem-level biogeochemical cycling and chemical transport; (iii) altered landscapes, successional trajectories, and creation of new habitats; (iv) altered seasonality and phenological mismatches; and (v) gains or losses of species and associated trophic interactions. We emphasize the need for developing a process-based understanding of interecosystem interactions, along with improved predictive models. We recommend enhanced use of the catchment scale as an integrated unit of study, thereby more explicitly considering the physical, chemical, and ecological processes and fluxes across a full freshwater continuum in a geographic region and spatial range of hydroecological units (e.g., stream-pond-lake-river-near shore marine environments).
Arens C.J., Hogan N.S., Kavanagh R.J., Mercer A.G., Kraak G.J.V.D., van den Heuvel M.R. (2015). Sublethal effects of aged oil sands-affected water on white sucker (Catostomus commersonii). Environmental Toxicology and Chemistry, 34(3) 589-599.

To investigate impacts of proposed oil sands aquatic reclamation techniques on benthic fish, white sucker (Catostomus commersonii Lacépède, 1803) were stocked in 2 experimental ponds-Demonstration Pond, containing aged fine tailings capped with fresh water, consistent with proposed end-pit lake designs, and South Bison Pond, containing aged unextracted oil sands material-to examine the effects of unmodified hydrocarbons. White sucker were stocked from a nearby reservoir at both sites in May 2010 and sampled 4 mo later to measure indicators of energy storage and utilization. Comparisons were then made with the source population and 2 reference lakes in the region. After exposure to aged tailings, white sucker had smaller testes and ovaries and reduced growth compared with the source population. Fish introduced to aged unextracted oil sands material showed an increase in growth over the same period. Limited available energy, endocrine disruption, and chronic stress likely contributed to the effects observed, corresponding to elevated concentrations of naphthenic acids, aromatic compounds in bile, and increased CYP1A activity. Because of the chemical and biological complexity of these systems, direct cause-effect relationships could not be identified; however, effects were associated with naphthenic acids, polycyclic aromatic hydrocarbons, ammonia, and high pH. Impacts on growth have not been previously observed in pelagic fishes examined in these systems, and may be related to differences in sediment interaction. Environ Toxicol Chem 2015;34:589-599.
Bahamonde P.A., Fuzzen M.L., Bennett C.J., Tetreault G.R., McMaster M.E., Servos M.R., Martyniuk C.J., Munkittrick K.R. (2015). Whole organism responses and intersex severity in rainbow darter (Etheostoma caeruleum) following exposures to municipal wastewater in the Grand River basin, ON, Canada. Part A. Aquatic Toxicology, 159 290-301.

Municipal wastewater effluents (MWWEs) contain anthropogenic substances that can exhibit endocrine-disrupting activity. These complex mixtures have been observed to exert adverse effects on fish. Rainbow darter (Etheostoma caeruleum, RBD) is a small benthic fish that is widespread throughout the Grand River, Ontario, Canada, and has been previously shown to be adversely affected by MWWE exposure in this watershed. The objectives of this study were to quantify biological responses in this sentinel species and intersex severity in male fish, in relation to the area of urbanization. It focused on RBD populations adjacent to wastewater outfalls in the Grand River watershed. In May 2011, nine sites across the urban gradient were selected to evaluate the impact of MWWEs. Endpoints for energy storage (i.e. condition factor, k; liversomatic index, LSI) as well as reproductive endpoints (i.e. gonadosomatic index, GSI; gonad development, hormone production), and intersex were assessed in the fish. Rainbow darter showed a high incidence of intersex downstream of the wastewater outfalls, especially below the largest treatment plant outfall at Kitchener (~85%). We applied an intersex index (score from 0 to 7) that considers the number of eggs within the testis and the stage of maturation of the egg. RBD exposed downstream of the largest wastewater outfall at Kitchener had a score of 3.81 ± 0.37 compared to upstream to the urban areas where there were no intersex males found other than a single individual with a score 1 (average intersex score of site 0.06 ± 0.06). In addition, several fish associated with the Kitchener outfall had macroscopic vitellogenic eggs in the testes (intersex scores 5 and 6). The sub-population of fish located at the wastewater outfall also showed a tendency towards skewed sex ratios (greater proportion of females to male fish) compared to the population at the reference sites. Male fish inhabiting the urbanized area of the Grand River also showed reduced levels of testosterone (T) and 11-ketotestosterone (11KT). Intersex males had the lower levels of 11KT relative to the upstream reference fish but could not be distinguished from normal males collected at the exposed sites. Despite the high levels of intersex at these sites, no relationships were evident among intersex severity and other measured endpoints such as GSI, LSI or in vitro steroid production. The effects observed appear to be associated with urbanization and exposure to treated MWWEs in the watershed. Although intersex incidence and severity was a very good indicator of wastewater exposure, intersex could not be directly linked to other effects in this wild population. The effects of MWWEs on transcriptional changes in adult RBD exposed to the effluents are reported in the corresponding report (Part B).
Bahamonde P.A., McMaster M.E., Servos M.R., Martyniuk C.J., Munkittrick K.R. (2015). Molecular pathways associated with the intersex condition in rainbow darter (Etheostoma caeruleum) following exposures to municipal wastewater in the Grand River basin, ON, Canada. Part B. Aquatic Toxicology, 159 302-316.

Rainbow darter (Etheostoma caeruleum; RBD) is a small benthic fish found in North America. This species is sensitive to sewage effluent, and intersex is found in up to 80% of males in near-field areas in the Grand River, Ontario, Canada. To learn more about the molecular signaling cascades associated with intersex, a developed customized oligonucleotide microarray (4. ×. 180. K) using next generation sequencing was developed to characterize the transcriptome in the gonad of male and female RBD. Gene expression profiling was performed in males and females from both a reference site and a polluted site. Males with and without intersex condition from the areas closest to effluent outfalls were compared to males and females from a reference site. Microarray analysis revealed that there was increased mRNA abundance for genes associated with oogenesis in intersex males (i.e. the presence of eggs within the testis), and a decrease in mRNA abundance for genes associated with spermatid development. In females exposed to effluent, cell processes related with hatching and ovulation were down-regulated, and genes involved in immune responses were increased in abundance. In the non-intersex males exposed to effluent, cell processes such as sperm cell adhesion were decreased at the transcript level relative to males from the reference site. Microarray analysis revealed that heat shock proteins (HSP) were significantly increased in non-intersex males exposed to effluent; however, HSPs were not differentially expressed in intersex males exposed to the effluent. Genes involved in sex differentiation (sox9, foxl2 and dmrt1) and reproduction (esr1, esrb, ar, vtg, cyp19a1 and cyp11a) were measured in males, females, and intersex individuals. Consistent with the intersex condition, many transcripts showed an intermediate expression level in intersex males when compared to phenotypic males and females. This study improves our knowledge regarding the molecular pathways that underlie the intersex condition and develops a suite of qPCR bioassays in RBD that are able to discriminate pollutant-exposed males without intersex from those males with intersex. Part A of this study reports on the effects of municipal wastewater effluents (MWWEs) on RBD in the Grand River and demonstrates that there are disruptions in higher level endpoints that include altered steroid levels. Here we develop a new tool for assessing and monitoring the intersex condition in RBD in polluted natural environments and begin to characterize gene networks that are associated with the condition.
Barrett T.J., Brasfield S.M., Carroll L.C., Doyle M.A., van den Heuvel M.R., Munkittrick K.R. (2015). Reproductive strategies and seasonal changes in the somatic indices of seven small-bodied fishes in Atlantic Canada in relation to study design for environmental effects monitoring. Environmental Monitoring and Assessment, 187(5).

Small-bodied fishes are more commonly being used in environmental effects monitoring (EEM) studies. There is a lack of understanding of the biological characteristics of many small-bodied species, which hinders study designs for monitoring studies. For example, 72 % of fish population surveys in Canada’s EEM program for pulp and paper mills that used small-bodied fishes were conducted outside of the reproductive period of the species. This resulted in an inadequate assessment of the EEM program’s primary effect endpoint (reproduction) for these studies. The present study examined seasonal changes in liver size, gonad size, and condition in seven freshwater and estuarine small-bodied fishes in Atlantic Canada. These data were used to examine differences in reproductive strategies and patterns of energy storage among species. Female gonadal recrudescence in all seven species began primarily in the 2-month period in the spring before spawning. Male gonadal development was concurrent with females in five species; however, gonadal recrudescence began in the fall in male three-spined stickleback (Gasterosteus aculeatus) and slimy sculpin (Cottus cognatus). The spawning period for each species was estimated from the decline in relative ovary size after its seasonal maximum value in spring. The duration of the spawning period reflected the reproductive strategy (single vs multiple spawning) of the species. Optimal sampling periods to assess reproductive impacts in each species were determined based on seasonal changes in ovary size and were identified to be during the prespawning period when gonads are developing and variability in relative gonad size is at a minimum.
Blanchfield P.J., Kidd K.A., Docker M.F., Palace V.P., Park B.J., Postma L.D. (2015). Recovery of a wild fish population from whole-lake additions of a synthetic estrogen. Environmental Science and Technology, 49(5) 3136-3144.

Despite widespread recognition that municipal wastewaters contain natural and synthetic estrogens, which interfere with development and reproduction of fishes in freshwaters worldwide, there are limited data on the extent to which natural populations of fish can recover from exposure to these compounds. We conducted whole-lake additions of an active component of the birth control pill (17α-ethynylestradiol; EE2) that resulted in the collapse of the fathead minnow (Pimephales promelas) population. Here we quantify physiological, population, and genetic characteristics of this population over the 7 years after EE2 additions stopped to determine if complete recovery was possible. By 3 years post-treatment, whole-body vitellogenin concentrations in male fathead minnow had returned to baseline, and testicular abnormalities were absent. In the spring of the fourth year, adult size-frequency distribution and abundance had returned to pretreatment levels. Microsatellite analyses clearly showed that postrecovery fish were descendants of the original EE2-treated population. Results from this whole-lake experiment demonstrate that fish can recover from EE2 exposure at the biochemical through population levels, although the timelines to do so are long for multigenerational exposures. These results suggest that wastewater treatment facilities that reduce discharges of estrogens and their mimics can improve the health of resident fish populations in their receiving environments.
Brasfield S.M., Mark Hewitt L., Chow L., Batchelor S., Rees H., Xing Z., Munkittrick K.R. (2015). Assessing the contribution of multiple stressors affecting small-bodied fish populations through a gradient of agricultural inputs in northwestern New Brunswick, Canada. Water Quality Research Journal of Canada, 50(2) 182-197.

Non-point source discharges, such as agricultural runoff, are often complex mixtures of chemical and non-chemical stressors. The complexity of runoff is compounded by its sporadic releases and few studies have attempted to assess the impacts of runoff on aquatic biota. In this study, an effects based approach was used to examine survival and reproduction of slimy sculpin (Cottus cognatus) in the intensive potato-farming areas of northwestern New Brunswick, Canada. Using non-lethal methods, fish were collected during the ice-free months through a gradient of agricultural intensity. These data were correlated with waterborne levels of pesticides, water temperatures and precipitation data. Results indicate that both adult and young-of-the-year (YOY) fish are longer and heavier in the downstream sites draining areas of higher agricultural intensity. Precipitation has a significant negative relationship with %YOY in the agricultural areas but not in the upstream forested area, indicating that contaminants are present in runoff caused by intensive rainfall events. Our results indicate that YOY sculpin may be at higher risk in the agricultural areas in years of heavier summer rains where peaks in pesticide levels occur. This study expands the existing knowledge base and development of non-lethal methods to define cause–effect relationships.
Braune B., Chételat J., Amyot M., Brown T., Clayden M., Evans M., Fisk A., Gaden A., Girard C., Hare A., Kirk J., Lehnherr I., Letcher R., Loseto L., Macdonald R., Mann E., McMeans B., Muir D., O'Driscoll N., Poulain A., Reimer K., Stern G. (2015). Mercury in the marine environment of the Canadian Arctic: Review of recent findings. Science of the Total Environment, 509-510 67-90.

This review summarizes data and information which have been generated on mercury (Hg) in the marine environment of the Canadian Arctic since the previous Canadian Arctic Contaminants Assessment Report (CACAR) was released in 2003. Much new information has been collected on Hg concentrations in marine water, snow and ice in the Canadian Arctic. The first measurements of methylation rates in Arctic seawater indicate that the water column is an important site for Hg methylation. Arctic marine waters were also found to be a substantial source of gaseous Hg to the atmosphere during the ice-free season. High Hg concentrations have been found in marine snow as a result of deposition following atmospheric mercury depletion events, although much of this Hg is photoreduced and re-emitted back to the atmosphere. The most extensive sampling of marine sediments in the Canadian Arctic was carried out in Hudson Bay where sediment total Hg (THg) concentrations were low compared with other marine regions in the circumpolar Arctic. Mass balance models have been developed to provide quantitative estimates of THg fluxes into and out of the Arctic Ocean and Hudson Bay.Several recent studies on Hg biomagnification have improved our understanding of trophic transfer of Hg through marine food webs. Over the past several decades, Hg concentrations have increased in some marine biota, while other populations showed no temporal change. Marine biota also exhibited considerable geographic variation in Hg concentrations with ringed seals, beluga and polar bears from the Beaufort Sea region having higher Hg concentrations compared with other parts of the Canadian Arctic. The drivers of these variable patterns of Hg bioaccumulation, both regionally and temporally, within the Canadian Arctic remain unclear. Further research is needed to identify the underlying processes including the interplay between biogeochemical and food web processes and climate change.
Buss D.F., Carlisle D.M., Chon T.S., Culp J., Harding J.S., Keizer-Vlek H.E., Robinson W.A., Strachan S., Thirion C., Hughes R.M. (2015). Stream biomonitoring using macroinvertebrates around the globe: a comparison of large-scale programs. Environmental Monitoring and Assessment, 187(1).

Water quality agencies and scientists are increasingly adopting standardized sampling methodologies because of the challenges associated with interpreting data derived from dissimilar protocols. Here, we compare 13 protocols for monitoring streams from different regions and countries around the globe. Despite the spatially diverse range of countries assessed, many aspects of bioassessment structure and protocols were similar, thereby providing evidence of key characteristics that might be incorporated in a global sampling methodology. Similarities were found regarding sampler type, mesh size, sampling period, subsampling methods, and taxonomic resolution. Consistent field and laboratory methods are essential for merging data sets collected by multiple institutions to enable large-scale comparisons. We discuss the similarities and differences among protocols and present current trends and future recommendations for monitoring programs, especially for regions where large-scale protocols do not yet exist. We summarize the current state in one of these regions, Latin America, and comment on the possible development path for these techniques in this region. We conclude that several aspects of stream biomonitoring need additional performance evaluation (accuracy, precision, discriminatory power, relative costs), particularly when comparing targeted habitat (only the commonest habitat type) versus site-wide sampling (multiple habitat types), appropriate levels of sampling and processing effort, and standardized indicators to resolve dissimilarities among biomonitoring methods. Global issues such as climate change are creating an environment where there is an increasing need to have universally consistent data collection, processing and storage to enable large-scale trend analysis. Biomonitoring programs following standardized methods could aid international data sharing and interpretation.
Carrer G.E., Rousseau A.N., St-Hilaire A., Jutras S. (2015). Mosaic surface storages of a small boreal catchment. Hydrological Processes, 29(6) 845-858.

Recent studies have suggested that the hydrologic connectivity of northern headwater catchments is likely controlled by antecedent moisture conditions and land cover patterns. A water storage model (EWS), based on water levels (WLs), specific yield (Sy) and surface elevation (SE) changes, was compared with a basic water budget of a small, boreal, patterned fen (13ha) during the ice-free period. Results showed that the EWS model reproduced well storage variations derived from the water budget. These results suggest that storage variations can be properly represented by the fluctuations of WLs when we consider the heterogeneous soil properties. However, storage deviations occurred at the daily scale and could be explained by a lack of information on water retention in unsaturated layers, canopy interceptions and preferential flows. Despite the significant impact of SE changes on the different peatland cover storage budgets (strings and lawns), using Sy mean values had a low impact on storage estimations. This can be explained by the large proportion of pools and high WLs throughout the fen. At the fen scale, high storage in the pools seemed to reduce the Sy difference between strings and lawns. The results of this study provide new insights about the complex hydrological behaviour of northern catchments and allow for conceiving new hydrological modelling perspectives.
Chiang G., Barra R., Díaz-Jaramillo M., Rivas M., Bahamonde P., Munkittrick K.R. (2015). Estrogenicity and intersex in juvenile rainbow trout (Oncorhynchus mykiss) exposed to Pine/Eucalyptus pulp and paper production effluent in Chile. Aquatic Toxicology, 164 126-134.

Pulp and paper mill effluents (PPMEs) have been shown to increase gonad size, cause early maturation, and disrupt hormone functions in native and non-native Chilean fish. In this study, we assessed reproductive (plasma vitellogenin; VTG, gonad development) and metabolic (ethoxyresorufin-. O-deethylase activity; EROD) end points, relative liver size (LSI) and condition factor (K) of juvenile female and male rainbow trout exposed to effluents. Unlike previous studies, which have focus either on the specific effects of effluent on fish in laboratory exposures or biotic population statuses downstream of discharge sites, we simultaneously assessed the impacts of PPMES on trout using two approaches: (1) laboratory exposures of tertiary treated PPME produced from processing Eucalyptus globulus or Pinus radiata; and (2) in situ bioassay downstream of the combined discharge of the same pulp mill. Despite an increase in the average gonadosomatic index (GSI) in exposed fish, no statistical differences in gonad size between exposed and unexposed individuals was detected. However, both female and male fish exposed to effluents showed significantly higher concentrations of plasma VTG, so more in fish exposed to Eucalyptus-based effluent when compared to Pinus PPME. In addition, male fish showed intersex characteristics in all exposure assays (Eucaliptus and Pinus) and, despite the low concentration of effluent in the river (<1% [v/v]), similar responses were observed in the caged fish. Finally, EROD activity was induced in both in situ exposures and laboratory assays at the higher PPME concentration (60-85% PPME). This study confirms estrogenic effects in Chilean fish exposed to PPME and the necessity for biological effects monitoring in addition to the assessment of physical-chemical endpoints as required in current government regulations.
Clayden M.G., Arsenault L.M., Kidd K.A., O'Driscoll N.J., Mallory M.L. (2015). Mercury bioaccumulation and biomagnification in a small Arctic polynya ecosystem. Science of the Total Environment, 509-510 206-215.

Recurring polynyas are important areas of biological productivity and feeding grounds for seabirds and mammals in the Arctic marine environment. In this study, we examined food web structure (using carbon and nitrogen isotopes, δ13C and δ15N) and mercury (Hg) bioaccumulation and biomagnification in a small recurring polynya ecosystem near Nasaruvaalik Island (Nunavut, Canada). Methyl Hg (MeHg) concentrations increased by more than 50-fold from copepods (Calanus hyperboreus) to Arctic terns (Sterna paradisaea), the abundant predators at this site. The biomagnification of MeHg through members of the food web - using the slope of log MeHg versus δ15N - was 0.157 from copepods (C. hyperboreus) to fish. This slope was higher (0.267) when seabird chicks were included in the analyses. Collectively, our results indicate that MeHg biomagnification is occurring in this small polynya and that its trophic transfer is at the lower end of the range of estimates from other Arctic marine ecosystems. In addition, we measured Hg concentrations in some poorly studied members of Arctic marine food webs [e.g. Arctic alligatorfish (Ulcina olrikii) and jellyfish, Medusozoa], and found that MeHg concentrations in jellyfish were lower than expected given their trophic position. Overall, these findings provide fundamental information about food web structure and mercury contamination in a small Arctic polynya, which will inform future research in such ecosystems and provide a baseline against which to assess changes over time resulting from environmental disturbance.
Cowie A.M., Wood R.K., Chishti Y., Feswick A., Loughery J.R., Martyniuk C.J. (2015). Transcript variability and physiological correlates in the fathead minnow ovary: Implications for sample size, and experimental power. Comparative Biochemistry and Physiology Part B Biochemistry and Molecular Biology, 187 22-30.

Fundamental studies characterizing transcript variability in teleost tissues are needed if molecular endpoints are to be useful for regulatory ecotoxicology. The objectives of this study were to (1) measure transcript variability of steroidogenic enzymes and steroid receptors in the fathead minnow (FHM; Pimephales promelas) ovary to better determine normal variability and the sample sizes needed to detect specific effect sizes and to (2) determine how expression patterns related to higher level endpoints used in some regulatory ecotoxicology programs (e.g. relative gonad size). Estrogen receptor 2b (. esr2b) and 5α-reductase a3 (. srd5a3) showed high variability in the ovary (CV. >. 1.0) while progesterone receptor (. pgr), androgen receptor (. ar), and esr2a showed comparatively low variability (CV. =. ~. 0.5--0.7). Using these estimates, a power analysis revealed that sample sizes for real-time PCR experiments would need to be. >20 to detect a 2-fold change for 7 of the transcripts examined; thus many molecular studies conducted in the fish ovary may have insufficient power to detect smaller effects. Two transcripts were correlated to steroid production in the ovary; cyp19a1 levels were positively correlated to in vitro E2 production, while ar levels were negatively correlated to in vitro T production. Thus, these transcripts may be informative molecular surrogates for ovarian steroid production. No transcript investigated showed any correlation to GSI, condition, or body weight/length. Molecular approaches in fish are increasingly used to assess biological impacts of chemical stressors; however additional studies are required that determine how molecular variability relates to higher level biological endpoints.
Curry C.J., Baird D.J. (2015). Habitat type and dispersal ability influence spatial structuring of larval Odonata and Trichoptera assemblages. Freshwater Biology, 60(10) 2142-2155.

Freshwater invertebrate assemblages are believed to be structured by both local and larger scale processes (i.e. dispersal). In rivers, the extent to which dispersal processes influence local assemblage composition may depend on both the taxon and habitat in question. Poor dispersers should display greater spatial structuring than strong dispersers. Likewise, assemblages in poorly connected habitats should experience greater dispersal limitation, and therefore greater spatial structuring. We sought to test these hypotheses using two contrasting orders of aquatic insect, Odonata and Trichoptera. Odonata are believed to have greater dispersal capacity than Trichoptera. In river ecosystems, these orders inhabit both main channel habitats and more poorly connected riverine wetlands. Multi-habitat surveys of larval Trichoptera and Odonata assemblages were conducted at 34 sites in three 5th-order New Brunswick rivers. The degree of spatial and environmental structuring in assemblages was assessed using redundancy analysis-based variance partitioning. We also assessed the performance of different model-based spatial predictors (asymmetric eigenvector maps, AEMs and principal coordinates of neighbourhood matrices, PCNMs). For main channel areas, variance explained purely by environmental variables was greater for Odonata, while the purely spatial component of variance was greater for Trichoptera, regardless of the class of spatial descriptor. In riverine wetlands, both the purely environmental and purely spatial components of variance explained were similar or were greater for Trichoptera than for Odonata. The component of variance explained by spatial variables was greater in riverine wetlands than main channel areas for both Odonata and Trichoptera for most spatial descriptors, suggesting that taxa inhabiting riverine wetlands may experience greater dispersal limitation. However, the magnitude of this difference was relatively small in most cases. Eigenvector-based spatial descriptors (PCNMs, AEMs, netPCNMs) explained more variance than traditional spatial descriptors. For Trichoptera, network-based predictors (AEMs, netPCNMs) explained more variance than PCNMs in main channel areas. Our results suggest that dispersal ability and habitat type can influence the degree of spatial structuring in aquatic insect assemblages. However, these patterns must be investigated across a wider range of insect groups and at larger spatial scales. Our results also suggest that biomonitoring programs should consider assemblage spatial structure in building reference condition models and that aquatic conservation planners must consider the type and spatial arrangement of habitats in reserve design. Eigenvector-based spatial descriptors hold promise for interpreting biodiversity patterns in freshwater invertebrates, but more work is required to relate patterns to actual dispersal behaviour.
Gibson J.F., Shokralla S., Curry C., Baird D.J., Monk W.A., King I., Hajibabaei M. (2015). Large-scale biomonitoring of remote and threatened ecosystems via high-throughput sequencing. Plos One, 10(10).

Biodiversity metrics are critical for assessment and monitoring of ecosystems threatened by anthropogenic stressors. Existing sorting and identification methods are too expensive and labour-intensive to be scaled up to meet management needs. Alternately, a high-throughput DNA sequencing approach could be used to determine biodiversity metrics from bulk environmental samples collected as part of a large-scale biomonitoring program. Here we show that both morphological and DNA sequence-based analyses are suitable for recovery of individual taxonomic richness, estimation of proportional abundance, and calculation of biodiversity metrics using a set of 24 benthic samples collected in the Peace-Athabasca Delta region of Canada. The high-throughput sequencing approach was able to recover all metrics with a higher degree of taxonomic resolution than morphological analysis. The reduced cost and increased capacity of DNA sequence-based approaches will finally allow environmental monitoring programs to operate at the geographical and temporal scale required by industrial and regulatory end-users.
Hayden B., Harrod C., Sonninen E., Kahilainen K.K. (2015). Seasonal depletion of resources intensifies trophic interactions in subarctic freshwater fish communities. Freshwater Biology, 60(5) 1000-1015.

Climate change in recent decades has resulted in an increase in both the density and diversity of consumers in subarctic freshwater ecosystems. Despite this, harsh winter conditions in the region limit productivity and may serve as a bottleneck driving trophic interactions within the fish community, potentially determining the outcome of climate change for resident biota. However, due to the difficulties in sampling during winter months, few studies have assessed seasonal variation in the ecological interactions between native and range-expanding species in subarctic regions. We examined seasonal variation in activity, diet (stomach content) and resource use (δ13C and δ15N stable isotope ratios) of two fishes: the resident cold-water-adapted European whitefish (Coregonus lavaretus L.) and the range-expanding cool-water-adapted ruffe (Gymnocephalus cernua L.) in lakes with low and high consumer density. Results were contrasted with seasonal availability of benthic and pelagic resources and indirect measures of individual fitness, that is condition, growth and estimated lipid content (muscle elemental C: N ratio) of both species. The effects of fish density were apparent in both the diet and resource use of whitefish, which altered their diet and displayed reduced stomach fullness during winter in high-density lakes. This was associated with an overall reduction in whitefish growth, condition and estimated lipid content in high-density lakes, which was especially pronounced during winter. Ruffe utilised a greater proportion of profundal resources than whitefish in both summer and winter, potentially exploiting a vacant niche. Ruffe maintained condition and lipid reserves throughout the winter, highlighting the potential for further northward range expansion of the species. Winter acts as a seasonal bottleneck in subarctic lakes, but assumptions that this bottleneck primarily selects against warmer-water-adapted invasive species such as ruffe may be too restrictive. The effects of seasonal resource depletion on fish condition and invertebrate density were most severe in lakes with a high density of fish, and in these conditions, the cold-water-adapted resident whitefish was most adversely affected.
Jiang Y., Nishimura P., van den Heuvel M.R., MacQuarrie K.T.B., Crane C.S., Xing Z., Raymond B.G., Thompson B.L. (2015). Modeling land-based nitrogen loads from groundwater-dominated agricultural watersheds to estuaries to inform nutrient reduction planning. Journal of Hydrology, 529(P1) 213-230.

Excessive nitrate loads from intensive potato production have been linked to the reoccurring anoxic events in many estuaries in Prince Edward Island (PEI), Canada. Community-led watershed-based nutrient reduction planning has been promoted as a strategy for water quality restoration and initial nitrate load criteria have been proposed for the impacted estuaries. An integrated modeling approach was developed to predict base flow nitrate loads to inform the planning activities in the groundwater-dominated agricultural watersheds. Nitrate load is calculated as base flow multiplied by the average of nitrate concentration at the receiving watershed outlet. The average of nitrate concentration is estimated as the integration of nitrate leaching concentration over the watershed area minus a nitrate loss coefficient that accounts for long-term nitrate storage in the aquifer and losses from the recharge to the discharge zones. Nitrate leaching concentrations from potato rotation systems were estimated with a LEACHN model and the land use areas were determined from satellite image data (2006-2009) using GIS. The simulated average nitrate concentrations are compared with the arithmetic average of nitrate concentration measurements in each of the 27 watersheds for model calibration and in 138 watersheds for model verifications during 2006-2009. Sensitivity of the model to the variations of land use mapping errors, nitrate leaching concentrations from key sources, and nitrate loss coefficient was tested. The calibration and verification statistics and sensitivity analysis show that the model can provide accurate nitrate concentration predictions for watersheds with drainage areas more than 5km2 and nitrate concentration over 2mgNL-1, while the model resolution for watersheds with drainage areas below 5km2 and/or nitrate concentration below 2mgNL-1 may not be sufficient for nitrate load management purposes. Comparisons of normalized daily stream discharges among the active hydrometric stations indicated that stream base flow could be prorated for nitrate load calculation from the nearest gauging station in the absence of discharge measurements. Annual nitrate losses, including aquifer long-term storage, denitrification, and riparian plant uptake were estimated to be 0.8mgNL-1, corresponding to 3.4kgNha-1. The maximum and median base flow nitrate loads to the estuaries from among the 27 calibration watersheds were predicted to be 28.4 and 8.7kgNha-1 respectively with a root mean square error (RMSE) as 2.3kgNha-1. From among the 75 watersheds selected for model verification, the maximum and median base flow nitrate loads to the estuaries were estimated to be 29 and 5.5kgNha-1 respectively with RMSE as 2.6kgNha-1. At the estuaries with nitrate loads above the medians, the predominant nitrate sources (75-98%) were derived from the potato rotation lands, highlighting the importance of N use management with potato production for water quality restoration; nitrate load derived from atmospheric N deposits was estimated to account for 3.6-13% of annual nitrate loads in watersheds with nitrate loads exceeding the median values. The application of the model to nutrient reduction planning in the Southwest River watershed implies that a significant change on cropping practices has to be made in order to mitigate the anoxic events in this highly impacted agricultural watershed.
Karami A., Courtenay S.C. (2015). Glutathione S-transferase activities in African catfish injected with β-naphthoflavone: effects of ploidy, gender, dose, and sampling time. Environmental Monitoring and Assessment, 187(11).

Glutathione S-transferases (GST) are considered among the most controversial biomarkers of water pollutants in fish with little known about factors influencing their activities. The objective of this study was to investigate how gender, dose, ploidy, and sampling time alter hepatic GST activities in African catfish (Clarias gariepinus) following β-naphthoflavone (β-NF) injection. Newly matured male and female diploid and triploid fish were intraperitoneally (i.p.) injected with 0, 15, or 75 mg/kg of β-NF, and livers were excised 24, 48, and 72 h post-injection. Results showed that hepatic GST activities were significantly inhibited by both doses of β-NF. Inhibition was greater in females than males, but no significant differences were observed between diploid and triploid fish. Enzymatic activities differed over time with lowest levels 72 h post-injection. These results extend our understanding of GST activity in fish and highlight the necessity of considering confounding factors when comparing different studies.
Karami A., Teh S.J., Zakaria M.P., Courtenay S.C. (2015). Ploidy-, gender-, and dose-dependent alteration of selected biomarkers in Clarias gariepinus treated with benzo[a]pyrene. Journal of Environmental Sciences China, 38 95-102.

Naturally-occurring and artificially-induced polyploids have been documented in various fish species but to date no comparison has been reported of the impacts of ploidy on fish biomarker responses to organic pollutants. This study describes effects of ploidy, gender, and dose on biliary fluorescent aromatic compound (FAC) concentrations, hepatic ethoxyresorufin- O-deethylase (EROD) and glutathione S-transferase (GST) activities in one of the most commonly cultured warm-water species, the African catfish Clarias gariepinus. Recently matured male and female diploid and triploid fish were intraperitoneally (i.p.) injected with 0, 5 or 25. mg/kg benzo[. a]pyrene (BaP) and liver and gallbladder were sampled 48. hr later. No significant differences were found between ploidies in bile concentrations of 7,8 dihydrodiolbenzo[. a]pyrene (7,8D BaP), 1-hydroxybenzo[. a]pyrene (1-OH BaP) or 3-hydroxybenzo[. a]pyrene (3-OH BaP). However, concentrations of the biliary FACs did differ between males and females at different dose of injection with generally higher concentrations in females at the low dose of BaP and higher concentrations in males at the higher BaP concentration. Hepatic EROD activity did not exhibit gender-dependent difference, whereas it was significantly higher in triploids than diploids. GST activities were not significantly influenced by any of the tested factors. This work advanced our understanding of the role of ploidy, gender, and dose in biotransformation of pollutants in fish.
Kurylyk B.L., MacQuarrie K.T.B., Caissie D., McKenzie J.M. (2015). Shallow groundwater thermal sensitivity to climate change and land cover disturbances: Derivation of analytical expressions and implications for stream temperature modeling. Hydrology and Earth System Sciences, 19(5) 2469-2489.

Climate change is expected to increase stream temperatures and the projected warming may alter the spatial extent of habitat for cold-water fish and other aquatic taxa. Recent studies have proposed that stream thermal sensitivities, derived from short-term air temperature variations, can be employed to infer future stream warming due to long-term climate change. However, this approach does not consider the potential for streambed heat fluxes to increase due to gradual warming of the shallow subsurface. The temperature of shallow groundwater is particularly important for the thermal regimes of groundwater-dominated streams and rivers. Also, recent studies have investigated how land surface perturbations, such as wildfires or timber harvesting, can influence stream temperatures by changing stream surface heat fluxes, but these studies have typically not considered how these surface disturbances can also alter shallow groundwater temperatures and streambed heat fluxes. In this study, several analytical solutions to the one-dimensional unsteady advection-diffusion equation for subsurface heat transport are employed to estimate the timing and magnitude of groundwater temperature changes due to seasonal and long-term variability in land surface temperatures. Groundwater thermal sensitivity formulae are proposed that accommodate different surface warming scenarios. The thermal sensitivity formulae suggest that shallow groundwater will warm in response to climate change and other surface perturbations, but the timing and magnitude of the subsurface warming depends on the rate of surface warming, subsurface thermal properties, bulk aquifer depth, and groundwater velocity. The results also emphasize the difference between the thermal sensitivity of shallow groundwater to short-term (e.g., seasonal) and long-term (e.g., multi-decadal) land surface-temperature variability, and thus demonstrate the limitations of using short-term air and water temperature records to project future stream warming. Suggestions are provided for implementing these formulae in stream temperature models to accommodate groundwater warming.
Kurylyk B.L., Macquarrie K.T.B., Linnansaari T., Cunjak R.A., Curry R.A. (2015). Preserving, augmenting, and creating cold-water thermal refugia in rivers: Concepts derived from research on the Miramichi River, New Brunswick (Canada). Ecohydrology, 8(6) 1095-1108.

Summer water temperatures are rising in many river systems in North America, and this warming trend is projected to intensify in the coming decades. Cold-water fish may alleviate thermal stress in summer by aggregating in discrete cold-water plumes that provide thermal refuge from high ambient river temperatures. Reliance on cold-water thermal refugia is expected to increase in a warming climate, and many river reaches already lack suitable thermal refugia as a result of an absence of thermal diversity. A comprehensive fish management strategy could proactively address this imminent threat to cold-water fish populations across North America by preserving existing thermal refugia, augmenting thermal anomalies to improve performance as refugia, and creating new thermal refugia in uniformly warm river reaches. We provide practical recommendations on how these measures can be accomplished based on insight derived from recent research focused on the Miramichi River, New Brunswick. Opportunities include limiting land use change, construction aggregate extraction (e.g. sand and gravel pits), and groundwater pumping/consumption. Existing thermal anomalies can be enhanced by controlling advective thermal mixing between cold-water tributaries and the river mainstem flow, installing riparian shading, and adding temporary structures for protection from avian predators. New refugia can be created by temporarily pumping groundwater to discrete points within the river during periods of thermal stress. These concepts are discussed in the context of a comprehensive thermal refugia management strategy. Copyright
Leclair L.A., Pohler L., Wiseman S.B., He Y., Arens C.J., Giesy J.P., Scully S., Wagner B.D., Van Den Heuvel M.R., Hogan N.S. (2015). In vitro assessment of endocrine disrupting potential of naphthenic acid fractions derived from oil sands-influenced water. Environmental Science and Technology, 49(9) 5743-5752.

Oil sands-influenced process waters have been observed to cause reproductive effects and to induced CYP1A activity in fishes; however, little progress has been made in determining causative agents. Naphthenic acids (NAs) are the predominant organic compounds in process-affected waters, but due to the complexity of the mixture, it has been difficult to examine causal linkages in fishes. The aim of this study was to use in vitro assays specific to reproductive and CYP1A mechanisms to determine if specific acid extractable fractions of NAs obtained from oil sands-influenced water are active toward reproductive processes or interact with the Ah receptor responsible for CYP1A activity. NAs were extracted from aged oil sands-influenced waters by use of acid precipitation, and the mixture was fractionated into three acidic and one neutral fraction. The four fractions were examined for Ah receptor-mediated potency by use of the H4IIE-luc bioassay, effects on production of steroid hormones by use of the H295R steroidogenesis assay, and sex steroid receptor binding activity using the yeast estrogen screen and yeast androgen screen. The mixtures were characterized by high resolution mass spectrometry, 1H nuclear magnetic resonance, and attenuated total reflectance infrared spectroscopy. The neutral fraction elicited Ah-receptor mediated activity after 24 h but not after 48 or 72 h. None of the fractions contained measurable levels of estrogen or androgen receptor agonists nor did they cause reductions in steroidogenesis. A number of fractions showed antiestrogenic or antiandrogenicity potency, with the neutral and main acidic fractions being the most potent. Neutral aromatic compounds are likely responsible for the CYP1A activity observed. Direct estrogenic, androgenic, or steroidogenic mechanisms are unlikely for NAs based on these results, but NAs act as potent antiandrogen or antiestrogens.
Lescord G.L., Kidd K.A., De Silva A.O., Williamson M., Spencer C., Wang X., Muir D.C.G. (2015). Perfluorinated and polyfluorinated compounds in lake food webs from the Canadian High Arctic. Environmental Science and Technology, 49(5) 2694-2702.

Per- and polyfluorinated alkyl substances (PFASs) enter Arctic lakes through long-range atmospheric transport and local contamination, but their behavior in aquatic food webs at high latitudes is poorly understood. This study compared the concentrations of perfluorocarboxylates, perfluorosulfonates, and fluorotelomer sulfonates (FTS) in biotic and abiotic samples from six high Arctic lakes near Resolute Bay, Nunavut, Canada. Two of these lakes are known to be locally contaminated by a small airport and Arctic char (Salvelinus alpinus) from these lakes had over 100 times higher total [PFAS] when compared to fish from neighboring lakes. Perfluorononanoate (PFOA) and perfluorooctanesulfonate (PFOS) dominated in char, benthic chironomids (their main prey), and sediments, while pelagic zooplankton and water were dominated by lower chain acids and perfluorodecanesulfonate (PFDS). This study also provides the first measures of perfluoroethylcyclohexanesulfonate (PFECHS) and FTS compounds in water, sediment, juvenile char, and benthic invertebrates from lakes in the high Arctic. Negative relationships between [PFAS] and δ15N values (indicative of trophic position) within these food webs indicated no biomagnification. Overall, these results suggest that habitat use and local sources of contamination, but not trophic level, are important determinants of [PFAS] in biota from freshwater food webs in the Canadian Arctic.
Lescord G.L., Kidd K.A., Kirk J.L., O'Driscoll N.J., Wang X., Muir D.C.G. (2015). Factors affecting biotic mercury concentrations and biomagnification through lake food webs in the Canadian high Arctic. Science of the Total Environment, 509-510 195-205.

In temperate regions of Canada, mercury (Hg) concentrations in biota and the magnitude of Hg biomagnification through food webs vary between neighboring lakes and are related to water chemistry variables and physical lake features. However, few studies have examined factors affecting the variable Hg concentrations in landlocked Arctic char (Salvelinus alpinus) or the biomagnification of Hg through their food webs. We estimated the food web structure of six high Arctic lakes near Resolute Bay, Nunavut, Canada, using stable carbon (δ13C) and nitrogen (δ15N) isotopes and measured Hg (total Hg (THg) in char, the only fish species, and methylmercury (MeHg) in chironomids and zooplankton) concentrations in biota collected in 2010 and 2011. Across lakes, δ13C showed that benthic carbon (chironomids) was the dominant food source for char. Regression models of log Hg versus δ15N (of char and benthic invertebrates) showed positive and significant slopes, indicting Hg biomagnification in all lakes, and higher slopes in some lakes than others. However, no principal components (PC) generated using all water chemistry data and physical characteristics of the lakes predicted the different slopes. The PC dominated by aqueous ions was a negative predictor of MeHg concentrations in chironomids, suggesting that water chemistry affects Hg bioavailability and MeHg concentrations in these lower-trophic-level organisms. Furthermore, regression intercepts were predicted by the PCs dominated by catchment area, aqueous ions, and MeHg. Weaker relationships were also found between THg in small char or MeHg in pelagic invertebrates and the PCs dominated by catchment area, and aqueous nitrate and MeHg. Results from these high Arctic lakes suggest that Hg biomagnification differs between systems and that their physical and chemical characteristics affect Hg concentrations in lower-trophic-level biota.
Martin J.W., Van Den Heuvel M.R., Hazewinkel R., Westcott K. (2015). ET&C perspectives. Environmental Toxicology and Chemistry, 34(12) 2682-2686.

Oil sands process-affected water (OSPW) accumulation on oil sands mine leases is an imminent policy challenge. Surface water policy in the Athabasca oil sands area is designed to achieve two water-management objectives, including to promote efficient water use, and to protect natural surface waters. These policy objectives have largely been pursued by regulation of freshwater withdrawals under Alberta's Water Act and wastewater-release regulations through Alberta's Environmental Protection and Enhancement Act. Opinions on the oil sand challenge from industry, government, and academic colleagues are presented. Although water-management objectives in the Athabasca oil sands area have been well served by existing OSPW-management approaches, varying opinions imply that there is a need to include consideration of environmental net effects and other environmental objectives in the continuous improvement of OSPW management.
McAlpine D.F., Soto D.X., Rutledge L.Y., Wheeldon T.J., White B.N., Goltz J.P., Kennedy J. (2015). Recent occurrences of wild-origin wolves (Canis spp.) in Canada south of the St. Lawrence river revealed by stable isotope and genetic analysis. Canadian Field Naturalist, 129(4) 386-394.

A free-ranging canid killed near Caraquet, New Brunswick, Canada, in 2012 exhibited a mitochondrial DnA sequence of Gray Wolf (Canis lupus) origin and a Y-chromosome haplotype of eastern Wolf (C. lycaon) origin. the animal, which is the first wolf recorded in New Brunswick since 1862, was identified as a Gray-eastern Wolf hybrid (C. lupus × C. lycaon) based on analysis of its autosomal microsatellite genotype. Stable carbon isotope values (δ13C) suggest that the Caraquet wolf was of wild origin. Likewise, δ13C analysis suggests that a wolf-coyote hybrid killed in Quebec south of the St. Lawrence River in 2002 was also of wild origin. however, δ13C values for a wolf from the same region in 2006 suggest that this animal spent most of its life feeding predominantly on non-wild-source food items. Recent occurrences of wild-origin animals south of the St. Lawrence River demonstrate that wolves are capable of dispersal to formerly occupied areas in southeastern Canada and the United States. however, limited natural dispersal alone will likely not be sufficient to re-establish wolves in northeastern North America.
Miller L.L., Isaacs M.A., Martyniuk C.J., Munkittrick K.R. (2015). Using molecular biomarkers and traditional morphometric measurements to assess the health of slimy sculpin (Cottus cognatus) from streams with elevated selenium in North-Eastern British Columbia. Environmental Toxicology and Chemistry, 34(10) 2335-2346.

Canadian fish-based environmental effects monitoring programs use individual and population-level endpoints to assess aquatic health. Impacts of coal mining and selenium (Se) exposure were assessed in slimy sculpin (Cottus cognatus) from reference streams located both inside and outside of a coal zone, and from 1 stream with a history of coal mining, using traditional environmental effects monitoring endpoints. In addition, physical characteristics of the streams and benthic macro-invertebrate communities were assessed. To determine whether the assessment of effects could be improved by including molecular markers, real-time polymerase chain reaction assays were optimized for genes associated with reproduction (vtg, esr1, star, cyp19a1, and gys2), and oxidative and cellular stress (sod1, gpx, gsr, cat, and hsp 90). Water Se levels exceeded guidelines in the stream with historical mining (4μg/L), but benthic macroinvertebrates did not exceed dietary thresholds (2-3μg/g dry wt). Whole-body Se levels were above British Columbia's tissue guideline in fish from all streams, but only above the draft US Environmental Protection Agency (USEPA) criterion (7.91μg/g dry wt) at the reference stream inside the coal zone. Some markers of cellular and oxidative stress were elevated in fish liver at the exposed site (sod1, gpx), but some were lower (cat, sod1, gpx, gsr, hsp90) in the gonads of fish inside the coal zone. Some of the differences in gene expression levels between the reference and impacted sites were sex dependent. Based on benthic macroinvertebrate assessments, the authors hypothesize that traditional and molecular differences in slimy sculpin at impacted sites may be driven by food availability rather than Se exposure. The present study is the first to adapt molecular endpoints in the slimy sculpin for aquatic health assessments.
Mocq J., St-Hilaire A., Cunjak R.A. (2015). Influences of Experts ’ Personal Experiences in Fuzzy Logic Modeling of Atlantic Salmon Habitat. North American Journal of Fisheries Management, 35(2) 271-280.

Abstract: The knowledge of scientific experts, which is regularly used in modeling, is acquired by training, education, and practical experiences that modify the experts’ perceptions. Using a case study dealing with fish habitat modeling, we investigated the possible influences and potential biases imparted by some of these personal experiences. Thirty salmon experts with different backgrounds and nationalities defined fuzzy sets and fuzzy rules in a fuzzy habitat model of three Atlantic Salmon Salmo salar life stages. Weighted usable area (WUA) curves were calculated for each expert by coupling the fuzzy model with a hydraulic model applied to the Romaine River (Quebec, Canada). Experts were then split into subgroups, and three possible experiential biases were tested: the experts’ main geographic region of expertise (Europe versus North America), their primary source of knowledge (fieldwork, scientific literature, or both), and their employment sector (public or private). A confidence interval was calculated around the median WUA curve for each subgroup by bootstrap resampling. A divergence in the confidence intervals (i.e., no overlap) indicated a significant influence of the tested experience. For all three considered life stages, we observed no significant impact of employment sector or knowledge source on modeled WUA. However, the experts’ geographic region of expertise had a significant influence on the output of the spawning adult habitat model. Consequently, the use of local expert knowledge in modeling is recommended. Received June 16, 2014; accepted December 1, 2014
Musetta-Lambert J.L., Scrosati R.A., Keppel E.A., Barbeau M.A., Skinner M.A., Courtenay S.C. (2015). Intertidal communities differ between breakwaters and natural rocky areas on ice-scoured Northwest Atlantic coasts. Marine Ecology Progress Series, 539 19-31.

This is the first study of the ecological significance of rocky breakwaters as habitat for intertidal biota in marine environments that freeze in winter. Percent cover of intertidal seaweeds and invertebrates was quantified on exposed (high wave action and winter ice scour) and sheltered sides of 18 breakwaters (>5 yr old) and compared with 18 natural rocky intertidal areas along 430 km of the southern Gulf of St. Lawrence coast (Atlantic Canada) in the summer of 2010. Sheltered areas of breakwaters differed from natural rocky shores in having lower biotic richness and total abundance. However, these indices were not significantly different between habitat types for exposed areas. Multivariate analysis revealed significant differences in community composition between breakwaters and natural rocky shores in both sheltered and exposed areas. Ulva spp. (U. intestinalis and U. lactuca), Hildenbrandia rubra, and Mytilus edulis (exposed areas only) were more abundant on breakwaters than on natural rocky shores, while Semibalanus balanoides, Calothrix spp., Fucus spp., Chordaria flagelliformis (exposed areas only), and Ascophyllum nodosum (sheltered areas only) were less abundant on breakwaters. Our study shows that breakwaters from marine shores affected by winter sea ice support substantially different biotic communities than natural rocky intertidal areas. Thus, the findings of this study provide vital information for management decisions related to habitat loss and compensation when the coastal landscape is altered through the construction of breakwaters.
Müller A.K., Brinkmann M., Baumann L., Stoffel M.H., Segner H., Kidd K.A., Hollert H. (2015). Morphological alterations in the liver of yellow perch (Perca flavescens) from a biological mercury hotspot. Environmental Science and Pollution Research, 22(22) 17330-17342.

Mercury (Hg) contamination is a global issue due to its anthropogenic release, long-range transport, and deposition in remote areas. In Kejimkujik National Park and National Historic Site, Nova Scotia, Canada, high concentrations of total mercury (THg) were found in tissues of yellow perch (Perca flavescens). The aim of this study was to evaluate a possible relationship between THg concentrations and the morphology of perch liver as a main site of metal storage and toxicity. Yellow perch were sampled from five lakes known to contain fish representing a wide range in Hg concentrations in fall 2013. The ultrastructure of hepatocytes and the distribution of Hg within the liver parenchyma were analyzed by transmission electron microscopy (TEM) and electron energy loss spectrometry (EELS). The relative area of macrophage aggregates (MAs) in the liver was determined using image analysis software and fluorescence microscopy. No relation between general health indicators (Fulton’s condition index) and THg was observed. In line with this, TEM examination of the liver ultrastructure revealed no prominent pathologies related to THg accumulation. However, a morphological parameter that appeared to increase with muscle THg was the relative area of MAs in the liver. The hepatic lysosomes appeared to be enlarged in samples with the highest THg concentrations. Interestingly, EELS analysis revealed that the MAs and hepatic lysosomes contained Hg.
Pearce N.J.T., Yates A.G. (2015). Agricultural best management practice abundance and location does not influence stream ecosystem function or water quality in the summer season. Water Switzerland, 7(12) 6861-6876.

Best management practices (BMPs) are tools commonly used to mitigate negative impacts of agriculture on water quality; however, the relationship between BMPs and aquatic ecological function is unknown. Our research goal was to determine the association between both stream ecosystem metabolism and water quality, and the abundance and location of four different BMPs in agricultural catchments. Dissolved oxygen was measured over a two-week period in mid-June and used to estimate ecosystem metabolism of 13 headwater streams representing a gradient of BMP implementation in Southern Ontario, Canada. Stepwise regression analyses were used to associate stream metabolism and water quality with metrics describing the abundance and location of BMPs within each catchment. Studied streams exhibited rates of metabolism comparable to catchments from other agricultural regions. However, metrics of BMP implementation were not associated with either stream metabolism or water quality. Our results suggest that BMPs in the studied agricultural catchments are not improving water quality or mitigating water quality impacts on stream metabolism during the summer season. We propose that seasonality of catchment hydrology and time lag effects associated with past agricultural land use may be masking the mitigation benefits of BMPs on stream ecosystem conditions during the summer season.
Samways K.M., Cunjak R.A. (2015). Increases in benthic community production and metabolism in response to marine-derived nutrients from spawning Atlantic salmon (Salmo salar). Freshwater Biology, 60(8) 1647-1658.

Atlantic salmon (Salmo salar) and other anadromous fishes represent a major vector for transporting marine-derived nutrients (MDNs) to Atlantic rivers. Marine-derived nutrient subsidies may be key for maintaining ecological processes and ecosystem function in river basins. Stream channels and mesocosms designed to approximate natural river systems were used to measure the response of stream productivity in two treatments, one with marine-derived nutrients from spawning Atlantic salmon and one without marine-nutrient subsidies (control). Biofilm biomass (measured as chlorophyll a) and benthic metabolism (measured as the net change in dissolved oxygen) were evaluated from artificial substrata encompassing pre-spawning, spawning and post-spawning periods. We calculated marine-nutrient contributions from spawning salmon using a simple empirical process model. We found that biofilm accrual was significantly greater with MDN inputs, with mesocosms having higher biomass (34.8 ± 1.2 mg chl a m-2) and growth rates (0.071 ± 0.002 mg m-2 day-1) than the stream channels (24.4 ± 4.8 mg chl a m-2 and 0.052 ± 0.003 mg m-2 day-1, respectively). Both control mesocosms and stream channels had significantly lower biomass (10.4 ± 0.7 mg chl a m-2 and 6.3 ± 2.5 mg chl a m-2, respectively) and growth rates (0.042 ± 0.008 mg m-2 day-1 and 0.029 ± 0.009 mg m-2 day-1, respectively) than treatment channels. Despite having a lower biofilm biomass, stream channels yielded a significantly greater final gross primary production of 2343.5 mg C m-2 day-1. The presence of MDNs in the stream channels shifted biofilm metabolism from heterotrophy (P/R = 0.283) to autotrophy (P/R = 2.422) within 112 days. Spawning Atlantic salmon contributed a total of 20.98 g m-2 of nitrogen and 1.04 g m-2 of phosphorous to each stream channel, through excretion and gametes alone. There was a strong predictable positive relationship between the increase in productivity and the amount of marine-derived nitrogen and phosphorous delivered. This study highlights the importance of marine-derived nutrients from Atlantic salmon for driving and maintaining freshwater productivity. Marine-nutrient subsidies relieve the 'bottom-up' constraints on stream productivity by facilitating the production of enough energy to support the food web, lessoning the reliance on outside energy sources.
Samways K.M., Leavitt P.R., Magnan P., Rodríguez M.A., Peres-Neto P.R. (2015). Convergent polymorphism between stream and lake habitats: The case of brook char. Canadian Journal of Fisheries and Aquatic Sciences, 72(9) 1406-1414.

Phenotypic variability represents an important factor allowing species to adapt to local environmental conditions, but mechanisms underlying such variation are incompletely understood. This study investigated whether habitat-specific demands on swimming performance or difference in trophic relationships in lakes (pelagic, littoral) and streams (riffle, pool) were significant predictors of phenotypic variation exhibited by brook char (Salvelinus fontinalis), the only fish in the study habitats. Specifically, we hypothesized that pelagic and riffle habitats would impose greater selective pressures associated with swimming, resulting in body morphologies that were dorsoventrally compressed, anterior–posteriorly elongated, and that exhibited a long, narrow caudal peduncle. Geometric morphometrics was applied in a quantitative analysis of body morphology among habitats, whereas stable isotope analysis was used to differentiate between food sources. Analyses revealed that while body morphology differed between lake and stream habitats, there was convergence between the pelagic and riffle habitats, as well as among littoral and riffle and pool environments. The littoral and pool habitats were thought to be more structurally complex, thereby selecting for increased maneuverability but lower sustained swimming and correspondingly deeper bodies with shorter, dorsoventrally expanded caudal peduncles. Carbon source and trophic position did not differ among habitats with a system, suggesting that feeding was not the main influence on morphological plasticity; however, fish in the stream were feeding at a higher trophic position than fish in the lake. These findings suggest that individual species may take advantage of morphological variation to better adapt local surroundings.
Samways K.M., Quiñones-Rivera Z.J., Leavitt P.R., Cunjak R.A. (2015). Spatiotemporal responses of algal, fungal, and bacterial biofilm communities in Atlantic rivers receiving marine-derived nutrient inputs. Freshwater Science, 34(3) 881-896.

Spawning anadromous fishes can enhance primary and secondary production in streams by providing marine-derived nutrients (MDN), but little is known of their effects on individual biofilm constituents (algae, fungi, and bacteria). To address this issue, we measured spatial and temporal changes in the abundance and composition of biofilm algae, fungi, and bacteria in 6 Atlantic rivers with contrasting influx of MDN. Each river had a natural barrier to anadromous fish migration, which established an upstream control and downstream treatment area, with Atlantic Salmon (Salmo salar), Alewife (Alosa pseudoharengus), Rainbow Smelt (Osmerus mordax), or Sea Lamprey (Petromyzon marinus) as the primary anadromous species. In areas receiving MDN, increases in algal and fungal biomass and bacterial density were maintained throughout the season. Algal communities showed the largest (2-10×) increase in abundance over control sites, and Rainbow Smelt spawning streams had the greatest accrual. The river with Alewife showed the largest (2×) increase in fungal biomass during the spawning period. Changes in bacterial density were greatest (2× increase) in the Rainbow Smelt spawning streams. An increase in spawning density (i.e., nutrient load) supported greater biomass accumulation, but the system appeared to saturate quickly. Biofilm in Rainbow Smelt and Alewife streams were enriched up to 2.5% in δ15N during spawning, whereas a 1%enrichment occurred in the Sea Lamprey and Atlantic Salmon streams compared with system baseline values. The degree to which MDN drive productivity and the mechanism of how these nutrients are incorporated to increase productivity and ultimately fish production remain unknown.
Sharaf M.S., Van Den Heuvel M.R., Stevens D., Kamunde C. (2015). Zinc and calcium modulate mitochondrial redox state and morphofunctional integrity. Free Radical Biology and Medicine, 84 142-153.

Zinc and calcium have highly interwoven functions that are essential for cellular homeostasis. Here we first present a novel real-time flow cytometric technique to measure mitochondrial redox state and show it is modulated by zinc and calcium, individually and combined. We then assess the interactions of zinc and calcium on mitochondrial H<inf>2</inf>O<inf>2</inf> production, membrane potential (ΔΨ<inf>m</inf>), morphological status, oxidative phosphorylation (OXPHOS), complex I activity, and structural integrity. Whereas zinc at low doses and both cations at high doses individually and combined promoted H<inf>2</inf>O<inf>2</inf> production, the two cations individually did not alter mitochondrial redox state. However, when combined at low and high doses the two cations synergistically suppressed and promoted, respectively, mitochondrial shift to a more oxidized state. Surprisingly, the antioxidants vitamin E and N-acetylcysteine showed pro-oxidant activity at low doses, whereas at high antioxidant doses NAC inhibited OXPHOS and dyscoupled mitochondria. Individually, zinc was more potent than calcium in inhibiting OXPHOS, whereas calcium more potently dissipated the ΔΨ<inf>m</inf> and altered mitochondrial volume and ultrastructure. The two cations synergistically inhibited OXPHOS but antagonistically dissipated ΔΨ<inf>m</inf> and altered mitochondrial volume and morphology. Overall, our study highlights the importance of zinc and calcium in mitochondrial redox regulation and functional integrity. Importantly, we uncovered previously unrecognized bidirectional interactions of zinc and calcium that reveal distinctive foci for modulating mitochondrial function in normal and disease states because they are potentially protective or damaging depending on conditions.
van den Heuvel M.R. (2015). In Response: An academic perspective on the release of oil sands process-affected water. Environmental Toxicology and Chemistry, 34(12) 2682-2684.
Vue S., Samways K.M., Cunjak R.A. (2015). Bioelectrical Impedance Analysis to Estimate Lipid Content in Atlantic Salmon Parr as Influenced by Temperature, PIT Tags, and Instrument Precision and Application in Field Studies. Transactions of the American Fisheries Society, 144(2) 235-245.

Abstract: The objective of this study was to investigate the effectiveness of bioelectrical impedance analysis (BIA) in field studies monitoring Atlantic Salmon Salmo salar parr, as related to temperature corrections, instrument precision, and passive integrated transponder (PIT) tags. Currently, BIA studies are restricted to laboratory settings where water temperature is controlled to decrease error in BIA predictions caused by fish body temperature. We compared models of predicted total and percent lipids with and without temperature corrections and found that temperature corrections reduced error caused by temperature. Without temperature corrections, an 8°C increase in temperature increased the predicted total lipids by 55%. After temperature corrections were added, the predicted total lipid only increased by 2.55%. Repeated measurements were collected on 40 salmon parr (56–115 mm FL) in four separate time trials (1 min, 1.5 h, 3 h, and 6 h), and we found that lipid content predictions between measurements were not significantly different; however, the variability within longer time trials was moderate (6.43% error). No significant differences were found in the predicted lipid value before or after PIT tags were removed from the body cavity, suggesting PIT tags do not affect BIA readings. On average, the difference between predicted total lipids after tag removal was 0.0023 and 0.02 g for 12.5-mm and 22-mm PIT tags, respectively. We also observed that increases in fish body temperature caused by handing resulted in increased variability in BIA estimates, indicating the need for temperature corrections.Received March 10, 2014; accepted September 22, 2014
Wood R.K., Seidel J.S., Martyniuk C.J. (2015). Transcripts involved in steroid biosynthesis and steroid receptor signaling are expressed early in development in the fathead minnow (Pimephales promelas). Comparative Biochemistry and Physiology Part B Biochemistry and Molecular Biology, 182 64-72.

Sex differentiation in organisms is correlated to sex steroid production and receptor signaling pathways involving androgens and estrogens. Timing of expression is critical, and characterization of sensitive windows is needed to determine how environmental stressors may perturb sex differentiation. The objectives of this study were to determine whether genes related to steroid biosynthesis, steroid receptor signaling, and those related to sex differentiation were expressed in pre-differentiated fathead minnow (FHM) embryos, an ecotoxicological model. Transcripts were measured over two weeks (1. day post fertilization (dpf) to 14. days), prior to sex differentiation. The first three time points investigated (1, 3, and 5. dpf) corresponded to the neurula stage, dorsal swim bladder pigmentation, and pre-hatch. The fourth time point (6. dpf) was collected immediately post-hatch and the fifth time point investigated was after 8. days of larval growth (14. dpf). The majority of transcripts investigated, for example estrogen, androgen, and thyroid receptors as well as steroid biosynthesis transcripts, were expressed within the first 72. hours of development; exceptions were star (steroidogenic acute regulatory protein) and cyp19a, which did not have detectable expression until 5. dpf (pre-hatch). Transcripts that increased in relative mRNA abundance over the first two weeks of development included ar, dax1, hsd11b2, hsd17b, cyp19a and thra. This study demonstrates that there is early expression of transcripts related to steroid biosynthesis, steroid receptor signaling, and sex differentiation in pre-hatch FHM embryos. Additional studies are required to determine their relative roles in male and female differentiation during these early developmental periods.
Zhang J., Koch I., Gibson L.A., Loughery J.R., Martyniuk C.J., Button M., Caumette G., Reimer K.J., Cullen W.R., Langlois V.S. (2015). Transcriptomic responses during early development following arsenic exposure in Western Clawed Frogs, Silurana tropicalis. Toxicological Sciences, 148(2) 603-617.

Arsenic compounds are widespread environmental contaminants and exposure elicits serious health issues, including early developmental anomalies. Depending on the oxidation state, the intermediates of arsenic metabolism interfere with a range of subcellular events, but the fundamental molecular events that lead to speciation-dependent arsenic toxicity are not fully elucidated. This study therefore assesses the impact of arsenic exposure on early development by measuring speciation and gene expression profiles in the developing Western clawed frog (Silurana tropicalis) larvae following the environmental relevant 0.5 and 1 ppm arsenate exposure. Using HPLC-ICP-MS, arsenate, dimethylarsenic acid, arsenobetaine, arsenocholine, and tetramethylarsonium ion were detected. Microarray and pathway analyses were utilized to characterize the comprehensive transcriptomic responses to arsenic exposure. Clustering analysis of expression data showed distinct gene expression patterns in arsenate treated groups when compared with the control. Pathway enrichment revealed common biological themes enriched in both treatments, including cell signal transduction, cell survival, and developmental pathways. Moreover, the 0.5 ppm exposure led to the enrichment of pathways and biological processes involved in arsenic intake or efflux, as well as histone remodeling. These compensatory responses are hypothesized to be responsible for maintaining an in-body arsenic level comparable to control animals. With no appreciable changes observed in malformation and mortality between control and exposed larvae, this is the first study to suggest that the underlying transcriptomic regulations related to signal transduction, cell survival, developmental pathways, and histone remodeling may contribute to maintaining ongoing development while coping with the potential arsenic toxicity in S. tropicalis during early development.
Aguilar C., González-Sansón G., Cabrera Y., Ruiz A., Allen Curry R. (2014). Inter-habitat variation in density and size composition of reef fishes from the Cuban Northwestern shelf. Revista De Biologia Tropical, 62(2) 589-602.

Movement and exchange of individuals among habitats is critical for the dynamics and success of reef fish populations. Size segregation among habitats could be taken as evidence for habitat connectivity, and this would be a first step to formulate hypotheses about ontogenetic inter-habitat migrations. The primary goal of our research was to find evidence of inter-habitat differences in size distributions and density of reef fish species that can be classified a priori as habitat-shifters in an extensive (~600km2) Caribbean shelf area in NW Cuba. We sampled the fish assemblage of selected species using visual census (stationary and transect methods) in 20 stations (sites) located in mangrove roots, patch reefs, inner zone of the crest and fore reef (12-16m depth). In each site, we performed ten censuses for every habitat type in June and September 2009. A total of 11 507 individuals of 34 species were counted in a total of 400 censuses. We found significant differences in densities and size compositions among reef and mangrove habitats, supporting the species-specific use of coastal habitats. Adults were found in all habitats. Reef habitats, mainly patch reefs, seem to be most important for juvenile fish of most species. Mangroves were especially important for two species of snappers (Lutjanus apodus and L. griseus), providing habitat for juveniles. These species also displayed well defined gradients in length composition across the shelf.
Armanini D.G., Idigoras Chaumel A., Monk W.A., Marty J., Smokorowski K., Power M., Baird D.J. (2014). Benthic macroinvertebrate flow sensitivity as a tool to assess effects of hydropower related ramping activities in streams in Ontario (Canada). Ecological Indicators, 46 466-476.

Within Canada, hydro-electric power is the leading source of energy for households and industry. It is thus critical to understand and minimize its ecological impacts, by developing management guidelines for hydropower operations. Flow peaking is a common practice at hydroelectric facilities as hydropower generation often tracks the demand in electricity, and understanding its ecological impacts is key to developing sustainable river management guidelines. Based on standard macroinvertebrate biomonitoring data, the Canadian Ecological Flow Index (CEFI) is a tool to assess flow sensitivity based on Canadian rivers. Having already demonstrated its utility to detect changes in flow conditions, CEFI was applied in this study to investigate the ecological effects of altering a peaking hydropower scheme, specifically by changing the ramping rate, or the rate of change of flow from minimum to maximum and back in a peaking cycle. Data were collected in two proximate rivers in Ontario: one experiencing hydropower ramping and the other with a natural flow regime, allowing the detection of the effects unlimited ramping using a BACI (Before-After/Control-Impact) design. In the regulated river, the first two years of the study were subjected to restricted ramping rate practices while unlimited ramping was permitted thereafter. Hydrological data were collected at each station and used to compute a series of 33 Indicators of Hydrologic Alteration (IHA) metrics to characterize the ecohydrological condition of the river systems. The benthic community responded to changes in ramping rate and CEFI was able to discriminate the alteration signal and to diagnose the impact. Hydrological descriptors of the effects of the ramping activities were clear drivers of the CEFI variation in the hydropower-ramping site. This study is the first to apply the CEFI approach to a BACI in situ experiment. The CEFI tool again proved to be a useful indicator of flow alteration, with great promise for its use in the development of hydroecological management guidelines. © 2014 Elsevier Ltd.
Bahamonde P.A., Tetreault G.R., McMaster M.E., Servos M.R., Martyniuk C.J., Munkittrick K.R. (2014). Molecular signatures in rainbow darter (Etheostoma caeruleum) inhabiting an urbanized river reach receiving wastewater effluents. Aquatic Toxicology, 148 211-220.

Rainbow darter (Etheostoma caeruleum) is a small benthic fish species found in North America that are abundant and distributed throughout the Grand River watershed, ON, Canada. Rainbow darter exhibit intersex in males at sites adjacent to municipal wastewater effluents (MWWE). In October 2010, female and male rainbow darter were collected at 3 sites (1 upstream reference and 2 downstream exposed sites) in the Grand River near the cities of Kitchener and Waterloo. The primary objectives of this research were (1) to characterize the responses of whole organism endpoints (i.e. condition factor (K), liversomatic (LSI) and gonadosomatic index (GSI), histopathology) to MWWEs and (2) to identify transcripts showing altered steady state abundance with exposure to MWWE in fish inhabiting municipal wastewater effluent-exposed areas. Genes measured in this study included vitellogenin, Sry-box containing protein 9 (sox9), forkhead box L2 (foxl2), doublesex and mab-3 related transcription factor 1 (dmrt1), cytochrome P450, family 11, subfamily A, polypeptide 1 (cyp11a) as well as estrogen (esr1, esrb) and androgen (ar) receptors. There were no changes in condition factor; however, there was a significant increase in LSI and a decrease in GSI in fish inhabiting downstream environments when compared with fish collected from the reference site. Males had a high incidence (~70%) of intersex in downstream sites; characterized by the presence of oocytes within the testis. In the gonad, there were sex specific differences for genes related to sexual differentiation; dmrt1 was only expressed in males whereas foxl2 and sox9 were highly expressed in females compared to males. Expression levels of ar and esr1 were higher in females than males. Conversely, esrb was not differentially expressed between sexes or among sites. There were no differences detected for the genes investigated within sex among sites. This study is the first to report on gene expression changes in the rainbow darter, with emphasis on the differences in transcript abundance between sexes and how these changes relate to exposures to MWWEs. Molecular approaches are being investigated for their potential application to field ecotoxicology, and molecular bioassays for relevant, sentinel species in environmental monitoring programs are required to better understand the impact of anthropogenic impacts on species at risk in river systems. © 2014 Elsevier B.V.
Bailey R.C., Linke S., Yates A.G. (2014). Bioassessment of Freshwater Ecosystems using the Reference Condition Approach: Comparing Established and New Methods with Common Data Sets. Freshwater Science, 33(4) 1204-1211.

Although used in many jurisdictions around the world, analytical approaches of the Reference Condition Approach (RCA) to bioassessment of freshwater ecosystems have evolved quite slowly over the past 2 decades. For this special series of papers in Freshwater Science, researchers analyzed 3 data sets that included both benthic macroinvertebrate and environmental data from a number of reference sites. Australian Capital Territory (ACT) reference sites (ntotal = 107) were wadeable streams in the upper Murrumbidgee River catchment, Australian Capital Territory, Australia. Yukon Territory (YT) reference sites were wadeable streams (ntotal = 158) in the Yukon Territory, Canada, part of the Yukon River basin. Great Lakes (GL) sites (ntotal = 164) were all nearshore (<20 m) lentic sites in the North American Great Lakes. For each data set, sites were divided into model-building (training) and model-testing (validation) groups. Each validation site was further subjected to 3 levels of simulated degradation based on the sensitivity of the biota to eutrophication. The analytical approaches ranged from standard or slight modifications of methods used in national programs (Australian River Assessment [AUSRIVAS], Canadian Aquatic Biomonitoring Network [CABIN]), to improved matching of sites to be assessed and appropriate reference sites, and Bayesian and machine-learning modeling. In comparing Type 1 error rates (proportion of validation sites deemed not in reference condition) and power (proportion of simulated impairment sites deemed not in reference condition), we found no obvious pattern among the 3 data sets or approaches. Approaches commonly used in RCA programs would benefit from incorporating newer methods that better match reference and test-site environments and build better predictive models.
Bissegger S., Martyniuk C.J., Langlois V.S. (2014). Transcriptomic profiling in Silurana tropicalis testes exposed to finasteride. General and Comparative Endocrinology, 203 137-145.

Investigations of endocrine disrupting chemicals found in aquatic ecosystems with estrogenic and androgenic modes of action have increased over the past two decades due to a surge of evidence of adverse effects in wildlife. Chemicals that disrupt androgen signalling and steroidogenesis can result in an imbalanced conversion of testosterone (T) into 17β-estradiol (E2) and other androgens such as 5α-dihydrotestosterone (5α-DHT). Therefore, a better understanding of how chemicals perturb these pathways is warranted. In this study, the brain, liver, and testes of Silurana tropicalis were exposed ex vivo to the human drug finasteride, a potent steroid 5α-reductase inhibitor and a model compound to study the inhibition of the conversion of T into 5α-DHT. These experiments were conducted (1) to determine organ specific changes in sex steroid production after treatment, and (2) to elucidate the transcriptomic response to finasteride in testicular tissue. Enzyme-linked immunosorbent assays were used to measure hormone levels in media following finasteride incubation for 6. h. Finasteride significantly increased T levels in the media of liver and testis tissue, but did not induce any changes in E2 and 5α-DHT production. Gene expression analysis was performed in frog testes and data revealed that finasteride treatment significantly altered 1,434 gene probes. Gene networks associated with male reproduction such as meiosis, hormone biosynthesis, sperm entry, gonadotropin releasing hormone were affected by finasteride exposure as well as other pathways such as oxysterol synthesis, apoptosis, and epigenetic regulation. For example, this study suggests that the mode of action by which finasteride induces cellular damage in testicular tissue as reported by others, is via oxidative stress in testes. This data also suggests that 5-reductase inhibition disrupts the expression of genes related to reproduction. It is proposed that androgen-disrupting chemicals may mediate their action via 5-reductases and that the effects of environmental pollutants are not limited to the androgen receptor signalling. © 2014 Elsevier Inc.
Caissie D., Kurylyk B.L., St-Hilaire A., El-Jabi N., MacQuarrie K.T.B. (2014). Streambed temperature dynamics and corresponding heat fluxes in small streams experiencing seasonal ice cover. Journal of Hydrology, 519(PB) 1441-1452.

Streambed temperature and heat fluxes are important for aquatic habitats as well as in the development and improvement of water temperature models. In the present study, measured streambed temperatures at different depths were used as a tracer to predict the magnitude and direction of groundwater flow using an advection-conduction heat transport model. This analysis was carried out under different conditions, namely under natural surface water temperature conditions (i.e., as measured in the field), under steady-state conditions (e.g. under stream ice cover) and for conditions where the surface water temperatures followed a sinusoidal function. In Catamaran Brook, results from the advection-conduction numerical model showed good agreement between predicted and observed streambed temperatures with root-mean-square errors (RMSEs) ranging between 0.07°C to 0.6°C. A comparison of streambed fluxes showed that the heat flux by conduction was more important during the summer period for upwelling conditions (mean value 96Wm-2 at 25°C), but was also present in winter (-20Wm-2). Variability in heat flux by conduction was also greater when the diel surface water temperature variability was high (e.g. range of 6°C). The heat flux by advection varied between -120 and 145Wm-2 (for typical water temperatures and vertical flow conditions within Catamaran Brook, 0-25°C and ±0.005mh-1). Short-term heat exchange (diel) occurred within the thermally active depth, typically <0.7m. The long-term annual streambed heat flux by conduction was also calculated and daily mean was generally less than ±11Wm-2. Winter conditions provided a unique opportunity to analyse streambed heat fluxes under steady-state conditions when both conduction and advection fluxes were present.
Chiang G., Munkittrick K.R., McMaster M.E., Barra R., Servos M. (2014). Regional Cumulative Effects Monitoring framework: Gaps and challenges for the Biobío river basin in south central Chile. Gayana, 78(2) 109-119.

Sustainable watershed management in the world is an issue that has taken much importance and attention in terms of quality and availability of water for all users in the basin. The economic growth experienced by Chile in recent years has led to increased stress on aquatic systems, especially in the Biobío river basin. The Biobío basin has faced with multiple expansions for hydroelectric power, and at the same time providing sources for competing demands from urbanization, industry, agriculture and irrigation, forestry, aquaculture, tourism, recreation, and it is a regional domain of indigenous peoples. There is a growing unease about the current process of managing single developments with Environmental Impacts Assessment (EIA). Assessing the impacts of all these threats to freshwater ecosystem is challenging. The Biobío offers an opportunity to make advances in a number of important areas for regional watershed management, including national standardization requirements for effects monitoring and for the development of a regional database. For Biobío river basin, development of such a conceptual framework requires several steps that include identifying: the scope (basin and/or subbasin) and setting (physiographic/geopolitics governance); threats to the system (past present and future); regional resource users and public services, and natural variation and gradients within the system. In these review we state what kind of pilot studies would be required to help design a Regional Cumulative Effects Monitoring Framework and must establish key design criteria including what species (species differential sensitivity) and parameters (level of organization), the magnitude of change we wish to detect and monitoring frequency are necessary to ensure sustainable management of the Biobío river basin.
Chishti Y.Z., Feswick A., Martyniuk C.J. (2014). Progesterone increases ex vivo testosterone production and decreases the expression of progestin receptors and steroidogenic enzymes in the fathead minnow (Pimephales promelas) ovary. General and Comparative Endocrinology, 199 16-25.

Progesterone (P4) is a metabolic precursor for a number of steroids, including estrogens and androgens. P4 also has diverse roles within the vertebrate ovary that include oocyte growth and development. The objectives of this study were to measure the effects of P4 on testosterone (T) and 17β-estradiol (E<inf>2</inf>) production in the fathead minnow (FHM) ovary and on the mRNA abundance of transcripts involved in steroidogenesis and steroid receptor signaling. Ovary explants were treated with P4 (10-6M) for 6 and 12h. P4 administration significantly increased T production ~3-fold at both 6 and 12h, whereas E<inf>2</inf> production was not affected, consistent with the hypothesis that excess P4 is not converted to terminal estrogens in the mature ovary. Nuclear progesterone receptor mRNA was decreased at 6h and membrane progesterone receptor gamma-2 mRNA was significantly down-regulated at both 6 and 12h; however there was no change in membrane progesterone receptor alpha or beta mRNA levels. Androgen receptor (ar) and estrogen receptor 2a (esr2a) mRNA were significantly reduced at 6h with P4 treatment, but there was no change in esr2b mRNA at either time point. Transcripts for enzymes in the steroid pathway (star, hsd11b2) were significantly lower at 6h compared to controls, whereas cyp17a and cyp19a mRNA abundance did not change with treatments at either time point. These data suggest that P4 incubation can lead to increased T production in the FHM ovary without a concomitant change in E<inf>2,</inf> and that the membrane bound progestin receptors are differentially regulated by P4 in the teleost ovary. As environmental progestins have received increased attention due to their suspected role as endocrine disruptors, mechanistic data on the role of exogenous P4 treatments in the male and female gonad is warranted. © 2014 Elsevier Inc.
Clayden M.G., Kidd K.A., Chételat J., Hall B.D., Garcia E. (2014). Environmental, geographic and trophic influences on methylmercury concentrations in macroinvertebrates from lakes and wetlands across Canada. Ecotoxicology, 23(2) 273-284.

Macroinvertebrates are a key vector in the transfer of methylmercury (MeHg) to fish. However, the factors that affect MeHg concentrations and bioaccumulation in these organisms are not as well understood as for fish, and studies on a broad geographic scale are lacking. In this study, we gathered published and unpublished MeHg and carbon (δ13C) and nitrogen (δ15N) stable isotope data for freshwater macroinvertebrates from 119 lakes and wetlands across seven Canadian provinces, along with selected physical, chemical and biological characteristics of these systems. Overall, water pH was the most important determinant of MeHg concentrations in both predatory and non-predatory invertebrates [R<inf>adj</inf>2 = 0.32, p < 0.001; multivariate canonical redundancy analysis (RDA)]. The location of lakes explained additional variation in invertebrate MeHg (partial R2 = 0.08 and 0.06 for latitude and longitude, respectively; RDA), with higher concentrations in more easterly and southerly regions. Both invertebrate foraging behaviour and trophic position (indicated by functional feeding groups and δ15N values, respectively) also predicted MeHg concentrations in the organisms. Collectively, results indicate that in addition to their feeding ecology, invertebrates accumulate more MeHg in acidic systems where the supply of MeHg to the food web is typically high. MeHg concentrations in macroinvertebrates may also be influenced by larger-scale geographic differences in atmospheric mercury deposition among regions. © 2014 Springer Science+Business Media New York.
Clayden M.G., Kidd K.A., Wyn B., Kirk J.L., Muir D.C.G., Odriscoll N.J. (2014). Response to comment on "mercury biomagnification through food webs is affected by physical and chemical characteristics of lakes". Environmental Science and Technology, 48(17) 10526-10527.
Curry R.A., Gautreau M.D., Culp J.M. (2014). Fin tissues as surrogates of white muscle when assessing carbon and nitrogen stable isotope levels for Arctic and brook char. Environmental Biology of Fishes, 97(6) 627-633.

Arctic char (Salvelinus alpinus) are a fish species ubiquitous to the fresh waters of Arctic region and brook char (Salvelinus fontinalis) are similarly common across the sub-Arctic region of eastern Canada. Populations can be small in numbers, especially farther north thus it is important to develop non-lethal methods of sampling these fish to minimize the invasiveness and impact of scientific research. We examined the stable isotopes of nitrogen and carbon in white muscle, caudal fin, and adipose fin tissues of Arctic char and brook char (S. fontinalis) from northern Quebec and Labrador, Canada. Our results revealed several broad conclusions. First, differences among muscle, caudal fin, and adipose fin tissues were ~1 ‰ for freshwater Arctic and brook char. Second, the two species within the same drainage had similar stable isotope levels and tissue differences. Third, anadromous Arctic char show similar, non-significant differences among these tissues for δ15N, but muscle δ13C was highly enriched. Fourth, the stable isotope levels and tissue differences were the same for anadromous Arctic char from two watersheds where char use distinctly different ocean environments. Overall, it appears that caudal fin tissue in particular is a useful surrogate for white muscle δ13C and δ15N levels for Arctic and brook char in this region and thus, a non-lethal collection of a small sample of caudal fin tissue will provide an accurate measure of white muscle isotope levels. © 2013 Springer Science+Business Media Dordrecht.
Dafforn K.A., Baird D.J., Chariton A.A., Sun M.Y., Brown M.V., Simpson S.L., Kelaher B.P., Johnston E.L. (2014). Faster, Higher and Stronger? The Pros and Cons of Molecular Faunal Data for Assessing Ecosystem Condition. Advances in Ecological Research, 51 1-40.

Ecological observation of global change processes is dependent on matching the scale and quality of biological data with associated geophysical and geochemical driver information. Until recently, the scale and quality of biological observation on natural assemblages has often failed to match data generated through physical or chemical platforms due to constraints of cost and taxonomic resolution. With the advent of next-generation DNA sequencing platforms, creating 'big data' scale observations of biological assemblages across a wide range of phylogenetic groups are now a reality. Here we draw from a variety of studies to illustrate the potential benefits and drawbacks of this new data source for enhancing our observation of ecological change compared with traditional methods. We focus on a key habitat-estuaries-which are among the most threatened by anthropogenic change processes. When community composition data derived using morphological and molecular approaches were compared, the increased level of taxonomic resolution from the molecular approach allowed for greater discrimination between estuaries. Apart from higher taxonomic resolution, there was also an order of magnitude more taxonomic units recorded in the molecular approach relative to the morphological. While the morphological data set was constrained to traditional macroinvertebrate sampling, the molecular tools could be used to sample a wide range of taxa from the microphytobenthos, e.g., diatoms and dinoflagellates. Furthermore, the information provided by molecular techniques appeared to be more sensitive to a range of well-established drivers of benthic ecology. Our results indicated that molecular approaches are now sufficiently advanced to provide not just equivalent information to that collected using traditional morphological approaches, but rather an order of magnitude bigger, better, and faster data with which to address pressing ecological questions.
Feswick A., Ings J.S., Doyle M.A., Bosker T., Munkittrick K.R., Martyniuk C.J. (2014). Transcriptomics profiling and steroid production in mummichog (Fundulus heteroclitus) testes after treatment with 5α-dihydrotestosterone. General and Comparative Endocrinology, 203 106-119.

5α-Dihydrotestosterone (DHT) is a potent androgen in mammals with multiple roles; however the physiological actions of DHT in male fishes are not well known. To address this knowledge gap, male mummichog (. Fundulus heteroclitus) were continuously exposed to 0, 5, and 50. μg/L DHT for 21. days. Following exposure, testes were separated for histology, ex vivo incubation to measure steroidogenic capacity, and gene expression analyses (real-time PCR and microarray). DHT significantly decreased ex vivo 11-ketotestosterone (11KT) production in males exposed to 50. μg/L DHT but not 5. μg/L DHT, and DHT exposure did not affect ex vivo testosterone production. Histological examination revealed that the amount of interlobular and connective tissue present in the testes was increased in the 50. μg/L DHT treatment. Despite reductions in the production of 11KT, DHT did not affect the expression of targeted genes in the steroidogenic pathway such as steroidogenic acute regulatory protein (. star), P450 side chain cleavage (. cyp11a1) and 11β-hydroxysteroid dehydrogenase (. hsd11b3). Microarray analysis in the testes of individuals from control and 50. μg/L DHT revealed that males exposed to 50. μg/L DHT showed regulated transcriptional sub-networks that were related to immunity, regulation of blood flow, lipids and xenobiotic clearance, suggesting that DHT may be involved in the physiological regulation of these processes in the fish testes. A second objective of this study was to determine the feasibility of measuring mRNA levels in tissues used for ex vivo steroid production by comparing RNA integrity and transcript levels in testes of both immediately flash frozen tissue and incubated tissue. There was no significant difference in RNA quality between the two time points, indicating RNA integrity can remain intact for at least 18. h in ex vivo assays, thereby providing a viable option for researchers assessing multi-level biological reproductive endpoints when limited tissue is available. While the gene expression levels of actb, efla, rps12, rps18, star, and hsd11b3 remained unchanged, esr2a (. esrba), esr2b (. esrbb) and cyp11a1 were significantly lower in incubated tissue compared to flash frozen tissue. Therefore caution must be used as the steady-state levels of select genes may change over time. This study improves our understanding of DHT action in the teleostean testis and generates new hypotheses regarding cell processes that are regulated by this underexplored and potent androgen. © 2014 Elsevier Inc.
Gray C., Baird D.J., Baumgartner S., Jacob U., Jenkins G.B., O'Gorman E.J., Lu X., Ma A., Pocock M.J.O., Schuwirth N., Thompson M., Woodward G. (2014). FORUM: Ecological networks: The missing links in biomonitoring science. Journal of Applied Ecology, 51(5) 1444-1449.

Monitoring anthropogenic impacts is essential for managing and conserving ecosystems, yet current biomonitoring approaches lack the tools required to deal with the effects of stressors on species and their interactions in complex natural systems. Ecological networks (trophic or mutualistic) can offer new insights into ecosystem degradation, adding value to current taxonomically constrained schemes. We highlight some examples to show how new network approaches can be used to interpret ecological responses. Synthesis and applications. Augmenting routine biomonitoring data with interaction data derived from the literature, complemented with ground-truthed data from direct observations where feasible, allows us to begin to characterise large numbers of ecological networks across environmental gradients. This process can be accelerated by adopting emerging technologies and novel analytical approaches, enabling biomonitoring to move beyond simple pass/fail schemes and to address the many ecological responses that can only be understood from a network-based perspective. Augmenting routine biomonitoring data with interaction data derived from the literature, complemented with ground-truthed data from direct observations where feasible, allows us to begin to characterise large numbers of ecological networks across environmental gradients. This process can be accelerated by adopting emerging technologies and novel analytical approaches, enabling biomonitoring to move beyond simple pass/fail schemes and to address the many ecological responses that can only be understood from a network-based perspective.
Green N.R., MacQuarrie K.T.B. (2014). An evaluation of the relative importance of the effects of climate change and groundwater extraction on seawater intrusion in coastal aquifers in Atlantic Canada. Hydrogeology Journal, 22(3) 609-623.

To investigate the relative importance of projected sea-level rise, climate change effects on recharge, and groundwater extraction on seawater intrusion in important coastal aquifers in Atlantic Canada, a three-dimensional numerical model of density-dependent groundwater flow coupled with solute transport was developed for the Richibucto region of New Brunswick. The model was used, with an efficient 2k factorial design approach, to perform simulations for the period 2011-2100. The results of the factorial analyses indicate that the relative importance of the three factors investigated varies depending on the model location considered. The effect of declining recharge is most significant at shallow to intermediate depths along the freshwater-seawater transition zone, while the effect of increasing pumping rates dominates at a location relatively close to the well field. The effect of sea-level rise is shown to be significant only at the much deeper inland toe of the transition zone. The spatial variation in importance is related to how different model boundary conditions influence freshwater flow at the different locations within the model domain. This investigation indicates that sea-level rise has the least significant effect (of the three factors considered) on future seawater intrusion in sandstone aquifers in the Richibucto region. © 2013 Springer-Verlag Berlin Heidelberg.
Guyette M.Q., Loftin C.S., Zydlewski J., Cunjak R. (2014). Carcass analogues provide marine subsidies for macroinvertebrates and juvenile Atlantic salmon in temperate oligotrophic streams. Freshwater Biology, 59(2) 392-406.

Anadromous fish populations entering freshwater ecosystems provide organic matter and marine-derived nutrients during spawning and subsequent mortalities of adults. Dams and other impediments to connectivity in rivers and streams have affected anadromous fish populations in many regions and prevented or reduced this influx of organic materials and nutrients. This study used historical data on the timing of delivery of marine-derived nutrients; we added a carcass analogue (pellets made from the carcasses of Chinook salmon, Oncorhynchus tschawytcha) to simulate potential effects of restored access of anadromous fish to streams. We used stable isotopes to document the extent of nutrient incorporation of nitrogen and carbon from the carcass analogue by macroinvertebrates and juvenile Atlantic salmon (Salmo salar) in salmon nursery streams. We stocked four headwater streams that historically hosted spawning Atlantic salmon and sea lamprey (Petromyzon marinus) in Maine, U.S.A. with Atlantic salmon fry and simulated timing of nutrient addition by spawning sea lamprey in the early summer and Atlantic salmon in the autumn. Macroinvertebrates and Atlantic salmon assimilated nitrogen (12-57% of total N) and carbon (21-65% of total C) from the added pellets, and the magnitude and duration of enrichment varied temporally and with macroinvertebrate functional feeding group. Assimilation of nutrients from carcass analogues was both direct and indirect, and a nutrient legacy was evident in the second year of sampling. Incorporation of nutrients from the pellets at a range of heights in the food web demonstrated the potential for marine-derived subsidies to contribute to freshwater ecosystem processes in Atlantic salmon nursery streams. © 2013 John Wiley & Sons Ltd.
Hayden B., Harrod C., Kahilainen K.K. (2014). Dual fuels: Intra-annual variation in the relative importance of benthic and pelagic resources to maintenance, growth and reproduction in a generalist salmonid fish. Journal of Animal Ecology, 83(6) 1501-1512.

Ecological systems are often characterized as stable entities. However, basal productivity in most ecosystems varies between seasons, particularly in subarctic and polar areas. How this variability affects higher trophic levels or entire food webs remains largely unknown, especially in these high-latitude regions. We undertook a year-long study of benthic (macroinvertebrate) and pelagic (zooplankton) resource availability, along with short (day/days: stomach content)-, medium (month: liver δ13C and δ15N isotopes)- and long-term (season: muscle δ13C and δ15N isotopes) assessments of resource use by a generalist fish, the European whitefish, in a deep, oligotrophic, subarctic lake in northern Europe. Due to the long ice-covered winter period, we expected to find general benthic reliance throughout the year, but also a seasonal importance of zooplankton to the diet, somatic growth and gonadal development of whitefish. Benthic and pelagic resource availability varied between seasons: peak littoral benthic macroinvertebrate density occurred in mid-winter, whereas maximum zooplankton density was observed in summer. Whitefish stomach content revealed a reliance on benthic prey items during winter and pelagic prey in summer. A seasonal shift from benthic to pelagic prey was evident in liver isotope ratios, but muscle isotope ratios indicated a year-round reliance on benthic macroinvertebrates. Whitefish activity levels as well as somatic and gonadal growth all peaked during the summer, coinciding with the zooplankton peak and the warmest water temperature. Stable isotopes of muscle consistently depicted the most important resource, benthic macroinvertebrates, whereas short-term indicators, that is, diet and stable isotopes of liver, revealed the seasonal significance of pelagic zooplankton for somatic growth and gonad development. Seasonal variability in resource availability strongly influences consumer growth and reproduction and may also be important in other ecosystems facing pronounced annual weather fluctuations.
Jardine T.D., Hadwen W.L., Hamilton S.K., Hladyz S., Mitrovic S.M., Kidd K.A., Tsoi W.Y., Spears M., Westhorpe D.P., Fry V.M., Sheldon F., Bunn S.E. (2014). Understanding and overcoming baseline isotopic variability in running waters. River Research and Applications, 30(2) 155-165.

Natural abundances of stable isotopes in lotic food webs yield valuable information about sources of organic matter for consumers and trophic structure. However, interpretation of isotopic information can be challenging in the face of variability in organisms at the base of food webs. Unionid and dreissenid mussels, commonly used as baseline organisms in lakes, are uncommon in many river settings and can have variable diets, thus making them unsuitable as a universal baseline for many river food web studies and often forcing reliance on more common benthic insects for this purpose. Turnover rates of body carbon and nitrogen in insects are relatively rapid (1 to 50days half-life). These rapid turnover rates in primary consumers can result in considerable temporal variability in δ13C that rivals that of algae (>10‰ range within a site). This suggests that using primary consumers as a surrogate baseline for algae may not circumvent the problem of temporal variability and the resultant mismatch of sources with longer-lived, slow-growing secondary and tertiary consumers. There are several strategies for reducing the influence of these confounding factors when bivalves with a known diet are not present. These include sampling over large spatial scales and correlating δ13C of consumers with the source of interest (e.g. benthic algae), sampling baseline organisms multiple times in the weeks preceding sampling of larger consumers (particularly in response to large changes in discharge) and using algal-detrital separation methods and multiple tracers as much as possible. Incorporating some of these recommendations and further exploring variability at the base of the food web will potentially provide greater insights into consumer-resource coupling in running waters and more robust conclusions about food web structure and energy flow in these dynamic systems. © 2012 John Wiley & Sons, Ltd.
Kidd K.A., Paterson M.J., Rennie M.D., Podemski C.L., Findlay D.L., Blanchfield P.J., Liber K. (2014). Direct and indirect responses of a freshwater food web to a potent synthetic oestrogen. Philosophical Transactions of the Royal Society B Biological Sciences, 369(1656).

Endocrine-disrupting chemicals (EDCs) in municipal effluents directly affect the sexual development and reproductive success of fishes, but indirect effects on invertebrate prey or fish predators through reduced predation or prey availability, respectively, are unknown. At the Experimental Lakes Area in northwestern Ontario, Canada, a long-term, whole-lake experiment was conducted using a before-after-control-impact design to determine both direct and indirect effects of the synthetic oestrogen used in the birth control pill, 17α-ethynyloestradiol (EE2). Algal, microbial, zooplankton and benthic invertebrate communities showed no declines in abundance during three summers of EE2 additions (5–6 ng l−1), indicating no direct toxic effects. Recruitment of fathead minnow (Pimephales promelas) failed, leading to a near-extirpation of this species both 2 years during (young-of-year, YOY) and 2 years following (adults and YOY) EE2 additions. Body condition of male lake trout (Salvelinus namaycush) and male and female white sucker (Catostomus commersonii) declined before changes in prey abundance, suggesting direct effects of EE2 on this endpoint. Evidence of indirect effects of EE2 was also observed. Increases in zooplankton, Chaoborus, and emerging insects were observed after 2 or 3 years of EE2 additions, strongly suggesting indirect effects mediated through the reduced abundance of several small-bodied fishes. Biomass of top predator lake trout declined by 23–42% during and after EE2 additions, most probably an indirect effect from the loss of its prey species, the fathead minnow and slimy sculpin (Cottus cognatus). Our results demonstrate that small-scale studies focusing solely on direct effects are likely to underestimate the true environmental impacts of oestrogens in municipal wastewaters and provide further evidence of the value of whole-ecosystem experiments for understanding indirect effects of EDCs and other aquatic stressors.
Kurylyk B.L., Macquarrie K.T.B. (2014). A new analytical solution for assessing climate change impacts on subsurface temperature. Hydrological Processes, 28(7) 3161-3172.

Groundwater temperature is an important water quality parameter that affects species distributions in subsurface and surface environments. To investigate the response of subsurface temperature to atmospheric climate change, an analytical solution is derived for a one-dimensional, transient conduction-advection equation and verified with numerical methods using the finite element code SUTRA. The solution can be directly applied to forward model the impact of future climate change on subsurface temperature profiles or inversely applied to produce a surface temperature history from measured borehole profiles. The initial conditions are represented using superimposed linear and exponential functions, and the boundary condition is expressed as an exponential function. This solution expands on a classic solution in which the initial and boundary conditions were restricted to linear functions. The exponential functions allow more flexibility in matching climate model projections (boundary conditions) and measured temperature-depth profiles (initial conditions). For example, measured borehole temperature data from the Sendai Plain and Tokyo, Japan, were used to demonstrate the improved accuracy of the exponential function for replicating temperature-depth profiles. Also, the improved accuracy of the exponential boundary condition was demonstrated using air temperature anomaly data from the Intergovernmental Panel on Climate Change. These air temperature anomalies were then used to forward model the effect of surficial thermal perturbations in subsurface environments with significant groundwater flow. The simulation results indicate that recharge can accelerate shallow subsurface warming, whereas upward groundwater discharge can enhance deeper subsurface warming. Additionally, the simulation results demonstrate that future groundwater temperatures obtained from the proposed analytical solution can deviate significantly from those produced with the classic solution. © 2013 John Wiley & Sons, Ltd.
Kurylyk B.L., MacQuarrie K.T.B., Voss C.I. (2014). Climate change impacts on the temperature and magnitude of groundwater discharge from shallow, unconfined aquifers. Water Resources Research, 50(4) 3253-3274.

Cold groundwater discharge to streams and rivers can provide critical thermal refuge for threatened salmonids and other aquatic species during warm summer periods. Climate change may influence groundwater temperature and flow rates, which may in turn impact riverine ecosystems. This study evaluates the potential impact of climate change on the timing, magnitude, and temperature of groundwater discharge from small, unconfined aquifers that undergo seasonal freezing and thawing. Seven downscaled climate scenarios for 2046-2065 were utilized to drive surficial water and energy balance models (HELP3 and ForHyM2) to obtain future projections for daily ground surface temperature and groundwater recharge. These future surface conditions were then applied as boundary conditions to drive subsurface simulations of variably saturated groundwater flow and energy transport. The subsurface simulations were performed with the U.S. Geological Survey finite element model SUTRA that was recently modified to include the dynamic freeze-thaw process. The SUTRA simulations indicate a potential rise in the magnitude (up to 34%) and temperature (up to 3.6C) of groundwater discharge to the adjacent river during the summer months due to projected increases in air temperature and precipitation. The thermal response of groundwater to climate change is shown to be strongly dependent on the aquifer dimensions. Thus, the simulations demonstrate that the thermal sensitivity of aquifers and baseflow-dominated streams to decadal climate change may be more complex than previously thought. Furthermore, the results indicate that the probability of exceeding critical temperature thresholds within groundwater-sourced thermal refugia may significantly increase under the most extreme climate scenarios. © 2014. American Geophysical Union. All Rights Reserved.
Lapointe N.W.R., Cooke S.J., Imhof J.G., Boisclair D., Casselman J.M., Curry R.A., Langer O.E., McLaughlin R.L., Minns C.K., Post J.R., Power M., Rasmussen J.B., Reynolds J.D., Richardson J.S., Tonn W.M. (2014). Principles for ensuring healthy and productive freshwater ecosystems that support sustainable fisheries. Environmental Reviews, 22(2) 110-134.

Freshwater ecosystems and the fisheries they support are increasingly threatened by human activities. To aid in their management and protection, we outline nine key principles for supporting healthy and productive ecosystems based on the best available science, including laws of physics and chemistry apply to ecology; population dynamics are regulated by reproduction, mortality, and growth; habitat quantity and quality are prerequisites of fish productivity; connectivity among habitats is essential for movements of fishes and their resources; freshwater species and their habitats are tightly linked to surrounding watersheds; biodiversity can enhance ecosystem resiliency and productivity; global processes affect local populations; anthropogenic stressors have cumulative effects; and evolutionary processes can be important. Based on these principles, we provide general recommendations for managing and protecting freshwater ecosystems and the fisheries they support, with examples of successful implementation for each strategy. Key management strategies include engage and consult with stakeholders; ensure that agencies have sufficient capacity, legislation, and authority to implement policies and management plans; define metrics by which fisheries resources and management success or failure will be measured; identify and account for threats to ecosystem productivity; adopt the precautionary approach to management; embrace adaptive management; implement ecosystem-based management; account for all ecosystem services provided by aquatic ecosystems; protect and restore habitat as the foundation for fisheries; and protect biodiversity. Ecosystems are complex with many intertwined components and ignoring linkages and processes significantly reduces the probability of management success. These principles must be considered when identifying management options and developing policies aiming to protect productive freshwater ecosystems and sustainable fisheries. © 2013 Published by NRC Research Press.
Lento J., Morin A. (2014). Filling the gaps in stream size spectra: Using electroshocking to collect large macroinvertebrates. Hydrobiologia, 732(1) 1-17.

Studies of stream benthic macroinvertebrate size distributions describe assemblages from random small area samplers or cobbles. Large organisms are often underestimated in these samples because of their mobility or low densities. This study compared the performance of cobble collection and a Hess sampler with electrobugging (using a backpack electroshocker to collect macroinvertebrates) to determine whether electrobugging could improve estimates of the biomass of large organisms. We sampled 12 stream sites, collecting cobbles and Hess samples and conducting 3-4 consecutive electrobugging passes (repeating until attrition was observed, following with kick samples). Electrobugging collected more biomass of mobile taxa than cobble or Hess samples, and collected greater taxonomic richness, particularly at sites with low algal biomass. However, it was less effective at collecting attached and immobile taxa. Electrobugging extended the size distribution range by up to eight size classes by collecting larger macroinvertebrates than the cobble or Hess methods, and collected significantly more taxa per size class. Size distributions created from only cobble or Hess samples clearly do not represent the entire benthic community, but our results indicate that electrobugging provides a means to improve estimates of the biomass of large, mobile taxa, providing a more accurate estimate of body size distributions. © 2014 Springer International Publishing Switzerland.
León-Olea M., Martyniuk C.J., Orlando E.F., Ottinger M.A., Rosenfeld C.S., Wolstenholme J.T., Trudeau V.L. (2014). Current concepts in neuroendocrine disruption. General and Comparative Endocrinology, 203 158-173.

In the last few years, it has become clear that a wide variety of environmental contaminants have specific effects on neuroendocrine systems in fish, amphibians, birds and mammals. While it is beyond the scope of this review to provide a comprehensive examination of all of these neuroendocrine disruptors, we will focus on select representative examples. Organochlorine pesticides bioaccumulate in neuroendocrine areas of the brain that directly regulate GnRH neurons, thereby altering the expression of genes downstream of GnRH signaling. Organochlorine pesticides can also agonize or antagonize hormone receptors, adversely affecting crosstalk between neurotransmitter systems. The impacts of polychlorinated biphenyls are varied and in many cases subtle. This is particularly true for neuroedocrine and behavioral effects of exposure. These effects impact sexual differentiation of the hypothalamic-pituitary-gonadal axis, and other neuroendocrine systems regulating the thyroid, metabolic, and stress axes and their physiological responses. Weakly estrogenic and anti-androgenic pollutants such as bisphenol A, phthalates, phytochemicals, and the fungicide vinclozolin can lead to severe and widespread neuroendocrine disruptions in discrete brain regions, including the hippocampus, amygdala, and hypothalamus, resulting in behavioral changes in a wide range of species. Behavioral features that have been shown to be affected by one or more these chemicals include cognitive deficits, heightened anxiety or anxiety-like, sociosexual, locomotor, and appetitive behaviors. Neuroactive pharmaceuticals are now widely detected in aquatic environments and water supplies through the release of wastewater treatment plant effluents. The antidepressant fluoxetine is one such pharmaceutical neuroendocrine disruptor. Fluoxetine is a selective serotonin reuptake inhibitor that can affect multiple neuroendocrine pathways and behavioral circuits, including disruptive effects on reproduction and feeding in fish. There is growing evidence for the association between environmental contaminant exposures and diseases with strong neuroendocrine components, for example decreased fecundity, neurodegeneration, and cardiac disease. It is critical to consider the timing of exposures of neuroendocrine disruptors because embryonic stages of central nervous system development are exquisitely sensitive to adverse effects. There is also evidence for epigenetic and transgenerational neuroendocrine disrupting effects of some pollutants. We must now consider the impacts of neuroendocrine disruptors on reproduction, development, growth and behaviors, and the population consequences for evolutionary change in an increasingly contaminated world. This review examines the evidence to date that various so-called neuroendocrine disruptors can induce such effects often at environmentally-relevant concentrations. © 2014 Elsevier Inc.
Liang X., Li W., Martyniuk C.J., Zha J., Wang Z., Cheng G., Giesy J.P. (2014). Effects of dechlorane plus on the hepatic proteome of juvenile Chinese sturgeon (Acipenser sinensis). Aquatic Toxicology, 148 83-91.

Dechlorane Plus (DP), an alternative to decabromodiphenyl ether (BDE-209), is a widely used polychlorinated flame retardant that is frequently detected in aquatic ecosystems. While the mechanisms of toxicity of BDE-209 have been well documented, less is known about the toxicity of DP. In this study, juvenile Chinese sturgeon (Acipenser sinensis) were treated with DP at doses of 1, 10, and 100mg/kg wet weight for 14 days via a single intraperitoneal injection (i.p.). After 14 days, liver proteomes of juvenile Chinese sturgeon were analyzed using two-dimensional electrophoresis (2-DE) coupled matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-TOF/TOF-MS). A total of 39 protein spots were significantly altered in abundance (>2-fold) and of these proteins, 27 were successfully identified. Proteins related to the stress response that included heat shock cognate protein 70 and T-complex protein 1 were significantly increased and decreased in abundance, respectively. Moreover, Ras-related protein Rab-6B and GDP dissociation inhibitor 2, proteins that are involved in small G-protein signal cascades, were decreased in abundance 2- to 5-fold. Annexin A4, which is associated with Ca2+ signaling pathways, was also markedly decreased by 2-fold in the liver. Pathway analysis of differentially regulated proteins revealed that DP interfered with metabolism and was associated with proteins related to apoptosis and cell differentiation. Based upon protein responses, we suggest that DP has effects on the generalized stress response, small G-protein signal cascades, Ca2+ signaling pathway, and metabolic process, and may induce apoptosis in the liver. This study offers novel mechanistic insight into the protein responses induced in the liver with DP, an increasingly used and understudied flame retardant. © 2014 Elsevier B.V.
Liang X., Martyniuk C.J., Cheng G., Zha J., Wang Z. (2014). Pyruvate carboxylase as a sensitive protein biomarker for exogenous steroid chemicals. Environmental Pollution, 189 184-193.

Assessing protein responses to endocrine disrupting chemicals is critical for understanding the mechanisms of chemical action and for the assessment of hazards. In this study, the response of the liver proteome of male rare minnows (Gobiocypris rarus) treated with 17β-estradiol (E2) and females treated with 17α-methyltestosterone (MT) were analyzed. A total of 23 and 24 proteins were identified with differential expression in response to E2 and MT, respectively. Pyruvate carboxylase (PC) was the only common differentially expressed protein in both males and females after E2- and MT-treatments. The mRNA as well as the protein levels of PC were significantly down-regulated compared with that of the controls (p < 0.05). Our results suggest that endocrine disruptors interfere with genes and proteins of the TCA cycle and PC may be a sensitive biomarker of exposure to exogenous steroid chemicals in the liver of fish. © 2014 Elsevier Ltd. All rights reserved.
Loughery J.R., Arciszewski T.J., Kidd K.A., Mercer A., Hewitt L.M., MacLatchy D.L., Munkittrick K.R. (2014). Understanding the chronic impacts of oil refinery wastewater requires consideration of sediment contributions to toxicity. Archives of Environmental Contamination and Toxicology, 66(1) 19-31.

Previous studies at an oil refinery in Saint John, New Brunswick, Canada, found a diminished fish community downstream of the effluent outfall that appeared to be associated with periodic low dissolved oxygen concentrations due to episodic discharges of contaminated transport vessel ballast water. This study was initiated after the ballast water was removed from the effluent to further investigate the potential causes of residual effects in the study stream, Little River. We used field caging of fish, laboratory bioassays, and chemical analysis of effluents and sediments from the field site to determine if the effluent or contaminated sediments were affecting the recovery of the fish community in Little River. The field studies suggested that exposed, caged fish were affected, displaying >40% increases in liver sizes and increased liver detoxification enzyme activity (cytochrome P450 1A, CYP1A); however, similar responses were absent in laboratory exposures that used effluent only. Adding sediments collected from the vicinity of the refinery's outfall to the laboratory bioassays reproduced some of the field responses. Chemical analyses showed high concentrations of PAHs in sediments but low concentrations in the effluent, suggesting that the PAHs in the sediment were contributing more to the impacts than the effluent. Application of effects-based monitoring is suggested as beneficial to identify impacts to fisheries where refinery effluents of this type are involved. © Springer Science+Business Media 2013.
Maheu A., Caissie D., St-Hilaire A., El-Jabi N. (2014). River evaporation and corresponding heat fluxes in forested catchments. Hydrological Processes, 28(23) 5725-5738.

River water temperature is a very important variable in ecological studies, especially for the management of fisheries and aquatic resources. Temperature can impact on fish distribution, growth, mortality and community dynamics. River evaporation has been identified as an important heat loss and a key process in the thermal regime of rivers. However, its quantification remains a challenge, mainly because of the difficulty of making direct measurements. The objectives of this study were to characterize the evaporative heat flux at different scales (brook vs river) and to improve the estimation of the evaporative heat flux in a stream temperature model at the hourly timescale. Using a mass balance approach with floating minipans, we measured river evaporation at an hourly timescale in a medium-sized river (Little Southwest Miramichi) and a small brook (Catamaran Brook) in New Brunswick, Canada. With these direct measurements of evaporation, we developed mass transfer equations to estimate hourly evaporation rates from microclimate conditions measured 2m above the stream. During the summer 2012, river evaporation was more important for the medium-sized river with a mean daily evaporation rate of 3.0mmday-1 in the Little Southwest Miramichi River compared with that of 1.0mmday-1 in Catamaran Brook. Evaporation was the main heat loss mechanism in the two studied streams and was responsible for 42% of heat losses in the Little Southwest Miramichi River and 34% of heat losses in Catamaran Brook during the summer.
Marlatt V.L., Sun J., Curran C.A., Bailey H.C., Kennedy C.K., Elphick J.R., Martyniuk C.J. (2014). Molecular responses to 17β-estradiol in early life stage salmonids. General and Comparative Endocrinology, 203 203-214.

Environmental estrogens (EE) are ubiquitous in many aquatic environments and biological responses to EEs in early developmental stages of salmonids are poorly understood compared to juvenile and adult stages. Using 17β-estradiol (E2) as a model estrogen, waterborne exposures were conducted on early life stage rainbow trout (. Oncorhynchus mykiss; egg, alevin, swim-up fry) and both molecular and physiological endpoints were measured to quantify the effects of E2. To investigate developmental stage-specific effects, laboratory exposures of 1. μg/L E2 were initiated pre-hatching as eyed embryos or post-hatching upon entering the alevin stage. High mortality (~90%) was observed when E2 exposures were initiated at the eyed embryo stage compared to the alevin stage (~35% mortality), demonstrating stage-specific sensitivity. Gene expression analyses revealed that vitellogenin was detectable in the liver of swim-up fry, and was highly inducible by 1. μg/L E2 (>200-fold higher levels compared to control animals). Experiments also confirmed the induction of vitellogenin protein levels in protein extracts isolated from head and tail regions of swim-up fry after E2 exposure. These findings suggest that induction of vitellogenin, a well-characterized biomarker for estrogenic exposure, can be informative measured at this early life stage. Several other genes of the reproductive endocrine axis (e.g. estrogen receptors and androgen receptors) exhibited decreased expression levels compared to control animals. In addition, chronic exposure to E2 during the eyed embryo and alevin stages resulted in suppressive effects on growth related genes (growth hormone receptors, insulin-like growth factor 1) as well as premature hatching, suggesting that the somatotropic axis is a key target for E2-mediated developmental and growth disruptions. Combining molecular biomarkers with morphological and physiological changes in early life stage salmonids holds considerable promise for further defining estrogen action during development, and for assessing the impacts of endocrine disrupting chemicals in vivo in teleosts. © 2014 Elsevier Inc.
Martyniuk C.J., Bissegger S., Langlois V.S. (2014). Reprint of "Current perspectives on the androgen 5 alpha-dihydrotestosterone (DHT) and 5 alpha-reductases in teleost fishes and amphibians". General and Comparative Endocrinology, 203 10-20.

The androgen 5 alpha-dihydrotestosterone (DHT) is a steroidogenic metabolite that has received little attention in non-mammalian species. DHT is produced by the reduction of the double-bond of testosterone by a group of enzymes called 5 alpha-reductases of which there can be multiple isoforms (i.e., srd5a1, srd5a2, and srd5a3). Data from amphibians suggest that the expression of the srd5a genes occurs in early development, and continues until adulthood; however insufficient data exist in fish species, where DHT is thought to be relatively biologically inactive. Here, we demonstrate that fathead minnow (FHM; Pimephales promelas) developing embryos and adults express srd5a enzyme isoforms. During FHM embryogenesis, both srd5a1 and srd5a3 mRNA levels were significantly correlated in expression levels while srd5a2 showed a more unique pattern of expression. In adult FHMs, males had significantly higher levels of srd5a2 in the liver and gonad compared to females. In the male and female liver, transcript levels for srd5a2 were more abundant compared to srd5a1 and srd5a3, suggesting a prominent role for srd5a2 in this tissue. Interestingly, the ovary expressed higher mRNA levels of srd5a3 than the testis. Thus, data suggest that srd5a isoforms can show sexually dimorphic expression patterns in fish. We also conducted a literature review of the biological effects observed in embryonic and adult fish and amphibians after treatments with DHT and DHT-related compounds. Treatments with DHT in teleost fishes and amphibians have resulted in unexpected biological responses that are characteristic of both androgens and anti-androgens. For example, in fish DHT can induce vitellogenin in vitro from male and female hepatocytes and can increase 17β-estradiol production from the teleost ovary. We propose, that to generate further understanding of the roles of DHT in non-mammals, studies are needed that (1) address how DHT is synthesized within tissues of fish and amphibians; (2) examine the full range of biological responses to endogenous DHT, and its interactions with other signaling pathways; and (3) investigate how DHT production varies with reproductive stage. Lastly, we suggest that the Srd5a enzymes can be targets of endocrine disruptors in fish and frogs, which may result in disruptions in the estrogen:androgen balance in aquatic organisms. © 2013 Elsevier Inc.
Mathieu-Denoncourt J., Martyniuk C.J., De Solla S.R., Balakrishnan V.K., Langlois V.S. (2014). Sediment contaminated with the azo dye disperse yellow 7 alters cellular stress- and androgen-related transcription in Silurana tropicalis larvae. Environmental Science and Technology, 48(5) 2952-2961.

Azo dyes are the most commonly used type of dye, accounting for 60-70% of all organic dye production worldwide. They are used as direct dyes in the textile, leather, printing ink, and cosmetic industries. The aim of this study was to assess the lethal and sublethal effects of the disazo dye Disperse Yellow 7 (DY7) in frogs to address a knowledge gap regarding mechanisms of toxicity and the potential for endocrine disrupting properties. Larvae of Silurana tropicalis (Western clawed frog) were exposed to DY7-contaminated water (0 to 22 μg/L) and sediment (0 to 209 μg/g) during early larval development. The concentrations used included the range of similar azo dyes found in surface waters in Canada. A significant decrease in tadpole survivorship was observed at 209 μg/g while there was a significant increase in malformations at the two highest concentrations tested in sediment. In the 209 μg/g treatment, DY7 significantly induced hsp70 (2.5-fold) and hsp90 (2.4-fold) mRNA levels, suggesting that cells required oxidative protection. The same treatment also altered the expression of two androgen-related genes: decreased ar (2-fold) and increased srd5a2 (2.6-fold). Furthermore, transcriptomics generated new hypotheses regarding the mechanisms of toxic action of DY7. Gene network analysis revealed that high concentrations of DY7 in sediment induced cellular stress-related gene transcription and affected genes associated with necrotic cell death, chromosome condensation, and mRNA processing. This study is the first to report on sublethal end points for azo dyes in amphibians, a growing environmental pollutant of concern for aquatic species. © 2014 American Chemical Society.
McAlpine D.F., Sollows M.C. (2014). A quadrat-sieve system for sampling freshwater mussels using SCUBA. Northeastern Naturalist, 21(1) N1-N4.

We describe a simple combined-quadrat-sieve system, suitable for in-river surveys of unionoid populations where SCUBA is required. The apparatus has allowed us to survey and excavate 0.25-m2 quadrats with mean search times of <7 min quadrat-1 over 4-hour dives. We have successfully detected mussels near the minimum size, more often retrieved by sieving at the surface, while minimizing habitat disturbance.
McDougall C.A., Anderson W.G., Peake S.J. (2014). Downstream Passage of Lake Sturgeon through a Hydroelectric Generating Station: Route Determination, Survival, and Fine-Scale Movements. North American Journal of Fisheries Management, 34(3) 546-558.

Downstream passage of Lake Sturgeon Acipenser fulvescens through hydroelectric facilities is known to occur but is poorly understood. Acoustic telemetry was used to investigate downstream-passage routes, survival, and fine-scale movements at the Slave Falls Generating Station, located on the Winnipeg River, Manitoba. Downstream-passage rates were estimated at 2.9% (range = 0.0-4.4%) per year for Slave Falls Reservoir adults and 21.1% (range = 19.3-22.9%) per year for subadults tagged in the lowermost section of the reservoir. No juvenile passage was observed. Lake Sturgeon movements immediately upstream of the Slave Falls Generating Station main sluiceway gates were related to bathymetric features. Fish that approached via deepwater habitat tended to abandon their downstream trajectory movements before or upon reaching the top of a relatively shallow (∼10 m depth) bedrock saddle that occurs ∼45 m upstream of the main sluiceway gates. Based on acoustic telemetry (fine-scale tracking and presence-absence data) and supplemental information, such as trash rack spacing and spill conditions, 7 of 11 (64%) observed downstream-passage events were concluded to have occurred via bottom-draw regulating sluices located in the northeastern end of the powerhouse. At least 91% of the observed downstream-passage events were survived. Results suggest that protection initiatives at hydroelectric facilities could exploit the Lake Sturgeon's bottom-oriented nature, with bottom-draw sluice gates likely providing a feasible way to facilitate safe downstream passage.Received June 28, 2013; accepted January 28, 2014. © 2014 © American Fisheries Society 2014.
Menberg K., Blum P., Kurylyk B.L., Bayer P. (2014). Observed groundwater temperature response to recent climate change. Hydrology and Earth System Sciences, 18(11) 4453-4466.

Climate change is known to have a considerable influence on many components of the hydrological cycle. Yet, the implications for groundwater temperature, as an important driver for groundwater quality, thermal use and storage, are not yet comprehensively understood. Furthermore, few studies have examined the implications of climate-change-induced groundwater temperature rise for groundwater-dependent ecosystems. Here, we examine the coupling of atmospheric and groundwater warming by employing stochastic and deterministic models. Firstly, several decades of temperature time series are statistically analyzed with regard to climate regime shifts (CRSs) in the long-term mean. The observed increases in shallow groundwater temperatures can be associated with preceding positive shifts in regional surface air temperatures, which are in turn linked to global air temperature changes. The temperature data are also analyzed with an analytical solution to the conduction-advection heat transfer equation to investigate how subsurface heat transfer processes control the propagation of the surface temperature signals into the subsurface. In three of the four monitoring wells, the predicted groundwater temperature increases driven by the regime shifts at the surface boundary condition generally concur with the observed groundwater temperature trends. Due to complex interactions at the ground surface and the heat capacity of the unsaturated zone, the thermal signals from distinct changes in air temperature are damped and delayed in the subsurface, causing a more gradual increase in groundwater temperatures. These signals can have a significant impact on large-scale groundwater temperatures in shallow and economically important aquifers. These findings demonstrate that shallow groundwater temperatures have responded rapidly to recent climate change and thus provide insight into the vulnerability of aquifers and groundwater-dependent ecosystems to future climate change.
Mennigen J.A., Martyniuk C.J., Seiliez I., Panserat S., Skiba-Cassy S. (2014). Metabolic consequences of microRNA-122 inhibition in rainbow trout, Oncorhynchus mykiss. BMC Genomics, 15(1).

Background: MicroRNAs (miRNAs) are small regulatory molecules which post-transcriptionally regulate mRNA stability and translation. Several microRNAs have received attention due to their role as key metabolic regulators. In spite of the high evolutionary conservation of several miRNAs, the role of miRNAs in lower taxa of vertebrates has not been studied with regard to metabolism. The liver-specific and highly abundant miRNA-122 is one of the most widely studied miRNA in mammals, where it has been implicated in the control of hepatic lipid metabolism. Following our identification of acute postprandial, nutritional and endocrine regulation of hepatic miRNA-122 isomiRNA expression in rainbow trout, we used complementary in silico and in vivo approaches to study the role of miRNA-122 in rainbow trout metabolism. We hypothesized that the role of miRNA-122 in regulating lipid metabolism in rainbow trout is conserved to that in mammals and that modulation of miRNA-122 function would result in altered lipid homeostasis and secondarily altered glucose homeostasis, since lipogenesis has been suggested to act as glucose sink in trout.Results: Our results show that miRNA-122 was functionally inhibited in vivo in the liver. Postprandial glucose concentrations increased significantly in rainbow trout injected with a miRNA-122 inhibitor, and this effect correlated with decreases in hepatic FAS protein abundance, indicative of altered lipogenic potential. Additionally, miRNA-122 inhibition resulted in a 20% decrease in plasma cholesterol concentration, an effect associated with increased expression of genes involved in cholesterol degradation and excretion.Conclusions: Overall evidence suggests that miRNA-122 may have evolved in early vertebrates to support liver-specific metabolic functions. Nevertheless, our data also indicate that metabolic consequences of miRNA-122 inhibition may differ quantitatively between vertebrate species and that distinct direct molecular targets of miRNA-122 may mediate metabolic effects between vertebrate species, indicating that miRNA-122 - mRNA target relationships may have undergone species-specific evolutionary changes. © 2014 Mennigen et al.; licensee BioMed Central Ltd.
Orlofske J.M., Baird D.J. (2014). A geometric morphometric approach to establish body-shape trait criteria for aquatic insects. Freshwater Science, 33(3) 978-994.

Body shapes of aquatic insect larvae reflect phenotypic responses to complex environmental conditions and can be used to infer habitat properties and indicate natural and anthropogenic perturbations in river ecosystems. Investigation of relationships between body shape and physical-habitat characteristics has been restricted by a lack of an objective schema for quantitative characterization of body-shape variation. We present a functional ecological framework for body-shape classification based on defined criteria. We applied a geometric morphometric (GM) approach to the general classification of body shape in 4 morphologically diverse orders, Ephemeroptera (E), Plecoptera (P), Trichoptera (T), and Odonata (O) collected from 3 sites with contrasting hydrological and hydraulic characteristics. We describe a robust classification of body shapes for E, P, and O, which possess a compartmentalized body plan, and suggest a preliminary classification for T. We compared GM body shapes with body-shape trait states available in trait databases and found discordance between the 2 classifications. We explored the value of GM body shapes to describe taxon shape structure of reference sites and to detect variation reflecting physical properties of the sites. GM body-shape classes can augment the trait states already available and enhance inference regarding habitat status. Patterns in the shape strategies of aquatic insects, particularly EPO taxa, can be used to extrapolate shape information for other taxonomic groups. GM provides a stable shape classification that can contribute to the description of different ecological strategies of aquatic insects. Expanding the scope of shape information available for many taxonomic groups can improve our understanding of how organism phenotype relates to environmental conditions and supports traits-based assessment. © 2014 by The Society for Freshwater Science.
Orlofske J.M., Baird D.J. (2014). Incorporating continuous trait variation into biomonitoring assessments by measuring and assigning trait values to individuals or taxa. Freshwater Biology, 59(3) 477-490.

Traits-based analyses of insect assemblages support biomonitoring programme objectives. To date, however, few traits-based metrics have demonstrated the degree of sensitivity or discriminatory power required by biomonitoring programmes. Trait information used for analyses is typically based on static descriptions of dynamic communities and is attributed only to taxonomic units. Given that traits can vary even among specimens from the same species, quantifying trait variation and its consequences could be essential for successful traits-based biomonitoring. Here, we study the consequences of measuring trait expression among individual specimens versus assigning trait states from published databases at the taxon level (genus or family) for the interpretation of trait patterns within aquatic insect assemblages. Specifically, do database body size trait states accurately reflect measured body size values of aquatic insects collected in biomonitoring samples and should body size data be aggregated at the taxon level or assessed at the specimen level to detect differences among sites? We assessed body size, a continuous trait linked to fundamental organism properties and ecological function, for four orders of aquatic insects: Ephemeroptera, Plecoptera, Trichoptera and Odonata. Invertebrate samples were collected from the Miramichi River basin (New Brunswick, Canada) according to the Canadian Aquatic Biomonitoring Network method. Concordance between measured specimen sizes and published trait states was poor; 55% of taxa expressed body sizes considerably smaller or larger than assigned database states. Recalibration of size classes based on specimen measurements yielded three size classes that facilitated detection of assemblage-aggregated size differences among reference sites. Measured body size trait values were able to distinguish these differences in community structure, while values derived from databases yielded erroneous patterns in the size structure among sites. Gaining accurate ecological insights from traits-based biomonitoring may require assessing trait properties at the scale of individual specimens. The benefits of this approach, however, should be balanced against additional effort required in the context of specific study or programme objectives. © 2013 Her Majesty the Queen in Right of Canada. Freshwater Biology © 2013 John Wiley & Sons Ltd.
Ouellet V., Secretan Y., St-Hilaire A., Morin J. (2014). Daily averaged 2D water temperature model for the St. Lawrence river. River Research and Applications, 30(6) 733-744.

A daily averaged two-dimensional water temperature model has been developed for the freshwater part of the St. Lawrence River, between Lake St. Louis and Trois-Rivières (Québec, Canada). The model was first calibrated and validated for the area of Lake St. Pierre, a natural enlargement of the river subject to strong lateral and longitudinal thermal variations. Forecasts from the Global Environmental Multiscale model were used in preference to observations from meteorological stations for model inputs, both to increase the spatial resolution and ultimately to allow the water temperature model to be used in predictive mode. The resulting model provided daily water temperature estimates with an overall root mean square error (RMSE) of 1.18°C and a Nash-Sutcliffe coefficient of 0.44. Comparisons between Landsat images and simulations demonstrated that the model not only simulated accurate water temperature values but also showed the adequacy of the model in general. It not only simulated local water temperature relatively accurately but also provided a good representation of the spatial water temperature patterns within the study area. The error varied between deep and shallow water areas. In deeper water, the overall RMSE is 0.41°C, and the modified Nash coefficient rises up to 0.92. Because shallow water areas are subject to greater variations, longer, more spatially dense data sets will be needed to refine the hydrodynamic and thermal budget models for those specific areas. © 2013 John Wiley & Sons, Ltd.
Ouellet V., Secretan Y., St-Hilaire A., Morin J. (2014). Water temperature modelling in a controlled environment: Comparative study of heat budget equations. Hydrological Processes, 28(2) 279-292.

One of the challenges when modelling a complex variable such as water temperature in rivers is that it can be difficult to determine the sources of error and to ensure that the simulations are truly representative of the reality. Therefore, a heat budget study was completed in a controlled environment, which excluded advection and bottom fluxes but enabled observation of all the other fluxes. A 21.42m3 pool was installed and insulated to limit heat exchange through the sides and bottom. All the major energy fluxes were monitored for a 50-day period. Different equations for individual heat budget terms were tested to determine their ability to reproduce the observations. This experiment also permitted to assess the relative importance of each component of the heat budget. Performance of each semi-empirical equation was determined by comparing predictions and measured values. It was thus possible to choose the formulae that best represented the measured heat exchange processes, while understanding the limits of some of the semi-empirical representations of heat exchange processes. The results highlight the importance of radiative terms into the heat budget because they controlled the major sources and sinks. The study also showed the importance of the wind function determination into the calculation of latent heat flux. The resulting water temperature model returned simulated hourly water temperature with an overall root mean square error of 0.71°C/h and a modified Nash-Sutcliffe coefficient of 0.97. © 2012 John Wiley & Sons, Ltd.
Pessier A.P., Baitchman E.J., Crump P., Wilson B., Griffith E., Ross H. (2014). Causes of Mortality in Anuran Amphibians From An Ex Situ Survival Assurance Colony in Panama. Zoo Biology, 33(6) 516-526.

The success of ex situ survival assurance populations as tools for amphibian conservation depends on the health and reproductive success of founder populations. Necropsy examination and histopathology of animals that die in assurance populations are useful for the identification of population-limiting disease problems and can help to direct applied research efforts in areas such as amphibian husbandry and nutrition. This study reviewed postmortem findings in 167 frogs from 13 species that died in a large Panamanian rescue and survival assurance population between 2006 and 2011. Common problems identified in long-term captive animals, especially in Atelopus species, were epithelial squamous metaplasia suggestive of vitamin A deficiency and a polycystic nephropathy resembling lesions seen in laboratory animals with electrolyte imbalances. Metabolic bone disease was a significant contributor to morbidity in captive-bred juvenile frogs of Gastrotheca cornuta, Hemiphractus fasciatus, and Hylomantis lemur. Findings common to multiple species included poor overall nutritional condition that was sometimes attributable to maladaptation to captive husbandry and epidermal hyperplasia and hyperkeratosis possibly reflecting environmental skin irritation. Infectious diseases and endoparasitism were most common in recently captured animals and included chytridiomycosis and Rhabdias sp. lungworms. Applied research efforts to improve sustainability of survival assurance populations should focus on elucidating optimal husbandry practices for diverse species, improving methods for nutritional supplementation of cultured insects and examination of the role of water composition in disease development.
Peters D.L., Monk W.A., Baird D.J. (2014). Cold-regions Hydrological Indicators of Change (CHIC) for ecological flow needs assessment. Hydrological Sciences Journal, 59(3-4) 502-516.

Ecological flow needs (EFN) frameworks incorporate a range of ecologically-relevant hydrological variables based on prior knowledge of river regime characteristics. However, when applied in cold regions, these approaches have largely ignored the influence of winter ice cover and the spring freshet on hydrological regimes: key components of river systems in cold regions with important direct effects on water quality, aquatic habitat and ecology. Here, we combine a review of the published literature on cold-regions hydrology and hydro-ecology with available hydrometric information for sites across Canada, a major cold-region country, to explore phenomena unique to these systems. We identify several ecologically-relevant hydrological measures (i.e. annual ice on/off dates, ice-cover duration, spring freshet initiation, peak water level during river ice break-up), pairing these with established metrics for incorporation into an enhanced suite of indicators specifically designed for cold regions. This paper presents the Cold-regions Hydrological Indicators of Change (CHIC), which can provide the basis for the assessment of EFN and climate change assessments in cold-region river ecosystems. Editor Z.W. Kundzewicz; Guest editor M. AcremanCitation Peters, D.L. Monk, W.A. and Baird, D.J. 2014. Cold-regions Hydrological Indicators of Change (CHIC) for ecological flow needs assessment. Hydrological Sciences Journal, 59 (3-4), 502-516. © 2014 © 2014 Crown Copyright.
Phalen L.J., Köllner B., Leclair L.A., Hogan N.S., van den Heuvel M.R. (2014). The effects of benzo[a]pyrene on leucocyte distribution and antibody response in rainbow trout (Oncorhynchus mykiss). Aquatic Toxicology, 147 121-128.

Polycyclic aromatic hydrocarbons (PAHs) are a group of compounds with immunotoxic and carcinogenic potential that may pose a threat to fish populations. This study aims to utilize a newly developed fish immunotoxicology model to determine the immune tissue/cell population level effects of PAHs on rainbow trout, using benzo[a]pyrene (BaP) as a representative immunotoxic PAH. Intraperitoneal injection of 25 or 100mg/kg BaP resulted in sustained exposure as indicated by biliary fluorescence at BaP wavelengths for up to 42 days. A new flow cytometry method for absolute counts of differential leucocyte distributions in spleen, blood, and head kidney was developed by combining absolute quantitative counts of total leukocytes in the tissue (3,3'-dihexyloxacarbocyanine iodide (DiOC<inf>6</inf>) dye) with relative differential counts using monoclonal antibodies for B cells, T cells, myeloid cells, and thrombocytes. Experiments indicated dose- and time-dependent decreases in the absolute number of B cells, myeloid cells, or T cells in blood, spleen, or head kidney after 7, 14 or 21 d of exposure. There was no change in the absolute numbers of erythrocytes or thrombocytes in any tissue. When rainbow trout were exposed to inactivated Aeromonas salmonicida after a 21 d exposure to 100mg/kg BaP, circulating antibody concentrations were decreased by 56%. It was concluded that BaP has a cell lineage-specific toxic effect on some immune cells of rainbow trout, and causes a decrease in circulating antibody levels. © 2013 Elsevier B.V.
Porter T.M., Gibson J.F., Shokralla S., Baird D.J., Golding G.B., Hajibabaei M. (2014). Rapid and accurate taxonomic classification of insect (class Insecta) cytochrome c oxidase subunit 1 (COI) DNA barcode sequences using a naïve Bayesian classifier. Molecular Ecology Resources, 14(5) 929-942.

Current methods to identify unknown insect (class Insecta) cytochrome c oxidase (COI barcode) sequences often rely on thresholds of distances that can be difficult to define, sequence similarity cut-offs, or monophyly. Some of the most commonly used metagenomic classification methods do not provide a measure of confidence for the taxonomic assignments they provide. The aim of this study was to use a naïve Bayesian classifier (Wang et al. Applied and Environmental Microbiology, 2007; 73: 5261) to automate taxonomic assignments for large batches of insect COI sequences such as data obtained from high-throughput environmental sequencing. This method provides rank-flexible taxonomic assignments with an associated bootstrap support value, and it is faster than the blast-based methods commonly used in environmental sequence surveys. We have developed and rigorously tested the performance of three different training sets using leave-one-out cross-validation, two field data sets, and targeted testing of Lepidoptera, Diptera and Mantodea sequences obtained from the Barcode of Life Data system. We found that type I error rates, incorrect taxonomic assignments with a high bootstrap support, were already relatively low but could be lowered further by ensuring that all query taxa are actually present in the reference database. Choosing bootstrap support cut-offs according to query length and summarizing taxonomic assignments to more inclusive ranks can also help to reduce error while retaining the maximum number of assignments. Additionally, we highlight gaps in the taxonomic and geographic representation of insects in public sequence databases that will require further work by taxonomists to improve the quality of assignments generated using any method. © 2014 Her Majesty the Queen in Right of Canada. Molecular Ecology Resources Published by John Wiley & Sons Ltd Reproduced with the permission of the Minister of Environment.
Roussel J.M., Perrier C., Erkinaro J., Niemelä E., Cunjak R.A., Huteau D., Riera P. (2014). Stable isotope analyses on archived fish scales reveal the long-term effect of nitrogen loads on carbon cycling in rivers. Global Change Biology, 20(2) 523-530.

Stable isotope analysis of organic matter in sediment records has long been used to track historical changes in productivity and carbon cycling in marine and lacustrine ecosystems. While flow dynamics preclude stratigraphic measurements of riverine sediments, such retrospective analysis is important for understanding biogeochemical cycling in running waters. Unique collections of riverine fish scales were used to analyse δ15N and δ13C variations in the food web of two European rivers that experience different degrees of anthropogenic pressure. Over the past four decades, dissolved inorganic N loading remained low and constant in the Teno River (70°N, Finland); in contrast, N loading increased fourfold in the Scorff River (47°N, France) over the same period. Archived scales of Atlantic salmon parr, a riverine life-stage that feeds on aquatic invertebrates, revealed high δ15N values in the Scorff River reflecting anthropogenic N inputs to that riverine environment. A strong correlation between dissolved inorganic N loads and δ13C values in fish scales was observed in the Scorff River, whereas no trend was found in the Teno River. This result suggests that anthropogenic N-nutrients enhanced atmospheric C uptake by primary producers and its transfer to fish. Our results illustrate for the first time that, as for lakes and marine ecosystems, historical changes in anthropogenic N loading can affect C cycling in riverine food webs, and confirm the long-term interactions between N and C biogeochemical cycles in running waters. © 2013 John Wiley & Sons Ltd.
Skinner M.A., Courtenay S.C., McKindsey C.W., Carver C.E., Mallet A.L. (2014). Experimental determination of the effects of light limitation from suspended bag oyster (Crassostrea virginica) aquaculture on the structure and photosynthesis of eelgrass (Zostera marina). Journal of Experimental Marine Biology and Ecology, 459 169-180.

Recent studies have hypothesized reduced eelgrass distribution in areas exposed to suspended bag oyster aquaculture of Crassostrea virginica in Eastern Canada is related to shading from aquaculture stock and equipment. The results of a 359-day manipulative field experiment support this hypothesis. Reductions in underwater light, at levels comparable to those found at suspended oyster operations, caused reduced eelgrass structure, morphometrics, and photosynthesis. Increased organic matter deposition under suspended bags neither led to biologically relevant declines in eelgrass metrics, nor mitigated the effects of light limitation. Shoot density, above-ground biomass, below-ground biomass, canopy height, leaf area index, leaf width, and photosynthetic capacity were all significantly reduced. These variables declined along a gradient of increased shading, with significant responses detected in as few as 67. days after exposure to 26% subsurface irradiance. Subsequent sampling 253. days after the removal of experimental treatments documented the potential for recovery in the form of seedling recruitment to the plots of heaviest impact. However, eelgrass response variables remained significantly reduced relative to controls, indicating previous assumptions of a rapid recovery potential for eelgrass exposed to suspended bag oyster aquaculture were incorrect. © 2014.
Van den Heuvel M.R., Hogan N.S., MacDonald G.Z., Berrue F., Young R.F., Arens C.J., Kerr R.G., Fedorak P.M. (2014). Assessing accumulation and biliary excretion of naphthenic acids in yellow perch exposed to oil sands-affected waters. Chemosphere, 95 619-627.

Naphthenic acids are known to be the most prevalent group of organic compounds in oil sands tailings-associated waters. Yellow perch (Perca flavescens) were exposed for four months to oil sands-influenced waters in two experimental systems located on an oil sands lease 30. km north of Fort McMurray Alberta: the Demonstration Pond, containing oil sands tailings capped with natural surface water, and the South Bison Pond, integrating lean oil sands. Yellow perch were also sampled from three lakes: Mildred Lake that receives water from the Athabasca River, Sucker Lake, at the edge of oil sands extraction activity, and Kimowin Lake, a distant reference site. Naphthenic acids were measured in perch muscle tissue using gas chromatography-mass spectrometry (GC-MS). Bile metabolites were measured by GC-MS techniques and by high performance liquid chromatography (HPLC) with fluorescence detection at phenanthrene wavelengths. A method was developed using liquid chromatography-high resolution mass spectrometry (LC-HRMS) to evaluate naphthenic acids in bile. Tissue analysis did not show a pattern of naphthenic acids accumulation in muscle tissue consistent with known concentrations in exposed waters. Bile fluorescence and LC-HRMS methods were capable of statistically distinguishing samples originating from oil sands-influenced waters versus reference lakes. Although the GC-MS and HPLC fluorescence methods were correlated, there were no significant correlations of these methods and the LC-HRMS method. In yellow perch, naphthenic acids from oil sands sources do not concentrate in tissue at a measurable amount and are excreted through a biliary route. LC-HRMS was shown to be a highly sensitive, selective and promising technique as an indicator of exposure of biota to oil sands-derived naphthenic acids. © 2013 Elsevier Ltd.
Van Geest J.L., Burridge L.E., Fife F.J., Kidd K.A. (2014). Feeding response in marine copepods as a measure of acute toxicity of four anti-sea lice pesticides. Marine Environmental Research, 101(1) 145-152.

Anti-sea lice pesticides used in salmon aquaculture are released directly into the environment where non-target organisms, including zooplankton, may be exposed. The toxicity of four pesticides to fieldcollected copepods was examined in 1-h exposures with lethality and feeding endpoints determined 5-h post-exposure using staining techniques. Copepods were immobilized within 1h, at aquaculture treatment concentrations of deltamethrin (AlphaMax®), cypermethrin (Excis®), and hydrogen peroxide (Interox®Paramove™50). All organisms showed vital staining, indicating immobilized organisms were still alive, thus LC50s were not determined. Feeding on carmine particles was inhibited and EC50s ranged from 0.017 to 0.067mg deltamethrin/L, 0.098e0.36mg cypermethrin/L, and 2.6e10mg hydrogen peroxide/L, representing 30-to 117-fold, 13-to 51-fold, and 120-to 460-fold dilutions of the respective aquaculture treatments. No effects were observed in copepods exposed to azamethiphos (Salmosan®) at 5-times the aquaculture treatment. Acute exposure to three of the four pesticides affected feeding and mobility of copepods at environmentally-realistic concentrations.
Van Geest J.L., Burridge L.E., Kidd K.A. (2014). The toxicity of the anti-sea lice pesticide AlphaMax® to the polychaete worm Nereis virens. Aquaculture, 430 98-106.

Polychaete worms have been suggested as a commercially valuable, extractive species to use in Integrated Multi-Trophic Aquaculture (IMTA) to remove organic materials (fish feces) released from salmon aquaculture. However, pesticides used to control parasitic sea lice infestations on salmon are also released from fish farms and non-target organisms may be exposed to these chemicals. In laboratory studies, the polychaete Nereis virens was exposed via water and sediment to the anti-sea lice pesticide AlphaMax® (active ingredient, deltamethrin). Worms exposed in water for 48. h exhibited mortality and impaired mobility in up to 100% of organisms, only at greater than 2-times the prescribed aquaculture treatment concentration. This would suggest negligible risk to worms from acute environmental exposure to AlphaMax® in water. Low mortality (≤. 20%) occurred in 7- or 30-d tests with sand or sediment spiked at relatively high concentrations (up to 0.72. μg. deltamethrin/g), but sublethal effects related to burrowing behavior and worm condition were observed at concentrations as low as 11. μg/g. Therefore, the long-term survival, growth, and ability of worms to perform their ecosystem function of processing organic waste could be affected, depending on the extent of deltamethrin accumulation in sediment. Environmental concentrations of deltamethrin in sediment near aquaculture sites are not presently known and are needed to assess risk to non-target organisms. © 2014 Elsevier B.V.
Van Geest J.L., Burridge L.E., Kidd K.A. (2014). Toxicity of two pyrethroid-based anti-sea lice pesticides, AlphaMax® and Excis®, to a marine amphipod in aqueous and sediment exposures. Aquaculture, 434 233-240.

Pyrethroid pesticides used to control ectoparasitic sea lice in salmon aquaculture are released in effluent plumes from cage sites and have the potential to adversely affect non-target organisms. Pyrethroids have been shown to be highly toxic to crustaceans, but the toxicity of the pyrethroid-based anti-sea lice pesticides AlphaMax® (active ingredient (a.i.) deltamethrin) and Excis® (a.i. cypermethrin) has not been thoroughly studied for non-target, marine benthic crustaceans such as amphipods. The amphipod Echinogammarus finmarchicus, which is ubiquitous in near-shore environments in the northern Atlantic Ocean, was collected from the field for use in laboratory toxicity tests. Amphipods were exposed to the two pesticides in 1- and 24-h water-only, single-pulsed exposures and 10-day spiked sediment tests. In water-only tests, immobility occurred within 1- or 24-h of exposure to the highest test concentrations and delayed mortality and immobility were observed following exposure to lower concentrations as well. Effect thresholds ranged from 6.7-70. ng/L for deltamethrin and 20-220. ng/L for cypermethrin. Organisms exposed to sediment were affected within 2-4. days; resulting 10-d LC50s were 16 and 80. ng/g (dry weight) for deltamethrin and cypermethrin, respectively. Results suggest that amphipods in an effluent plume may be exposed to aqueous concentrations of pyrethroids sufficient to cause adverse effects, including delayed toxicity. In contrast, the 10-day sediment LC50s were much higher than (limited) reported environmental concentrations in sediment. Overall, these results suggest a low potential for risk from sediment exposures for a northern Atlantic species of amphipod that inhabits the near-shore environment where cage aquaculture sites are located. © 2014 Elsevier B.V.
Worrall T.P., Dunbar M.J., Extence C.A., Laizé C.L.R., Monk W.A., Wood P.J. (2014). The identification of hydrological indices for the characterization of macroinvertebrate community response to flow regime variability. Hydrological Sciences Journal, 59(3-4) 645-658.

The importance of flow regime variability for maintaining ecological functioning and integrity of river ecosystems has been firmly established in both natural and anthropogenically modified systems. River flow regimes across lowland catchments in eastern England are examined using 47 variables, including those derived using the Indicators of Hydrologic Alteration (IHA) software. A principal component analysis method was used to identify redundant hydrological variables and those that best characterized the hydrological series (1986-2005). A small number of variables (<6) characterized up to 95% of the statistical variability in the flow series. The hydrological processes and conditions that the variables represent were found to be significant in structuring the in-stream macroinvertebrate community Lotic-invertebrate Index for Flow Evaluation (LIFE) scores at both the family and species levels. However, hydrological variables only account for a relatively small proportion of the total ecological variability (typically <10%). The research indicates that a range of other factors, including channel morphology and anthropogenic modification of in-stream habitats, structure riverine macroinvertebrate communities in addition to hydrology. These factors need to be considered in future environmental flow studies to enable the characterization of baseline/reference conditions for management and restoration purposes. Editor Z.W. Kundzewicz; Guest editor M. AcremanCitation Worrall, T.P., Dunbar, M.J., Extence, C.A., Laizé, C.L.R., Monk, W.A., and Wood, P.J., 2014. The identification of hydrological indices for the characterization of macroinvertebrate community response to flow regime variability. Hydrological Sciences Journal, 59 (3-4), 645-658. © 2014 © 2014 IAHS Press.
Yates A.G., Brua R.B., Corriveau J., Culp J.M., Chambers P.A. (2014). Seasonally driven variation in spatial relationships between agricultural land use and in-stream nutrient concentrations. River Research and Applications, 30(4) 476-493.

Geographic information system (GIS) based distance weighted models were applied to determine critical areas of agricultural influence in nine agriculturally dominated, prairie subcatchments in southern Manitoba, Canada. Models were generated using a range of coefficients to represent nutrient overland and in-stream attenuation between agricultural source areas and stream sampling stations. Coefficients were also used to represent increased attenuation during overland travel through areas with natural vegetation. Water samples collected at intervals throughout the open water season were used to establish associations between areas of influence and in-stream total nitrogen and phosphorus concentrations in each season and under different flow conditions. Critical areas of influence varied seasonally with areas of influence expanding with individual rainfall events. Inclusion of natural vegetated areas on the landscape resulted in substantial increases in model power for only one scenario. Agriculture in areas within approximately 100m of the stream channel appears to be the most critical driver of in-stream nutrient conditions during most seasons and under most flow conditions. Best management practices, such as vegetated buffer strips, should be most effective in controlling nutrient losses to southern Manitoba streams when situated within stream corridor, as opposed to upland areas, which appear to have minimal impact on in-stream conditions. © 2013 John Wiley & Sons, Ltd.
Yates A.G., Brua R.B., Culp J.M., Chambers P.A., Wassenaar L.I. (2014). Sensitivity of structural and functional indicators depends on type and resolution of anthropogenic activities. Ecological Indicators, 45 274-284.

Few researchers have assessed the important management questions regarding the sensitivity of indicators of aquatic ecosystem condition and the specificity with which anthropogenic development activities are described. Furthermore, there is limited knowledge as to the potential of structural and functional indicators to generate complementary knowledge about ecological condition that can be used to inform watershed management. We assessed 20 metrics of ecological structure and function at 19 riverine sites across the Red River watershed in the summer of 2010 using a gradient approach to test predictions that: (1) indicator sensitivity would vary with the specificity at which landscape development is described (i.e., coarse - land use [e.g., agriculture], medium - specific human activities [e.g., crop cultivation] and fine - management practices [e.g., crop rotation]); and (2) structural and functional indicators respond to different types and specificity of anthropogenic development. Evaluation of indicators revealed that indicator sensitivity was frequently greater for assessment of specific human activities (i.e., wastewater treatment, crop cultivation or livestock production), than for broad land-use categories (i.e., agriculture or urban). Structural and functional indicators were often associated with different types of anthropogenic development suggesting additive rather than redundant assessment information. Structural indicators were almost exclusively associated with crop cultivation and agricultural land cover. In contrast, functional indicators were generally associated with gradients of wastewater treatment and urban land cover. Our results demonstrate that aquatic ecosystem assessment programs would benefit from considering the specific anthropogenic development activity to be assessed and managed in order to evaluate and select the most sensitive indicators of stream condition. Furthermore, combined use of structural and functional indicators in aquatic monitoring program appears to improve detection of anthropogenic impacts in a multiple stressor environment. © 2014 Crown Copyright and Elsevier Limited.
Zhang J., Carnduff L., Norman G., Josey T., Wang Y., Sawyer T.W., Martyniuk C.J., Langlois V.S. (2014). Transcriptional profiling in rat hair follicles following simulated blast insult: A new diagnostic tool for traumatic brain injury. Plos One, 9(8).

With wide adoption of explosive-dependent weaponry during military activities, Blast-induced neurotrauma (BINT)-induced traumatic brain injury (TBI) has become a significant medical issue. Therefore, a robust and accessible biomarker system is in demand for effective and efficient TBI diagnosis. Such systems will also be beneficial to studies of TBI pathology. Here we propose the mammalian hair follicles as a potential candidate. An Advanced Blast Simulator (ABS) was developed to generate shock waves simulating traumatic conditions on brains of rat model. Microarray analysis was performed in hair follicles to identify the gene expression profiles that are associated with shock waves. Gene set enrichment analysis (GSEA) and sub-network enrichment analysis (SNEA) were used to identify cell processes and molecular signaling cascades affected by simulated bomb blasts. Enrichment analyses indicated that genes with altered expression levels were involved in central nervous system (CNS)/peripheral nervous system (PNS) responses as well as signal transduction including Ca 2+, K+-transportation-dependent signaling, Toll-Like Receptor (TLR) signaling and Mitogen Activated Protein Kinase (MAPK) signaling cascades. Many of the pathways identified as affected by shock waves in the hair follicles have been previously reported to be TBI responsive in other organs such as brain and blood. The results suggest that the hair follicle has some common TBI responsive molecular signatures to other tissues. Moreover, various TBI-associated diseases were identified as preferentially affected using a gene network approach, indicating that the hair follicle may be capable of reflecting comprehensive responses to TBI conditions. Accordingly, the present study demonstrates that the hair follicle is a potentially viable system for rapid and non-invasive TBI diagnosis. © 2014 Zhang et al.
Armanini D.G., Monk W.A., Carter L., Cote D., Baird D.J. (2013). Towards generalised reference condition models for environmental assessment: A case study on rivers in Atlantic Canada. Environmental Monitoring and Assessment, 185(8) 6247-6259.

Evaluation of the ecological status of river sites in Canada is supported by building models using the reference condition approach. However, geography, data scarcity and inter-operability constraints have frustrated attempts to monitor national-scale status and trends. This issue is particularly true in Atlantic Canada, where no ecological assessment system is currently available. Here, we present a reference condition model based on the River Invertebrate Prediction and Classification System approach with regional-scale applicability. To achieve this, we used biological monitoring data collected from wadeable streams across Atlantic Canada together with freely available, nationally consistent geographic information system (GIS) environmental data layers. For the first time, we demonstrated that it is possible to use data generated from different studies, even when collected using different sampling methods, to generate a robust predictive model. This model was successfully generated and tested using GIS-based rather than local habitat variables and showed improved performance when compared to a null model. In addition, ecological quality ratio data derived from the model responded to observed stressors in a test dataset. Implications for future large-scale implementation of river biomonitoring using a standardised approach with global application are presented. © 2012 The Author(s).
Bahamonde P.A., Munkittrick K.R., Martyniuk C.J. (2013). Intersex in teleost fish: Are we distinguishing endocrine disruption from natural phenomena? General and Comparative Endocrinology, 192 25-35.

Intersex is defined as the simultaneous presence of male and female gonadal tissue in a gonochoristic (fixed-sex) species. The intersex condition has been documented in both wild and laboratory animals, including fish, amphibians, and reptiles. In aquatic animals, intersex is often viewed as a signature effect of exposure to endocrine disrupting compounds. At least 37 fish species from 17 families have been identified with intersex gonads in 54 field survey studies. However, reports of the occurrence of intersex at reference sites have led to speculation that a baseline level of intersex is "normal". The objective of this critical review was to assess factors potentially associated with baseline levels of intersex in fish and to examine the mechanisms involved in the intersex condition in order to identify priority research areas. Based on current literature, the relationship between intersex and physiological parameters such as plasma sex steroids and vitellogenin is not well characterized or conclusive. Moreover, the literature is not definitive on whether field studies are distinguishing between natural intersex and intersex due to stressors. High throughput transcriptomics will improve understanding of how intersex condition manifests after exposure to aquatic pollution and it is recommended that studies consider both males with and without intersex that inhabit the same polluted site in order to differentiate pathways associated with xenobiotic responses versus molecular pathways associated with intersex. Other experimental design considerations for field studies examining intersex include data collection on life history (e.g. migratory patterns) and improved reference site characterization. © 2013 Elsevier Inc.
Baillie B.R., Hicks B.J., van den Heuvel M.R., Kimberley M.O., Hogg I.D. (2013). The effects of wood on stream habitat and native fish assemblages in New Zealand. Ecology of Freshwater Fish, 22(4) 553-566.

Historic deforestation has deprived many river systems of their natural wood loadings. To study the effects of the loss of wood from waterways, a field trial was conducted in three small forested streams in New Zealand. The objectives were to (i) examine differences in fish assemblages among wooded pools (where wood provided cover), open pools and riffles and (ii) measure the effects of wood removal on channel morphology and fish assemblages. In the first part of the study, no significant differences were found in total fish density among the three habitats. However, total fish biomass was significantly higher in wooded pools (64% of total fish biomass) compared with open pools and riffles. Mean density and biomass of banded kokopu (Galaxias fasciatus) and mean biomass of longfin eel (Anguilla dieffenbachii) were highest in wooded pools, whereas the density and biomass of bluegill bully (Gobiomorphus hubbsi) and torrentfish (Cheimarrichthys fosteri) were highest in riffles. In the second part of the study, wood was removed from a 200-m section (treatment) in each stream, significantly reducing pool area and increasing the proportion of channel area and length in riffles. At the habitat scale, banded kokopu and large longfin eel were the two species mostly affected by wood removal. At the reach scale, banded kokopu biomass was significantly lower in the treatment sections. Although wooded pools were a small portion of total habitat, they provided important habitat for two of New Zealand's larger native fish taxa. © 2013 John Wiley & Sons A/S.
Batchelar K.L., Kidd K.A., Drevnick P.E., Munkittrick K.R., Burgess N.M., Roberts A.P., Smith J.D. (2013). Evidence of impaired health in yellow perch (Perca flavescens) from a biological mercury hotspot in northeastern north America. Environmental Toxicology and Chemistry, 32(3) 627-637.

Few studies have investigated the effects of mercury (Hg) on wild fish from remote areas, even though these fish can have high total Hg concentrations. In Kejimkujik National Park and National Historic Site (KNPNHS), Nova Scotia, Canada, concentrations of total Hg in many yellow perch (Perca flavescens) currently exceed the estimated threshold level for adverse effects in fish (0.2μgHgg-1 (wet wt), whole body). To determine whether Hg exposure is adversely affecting the general health of these fish, the authors collected male and female perch in the fall of 2009 and 2010 from 12 lakes within KNPNHS. The health endpoints condition, liver somatic index (LSI), and macrophage aggregates (MAs; indicators of oxidative stress and tissue damage) in the liver, kidney, and spleen were examined, and in female perch were compared between lakes and related to Hg concentrations measured in the muscle and liver tissue. No negative relationships between fish condition or LSI and Hg were found. However, within the liver, kidney, and spleen tissues of females, the relative area occupied by MAs was positively related to both muscle and liver Hg concentrations, indicating the health of these perch was adversely affected at the cellular level. These findings raise concerns for the health of these perch as well as for other wild fish populations known to have similarly elevated Hg concentrations. © 2013 SETAC.
Batchelar K.L., Kidd K.A., Munkittrick K.R., Drevnick P.E., Burgess N.M. (2013). Reproductive health of yellow perch (Perca flavescens) from a biological mercury hotspot in Nova Scotia, Canada. Science of the Total Environment, 454-455 319-327.

Methylmercury (MeHg) exposure is known to adversely affect the reproductive health of laboratory fish, but its impacts on the sexual development of wild fishes are not well studied. Kejimkujik National Park and National Historic Site (KNPNHS) region of Nova Scotia, Canada, has been identified as a biological mercury (Hg) hotspot. To determine whether Hg was adversely affecting the reproductive health of wild yellow perch (Perca flavescens), sexually mature male and female perch were collected from 12 lakes within KNPNHS (mean muscle total Hg: 0.28-0.54. μg/g ww). Gonadosomatic index and germ cell development of male and female perch were measured, as well as the plasma 17β-estradiol concentrations of females. These endpoints were compared between lakes, and were related to Hg concentrations measured in perch muscle and liver tissues. Our results indicate that the reproductive health of male and female perch was not adversely impacted by Hg, although a positive relationship existed between the proportions of primary spermatocytes in male testes and muscle total Hg concentrations. Perch were sampled at an early stage of recrudescence, and the tissue Hg concentrations in these perch were generally lower than those in laboratory studies reporting impacts on reproductive health, both of which may explain the absence of effects. Based on the measured endpoints, it appears that reproduction in perch was not affected at Hg concentrations known to affect fish eating wildlife. © 2013 Elsevier B.V.
Bergman A., Heindel J.J., Kasten T., Kidd K.A., Jobling S., Neira M., Zoeller R.T., Becher G., Bjerregaard P., Bornman R., Brandt I., Kortenkamp A., Muir D., Drisse M.N.B., Ochieng R., Skakkebaek N.E., Byléhn A.S., Iguchi T., Toppari J., Woodruff T.J. (2013). The impact of endocrine disruption: A consensus statement on the state of the science. Environmental Health Perspectives, 121(4) A104-A106.
Biggs K., Seidel J.S., Wilson A., Martyniuk C.J. (2013). γ-Amino-butyric acid (GABA) receptor subunit and transporter expression in the gonad and liver of the fathead minnow (Pimephales promelas). Comparative Biochemistry and Physiology A Molecular and Integrative Physiology, 166(1) 119-127.

γ-Amino-butyric acid (GABA) is the major inhibitory neurotransmitter in the vertebrate central nervous system. GABA receptors and synthesizing enzymes have also been localized to peripheral tissues including the liver, oviduct, uterus and ovary of mammals but the distribution and role of GABA in peripheral tissues of fish has not been fully investigated. The objectives of this study were to (1) determine if mRNA encoding GABA synthesizing enzymes (glutamic acid decarboxylase 65 and 67; gad65 and gad67), GABA transporters, and GABA<inf>A</inf> receptor subunits are localized to liver and gonad of fathead minnow (Pimephales promelas) (FHM) (2) investigate the effects of GABA on ovarian 17β-estradiol (E2) production, and (3) measure transcript responses in the ovary after in vitro incubation to GABA. Real-time PCR assays were developed for gad65, gad67, vesicular GABA transporter (vgat) and GABA transporter 1 (gat1), and select GABA<inf>A</inf> receptor subunits (gabra1, gabra5, gabrb1, gabrb2, gabrg1, gabrg2). All transcripts were localized to the brain as expected; however transcripts were also detected in the liver, ovary, and testis of FHMs. In the female liver, gad65 mRNA was significantly higher in expression compared to the male liver. Transcripts for gad67 were the highest in the brain>gonad>liver and in the gonads, gad67 was significantly higher in expression than gad65 mRNA. In the liver and gonad, the relative abundance of the subunits followed a general trend of gabrb1>gabrb2=gabrg1=gabrg2>gabra1=gabra5. To explore the effects of GABA in the ovary, tissue explants from reproductive female FHMs were treated with GABA (10-10, 10-8 and 10-6M) for 12h. GABA had no significant effect on 17β-estradiol production or on mRNA abundance for genes involved in ovarian steroidogenesis (e.g., 11βhsd, cyp17, cyp19a). There was a significant decrease in estrogen receptor 2a (esr2a) mRNA with 10-10M GABA. This study begins to investigate the GABA system in non-neural tissues of teleost fish and addresses the broader topic regarding the peripheral roles of neurotransmitters. © 2013 Elsevier Inc.
Bosker T., Mudge J.F., Munkittrick K.R. (2013). Statistical reporting deficiencies in environmental toxicology. Environmental Toxicology and Chemistry, 32(8) 1737-1739.

Null hypothesis significance testing is one of the most widely used forms of statistical testing in environmental toxicology. In this short communication, the authors show that the reporting of statistical information when using null hypothesis significance testing is frequently inadequate in environmental toxicology research. The authors demonstrate this by analyzing the statistical information reported for papers employing t tests or analyses of variance in the Environmental Toxicology section of Environmental Toxicology and Chemistry in 2010, which comprised 68% of papers published by this journal in that year. Of these papers, 60% fail to report exact p values, 85% fail to provide degrees of freedom, and 90% fail to report critical effect sizes. Statistical power was reported in only <2% of the published papers. The insufficient provision of statistical information makes interpretation of study results by reviewers and readers difficult. Consistently reporting exact p values with degrees of freedom, considering and explicitly stating biologically relevant critical effect sizes, and reporting statistical power associated with nonsignificant results would be easy to implement and would promote scientific progress in environmental toxicology through increased statistical transparency. © 2013 SETAC.
Bosker T., Munkittrick K.R., Nacci D.E., Maclatchy D.L. (2013). Laboratory spawning patterns of mummichogs, fundulus heteroclitus (Cyprinodontiformes: Fundulidae). Copeia(3) 527-538.

The common estuarine fish species Fundulus heteroclitus or Mummichog has long been used in ecotoxicological studies; however, their periodic spawning pattern is perceived to limit their use in reproductive bioassays and the availability of sensitive life stages. This study evaluated the lunar periodicity of spawning, egg production, and changes in gonadosomatic index (IG) in the laboratory using wild and F1-generation Mummichogs that originated from three different geographic areas: the northern extreme part of their geographic range (New Brunswick, Canada; 45°N), the middle of the northern subspecies range (Massachusetts, USA; 41°N), and within the southern subspecies range (Virginia, USA; 37°N). Unlike some previous studies of wild and laboratory-held fish, Mummichogs from all locations were continuous spawners over a prolonged period of time (8+ weeks) under laboratory conditions. However, there was greater variance in egg production in smaller fish (≤70 mm total length) compared to larger fish. Our results demonstrate the potential to use Mummichogs consistently in testing protocols due to the absence of lunar spawning in the laboratory, and further suggest that larger fish should be used to optimize the power to interpret results when conducting reproductive bioassays. © 2013 by the American Society of Ichthyologists and Herpetologists.
Brasfield S.M., Tetreault G.R., McMaster M.E., Bennett J., Munkittrick K.R. (2013). Seasonal patterns of gonad size, liver size, and in vitro gonadal steroidogenic capacity in slimy sculpin (Cottus cognatus). Water Quality Research Journal of Canada, 48(3) 243-254.

The objective of this study was to characterize the reproductive seasonality of slimy sculpin (Cottus cognatus), a small-bodied, benthic spring spawning species. Sculpin are unique compared with other temperate fish species because they have a reproductive pattern where gonadal maturation occurs over winter in northern areas of its distribution. Previous studies have involved pre-spawning sampling (early spring in North America) and post-spawning sampling (early fall in North America). However, seasonal changes in gonadosomatic index, hepatosomatic index, condition factor, and in vitro gonadal production of estradiol (E<inf>2</inf>) and testosterone (T) in females and T and 11-ketotestosterone (11-KT) in males have not been characterized. Following a summer quiescent period, female sculpin showed an increase in gonadal hormone production during the fall, which was associated with increases in gonad and liver sizes, however males experienced a much shorter resting phase following spawning in May. Elevated production of both T and 11-KT appears to both signal the initiation of gonadal growth in September and contribute to gonadal maturation over the winter. This study is important because it is the first characterization of the seasonal reproductive pattern in sculpin and it describes the patterns of gonad development and seasonal changes in condition and liver size in this species as it prepares for spawning. © IWA Publishing 2013.
Chishti Y.Z., Feswick A., Munkittrick K.R., Martyniuk C.J. (2013). Transcriptomic profiling of progesterone in the male fathead minnow (Pimephales promelas) testis. General and Comparative Endocrinology, 192 115-125.

P4 is a hormone with diverse functions that include roles in reproduction, growth, and development. The objectives of this study were to examine the effects of P4 on androgen production in the mature teleost testis and to identify molecular signaling cascades regulated by P4 to improve understanding of its role in male reproduction. Fathead minnow (FHM) testis explants were treated in vitro with two concentrations of P4 (10-8 and 10-6M) for 6 and 12h. P4 significantly increased testosterone (T) production in the FHM testis but did not affect 11-ketotestosterone. Gene network analysis revealed that insulin growth factor (Igf1) and tumor necrosis factor receptor (Tnfr) signaling was significantly depressed with P4 treatment after 12h. There was also a 20% increase in a gene network for follicle-stimulating hormone secretion and an 18% decrease in genes involved in vasopressin signaling. Genes in steroid metabolism (e.g. star, cyp19a, 11bhsd) were not significantly affected by P4 treatments in this study, and it is hypothesized that pre-existing molecular machinery may be more involved in the increased production of T rather than the de novo expression of steroid-related transcripts and receptors. There was a significant decrease in prostaglandin E synthase 3b (cytosolic) (ptges3b) after treatment with P4, suggesting that there is cross talk between P4 and prostaglandin pathways in the reproductive testis. P4 has a role in regulating steroid production in the male testis and may do so by modulating gene networks related to endocrine pathways, such as Igf1, Tnfr, and vasopressin. © 2013 Elsevier Inc.
Clayden M.G., Kidd K.A., Wyn B., Kirk J.L., Muir D.C.G., O'Driscoll N.J. (2013). Mercury biomagnification through food webs is affected by physical and chemical characteristics of lakes. Environmental Science and Technology, 47(21) 12047-12053.

Mercury (Hg) contamination in aquatic systems remains a global concern because the organic form, methyl Hg (MeHg), can biomagnify to harmful concentrations in fish, fish-eating wildlife, and humans. Food web transfer of MeHg has been explored using models of log MeHg versus relative trophic position (nitrogen isotopes, δ15N), but regression slopes vary across systems for unknown reasons. In this study, MeHg biomagnification was determined for 11 lake food webs in Kejimkujik National Park, Nova Scotia, Canada, and compared to physical and chemical lake characteristics using principal component and multiple regression analyses. MeHg biomagnification (regression slopes of log MeHg versus baseline-adjusted δ15N for fishes and invertebrates) varied significantly across lakes and was higher in systems with lower aqueous nutrient/MeHg/chloride scores. This is one of the largest, consistent data sets available on MeHg biomagnification through temperate lake food webs and the first study to use a principal component and multiple regression approach to understand how lake chemical and physical characteristics interact to affect biomagnification among systems. Overall, our results show that the magnitude of MeHg biomagnification through lake food webs is related to the chemical and physical characteristics of the systems, but the underlying mechanisms warrant further investigation. © 2013 American Chemical Society.
Corriveau J., Chambers P.A., Culp J.M. (2013). Seasonal variation in nutrient export along streams in the northern great plains. Water Air and Soil Pollution, 224(7).

Spatial and temporal trends in nutrient concentrations and loads were analyzed for three rivers in the Red River watershed, Manitoba, Canada to determine changes in nutrient export across hydrologic seasons and along river continua in the Great Plains. Annual patterns in all three rivers were strongly influenced by the snowmelt period: 25-89 % of the total annual river volume, 42-92 % of the total annual TP load, and 41-81 % of the total annual TN load were delivered during snowmelt. Concentrations of TP and TN varied among the hydrologic seasons (snowmelt, summer, fall, and winter), but showed more variability and larger values during winter and snowmelt, with peak values reaching 1.960 mg TP L-1 and 16.07 mg TN L-1. Although the flat topography and semi-arid climate of the Red River watershed results in hydrological disconnects along river continua, discharge and nutrient export increased along the three river gradients. In contrast, TP or TN concentrations showed no significant longitudinal change for the two agriculturally dominated watersheds yet increased along the forested stream. Our finding that TP and TN exports from northern Great Plains rivers are strongly influenced by seasonal hydrology, with snowmelt being a critical period for nutrient export has implications for design and implementation of appropriate management practices to minimize nutrient export to proximal and downstream aquatic ecosystems. © 2013 Her Majesty the Queen in Right of Canada.
Culp J.M., Brua R.B., Benoy G.A., Chambers P.A. (2013). Development of reference conditions for suspended solids in streams. Canadian Water Resources Journal, 38(2) 85-98.

Our aim was to develop protective physical and biological thresholds that identify the upper limit of the least disturbed (reference) condition for total suspended solids (TSS). The study focuses on streams in agricultural regions across Canada from which we collected contemporary TSS and benthic invertebrate data, and compiled long-term TSS data sets. Reference conditions for TSS were analyzed by five approaches previously applied in Canada, Australia and New Zealand, and the USA. In addition, ecological reference conditions for TSS were developed using regression-tree analysis to determine change-points along TSS gradients for three invertebrate metrics (percentage Ephemeroptera-Plecoptera-Tri-choptera, total richness, and modified family biotic index). Increased agricultural land-cover was linked to higher TSS in most agricultural regions which, in turn, was associated with degraded environmental conditions and a reduction in the relative abundance of pollution-intolerant taxa. The five physical approaches produced a narrow range of regional TSS reference condition values (2.7 to 6.2 mg L-1). Ecological reference conditions for TSS ranged from 3.5 to 11.1 mg L-1 across Canada. We conclude that long-term TSS databases may serve to generate interim sediment criteria because ecological reference conditions were similar to those calculated from physical data alone. These interim sediment criteria may be appropriate targets for use in evaluation of restoration programs designed to improve environmental quality of aquatic ecosystems (e.g., beneficial or best management practice applications). © 2013 Her Majesty in Right of Canada.
Cunjak R.A., Linnansaari T., Caissie D. (2013). The complex interaction of ecology and hydrology in a small catchment: A salmon's perspective. Hydrological Processes, 27(5) 741-749.

For the past 22years, we have monitored hydro-meteorological conditions and fish population dynamics in Catamaran Brook, a 52km2 catchment in the Miramichi River system of New Brunswick, Canada. Given the long-term nature of the multidisciplinary dataset, we are able to provide an overview of the complex interaction between streamflow and fish population dynamics drawing on previously published material as well as new data analyses. For autumn-spawning fishes like the Atlantic salmon, access to headwater reaches was directly related to streamflow during late October (when they ascend spawning tributaries), as well as the propensity of beaver dams in the stream (also a function of streamflow). Winter streamflow was positively correlated with egg survival, except when rain-on-snow conditions induced severe ice break-up events that likely caused the highest mortalities on record for salmon and other fishes. Juvenile recruitment was significantly influenced by density-dependent processes of growth and competition but further mediated by density-independent factors like winter flow. In spring, fry emergence was largely temperature-driven, although peaks in fry drift were sometimes synchronized with secondary discharge peaks and temperature. Tributaries like Catamaran Brook provide thermal refugia for coolwater fishes like salmon and trout during the summer when wide, shallow main-stem Atlantic rivers experience low discharge and high water temperatures that induce physiological and behavioural stress (i.e. >23°C). These phenomena are discussed in detail, especially in terms of how they may be compromised by future changes in hydrologic conditions resulting from predicted climate change scenarios. © 2012 John Wiley & Sons, Ltd.
Danielescu S., MacQuarrie K.T.B. (2013). Nitrogen and oxygen isotopes in nitrate in the groundwater and surface water discharge from two rural catchments: Implications for nitrogen loading to coastal waters. Biogeochemistry, 115(1-3) 111-127.

In Prince Edward Island, Canada, widespread intensive potato production has contributed to elevated nitrate concentrations in groundwater and streams, and eutrophic or anoxic conditions occur regularly in several estuarine systems. In this research, the stable isotopes of nitrogen and oxygen in nitrate in intertidal groundwater discharge and stream water were used, in conjunction with water quality and quantity data and land use information, to better understand the characteristics of nitrate delivered to two small estuaries with contrasting land use in their contributory catchments. Most of the water samples collected during the two-year study had isotopic signatures that fell in the range expected for nitrate derived from ammonium-based fertilizers (26.5 % of the samples) or in the overlapping range formed between ammonium-based fertilizers and nitrate derived from soil (64 % of the samples). Overall, isotopic signatures spanned over relatively narrow ranges, and correlations with other water quality parameters, or catchment characteristics, were weak. Nitrate in groundwater discharge and surface water in the Trout River catchment exhibited significantly different isotopic signatures only for the nitrogen isotope, while in the McIntyre Creek catchment groundwater discharge and surface water had similar isotopic signatures. When the isotopic results for the waters from the two catchments were compared, the surface waters were found to be similar, while the isotopic signatures of nitrate in groundwater were distinct only for the nitrogen isotope. Denitrification in the two study catchments was not evident based on the isotopic results for nitrate; however, in the case of the Trout River catchment, where a small freshwater pond exists, an average nitrate load reduction of 14 % was inferred based on a comparison of nitrate loads entering and leaving the pond. Overall, it appears that natural attenuation processes, occurring either in the streams or groundwater flow systems, do not significantly reduce nitrate loading to these estuaries. © 2013 Springer Science+Business Media Dordrecht.
Doyle M.A., Bosker T., Martyniuk C.J., MacLatchy D.L., Munkittrick K.R. (2013). The effects of 17-α-ethinylestradiol (EE2) on molecular signaling cascades in mummichog (Fundulus heteroclitus). Aquatic Toxicology, 134-135 34-46.

Exposures to ≤10. ng/L of 17-α-ethinylestradiol (EE2) will reduce or shut down egg production in freshwater fish models, while mummichog (Fundulus heteroclitus), an estuarine species, are able to produce eggs at EE2 concentrations >3000. ng/L. The objective of this study was to gain mechanistic insight into how mummichog are able to produce eggs during exposures to high EE2. Mummichog were exposed to 0, 50 or 250. ng/L of EE2 for 14. d. There were no changes in gonadosomatic index, liversomatic index, gonad development, or plasma estradiol levels after exposure to EE2. However, testosterone significantly decreased with EE2 exposures (50, 250. ng/L). Microarray analysis in the liver revealed that cell processes associated with lipids were affected by EE2 at the transcriptome level. Based on the transcriptomics data, we hypothesize that mummichog are able to maintain lipid transport and uptake into the ovary and this may be associated with apolipoproteins, facilitating normal oocyte development. Novel gene regulatory networks for protein modification targets were also constructed to learn more about the potential roles of estrogens in the teleost liver. Although post-translational modifications (PTMs) are important regulatory mechanisms, the roles of PTMs in protein regulation in fish and the susceptibility of PTMs to aquatic pollutants are largely unexplored and may offer novel insight into mechanisms of endocrine disruption. © 2013 Elsevier B.V.
Dubé M.G., Duinker P., Greig L., Carver M., Servos M., McMaster M., Noble B., Schreier H., Jackson L., Munkittrick K.R. (2013). A framework for assessing cumulative effects in watersheds: an introduction to Canadian case studies. Integrated Environmental Assessment and Management, 9(3) 363-369.

From 2008 to 2013, a series of studies supported by the Canadian Water Network were conducted in Canadian watersheds in an effort to improve methods to assess cumulative effects. These studies fit under a common framework for watershed cumulative effects assessment (CEA). This article presents an introduction to the Special Series on Watershed CEA in IEAM including the framework and its impetus, a brief introduction to each of the articles in the series, challenges, and a path forward. The framework includes a regional water monitoring program that produces 3 core outputs: an accumulated state assessment, stressor-response relationships, and development of predictive cumulative effects scenario models. The framework considers core values, indicators, thresholds, and use of consistent terminology. It emphasizes that CEA requires 2 components, accumulated state quantification and predictive scenario forecasting. It recognizes both of these components must be supported by a regional, multiscale monitoring program. Copyright © 2013 SETAC.
Dubé M.G., Muldoon B., Wilson J., Maracle K.B. (2013). Accumulated state of the Yukon River watershed: part I critical review of literature. Integrated Environmental Assessment and Management, 9(3) 426-438.

A consistent methodology for assessing the accumulating effects of natural and manmade change on riverine systems has not been developed for a whole host of reasons including a lack of data, disagreement over core elements to consider, and complexity. Accumulated state assessments of aquatic systems is an integral component of watershed cumulative effects assessment. The Yukon River is the largest free flowing river in the world and is the fourth largest drainage basin in North America, draining 855,000 km(2) in Canada and the United States. Because of its remote location, it is considered pristine but little is known about its cumulative state. This review identified 7 "hot spot" areas in the Yukon River Basin including Lake Laberge, Yukon River at Dawson City, the Charley and Yukon River confluence, Porcupine and Yukon River confluence, Yukon River at the Dalton Highway Bridge, Tolovana River near Tolovana, and Tanana River at Fairbanks. Climate change, natural stressors, and anthropogenic stresses have resulted in accumulating changes including measurable levels of contaminants in surface waters and fish tissues, fish and human disease, changes in surface hydrology, as well as shifts in biogeochemical loads. This article is the first integrated accumulated state assessment for the Yukon River basin based on a literature review. It is the first part of a 2-part series. The second article (Dubé et al. 2013a, this issue) is a quantitative accumulated state assessment of the Yukon River Basin where hot spots and hot moments are assessed outside of a "normal" range of variability. Copyright © 2012 SETAC.
Dubé M.G., Wilson J.E. (2013). Accumulated state assessment of the Peace-Athabasca-Slave River system. Integrated Environmental Assessment and Management, 9(3) 405-425.

Effects-based analysis is a fundamental component of watershed cumulative effects assessment. This study conducted an effects-based analysis for the Peace-Athabasca-Slave River System, part of the massive Mackenzie River Basin, encompassing 20% of Canada's total land mass and influenced by cumulative contributions of the W.A.C. Bennett Dam (Peace River) and industrial activities including oil sands mining (Athabasca River). This study assessed seasonal changes in 1) Peace River water quality and quantity before and after dam development, 2) Athabasca River water quality and quantity before and after oil sands developments, 3) tributary inputs from the Peace and Athabasca Rivers to the Slave River, and 4) upstream to downstream differences in water quality in the Slave River. In addition, seasonal benchmarks were calculated for each river based on pre-perturbation post-perturbation data for future cumulative effects assessments. Winter discharge (January-March) from the Peace and Slave Rivers was significantly higher than before dam construction (pre-1967) (p < 0.05), whereas summer peak flows (May-July) were significantly lower than before the dam showing that regulation has significantly altered seasonal flow regimes. During spring freshet and summer high flows, the Peace River strongly influenced the quality of the Slave River, as there were no significant differences in loadings of dissolved N, total P (TP), total organic C (TOC), total As, total Mn, total V, and turbidity and specific conductance between these rivers. In the Athabasca River, TP and specific conductance concentrations increased significantly since before oil sands developments (1967-2010), whereas dissolved N and sulfate have increased after the oil sands developments (1977-2010). Recently, the Athabasca River had significantly higher concentrations of dissolved N, TP, TOC, dissolved sulfate, specific conductance, and total Mn than either the Slave or the Peace Rivers during the winter months. The transboundary nature of the Peace, Athabasca, and Slave River basins has resulted in fragmented monitoring and reporting of the state of these rivers, and a more consistent monitoring framework is recommended. Copyright © 2012 SETAC.
Dubé M.G., Wilson J.E., Waterhouse J. (2013). Accumulated state assessment of the Yukon River watershed: part II quantitative effects-based analysis integrating Western science and traditional ecological knowledge. Integrated Environmental Assessment and Management, 9(3) 439-455.

This article is the second in a 2-part series assessing the accumulated state of the transboundary Yukon River (YR) basin in northern Canada and the United States. The determination of accumulated state based on available long-term (LT) discharge and water quality data is the first step in watershed cumulative effect assessment in the absence of sufficient biological monitoring data. Long-term trends in water quantity and quality were determined and a benchmark against which to measure change was defined for 5 major reaches along the YR for nitrate, total and dissolved organic carbon (TOC and DOC, respectively), total phosphate (TP), orthophosphate, pH, and specific conductivity. Deviations from the reference condition were identified as "hot moments" in time, nested within a reach. Significant increasing LT trends in discharge were found on the Canadian portion of the YR. There were significant LT decreases in nitrate, TOC, and TP at the Headwater reach, and significant increases in nitrate and specific conductivity at the Lower reach. Deviations from reference condition were found in all water quality variables but most notably during the ice-free period of the YR (May-Sept) and in the Lower reach. The greatest magnitudes of outliers were found during the spring freshet. This study also incorporated traditional ecological knowledge (TEK) into its assessment of accumulated state. In the summer of 2007 the YR Inter Tribal Watershed Council organized a team of people to paddle down the length of the YR as part of a "Healing Journey," where both Western Science and TEK paradigms were used. Water quality data were continuously collected and stories were shared between the team and communities along the YR. Healing Journey data were compared to the LT reference conditions and showed the summer of 2007 was abnormal compared to the LT water quality. This study showed the importance of establishing a reference condition by reach and season for key indicators of water health to measure change, and the importance of placing synoptic surveys into context of LT accumulated state assessments. Copyright © 2013 SETAC.
Duro D.C., Franklin S.E., Dubé M.G. (2013). Hybrid object-based change detection and hierarchical image segmentation for thematic map updating. Photogrammetric Engineering and Remote Sensing, 79(3) 259-268.

A hybrid object-based change detection (OBCD) method incorporating a hierarchical image segmentation strategy and cross-correlation analysis (CCA) is described and demonstrated. The proposed hybrid OBCD method was used to update an existing thematic map derived from Landsat-5 and -7 imagery (circa 2000), with imagery consisting of markedly different sensor specifications (Landsat-2, circa 1976). The proposed hierarchical image segmentation strategy successfully constrained change objects within existing land cover boundaries, avoiding the production of "sliver objects," an issue related to other image segmentation strategies used in OBCD. In combination with the CCA method, the hybrid OBCD method is capable of generating change thresholds for individual land-cover classes, providing a mechanism to limit the amount of spurious change detected. Two change threshold methods were tested: (a) change threshold values based on two standard deviations, and, (b) an unsupervised threshold method. No statistically significant difference was found between these threshold methods. © 2013 American Society for Photogrammetry and Remote Sensing.
Díaz-Jaramillo M., da Rocha A.M., Chiang G., Buchwalter D., Monserrat J.M., Barra R. (2013). Biochemical and behavioral responses in the estuarine polychaete Perinereis gualpensis (Nereididae) after in situ exposure to polluted sediments. Ecotoxicology and Environmental Safety, 89 182-188.

In situ translocation experiments are advantageous relative to traditional laboratory experiments, particularly for understanding the bioavailability of trace metals like mercury (Hg). Individuals of the polychaete Perinereis gualpensis were translocated from a reference site (Raqui estuary, Chile) to an estuarine site with significant sediment Hg concentrations (Lenga estuary: 1.78-9.89. mg/kg). Individuals were exposed in polluted and non-polluted sediments for 21 days and sampled every 7 days with cages deployed at three different depths. Tissue Hg concentrations were measured in conjunction with oxidative stress responses. Translocated polychaetes rapidly accumulated Hg. Glutathione S-transferase (GST) activities measured from posterior body regions were 2-fold higher than control activities after 21 days of exposure. Other antioxidant measures were idiosyncratic. Distinct burrowing behavior differences were observed; control polychaetes exhibited more homogenous vertical distributions, whereas in Lenga, worms tended to remain in upper layers. These studies demonstrate that under natural conditions, Hg is highly bioavailable to polychaetes affecting both biochemical and behavioral responses after relatively short-term exposure. © 2012 Elsevier Inc.
Ellis T.R., Linnansaari T., Cunjak R.A. (2013). Passive integrated transponder (PIT) tracking versus snorkeling: Quantification of fright bias and comparison of techniques in habitat use studies. Transactions of the American Fisheries Society, 142(3) 660-670.

Quantitative assessment of day and night fright bias (i.e., flight response) of Atlantic Salmon Salmo salar parr during passive integrated transponder (PIT) tracking surveys was carried out during summer (water temperature, 18-22°C) and autumn (water temperature, <3°C). In addition, PIT-tracking and snorkeling survey methods were compared to assess whether the two methods result in similar habitat use data for Atlantic Salmon parr at the same study site. During summer fright bias surveys, 0-15% of parr displayed a flight response to PIT-tracking techniques in the riffle-run-pool habitat types commonly used by Atlantic Salmon parr; 24-25% displayed a flight response in relatively unused, shallow, calm water habitats. No flight responses were observed in autumn surveys with colder water temperatures in any habitat type. Larger numbers of salmon parr were observed using PIT tracking regardless of stream discharge. Furthermore, significant differences in habitat use frequency curves between these two methods were observed due largely to higher Atlantic Salmon parr abundances being detected by PIT tracking in shallow water depths at lower discharges and the ability to detect inactive salmon parr hiding within the substrate. PIT tracking was found to be a valid method for habitat assessment and provides more reliable habitat use data than traditional snorkeling methods in small streams. © American Fisheries Society 2013.
Es-Salhi M.A., Clément M., St-Hilaire A., Caissie D., Courtenay S.C. (2013). Influence of hydrological conditions and peat extraction operations on suspended sediment concentration and deposition in the East Branch Portage River, New Brunswick (Canada). Water Quality Research Journal of Canada, 48(4) 305-320.

Peat extraction activities often generate sediments that can be transported into streams and rivers. These sediments have sometimes been shown to negatively affect the natural environment. This study investigated the effects of peat production on the East Branch Portage River, New Brunswick (NB), Canada. Relationships between discharge, precipitation and suspended sediment concentration (SSC) were analysed. The effect of sedimentation pond maintenance activities on SSC was also studied. Finally, the grain size distribution and organic content of deposited sediments were quantified at five sites downstream of the pond. Three water quality stations were monitored during the ice-free period in 2007 and 2008. Results showed that SSC was not significantly correlated with precipitation and weakly correlated with discharge, although some of the high SSC events were triggered by high discharge and precipitation. Pond maintenance alone failed to ensure optimal sedimentation pond efficiency. In 2008, SSC increased a few days after pond maintenance. The NB SSC 25 mg/L guideline was exceeded at all stations in both years. Analysis of variance results showed that there were significant differences in the grain size distribution of deposited sediments at the five sampled sites. Sand was the prevailing sediment type deposited downstream of the sedimentation pond. © IWA Publishing 2013.
Feswick A., Griffitt R.J., Siebein K., Barber D.S. (2013). Uptake, retention and internalization of quantum dots in Daphnia is influenced by particle surface functionalization. Aquatic Toxicology, 130-131 210-218.

Nanomaterials are a diverse group of compounds whose inevitable release into the environment warrants study of the fundamental processes that govern the ingestion, uptake and accumulation in aquatic organisms. Nanomaterials have the ability to transfer to higher trophic levels in aquatic ecosystems, and recent evidence suggests that the surface chemistry of both the nanoparticle and biological membrane can influence uptake kinetics. Therefore, our study investigates the effect of surface functionalization on uptake, internalization and depuration in Daphnia spp. Uncharged (polyethylene glycol; PEG), positively charged (amino-terminated: NH<inf>2</inf>) and negatively charged (carboxyl-modified; COOH) cadmium selenide/zinc sulfide quantum dots were used to monitor ingestion, uptake and depuration of nanometals in Daphnia magna and Ceriodaphnia dubia over 24h of exposure. These studies demonstrated that particles with higher negative charge (COOH quantum dots) were taken up to a greater extent by Daphnia (259.17±17.70 RFU/20 Daphnia) than either the NH<inf>2</inf> (150.01±18.91) or PEG quantum dots (95.17±9.78), however this is likely related to the functional groups attached to the nanoparticles as there were no real differences in zeta potential. Whole body fluorescence associates well with fluorescent microscopic images obtained at the 24h timepoint. Confocal and electron microscopic analysis clearly demonstrated that all three types of quantum dots could cross the intestinal epithelial barrier and be translocated to other cells. Upon cessation of exposure, elimination of all three materials was biphasic with rapid initial clearance that likely represents elimination of material remaining in the GI tract followed by a much slower elimination phase that likely represents elimination of internalized material. These studies demonstrate that daphnids can take up intact nanomaterial from the water column and that this uptake is strongly influenced by particle surface functionalization. In addition, the usefulness of using quantum dots as a proxy for other nanometals (no acute toxicity, clear visualization in electron microscopy), in conjunction with several different imaging techniques in assessing uptake and accumulation of nanoparticles in daphnids was demonstrated. © 2013 Elsevier B.V.
Finley M.A., Courtenay S.C., Teather K.L., Hewitt L.M., Holdway D.A., Hogan N.S., van den Heuvel M.R. (2013). Evaluating cumulative effects of anthropogenic inputs in Prince Edward Island estuaries using the mummichog (Fundulus heteroclitus). Integrated Environmental Assessment and Management, 9(3) 496-507.

Estuarine eutrophication as a result of agricultural land use, including the use of chemical fertilizers, is increasing worldwide. Prince Edward Island (PEI), Canada has very high agricultural intensity by international standards with approximately 44% of the land area under production, and some watersheds in excess of 75% agricultural land-use. The type of agriculture is also intensive with primarily row crops that have high chemical fertilizer and pesticide usage. In light of these stressors, the hypothesis of this study was that mummichog (Fundulus heteroclitus) population parameters would change with point and nonpoint source pollution, and that multivariate statistics could be used to draw associations with specific stressors. Fish were sampled on a monthly basis from May through August at 7 estuaries spanning a range of land use, nutrient, and contaminant loadings. A suite of environmental variables were simplified into 3 principal components: PC1 representing agricultural land use, N loading, and plant habitat, PC2 being dominated by sediment sand and silt distribution, and PC3 largely reflecting P loading and sediment organic matter. There were significant differences in abundance of both adult and young-of-the-year mummichog, and these changes associated most strongly with PC1, the largely N-driven agricultural influences. In contrast, somatic variables such as liver and gonad size did not show strong association with the environmental quality principal component scores. The sand and silt PC2 appeared to have the opposite association with the biological data, with siltier environments correlating to older, larger, less dense populations of mummichog. Although pesticide residues were detected in estuarine sediment, there was no clear relationship between these and watershed agricultural intensity or biochemical indicators. There was, however, a strong relationship between agricultural environmental variables (PC1) and in vitro steroid production that is suggestive of a potential chemical effect. Eutrophication appeared to be a primary stressor affecting mummichog populations, as nutrient enrichment was associated with changes in habitat variables and these in turn were associated with high mummichog density. Thus, mummichog population demographics appear to have use as an indicator of adverse or worsening conditions in estuaries. We concluded that, based on the subset of environmental factors evaluated, the nonpoint-source inputs of sediments and nutrients exerted the greatest influence on mummichog populations in PEI estuaries. Copyright © 2013 SETAC.
Foucher D., Hintelmann H., Al T.A., MacQuarrie K.T. (2013). Mercury isotope fractionation in waters and sediments of the Murray Brook mine watershed (New Brunswick, Canada): Tracing mercury contamination and transformation. Chemical Geology, 336 87-95.

Mercury isotope fractionation was investigated in different environmental compartments of a mining-impacted ecosystem, the watershed of the Murray Brook deposit in northern New Brunswick, Canada. Mercury contaminated ground water, surface water as well as sediment and samples of suspended particulate matter were collected alongside Gossan Creek downstream of mine tailings and analyzed for mercury isotopic composition. While leachates from the tailings and ground water samples showed a uniform and similar mercury isotopic signature confirming the predominant role of the mining residues in the contamination of the surrounding environment, samples collected from the surface flow system provided evidence of significant mass-dependent fractionation of mercury with distance from the source. As dissolved mercury contents steadily decreased from 31.1 to 1.4μg Hg L-1 with distance from the headwaters of the stream, δ202Hg in the creek water progressively increased resulting in a fractionation of ~0.9% over 1.6km. As a result, mercury isotopic ratios in the creek appeared to closely follow a Rayleigh model assuming a constant fractionation factor α(reactant/product) of 1.00038. Stream bed sediments also demonstrated an enrichment of heavy isotopes along the creek with an isotopic shift of ~1% over the distance of Gossan Creek (3100m). Although mercury losses from the water column result partly from partitioning to the sediments, measured mercury isotopic ratios differences between dissolved and solid phases were likely small and this study did not observe significant fractionation due to partitioning processes. Results rather suggested that fractionation observed in the surface water system of Gossan Creek is most likely the result of a combined effect of reduction and volatilisation processes, the lighter isotopes being preferentially reduced and evaporated from the water column. Additional sediment samples collected along reaches of Eighteen Mile Brook and the Upsalquitch River that receive water from Gossan Creek, and from tributaries unaffected by the mine contamination were analyzed for mercury isotopic composition. Data obtained from those sediments clearly demonstrated that mercury derived from mining activities is isotopically different from mercury naturally present in the area. Measured isotopic differences can ultimately be employed to trace sources of mercury, notwithstanding potential fractionation caused by natural transformation processes. © 2012 Elsevier B.V.
Garcia-Reyero N., Martyniuk C.J., Kroll K.J., Escalon B.L., Spade D.J., Denslow N.D. (2013). Transcriptional signature of progesterone in the fathead minnow ovary (Pimephales promelas). General and Comparative Endocrinology, 192 159-169.

A growing number of studies have examined transcriptional responses to sex steroids along the hypothalamic-pituitary-gonadal axis in teleost fishes. However, data are lacking on the molecular cascades that underlie progesterone signaling. The objective of this study was to characterize the transcriptional response in the ovary of fathead minnows (. Pimephales promelas) in response to progesterone (P4). Fathead minnow ovaries were exposed in vitro to 500. ng P4/L. Germinal vesicle migration and breakdown (GVBD) was observed and microarrays were used to identify gene cascades affected by P4. Microarray analysis identified 1702 differentially expressed transcripts after P4 treatment. Functional enrichment analysis revealed that transcripts involved in the molecular functions of protein serine/threonine kinase activity, ATP binding, and activity of calcium channels were increased after P4 treatment. There was an overwhelming decrease in levels of transcripts of genes that are structural constituents of ribosomes with P4 treatment. There was also evidence for gene expression changes in steroid and maturation-related transcripts. Pathway analyses identified cell cycle regulation, insulin action, hedgehog, and B cell activation as pathways containing an over-representation of highly regulated transcripts. Significant regulatory sub-networks of P4-mediated transcripts included genes regulated by tumor protein p53 and E2F transcription factor 1. These data provide novel insight into the molecular signaling cascades that underlie P4-signaling in the ovary and identify genes and processes that may indicate premature GVBD due to environmental pollutants that mimic progestins. © 2013.
Jardine T.D., Kidd K.A., O' Driscoll N. (2013). Food web analysis reveals effects of pH on mercury bioaccumulation at multiple trophic levels in streams. Aquatic Toxicology, 132-133 46-52.

Biomagnification processes and the factors that govern them, including those for mercury (Hg), are poorly understood in streams. Total and methyl Hg concentrations and relative trophic position (using δ15N) were analyzed in biofilm and invertebrates from 21 streams in New Brunswick, Canada to assess food web biomagnification leading to the common minnow blacknose dace (Rhinichthys atratulus), a species known to have Hg concentrations that are higher in low pH waters. Biomagnification slopes within stream food webs measured using Hg vs. δ15N or corresponding trophic levels (TL) differed depending on the chemical species analyzed, with total Hg exhibiting increases of 1.3-2.5 per TL (mean slope of total Hg vs. δ15N=0.14±0.06 S.D., range=0.06-0.20) and methyl Hg showing a more pronounced increase of 2.8 to 6.0 per TL (mean slope of methyl Hg vs. δ15N=0.30±0.08 S.D., range=0.22-0.39). While Hg biomagnification slopes through the entire food web (Trophic Magnification Factors, TMFs) were not influenced by water chemistry (pH), dietary concentrations of methyl Hg strongly influenced biomagnification factors (BMFs) for consumer-diet pairs within the food web at lower trophic levels, and BMFs between dace and predatory invertebrates were significantly higher in low pH waters. These analyses, coupled with observations of higher Hg in primary producers in streams with low pH, suggest that pH influences both baseline concentrations and biomagnification of Hg in these systems. Because higher Hg concentrations in the diets of primary consumers and predatory insects in lower pH waters led to lower BMFs, these feeding groups showed insignificant relationships between Hg and pH; thus, altered BMFs associated with dietary concentrations can dampen the effects of environmental conditions on Hg concentrations. © 2013 Elsevier B.V.
Karami A., Keiter S., Hollert H., Courtenay S.C. (2013). Fuzzy logic and adaptive neuro-fuzzy inference system for characterization of contaminant exposure through selected biomarkers in African catfish. Environmental Science and Pollution Research, 20(3) 1586-1595.

This study represents a first attempt at applying a fuzzy inference system (FIS) and an adaptive neuro-fuzzy inference system (ANFIS) to the field of aquatic biomonitoring for classification of the dosage and time of benzo[a]pyrene (BaP) injection through selected biomarkers in African catfish (Clarias gariepinus). Fish were injected either intramuscularly (i. m.) or intraperitoneally (i. p.) with BaP. Hepatic glutathione S-transferase (GST) activities, relative visceral fat weights (LSI), and four biliary fluorescent aromatic compounds (FACs) concentrations were used as the inputs in the modeling study. Contradictory rules in FIS and ANFIS models appeared after conversion of bioassay results into human language (rule-based system). A "data trimming" approach was proposed to eliminate the conflicts prior to fuzzification. However, the model produced was relevant only to relatively low exposures to BaP, especially through the i. m. route of exposure. Furthermore, sensitivity analysis was unable to raise the classification rate to an acceptable level. In conclusion, FIS and ANFIS models have limited applications in the field of fish biomarker studies. © 2012 Springer-Verlag.
Kovacs T.G., Martel P.H., O'Connor B.I., Hewitt L.M., Parrott J.L., McMaster M.E., MacLatchy D.L., Van Der Kraak G.J., Van Den Heuvel M.R. (2013). A survey of Canadian mechanical pulp and paper mill effluents: Insights concerning the potential to affect fish reproduction. Journal of Environmental Science and Health Part A Toxic Hazardous Substances and Environmental Engineering, 48(10) 1178-1189.

Building on breakthroughs recently made at kraft mills, a survey of mechanical pulp and paper mill effluents was undertaken to gain insights concerning potential effects on fish reproduction. Effluents from seven Canadian mills were characterized chemically for conventional parameters such as biochemical oxygen demand (BOD) and total suspended solids (TSS). Each sample was further subjected to solvent extraction followed by gas chromatographic separation for the determination of resin/fatty acids and for the estimation of a gas chromatography (GC) profile index. Each mill effluent was assessed for the potential to affect fish reproduction in the laboratory using a five day adult fathead minnow (Pimephales promelas) egg production bioassay with exposures to 100% effluent. The seven effluents were found to have substantial variation both in terms of chemical characterization and effects on fish reproduction. Temporal variations were also noted in effluent quality at mills sampled on different occasions. Similar to what has been observed for kraft mills, a general trend of greater reductions in egg production caused by effluents with greater BOD concentrations and GC profile indices was noted. Effluents with BOD > 25 mg/L and GC Profile indices >5.0 caused a complete cessation of egg production. At the same time, about half of the total effluents sampled had BOD < 25 mg/L and GC profile indices <5.0 and caused no significant effects on egg production, suggesting these values may be useful as effluent quality targets for mechanical pulp and paper mills. However, 3 out of 14 effluents sampled had BOD < 25 mg/L and GC profile indices <5.0 and caused significant reductions in egg production. The reason(s) for reproductive effects caused by such effluents is presently unclear. The effluent quality parameters considered in this study may require further refinement to address their utility in predicting the adverse reproductive effects induced by effluents from mechanical pulp and paper mills. © 2013 Taylor & Francis Group, LLC.
Kruitbos L.M., Tetzlaff D., Soulsby C., Buttle J., Carey S.K., Laudon H., McDonnell J.J., McGuire K., Seibert J., Cunjak R., Shanley J. (2013). Erratum to: Hydroclimatic and hydrochemical controls on Plecoptera diversity and distribution in northern freshwater ecosystems(Hydrobiologia, (2012), 693, (39-53), 10.1007/s10750-012-1085-1). Hydrobiologia, 702(1) 297.
Kurylyk B.L., MacQuarrie K.T.B. (2013). The uncertainty associated with estimating future groundwater recharge: A summary of recent research and an example from a small unconfined aquifer in a northern humid-continental climate. Journal of Hydrology, 492 244-253.

Global climate models (GCMs) project significant changes to regional and globally-averaged precipitation and air temperature, and these changes will likely have an associated impact on groundwater recharge. A common approach in recent climate change-impact studies is to employ multiple downscaled climate change scenarios to drive a hydrological model and project an envelope of recharge possibilities. However, each step in this process introduces variability into the hydrological results, which translates to uncertainty in the future state of groundwater resources. In this contribution, seven downscaled future climate scenarios for a northern humid-continental climate in eastern Canada were generated from selected combinations of GCMs, emission scenarios, and downscaling approaches. Meteorological data from the climate scenarios and field data from a small unconfined aquifer were used to estimate groundwater recharge with the soil water balance model HELP3. HELP3 simulations for the period 2046-2065 indicated that projected recharge was most sensitive to the selected downscaling/debiasing algorithm and GCM. Projected changes in average annual recharge varied from an increase of 58% to a decrease of 6% relative to the 1961-2000 reference period. Such a large range in projected recharge provides very little useful information regarding the future state of groundwater resources. Additional results from recent comparable studies are compiled and discussed. Based on the results obtained from the present case study and the other studies reviewed, the limitations of current approaches for projecting future recharge are identified, and several suggestions for research opportunities to advance this field are offered. © 2013 Elsevier B.V.
Kurylyk B.L., P.-A. Bourque C., Macquarrie K.T.B. (2013). Potential surface temperature and shallow groundwater temperature response to climate change: An example from a small forested catchment in east-central NB (Canada). Hydrology and Earth System Sciences, 17(7) 2701-2716.

Global climate models project significant changes to air temperature and precipitation regimes in many regions of the Northern Hemisphere. These meteorological changes will have associated impacts to surface and shallow subsurface thermal regimes, which are of interest to practitioners and researchers in many disciplines of the natural sciences. For example, groundwater temperature is critical for providing and sustaining suitable thermal habitat for cold-water salmonids. To investigate the surface and subsurface thermal effects of atmospheric climate change, seven downscaled climate scenarios (2046-2065) for a small forested catchment in NB, Canada were employed to drive the surface energy and moisture flux model, ForHyM2. Results from these seven simulations indicate that climate change-induced increases in air temperature and changes in snow cover could increase summer surface temperatures (range -0.30 to +3.49 C, mean +1.49 C), but decrease winter surface temperatures (range -1.12 to +0.08 C, mean -0.53 C) compared to the reference period simulation. Thus, changes to the timing and duration of snow cover will likely decouple changes in mean annual air temperature (mean +2.11 C) and mean annual ground surface temperature (mean +1.06 C). Projected surface temperature data were then used to drive an empirical surface to groundwater temperature transfer function developed from measured surface and groundwater temperature. Results from the empirical transfer function suggest that changes in groundwater temperature will exhibit seasonality at shallow depths (1.5 m), but be seasonally constant and approximately equivalent to the change in the mean annual surface temperature at deeper depths (8.75 m). The simulated increases in future groundwater temperature suggest that the thermal sensitivity of baseflow-dominated streams to decadal climate change may be greater than previous studies have indicated. © Author(s) 2013.
Kurylyk B.L., Watanabe K. (2013). The mathematical representation of freezing and thawing processes in variably-saturated, non-deformable soils. Advances in Water Resources, 60 160-177.

Recently, there has been a revival in the development of models simulating coupled heat and water transport in cold regions. These models represent significant advances in our ability to simulate the sensitivity of permafrost environments to future climate change. However, there are considerable differences in model formulations arising from the diverse backgrounds of researchers and practitioners in this field. The variability in existing model formulations warrants a review and synthesis of the underlying theory to demonstrate the implicit assumptions and limitations of a particular approach. This contribution examines various forms of the Clapeyron equation, the relationship between the soil moisture curve and soil freezing curve, and processes for developing soil freezing curves and hydraulic conductivity models for partially frozen soils. Where applicable, results from recent laboratory tests are presented to demonstrate the validity of existing theoretical formulations. Identified variations in model formulations form the basis for briefly comparing and contrasting existing models. Several unresolved questions are addressed to highlight the need for further research in this rapidly expanding field. © 2013 Elsevier Ltd.
Langlois V.S., Martyniuk C.J. (2013). Genome wide analysis of Silurana (Xenopus) tropicalis development reveals dynamic expression using network enrichment analysis. Mechanisms of Development, 130(4-5) 304-322.

Development involves precise timing of gene expression and coordinated pathways for organogenesis and morphogenesis. Functional and sub-network enrichment analysis provides an integrated approach for identifying networks underlying development. The objectives of this study were to characterize early gene regulatory networks over Silurana tropicalis development from NF stage 2 to 46 using a custom Agilent 4. ×. 44. K microarray. There were >8000 unique gene probes that were differentially expressed between Nieuwkoop-Faber (NF) stage 2 and stage 16, and >2000 gene probes differentially expressed between NF 34 and 46. Gene ontology revealed that genes involved in nucleosome assembly, cell division, pattern specification, neurotransmission, and general metabolism were increasingly regulated throughout development, consistent with active development. Sub-network enrichment analysis revealed that processes such as membrane hyperpolarisation, retinoic acid, cholesterol, and dopamine metabolic gene networks were activated/inhibited over time. This study identifies RNA transcripts that are potentially maternally inherited in an anuran species, provides evidence that the expression of genes involved in retinoic acid receptor signaling may increase prior to those involved in thyroid receptor signaling, and characterizes novel gene expression networks preceding organogenesis which increases understanding of the spatiotemporal embryonic development in frogs. © 2013 Elsevier Ireland Ltd.
Lavoie R.A., Jardine T.D., Chumchal M.M., Kidd K.A., Campbell L.M. (2013). Biomagnification of mercury in aquatic food webs: A worldwide meta-analysis. Environmental Science and Technology, 47(23) 13385-13394.

The slope of the simple linear regression between log<inf>10</inf> transformed mercury (Hg) concentration and stable nitrogen isotope values (δ15N), hereafter called trophic magnification slope (TMS), from several trophic levels in a food web can represent the overall degree of Hg biomagnification. We compiled data from 69 studies that determined total Hg (THg) or methyl Hg (MeHg) TMS values in 205 aquatic food webs worldwide. Hg TMS values were compared against physicochemical and biological factors hypothesized to affect Hg biomagnification in aquatic systems. Food webs ranged across 1.7 ± 0.7 (mean ± SD) and 1.8 ± 0.8 trophic levels (calculated using δ15N from baseline to top predator) for THg and MeHg, respectively. The average trophic level (based on δ15N) of the upper-trophic-level organisms in the food web was 3.7 ± 0.8 and 3.8 ± 0.8 for THg and MeHg food webs, respectively. For MeHg, the mean TMS value was 0.24 ± 0.08 but varied from 0.08 to 0.53 and was, on average, 1.5 times higher than that for THg with a mean of 0.16 ± 0.11 (range: -0.19 to 0.48). Both THg and MeHg TMS values were significantly and positively correlated with latitude. TMS values in freshwater sites increased with dissolved organic carbon and decreased with total phosphorus and atmospheric Hg deposition. Results suggest that Hg biomagnification through food webs is highest in cold and low productivity systems; however, much of the among-system variability in TMS values remains unexplained. We identify critical data gaps and provide recommendations for future studies that would improve our understanding of global Hg biomagnification. © 2013 American Chemical Society.
Leclair L.A., MacDonald G.Z., Phalen L.J., Köllner B., Hogan N.S., van den Heuvel M.R. (2013). The immunological effects of oil sands surface waters and naphthenic acids on rainbow trout (Oncorhynchus mykiss). Aquatic Toxicology, 142-143 185-194.

There is concern surrounding the immunotoxic potential of naphthenic acids (NAs), a major organic constituent in waters influenced by oil sands contamination. To assess the immunological response to NAs, rainbow trout (Oncorhynchus mykiss) waterborne exposures were conducted with oil sands-influenced waters, NAs extracted and purified from oil sands tailings waters, and benzo[a]pyrene (BaP) as a positive control. After a 7. d exposure, blood, spleen, head kidney, and gill samples were removed from a subset of fish in order to evaluate the distribution of thrombocytes, B-lymphocytes, myeloid cells, and T-lymphocytes using fluorescent antibodies specific for those cell types coupled with flow cytometry. The remaining trout in each experimental tank were injected with inactivated Aeromonas salmonicida and held in laboratory water for 21. d and subjected to similar lymphatic cell evaluation in addition to evaluation of antibody production. Fluorescent metabolites in bile as well as liver CYP1A induction were also determined after the 7 and 21. d exposure. Oil sands waters and extracted NAs exposures resulted in an increase in bile fluorescence at phenanthrene wavelengths, though liver CYP1A was not induced in those treatments as it was with the BaP positive control. Trout in the oil sands-influenced water exposure showed a decrease in B- and T-lymphocytes in blood as well as B-lymphocytes and myeloid cells in spleen and an increase in B-lymphocytes in head kidney. The extracted NAs exposure showed a decrease in thrombocytes in spleen at 8. mg/L and an increase in T-lymphocytes at 1. mg/L in head kidney after 7. d. There was a significant decrease in antibody production against A. salmonicida in both oil sands-influenced water exposures. Because oil sands-influenced waters affected multiple immune parameters, while extracted NAs impacts were limited, the NAs tested here are likely not the cause of immunotoxicity found in the oil sands-influenced water. © 2013 Elsevier B.V.
Lento J., Monk W.A., Culp J.M., Curry R.A., Cote D., Luiker E. (2013). Responses of low arctic stream benthic macroinvertebrate communities to environmental drivers at nested spatial scales. Arctic Antarctic and Alpine Research, 45(4) 538-551.

We explored the importance of environmental drivers in structuring benthic macroinvertebrate communities along a spatial hierarchy (local to landscape scale) in Low Arctic stream systems that were previously unstudied. Macroinvertebrate communities from 29 sites in Low Arctic areas of northern Labrador and Québec, Canada, were quantified by taxonomic structure and biological metrics. Environmental variables were quantified at site, reach, and catchment scales using field-collected data and geospatial information. The first three axes of Redundancy Analysis (RDA) ordinations explained 21.0-40.6% of the unconstrained variance in taxonomic structure and biological metrics. Biological data were most highly correlated with site-scale variables, but variables at each spatial scale were highly correlated with community structure. Across all scales, one of the strongest gradients involved environmental drivers that could be associated with habitat structure and instability. Abundance of the chironomid subfamily Diamesinae, a tolerant taxon in high-latitude and high-elevation systems, was highly positively associated with this habitat gradient. This hierarchical framework provides a knowledge base for the development of a sustainable long-term monitoring approach for Low Arctic aquatic ecosystems. By incorporating measures of environmental drivers at multiple spatial scales, future monitoring efforts may more effectively respond to current and future pressures on aquatic biodiversity.
Linnansaari T., Cunjak R.A. (2013). Effects of ice on behaviour of juvenile Atlantic salmon (Salmo salar). Canadian Journal of Fisheries and Aquatic Sciences, 70(10) 1488-1497.

The behaviour of Atlantic salmon (Salmo salar) parr was compared among three periods of winter (pre-ice period, PI; period of subsurface ice, SSI; period of surface ice, SI). Salmon parr remained nocturnal regardless of the ice conditions. The level of nocturnal activity was similar during PI and SI periods but was significantly reduced during the SSI period. Immobility was also highest during the SSI period, but was only partly attributable to salmon parr being trapped under ice. No differences in daytime activity among ice periods were observed. Two nocturnal movement tactics were observed: (i) "emerge-settle-return" and (ii) "emerge-move-return". The tactics were used similarly during PI and SSI periods, but the "move" tactic was predominant during the SI period. Atlantic salmon parr showed a strong tendency to return to their "home stone" after a period of activity. Homing was reduced during the SSI period, but the distance moved to a new home stone was typically <10 m. In general, salmon parr were able to cope well with subsurface and surface ice.
MacDonald G.Z., Hogan N.S., Köllner B., Thorpe K.L., Phalen L.J., Wagner B.D., van den Heuvel M.R. (2013). Immunotoxic effects of oil sands-derived naphthenic acids to rainbow trout. Aquatic Toxicology, 126 95-103.

Naphthenic acids are the major organic constituents in waters impacted by oil sands. To investigate their immunotoxicity, rainbow trout (Oncorhynchus mykiss) were injected with naphthenic acids extracted from aged oil sands tailings water. In two experiments, rainbow trout were injected intraperitoneally with 0, 10, or 100. mg/kg of naphthenic acids, and sampled after 5 or 21. d. Half of the fish from the 21. d exposure were co-exposed to inactivated Aeromonas salmonicida (A.s.) to induce an immune response. A positive control experiment was conducted using an intraperitoneal injection of 100. mg/kg of benzo[a]pyrene, a known immune suppressing compound. T-lymphocytes, B-lymphocytes, thrombocytes, and myeloid cells were counted in blood and lymphatic tissue using flow cytometry. In the 5. d exposure, there was a reduction in blood leucocytes and spleen thrombocytes at the 100. mg/kg dose. However, at 21. d, leucocyte populations showed no effects of exposure with the exception that spleen thrombocyte populations increase at the 100. mg/kg dose. In the 21. d exposure, B- and T-lymphocytes in blood showed a significant Dose. ×. A.s. interaction, indicating stimulated blood cell proliferation due to naphthenic acids alone as well as due to A.s. Naphthenic acid injections did not result in elevated bile fluorescent metabolites or elevated hepatic EROD activity. In contrast to naphthenic acids exposures, as similar dose of benzo[a]pyrene caused a significant decrease in B- and T-lymphocyte absolute counts in blood and relative B-lymphocyte counts in spleen. Results suggest that the naphthenic acids may act via a generally toxic mechanism rather than by specific toxic effects on immune cells. © 2012 Elsevier B.V.
Marlatt V.L., Lo B.P., Ornostay A., Hogan N.S., Kennedy C.J., Elphick J.R., Martyniuk C.J. (2013). The effects of the urea-based herbicide linuron on reproductive endpoints in the fathead minnow (Pimephales promelas). Comparative Biochemistry and Physiology C Toxicology and Pharmacology, 157(1) 24-32.

Linuron is a widely used urea-based herbicide that has anti-androgenic activity in both fish and rodents. To further elucidate the potential mode of action (MOA) of linuron on the vertebrate endocrine system, adult male and female fathead minnows were exposed for 21 days to dechlorinated water, a solvent control, 17β-estradiol (E2; 0.1 μg/L), dihydrotestosterone (DHT; 100 μg/L), linuron (1, 10, 100 μg/L) and one co-treatment of DHT (100 μg/L) and linuron (100 μg/L). There were no effects of linuron on egg hatching, 7 day egg survival, nuptial tubercle formation or gonadal histopathology. Administration of DHT and 1 and 100 μg/L linuron reduced plasma vitellogenin in females, while male plasma vitellogenin were induced after E2 exposure and co-exposure of DHT and linuron. Ovarian mRNA levels were examined for several genes involved in steroidogenesis (e.g. p450scc, cyp19a, star, tspo, hsd17b and hsd11b) and estrogen-mediated responses (esr1, esr2b, esr2a). Only p450scc mRNA was significantly decreased with DHT + linuron co-treatment. Clustering of steroidogenic mRNA transcript expression patterns revealed that patterns for linuron were more similar to E2 compared to DHT. Collectively, this study supports the hypothesis that linuron may not be a pure anti-androgen and may have multiple MOAs that affect vertebrate reproduction. © 2012 Elsevier Inc.
Martyniuk C.J., Alvarez S. (2013). Proteome analysis of the fathead minnow (Pimephales promelas) reproductive testes. Journal of Proteomics, 79 28-42.

Proteomics is becoming more widely used as a tool in fish physiology and toxicology and can offer mechanistic insight into organism responses to environmental signals and stressors. Using a LTQ Orbitrap Velos MS/MS, we detected 1075 proteins in the reproductive testis of fathead minnow. Proteins localized to the testis included those with a role in spermatogenesis, DNA repair, gamete meiosis, and proteins that have methylation and phosporylation activity, which are important regulatory mechanisms required for sperm maturation. Enrichment analysis revealed that proteins involved in translation, excision DNA repair, and chromatin remodeling were significantly enriched in the testis (> 25% protein coverage of the cellular pathways). Proteins involved in RNA metabolism, spliceosome assembly, metabolism, and DNA unwinding were localized to the testis, and the DEAD (Asp-Glu-Ala-Asp) box RNA-dependent helicase family was well represented in this reproductive tissue. Based upon common detected proteins and functional processes between FHMs and the more ancient sharks, other ray-finned fishes, and mammals, we hypothesize that biological processes involved in the testis (DNA unwinding, RNA processing, spliceosome assembly) have been conserved throughout vertebrate evolution. This study provides the foundation for more in depth proteomics studies investigating the effects of hormones and endocrine disruptors in the teleostean testes. © 2012 Elsevier B.V.
Martyniuk C.J., Bissegger S., Langlois V.S. (2013). Current perspectives on the androgen 5 alpha-dihydrotestosterone (DHT) and 5 alpha-reductases in teleost fishes and amphibians. General and Comparative Endocrinology, 194 264-274.

The androgen 5 alpha-dihydrotestosterone (DHT) is a steroidogenic metabolite that has received little attention in non-mammalian species. DHT is produced by the reduction of the double-bond of testosterone by a group of enzymes called 5 alpha-reductases of which there can be multiple isoforms (i.e., srd5a1, srd5a2, and srd5a3). Data from amphibians suggest that the expression of the srd5a genes occurs in early development, and continues until adulthood; however insufficient data exist in fish species, where DHT is thought to be relatively biologically inactive. Here, we demonstrate that fathead minnow (FHM; Pimephales promelas) developing embryos and adults express srd5a enzyme isoforms. During FHM embryogenesis, both srd5a1 and srd5a3 mRNA levels were significantly correlated in expression levels while srd5a2 showed a more unique pattern of expression. In adult FHMs, males had significantly higher levels of srd5a2 in the liver and gonad compared to females. In the male and female liver, transcript levels for srd5a2 were more abundant compared to srd5a1 and srd5a3, suggesting a prominent role for srd5a2 in this tissue. Interestingly, the ovary expressed higher mRNA levels of srd5a3 than the testis. Thus, data suggest that srd5a isoforms can show sexually dimorphic expression patterns in fish. We also conducted a literature review of the biological effects observed in embryonic and adult fish and amphibians after treatments with DHT and DHT-related compounds. Treatments with DHT in teleost fishes and amphibians have resulted in unexpected biological responses that are characteristic of both androgens and anti-androgens. For example, in fish DHT can induce vitellogenin in vitro from male and female hepatocytes and can increase 17β-estradiol production from the teleost ovary. We propose, that to generate further understanding of the roles of DHT in non-mammals, studies are needed that (1) address how DHT is synthesized within tissues of fish and amphibians; (2) examine the full range of biological responses to endogenous DHT, and its interactions with other signaling pathways; and (3) investigate how DHT production varies with reproductive stage. Lastly, we suggest that the Srd5a enzymes can be targets of endocrine disruptors in fish and frogs, which may result in disruptions in the estrogen:androgen balance in aquatic organisms. © 2013 Elsevier Inc.
Martyniuk C.J., Feswick A., Fang B., Koomen J.M., Barber D.S., Gavin T., LoPachin R.M. (2013). Protein targets of acrylamide adduct formation in cultured rat dopaminergic cells. Toxicology Letters, 219(3) 279-287.

Acrylamide (ACR) is an electrophilic unsaturated carbonyl derivative that produces neurotoxicity by forming irreversible Michael-type adducts with nucleophilic sulfhydryl thiolate groups on cysteine residues of neuronal proteins. Identifying specific proteins targeted by ACR can lead to a better mechanistic understanding of the corresponding neurotoxicity. Therefore, in the present study, the ACR-adducted proteome in exposed primary immortalized mesencephalic dopaminergic cells (N27) was determined using tandem mass spectrometry (LTQ-Orbitrap). N27 cells were characterized based on the presumed involvement of CNS dopaminergic damage in ACR neurotoxicity. Shotgun proteomics identified a total of 15,243 peptides in N27 cells of which 103 unique peptides exhibited ACR-adducted Cys groups. These peptides were derived from 100 individual proteins and therefore ~0.7% of the N27 cell proteome was adducted. Proteins that contained ACR adducts on multiple peptides included annexin A1 and pleckstrin homology domain-containing family M member 1. Sub-network enrichment analyses indicated that ACR-adducted proteins were involved in processes associated with neuron toxicity, diabetes, inflammation, nerve degeneration and atherosclerosis. These results provide detailed information regarding the ACR-adducted proteome in a dopaminergic cell line. The catalog of affected proteins indicates the molecular sites of ACR action and the respective roles of these proteins in cellular processes can offer insight into the corresponding neurotoxic mechanism. © 2013 Elsevier Ireland Ltd.
Martyniuk C.J., Houlahan J. (2013). Assessing gene network stability and individual variability in the fathead minnow (Pimephales promelas) transcriptome. Comparative Biochemistry and Physiology Part D Genomics and Proteomics, 8(4) 283-291.

Transcriptomics is increasingly used to assess biological responses to environmental stimuli and stressors such as aquatic pollutants. However, fundamental studies characterizing individual variability in mRNA levels are lacking, which currently limits the use of transcriptomics in environmental monitoring assessments. To address individual variability in transcript abundance, we performed a meta-analysis on 231 microarrays that were conducted in the fathead minnow (FHM), a widely used toxicological model. The mean variability for gene probes was ranked from most to least variable based upon the coefficient of variation. Transcripts that were the most variable in individual tissues included NADH dehydrogenase flavoprotein 1, GTPase IMAP family member 7-like and v-set domain-containing T-cell activation inhibitor 1-like while genes encoding ribosomal proteins (rpl24 and rpl36), basic transcription factor 3, and nascent polypeptide-associated complex alpha subunit were the least variable in individuals across a range of microarray experiments. Gene networks that showed high variability (based upon the variation in expression of individual members within the network) included cell proliferation, metabolism (steroid, lipids, and glucose), cell adhesion, vascularization, and regeneration while those that showed low variability (more stability) included mRNA and rRNA processing, regulation of translational fidelity, RNA splicing, and ribosome biogenesis. Real-time PCR was conducted on a subset of genes for comparison of variability collected from the microarrays. There was a significant positive relationship between the two methods when measuring individual variability, suggesting that variability detected in microarray data can be used to guide decisions on sample sizes for measuring transcripts in real-time PCR experiments. A power analysis revealed that measuring estrogen receptor ba (esrba) requires fewer biological replicates than that of estrogen receptor bb (esrbb) in the gonad and samples sizes required to detect a 50% change for reproductive-related transcripts is between 12 and 20. Characterizing individual variability at the molecular level will prove necessary as efforts are made toward integrating molecular tools into environmental risk assessments. © 2013 Elsevier Inc. All rights reserved.
Martyniuk C.J., Prucha M.S., Doperalski N.J., Antczak P., Kroll K.J., Falciani F., Barber D.S., Denslow N.D. (2013). Gene Expression Networks Underlying Ovarian Development in Wild Largemouth Bass (Micropterus salmoides). Plos One, 8(3).

Background: Oocyte maturation in fish involves numerous cell signaling cascades that are activated or inhibited during specific stages of oocyte development. The objectives of this study were to characterize molecular pathways and temporal gene expression patterns throughout a complete breeding cycle in wild female largemouth bass to improve understanding of the molecular sequence of events underlying oocyte maturation. Methods: Transcriptomic analysis was performed on eight morphologically diverse stages of the ovary, including primary and secondary stages of oocyte growth, ovulation, and atresia. Ovary histology, plasma vitellogenin, 17β-estradiol, and testosterone were also measured to correlate with gene networks. Results: Global expression patterns revealed dramatic differences across ovarian development, with 552 and 2070 genes being differentially expressed during both ovulation and atresia respectively. Gene set enrichment analysis (GSEA) revealed that early primary stages of oocyte growth involved increases in expression of genes involved in pathways of B-cell and T-cell receptor-mediated signaling cascades and fibronectin regulation. These pathways as well as pathways that included adrenergic receptor signaling, sphingolipid metabolism and natural killer cell activation were down-regulated at ovulation. At atresia, down-regulated pathways included gap junction and actin cytoskeleton regulation, gonadotrope and mast cell activation, and vasopressin receptor signaling and up-regulated pathways included oxidative phosphorylation and reactive oxygen species metabolism. Expression targets for luteinizing hormone signaling were low during vitellogenesis but increased 150% at ovulation. Other networks found to play a significant role in oocyte maturation included those with genes regulated by members of the TGF-beta superfamily (activins, inhibins, bone morphogenic protein 7 and growth differentiation factor 9), neuregulin 1, retinoid X receptor, and nerve growth factor family. Conclusions: This study offers novel insight into the gene networks underlying vitellogenesis, ovulation and atresia and generates new hypotheses about the cellular pathways regulating oocyte maturation. © 2013 Martyniuk et al.
McDougall C.A., Blanchfield P.J., Peake S.J., Anderson W.G. (2013). Movement Patterns and Size-Class Influence Entrainment Susceptibility of Lake Sturgeon in a Small Hydroelectric Reservoir. Transactions of the American Fisheries Society, 142(6) 1508-1521.

Hydroelectric development is considered a threat to the recovery of Lake Sturgeon Acipenser fulvescens populations, in part because of injury and mortality concerns caused by interaction with hydroelectric facilities. Lake Sturgeon resident in small impoundments may be particularly susceptible to entrainment, depending on movement and habitat usage patterns. Using acoustic telemetry, we monitored coarse-scale movements of 99 juvenile, subadult and adult Lake Sturgeon captured throughout a 10-km-long hydroelectric reservoir. Overall, adults moved over larger ranges than did smaller size-classes. However, all size-classes utilized habitat immediately upstream of hydroelectric facilities, and during the 18-month study period, 27% of subadults tagged in the lowermost section of the reservoir, and 8.7% of adults tagged throughout the reservoir were entrained. Movements of juveniles and subadults were generally restricted to extended sections (2-6 km) of contiguous deepwater habitat (>15 m), and passage through the two shallow river narrows that subdivide the reservoir were rare. Over half of the tagged adults (52%) moved upstream or downstream through one or both river narrows, albeit infrequently. Initial residency influenced entrainment susceptibility for juveniles and subadults but not for adults. Results suggest that Lake Sturgeon resident in small impoundments are susceptible to entrainment. However, the presence of river narrows, which function as natural movement restrictors, may largely preclude susceptibility of juveniles and subadults resident in upstream sections. Received September 24, 2012; accepted June 10, 2013. © 2013 Copyright Taylor and Francis Group, LLC.
McDougall C.A., Hrenchuk C.L., Anderson W.G., Peake S.J. (2013). The Rapid Upstream Migration of Pre-Spawn Lake Sturgeon following Trap-and-Transport over a Hydroelectric Generating Station. North American Journal of Fisheries Management, 33(6) 1236-1242.

Spawning migrations of Lake Sturgeon Acipenser fulvescens are often blocked by dams, and fishway designs suitable for volitional upstream passage, particularly over high-head structures, remain elusive. Trap-and-transport has potential as a management tool but has yet to be evaluated in Lake Sturgeon. In spring 2009, six male and six female Lake Sturgeon in prespawn condition were captured using gill nets downstream of the Seven Sisters Generating Station, located on the Winnipeg River, Manitoba. Each fish received an acoustic transmitter and was released ∼ 500 m upstream of the station. Four stationary receivers were deployed in the 41-km stretch of river between the Seven Sisters and Slave Falls generating stations to monitor upstream movements, while an additional four were deployed downstream of Seven Sisters to monitor potential fallback. Following trap-and-transport, all 11 detected fish were observed moving rapidly upstream through backwatered habitats, into the stretch of river where Lake Sturgeon spawning sites occur, before or coincident with the onset of the spawning period. No fallback was observed during initial ascents. While further research is required, trap-and-transport of Lake Sturgeon may be a useful tool for fisheries managers wishing to facilitate historical spawning migrations interrupted by dams. Received February 18, 2013; accepted July 24, 2013. © 2013 Copyright Taylor and Francis Group, LLC.
Meina E.G., Lister A., Bosker T., Servos M., Munkittrick K., MacLatchy D. (2013). Effects of 17α-ethinylestradiol (EE2) on reproductive endocrine status in mummichog (Fundulus heteroclitus) under differing salinity and temperature conditions. Aquatic Toxicology, 134-135 92-103.

Exposure to 17α-ethinylestradiol (EE<inf>2</inf>), a synthetic estrogen, has previously been shown to decrease reproductive endocrine status and egg production in northern mummichog (Fundulus heteroclitus macrolepidotus). The objective of this study was to evaluate if variations in salinity or temperature conditions of EE<inf>2</inf>-exposed mummichog modify the effect on whole organism reproductive endocrine status and gonadal steroidogenesis. Mummichog were exposed in vivo for 14 days to 0, 50 and 250ng/L EE<inf>2</inf> in 0, 16 and 32ppt salinity at 18°C and to 0 and 250ng/L EE<inf>2</inf> at 10, 18 and 26°C at 16ppt. There was a little overall effect of salinity on measured endpoints. In the salinity exposure, 250ng/L EE<inf>2</inf>-exposed females had significantly reduced 17β-estradiol (E<inf>2</inf>) levels. Increased temperature triggered gonadal growth in both sexes and increased plasma E<inf>2</inf> and E<inf>2</inf> production and decreased 11-KT (11-ketotestosterone) production. EE<inf>2</inf> counteracted the effect of temperature by depressing gonadal growth in males. In both exposures, EE<inf>2</inf> effects on testosterone (T) production were variable. The use of steroidogenic precursors (25-OH-cholesterol, and/or pregnenolone and/or testosterone) in the in vitro gonadal incubations indicated decreased E<inf>2</inf> production in females and 11-KT production in males were predominately due to suppression of the terminal conversion step between T and E<inf>2</inf> or 11-KT. Ovarian aromatase A (cyp19a) gene expression at 16ppt and 18°C was not affected by 250ng/L EE<inf>2</inf> (the only treatment combinations tested). Overall, temperature is a factor regulating northern mummichog reproduction; EE<inf>2</inf> overrides its effects and disrupts the terminal step of steroidogenesis. Our results should be considered in designing future estuarine fish bioassays and in understanding effects of estrogenic endocrine disruptors in estuaries. © 2013 Elsevier B.V.
Miller D.H., Tietge J.E., Mcmaster M.E., Munkittrick K.R., Xia X., Ankley G.T. (2013). Assessment of status of white sucker (Catostomus commersoni) populations exposed to bleached kraft pulp mill effluent. Environmental Toxicology and Chemistry, 32(7) 1592-1603.

Credible ecological risk assessments often need to include analysis of population-level impacts. In the present study, a predictive model was developed to investigate population dynamics for white sucker (Catostomus commersoni) exposed to pulp mill effluent at a well-studied site in Jackfish Bay, Lake Superior, Canada. The model uniquely combines a Leslie population projection matrix and the logistic equation to translate changes in the fecundity and the age structure of a breeding population of white sucker exposed to pulp mill effluent to alterations in population growth rate. Application of this density-dependent population projection model requires construction of a life table for the organism of interest, a measure of carrying capacity, and an estimation of the effect of stressors on vital rates. A white sucker population existing at carrying capacity and subsequently exposed to pulp mill effluent equivalent to a documented exposure experienced during the period 1988 to 1994 in Jackfish Bay would be expected to exhibit a 34% to 51% annual decrease in recruitment during the first 5 yr of exposure and approach a population size of 71% of carrying capacity. The Jackfish Bay study site contains monitoring data for biochemical endpoints in white sucker, including circulating sex steroid concentrations, that could be combined with population modeling to utilize the model demonstrated at the Jackfish Bay study site for investigation of other white sucker populations at sites that are less data-rich. © 2013 SETAC.
Mocq J., St-Hilaire A., Cunjak R.A. (2013). Assessment of Atlantic salmon (Salmo salar) habitat quality and its uncertainty using a multiple-expert fuzzy model applied to the Romaine River (Canada). Ecological Modelling, 265 14-25.

Many tools have been developed to evaluate environmental flows, including physical microhabitat models like PHASBIM and HABSCORE, which require habitat suitability curves. Unfortunately, the models and curves are often used in stream-specific applications and are rarely easily exportable. With the aim to address this shortcoming, we developed several habitat suitability indices sets for three Atlantic salmon (Salmo salar) life stages (young-of-the-year (YOY), parr, spawning adults) with the help of fuzzy logic modeling. Using the knowledge of twenty-seven experts, from both sides of the Atlantic Ocean, we defined fuzzy sets of four variables (depth, substrate size, velocity and Habitat Suitability Index, or HSI) and associated fuzzy rules. When applied to the Romaine River (Canada), median curves of standardized Weighted Usable Area (WUA) were calculated and a confidence interval was obtained by bootstrap resampling. Despite the large range of WUA covered by the expert WUA curves, confidence intervals were relatively narrow: an average width of 0.095 (on a scale of 0 to 1) for spawning habitat, 0.155 for parr rearing habitat and 0.160 for YOY rearing habitat. In addition, Student's t-test showed significant differences in predicted HSI between presence and absence, for parr and YOY, and RM_ANOVA showed significant differences for parr only. When considering an environmental flow value corresponding to 90% of the maximum reached by WUA curve, results seem acceptable for the Romaine River. Generally, this proposed fuzzy logic method seems suitable to model habitat availability for the three life stages, while also providing an estimate of uncertainty in salmon preferences. © 2013 Elsevier B.V.
Monk W.A., Wilbur N.M., Allen Curry R., Gagnon R., Faux R.N. (2013). Linking landscape variables to cold water refugia in rivers. Journal of Environmental Management, 118 170-176.

The protection of coldwater refugia within aquatic systems requires the identification of thermal habitats in rivers. These refugia provide critical thermal habitats for brook trout (Salvelinus fontinalis) and Atlantic salmon (Salmo salar) during periods of thermal stress, for example during summer high temperature events. This study aims to model these refugia using georeferenced thermal infrared images collected during late July 2008 and 2009 for a reach of the Cains River, New Brunswick, Canada. These images were paired with geospatial catchment variables to identify the driving factors for coldwater refugia located within tributaries to the main channel. Using Partial Least Square (PLS) Regression, results suggest that median temperatures of tributary catchments are driven by their position within the landscape including slope in addition to the density of wetlands and mixed forest within the upstream catchment. Similar results are presented when PLS models were developed to predict the magnitude of the cold water refugia (i.e. the difference between the mainstem water temperature and the thermal refugia). These results suggest that thermal infrared images can be used to predict critical summer habitats for coldwater fishes. © 2013 Elsevier Ltd.
Orlofske J.M., Baird D.J. (2013). The tiny mayfly in the room: Implications of size-dependent invertebrate taxonomic identification for biomonitoring data properties. Aquatic Ecology, 47(4) 481-494.

The appropriate level of taxonomic identification, taxonomic sufficiency, for biomonitoring purposes continues to be controversial. Taxonomic sufficiency, however, fails to address the bias created by size-dependent taxonomic identification, which can result in coarse-resolution identification for immature specimens lacking distinguishing characteristics. Our study provides a direct test for this potential systematic bias in biomonitoring data by examining two morphological traits: body size and shape of key organisms (Ephemeroptera, Plecoptera, Trichoptera and Odonata) collected from standard aquatic biomonitoring samples. Direct measurement of body size and a geometric morphometric description of body shape provide consistent, quantitative variables to describe the composition of specimens identified at different levels of taxonomic resolution (genus or family). Corroborating our expectations, we observed evidence of systematic size bias in family-level identifications. Specimens that could only reliably be identified to the family level were significantly smaller than specimens identified to the genus level. Qualitative comparisons of shape variation between specimens demonstrated a high degree of variation in specimens identified only at the family level and support the conclusion that specimens identified at the family level possess multiple constituent taxa (genera or species). Thus, size-dependent taxonomy can have negative consequences for the accurate determination of biodiversity and may invalidate common biomonitoring metrics. Improvements to biomonitoring protocols through technological advances, including DNA-based taxonomy to augment specimen identification, should effectively remove the size-bias problem in the long term. In the short-term, recognizing instances of size bias, the degree to which it may impact bioassessment and exploring methods for remediation, including traits-based assessments, can enhance data quality and inferences derived from biomonitoring studies. © 2013 The Author(s).
Orlofske J.M., Monk W.A., Baird D.J. (2013). Ecohydraulics for River Management: Can Mesoscale Lotic Macroinvertebrate Data Inform Macroscale Ecosystem Assessment? Ecohydraulics an Integrated Approach 357-374.
Ornostay A., Cowie A.M., Hindle M., Baker C.J.O., Martyniuk C.J. (2013). Classifying chemical mode of action using gene networks and machine learning: A case study with the herbicide linuron. Comparative Biochemistry and Physiology Part D Genomics and Proteomics, 8(4) 263-274.

The herbicide linuron (LIN) is an endocrine disruptor with an anti-androgenic mode of action. The objectives of this study were to (1) improve knowledge of androgen and anti-androgen signaling in the teleostean ovary and to (2) assess the ability of gene networks and machine learning to classify LIN as an anti-androgen using transcriptomic data. Ovarian explants from vitellogenic fathead minnows (FHMs) were exposed to three concentrations of either 5α-dihydrotestosterone (DHT), flutamide (FLUT), or LIN for 12 h. Ovaries exposed to DHT showed a significant increase in 17β-estradiol (E<inf>2</inf>) production while FLUT and LIN had no effect on E<inf>2</inf>. To improve understanding of androgen receptor signaling in the ovary, a reciprocal gene expression network was constructed for DHT and FLUT using pathway analysis and these data suggested that steroid metabolism, translation, and DNA replication are processes regulated through AR signaling in the ovary. Sub-network enrichment analysis revealed that FLUT and LIN shared more regulated gene networks in common compared to DHT. Using transcriptomic datasets from different fish species, machine learning algorithms classified LIN successfully with other anti-androgens. This study advances knowledge regarding molecular signaling cascades in the ovary that are responsive to androgens and anti-androgens and provides proof of concept that gene network analysis and machine learning can classify priority chemicals using experimental transcriptomic data collected from different fish species. © 2013 Elsevier Inc. All rights reserved.
Ouellet J.D., Dubé M.G., Niyogi S. (2013). A single metal, metal mixture, and whole-effluent approach to investigate causes of metal mine effluent effects on fathead minnows (Pimephales promelas). Water Air and Soil Pollution, 224(3).

Although many studies have examined effects of metal mine effluents (MMEs) on receiving environments, few have compared the roles of individual and mixed metals relative to whole effluents. The objective of the present set of studies was to examine whether Cu, Ni, or Se, alone or in a mixture, causes comparable effects to those observed in fathead minnows (Pimephales promelas) exposed to an environmentally relevant MME (45 % process water effluent [PWE]). Metal bioaccumulation, fathead minnow (FHM) morphometrics, and egg production were compared between treatments over a 21-day exposure. FHMs were exposed to similar waterborne concentrations and species of metals in single and mixed metal treatments relative to 45 % PWE. FHMs were also exposed to similar concentrations of metals in single and mixed metal treatments relative to 45 % PWE through the diet (Chironomus dilutus - a representative prey species). However, only FHMs exposed to 45 % PWE had reduced egg production (60-80 % less than controls). Our findings indicate that Cu, Ni, and Se exposures and bioaccumulation did not contribute to decreased reproductive output in FHMs under the conditions that were examined. We also found no evidence to believe that these metals were responsible for decreased egg production in PWE. It is therefore reasonable to suggest that these metals have limited potential to cause reproductive effects in MMEs with similar composition and water chemistry conditions. Overall, this study highlights the importance of examining single and mixed metal exposures prior to suggesting that adverse effects in fish exposed to MMEs occur due to bioaccumulation of metal(s). © 2013 Springer Science+Business Media Dordrecht.
Ouellet J.D., Dubé M.G., Niyogi S. (2013). Influence of elevated alkalinity and natural organic matter (NOM) on tissue-specific metal accumulation and reproductive performance in fathead minnows during chronic, multi-trophic exposures to a metal mine effluent. Ecotoxicology and Environmental Safety, 95 104-112.

Metal bioavailability in aquatic organisms is known to be influenced by various water chemistry parameters. The present study examined the influence of alkalinity and natural organic matter (NOM) on tissue-specific metal accumulation and reproductive performance of fathead minnows (Pimephales promelas) during environmentally relevant chronic exposures to a metal mine effluent (MME). Sodium bicarbonate (NaHCO<inf>3</inf>) or NOM (as commercial humic acid) were added to a Canadian MME [45 percent process water effluent (PWE)] in order to evaluate whether increases in alkalinity (3-4 fold) or NOM (~1.5-3mg/L dissolved organic carbon) would reduce metal accumulation and mitigate reproductive toxicity in fathead minnows during a 21-day multi-trophic exposure. Eleven metals (barium, boron, cobalt, copper, lithium, manganese, molybdenum, nickel, rubidium, selenium, and strontium) were elevated in the 45 percent PWE relative to the reference water. Exposure to the unmodified 45 percent PWE resulted in a decrease of fathead minnow egg production (~300 fewer eggs/pair) relative to the unmodified reference water, over the 21-day exposure period. Water chemistry modifications produced a modest decrease in free ion activity of some metals (as shown by MINTEQ, Version 3) in the 45 percent PWE exposure water, but did not alter the metal burden in the treatment-matched larval Chironomus dilutus (the food source of fish during exposure). The tissue-specific metal accumulation increased in fish exposed to the 45 percent PWE relative to the reference water, irrespective of water chemistry modifications, and the tissue metal concentrations were found to be similar between fish in the unmodified and modified 45 percent PWE (higher alkalinity or NOM) treatments. Interestingly however, increased alkalinity and NOM markedly improved fish egg production both in the reference water (~500 and ~590 additional eggs/pair, respectively) and 45 percent PWE treatments (~570 and ~260 additional eggs/pair, respectively), although fecundity over 21 day exposure consistently remained lower in the 45 percent PWE treatment groups relative to the treatment-matched reference groups. Collectively, these findings suggest that metal accumulation caused by chronic 45 percent PWE exposure cannot solely explain the reproductive toxicity in fish, and decrease in food availability (decrease in C. dilutus abundance in 45 percent PWE exposures) might have played a role. In addition, it appears that NaHCO<inf>3</inf> or humic acid mitigated reproductive toxicity in fish exposed to 45 percent PWE by their direct beneficial effects on the physiological status of fish. © 2013 Elsevier Inc.
Ouellet J.D., Dubé M.G., Niyogi S. (2013). The influence of food quantity on metal bioaccumulation and reproduction in fathead minnows (Pimephales promelas) during chronic exposures to a metal mine effluent. Ecotoxicology and Environmental Safety, 91 188-197.

Metal mine effluents can impact fish in the receiving environment via both direct effects from exposure as well as indirect effects via food web. The main objective of the present study was to assess whether an indirect effect such as reduced food (prey) availability could influence metal accumulation and reproductive capacity in fish during chronic exposure to a metal mine effluent. Breeding pairs of fathead minnows (Pimephales promelas) were exposed to either reference water (RW) or an environmentally relevant metal mine effluent [45 percent process water effluent (PWE)] for 21 days and fed either low food quantities [LF (a daily ration of 6-10 percent body weight)] or normal food quantities [NF (a daily ration of 20-30 percent body weight)] in artificial stream systems. Fish in RW treatments were fed Chironomus dilutus larvae cultured in RW (Treatments: RW-NF or RW-LF), while fish in PWE treatments were fed C. dilutus larvae cultured in PWE (Treatments: PWE-NF or PWE-LF). Tissue-specific (gill, liver, gonad and carcass) metal accumulation, egg production, and morphometric parameters in fish were analyzed. Fathead minnows that were exposed to LF rations had significantly smaller body, gonad and liver sizes, and were in a relatively poor condition compared to fathead minnows exposed to NF rations, regardless of the treatment water type (RW or PWE) (two-way ANOVA; p<0.05). Although elevated concentrations of copper, nickel, rubidium, selenium, and thallium were recorded in C. dilutus cultured in PWE, only the concentrations of rubidium, selenium and thallium increased in tissues of fish in PWE treatments. Interestingly though, despite the greater abundance of metal-contaminated food in the PWE-NF treatment, tissue metal accumulation pattern were almost similar between the PWE-NF and PWE-LF treatments, except for higher liver barium, cobalt and manganese concentrations in the latter treatment. This indicated that a higher food ration could help reduce the tissue burden of at least some metals and thereby ameliorate the toxicity of metal-mine effluents in fish. More importantly, cumulative egg production in fish was found to be lowest in the PWE-LF treatment, whereas fish egg production in the PWE-NF treatment was not impacted. Overall, these findings suggest that decreased food abundance could have a greater impact than metal accumulation in target tissues on the reproductive capacity of fish inhabiting metal-mine effluent receiving environments. © 2013 Elsevier Inc..
Pahl-Wostl C., Arthington A., Bogardi J., Bunn S.E., Hoff H., Lebel L., Nikitina E., Palmer M., Poff L.R.N., Richards K., Schlüter M., Schulze R., St-Hilaire A., Tharme R., Tockner K., Tsegai D. (2013). Environmental flows and water governance: Managing sustainable water uses. Current Opinion in Environmental Sustainability, 5(3-4) 341-351.

Human water security is often achieved with little consideration of environmental consequences and, even when these are acknowledged, the trade-offs between human and environmental water needs are increasing in frequency and amplitude on the increase. The environmental flows concept has continued to evolve in response to these challenges. However, the field is characterized by a limited transferability of insights, due to the prevalence of specific case-study analyses and a lack of research on the governance of environmental flows. Building on recent advances in environmental flow science, water governance and management, we identify a clear need for a more systematic approach to the determination of environmental flow requirements (EFRs) on both the natural and social science fronts and, in particular, on the interaction between social/political and environmental systems. We suggest a framework that details as to how these advances and interactions can be achieved. The framework supports scientific analysis and practical implementation of EFRs involving systematic compilation, sharing and evaluation of experiences from different riverine ecosystems and governance systems around the globe. The concept of ecosystem services is introduced into the framework to raise awareness for the importance of ecosystem functions for the resilience of social-ecological systems, to support negotiation of trade-offs and development of strategies for adaptive implementation. Experience in implementation of environmental flow policies reveals the need for an engaged, transdisciplinary research approach where research is closely linked to implementation initiatives on the ground. We advocate that this is more effective at building the foundations for sustainable water management. © 2013 Elsevier B.V.
Parks D.H., Mankowski T., Zangooei S., Porter M.S., Armanini D.G., Baird D.J., Langille M.G.I., Beiko R.G. (2013). GenGIS 2: Geospatial Analysis of Traditional and Genetic Biodiversity, with New Gradient Algorithms and an Extensible Plugin Framework. Plos One, 8(7).

GenGIS is free and open source software designed to integrate biodiversity data with a digital map and information about geography and habitat. While originally developed with microbial community analyses and phylogeography in mind, GenGIS has been applied to a wide range of datasets. A key feature of GenGIS is the ability to test geographic axes that can correspond to routes of migration or gradients that influence community similarity. Here we introduce GenGIS version 2, which extends the linear gradient tests introduced in the first version to allow comprehensive testing of all possible linear geographic axes. GenGIS v2 also includes a new plugin framework that supports the development and use of graphically driven analysis packages: initial plugins include implementations of linear regression and the Mantel test, calculations of alpha-diversity (e.g., Shannon Index) for all samples, and geographic visualizations of dissimilarity matrices. We have also implemented a recently published method for biomonitoring reference condition analysis (RCA), which compares observed species richness and diversity to predicted values to determine whether a given site has been impacted. The newest version of GenGIS supports vector data in addition to raster files. We demonstrate the new features of GenGIS by performing a full gradient analysis of an Australian kangaroo apple data set, by using plugins and embedded statistical commands to analyze human microbiome sample data, and by applying RCA to a set of samples from Atlantic Canada. GenGIS release versions, tutorials and documentation are freely available at http://kiwi.cs.dal.ca/GenGIS, and source code is available at https://github.com/beiko-lab/gengis. © 2013 Parks et al.
Pestana J.L.T., Baird D.J., Soares A.M.V.M. (2013). Predator threat assessment in Daphnia magna: The role of kairomones versus conspecific alarm cues. Marine and Freshwater Research, 64(8) 679-686.

Studying the finely tuned mechanism of predation risk assessment allows for a better understanding of how prey organisms make key decisions under different levels of predation pressure. We studied the relative importance of conspecific alarm cues and fish kairomones as initiators of D. magna antipredator defences. By exposing a clone of D. magna to different infochemicals that simulated the presence of an active fish predator, we observed cue-specific responses in terms of altered feeding behaviour, respiration and life-history traits. Results agreed with the hypothesis that D. magna processes information from alarm cues from macerated conspecifics and from predator kairomones to assess the level of predation risk, adjusting the magnitude of their responses to the different levels of threat perceived. Results support the findings of other investigations and further show that single cues (fish kairomones or alarm cues) triggered feeding reduction and increased oxygen consumption, whereas fish kairomones only elicited D. magna life-history responses. Prey-specific alarm cues can thus modify the response of Daphnia to trout kairomones and this combination of both chemical cues appears to be necessary to trigger the full deployment of antipredator responses and avoid unnecessary costs arising from maladaptive responses. © IAWF 2013.
Peters D.L., Atkinson D., Monk W.A., Tenenbaum D.E., Baird D.J. (2013). A multi-scale hydroclimatic analysis of runoff generation in the Athabasca River, Western Canada. Hydrological Processes, 27(13) 1915-1934.

A multi-scale hydroclimatic study of runoff generation in the Athabasca River watershed located in western Canada is presented. Mann-Kendall trend detection tests performed on hydrometric data for the lower Athabasca River (LAR) revealed predominantly significant (p<0.05) declines in annual and open-water season median/mean runoff indices over 1958-2009, with the ice-influenced season experiencing significant declines in the median and not the mean. The presence or absence of significant declines in the 25th and 75th runoff percentiles helped explain these results. The only noteworthy result from the mid-point of the watershed was a probable (p<0.10) decline in median open-water runoff, which was not seen over the 1913-2009 period. Divergent seasonal runoff trends from the headwater zone were seen since 1958 and back to 1913, increasing ice-influenced and declining open-water season runoff trends. Although precipitation was observed to decline over 1958-2009, only the LAR watershed scale annual index emerged as a probable decline. Multiple non-linear regression analysis indicated that variation in precipitation explained >67% of the annual median/mean LAR runoff variability since 1958. A first-order precipitation driven hindcasting model suggested that LAR watershed scale runoff may have increased since 1913, warranting further study. A correlation analysis of climatic teleconnections with median/mean runoff indices revealed that the winter North Pacific American index showed a strong, positive association with open-water runoff. The results from our study demonstrated that potentially inconsistent and/or divergent trend results can be obtained when using different time periods and/or regions of the watershed, emphasizing that extreme caution should be exercised when extrapolating sub-watershed results to the watershed scale, or to adjacent watersheds. Our multi-scale study approach also identified the drainage area between Athabasca and Fort McMurray as a zone that influenced runoff declines observed at the LAR watershed scale since 1958, which warrants further investigation with competent hydrological models. © 2013 John Wiley & Sons Ltd and Her Majesty the Queen in Right of Canada Reproduced with the permission of the Ministry of the Environment.
Proulx-McInnis S., St-Hilaire A., Rousseau A.N., Jutras S., Carrer G., Levrel G. (2013). Seasonal and monthly hydrological budgets of a fen-dominated forested watershed, James Bay region, Quebec. Hydrological Processes, 27(10) 1365-1378.

The hydrology of Quebec, Canada, boreal fens is poorly documented. Many peatlands are located in watersheds with impounded rivers. In such cases, their presence influences reservoir inflows. In recent years, some fens have been subjected to an increase of their wet area, a sign that they may be evolving towards an aquatic ecosystem. This dynamic process is called aqualysis. This article presents the seasonal and monthly hydrological budgets of a small watershed including a highly aqualysed fen (James Bay region). The monitoring of precipitation (P), runoff (Q) and groundwater levels (WL) was conducted during the ice-free season. Three semiempirical equations (Thornthwaite, Priestley-Taylor and Penman-Monteith) were used and compared to calculate potential evapotranspiration. The first two equations, having fewer parameters, estimate higher potential evapotranspiration values than the third equation. The use of pressure-level gauges installed in wells, for the calculation of peatland water storage, is inconclusive. Swelling of peat, peat decomposition and plant composition could be responsible for nonnegligible amounts of absorbed water, which are not entirely accounted for by well levels. The estimation of peat matrix water storage is potentially the largest source of error and the limiting factor to calculate water balances in this environment. The results show that the groundwater level and the water storage vary depending on the season and especially after a heavy rainfall. Finally, the results illustrate the complexity of water routing through the site and thus raise several questions to be resolved in the future. © 2012 John Wiley & Sons, Ltd.
Ryan M.J., Stern G.A., Kidd K.A., Croft M.V., Gewurtz S., Diamond M., Kinnear L., Roach P. (2013). Biotic interactions in temporal trends (1992-2010) of organochlorine contaminants in the aquatic food web of Lake Laberge, Yukon Territory. Science of the Total Environment, 443 80-92.

Declines in 6 organochlorine (OC) contaminant groups; chlordane (CHL), DDT, HCH, toxaphene (CHB), PCB and chlorinated benzenes (CBz) were measured in biota of a sub-Arctic lake (Lake Laberge, YT) following the closure of a commercial fishery in 1991. This study examined morphological (length, weight, age), biochemical (lipid content, δ13C, δ15N), population and OC data for 9 fishes and zooplankton between 1993 and 2003 (2010 for lake trout) to investigate causes for the OC declines. Growth dilution was a major factor influencing the decrease of OCs in lake trout, round whitefish and possibly zooplankton most notably in the early 2000s. A decline in lipids of most fish species also contributed to OC declines, although no such change was evident for zooplankton. It is suspected that increases in fish populations or climate variations over the 1990s, may have contributed towards a shift in plankton community composition. From 1991 to 1999, CPUE increased for 7 of the fish species and declined for 2 others. Concurrently, the zooplankton community shifted from an abundance of C. scutifer in 1993 to dominance by D. pribilofensis in 2001. Nitrogen and carbon stable isotope data suggested that food web interactions for most fish species have not changed over time. Although concentrations of OCs have declined in many fishes, the "rate" of OC transfer (using slopes of log OC vs. nitrogen isotope ratios) through the food web was greater in 2001 than in 1993. Overall, the declines in OC concentrations in the fish from Lake Laberge occurred concurrently with changes in their growth, lipid, and abundance, suggesting that ecosystem responses to the closure of the fishery were in part responsible for the lower contaminants in these fishes. As a result of this study, the Yukon government rescinded the health advisory for limiting the consumption of fish from Lake Laberge. © 2012 Elsevier B.V.
Schein A., Courtenay S.C., Kidd K.A., Campbell K.A., van den Heuvel M.R. (2013). Food web structure within an estuary of the southern Gulf of St. Lawrence undergoing eutrophication. Canadian Journal of Fisheries and Aquatic Sciences, 70(12) 1805-1812.

This study compared food web structure in eutrophied Ulva lactuca-dominated areas within an estuary in the Southern Gulf of St. Lawrence, with Zostera marina beds within the same estuary. The estuarine food web consisted only of primary producers, mesograzers, and secondary grazers, with the absence of piscivorous top predators. It was hypothesized that the altered plant habitat would lead to structural changes in the food web and the dominance of benthic carbon. Stomach contents from mummichog (Fundulus heteroclitus), fourspine stickleback (Apeltes quadracus), and American eel (Anguilla rostrata) showed that only mummichog had significant differences in prey items between the different habitats. Stable isotopes showed that there were no significant differences in the food web structure and individual species' 13C values. A 13C spike in particulate organic matter during the onset of anoxia in July, presumably due to bacterial blooms, indicated the complete dominance of benthic carbon the pelagic food web during this month. Thus, blooms of heterotrophs during anoxic events may have the greatest influence on nutrient cycling in estuaries undergoing eutrophication.
Servos M.R., Munkittrick K.R., Constantin G., Mngodo R., Aladin N., Choowaew S., Hap N., Kidd K.A., Odada E., Parra O., Phillips G., Ryanzhin S., Urrutia R. (2013). Science and management of transboundary lakes: Lessons learned from the global environment facility program. Environmental Development, 7(1) 17-31.

The International Waters Science Project Lakes Working Group reviewed 58 Global Environment Facility (GEF) projects that addressed serious environmental and human development issues in transboundary lakes. The lessons learned from the review of these projects were integrated with the intention to contribute to the design and success of future projects. Issues that will continue to impact lake ecosystems and their management include changing agricultural practices, resource extraction, emerging contaminants, energy policies, and water allocation. Future lakes projects addressing these issues must also consider the potential confounding effects of changing land use and climate on watershed processes, water quality, food web structure and biodiversity. Current and future scientific challenges include developing strategies for climate adaptation, improving the capacity to detect change and enhancing the application of an ecosystem approach within lakes management. Failure to consider the unique physical and biological features and processes in lakes can be a barrier to effective remediation. The spatial and temporal variability in lakes and their often slow response to remedial actions need to be considered in the design of monitoring programs. Factors that improved the success of GEF transboundary projects included early and strong communication, engagement of stakeholders, rigorous peer review and international science teams linked to local capacity building and policy development. The application of both natural and socio-economic science based assessment, and adaptive management were essential for full project implementation and led to optimization of water resources allocation while sustaining ecosystems on which social and economic systems depend. © 2013 Elsevier B.V.
Sigourney D.B., Letcher B.H., Obedzinski M., Cunjak R.A. (2013). Interactive effects of life history and season on size-dependent growth in juvenile Atlantic salmon. Ecology of Freshwater Fish, 22(4) 495-507.

Size-dependent growth (SDG) is an important process in structuring populations as well as determining life history outcomes. Despite its importance, there have been few investigations from observational studies focusing on the interaction between life history decisions and SDG. In this study, we used data on individually tagged Atlantic salmon from both the laboratory and the field to investigate differences in SDG among two life history groups, parr and smolts. In the laboratory, we found little evidence of SDG in parr but seasonally dependent SDG in the smolt group. Smolts showed at strong compensatory response over the winter months just prior to the smolt transformation window. In the field, we found little evidence of SDG early in ontogeny (i.e., age 0+ fall and winter). There was some evidence of depensatory growth (positive SDG) during the age 1+ spring among both life history groups that may reflect random habitat variation or the monopolisation of resources. After the age 1+ spring, we found that smolts were more likely to show a compensatory effect (negative SDG) than parr. This effect was strongest, as they approached the smolt window in the spring of their age 2+ year. These results suggest (i) SDG is common in Atlantic salmon; however, the form and extent of life history depends on (ii) season and (iii) life history. For individuals that adopt a smolt life history, trade-offs between freshwater survival and sea survival may lead to a convergent growth pattern, as they approach the smolt migration window. © 2013 John Wiley & Sons A/S.
Skinner M.A., Courtenay S.C., McKindsey C.W. (2013). Reductions in distribution, photosynthesis, and productivity of eelgrass Zostera marina associated with oyster Crassostrea virginica aquaculture. Marine Ecology Progress Series, 486 105-119.

This study provides the first quantitative description of the influence of suspended bag oyster aquaculture (SBOA) of Crassostrea virginica on the distribution, morphology, physiology, and productivity of eelgrass Zostera marina. We explored possible mechanisms related to decreased light availability, nutrient stress, organic loading, and physical damage from bags or boats. Surveys at multiple spatial scales across a 125 km range of Atlantic Canadian bays and estuaries demonstrated consistent declines in eelgrass biomass by as much as 79% at commercial culture leases versus reference areas. Reductions in biomass were negatively related to both oyster stocking density and the age of culture leases. We further observed reductions in the capacity of eelgrass photochemistry at culture sites, accompanied by primary production declines of 37.9%. Our data suggest that these reductions in Z. marina distribution, productivity, and photosynthetic rates are primarily occurring as a result of light limitation caused by shading from aquaculture equipment. © Fisheries and Oceans Canada 2013.
Sollows M.C., McAlpine D.F., Munkittrick K.R. (2013). Density and abundance of the Freshwater Pearl Mussel, Margaritifera margaritifera, in the Kennebecasis River, New Brunswick and evidence of recent recruitment. Canadian Field Naturalist, 127(4) 303-309.

Freshwater Pearl Mussel, Margaritifera margaritifera (l., 1758) populations are endangered or threatened throughout Europe, and those in eastern Canada are believed to be some of the most abundant populations remaining worldwide. Although M. margaritifera occurs widely in Atlantic Canada, there is little information to allow its conservation status in the region to be assessed or to place these populations in a global context. using 0.25 m2 survey quadrats, maximum densities of M. margaritifera in six mussel beds on the Kennebecasis River and a tributary in southeastern New Brunswick were found to range from 12 to 200 m-2. Mean densities at the five mainstem sites ranged from to 1.9 m-2 (SE±0.4) to16.0 m-2 (±4.3). Mean density on the tributary stream was 1.2 m-2 (SE±0.7). Abundance of M. margaritifera at the six sites ranged from 4,536 (SE±2,600) to 55,520 (SE±14,768) and together the six mussel beds supported an estimated 161,315 Freshwater Pearl Mussels. the presence of juvenile M. margaritifera as small as 11.5 mm at the most upstream site, and Freshwater Pearl Mussels <30 mm at all sites, indicates that there had been recruitment of M. margaritifera juveniles in the Kennebecasis River in the 4-6 years prior to the 2007-2008 study.
Soto D.X., Gacia E., Catalan J. (2013). Freshwater food web studies: A plea for multiple tracer approach. Limnetica, 32(1) 97-106.

Food webs are complex systems of interactions between ecosystem species. Beyond the direct analysis of stomach contents, stable isotopes of carbon (δ13C) and nitrogen (δ15N) have been used widely to evaluate these trophic relationships and calculate the relative contribution of food sources to a consumer's diet using mixing models. However, there are still some constraints on the use of these traditional tracers that limit their output. Here, we briefly comment on the potential of using multiple tracers (i.e., stable isotopes of C, N and H; trace metals), and applying recent numerical approaches (i.e. Bayesian mixing models) to advance the understanding of complex aquatic food webs. Stable isotopes of hydrogen (δ 2H), normally used to examine large-scale migration patterns of terrestrial animals, have been recently proposed as a complementary trophic tracer in aquatic ecosystems. The principle for this application is the large isotopic difference in δ2H among food items that can be found in some aquatic systems. Other potential trophic indicators are such substances that accumulate through diet (e.g., trace metals). These substances are traditionally studied from bioaccumulation or toxicological perspectives, but there are indications that encourage their use for tracing food web interactions. Bayesian mixing models, which are able to incorporate several sources of variability and multiple food sources in the model, can help to solve puzzling results. In summary, we suggest that the simultaneous use of multiple tracers will provide more reliable results than any of them in isolation. The challenge is to develop methods to combine them enhancing their strengths and minimizing uncertainty. © Asociación Ibérica de Limnología, Madrid. Spain.
Soto D.X., Hobson K.A., Wassenaar L.I. (2013). The influence of metabolic effects on stable hydrogen isotopes in tissues of aquatic organisms. Isotopes in Environmental and Health Studies, 49(3) 305-311.

A steady-state mass-balance model describing controls on the stable hydrogen isotopic ratios (δ2H) of tissues in fish was previously developed but physiological effects related to fish size and growth had not been tested. Here, we assessed the influence of size (or growth rate) on tissue δ2H composition of a fish species (Poecilia reticulata) and the incorporation of metabolic products derived from dietary lipids (water, NADH). Sampled tissues were obtained from individuals that grew at different rates while raised on an isotopically homogeneous commercial diet (lipid-free fraction, δ2H=-95±2 ‰; and dietary lipids,-198±11 ‰) under different controlled water hydrogen isotopic composition (δ2H=-128±3 ‰;+17±5 ‰; and+202±5 ‰). Our findings suggested that fish growth rate was correlated positively with the degree of incorporation of metabolic products from dietary lipids that, in turn, influenced both fish tissue protein and lipid δ2H values. We conclude that δ2H measurements of lipids (and, subsequently, of body water) in fish could become a physiological tool that provides insights into fish growth rates. © 2013 © 2013 Taylor & Francis.
Soto D.X., Wassenaar L.I., Hobson K.A. (2013). Stable hydrogen and oxygen isotopes in aquatic food webs are tracers of diet and provenance. Functional Ecology, 27(2) 535-543.

The stable hydrogen and oxygen isotope (δ2H and δ18O) composition of animal tissues are well-established tracers for terrestrial migration ecology and wildlife forensics. However, the behaviour of these isotopes in aquatic ecosystems and their potential as tracers of diet and provenance are complicated because of inputs from ambient H<inf>2</inf>O and diet. We conducted controlled aquaria-based experiments to quantify the mechanisms that drive the H and O isotopic flow within and among aquatic species. The isotopic composition of water and diet of two aquatic species (Chironomus tentans and Poecilia reticulata), representing two trophic levels, was varied in six isothermal treatments. Both species were raised from juvenile to adult to ensure that tissues were in isotopic equilibrium with their dietary and environmental conditions (ambient water, food, dissolved oxygen). We measured water, dissolved O<inf>2</inf>, diet, tissue protein and lipids for δ2H or δ18O. The flows of H and O isotopes for tissue formation in aquatic organisms were parameterized using a steady-state multi-pool mass-balance model. The ambient H<inf>2</inf>O contribution to tissue protein H and O isotopes in both species was significant (30-50% for 2H and >80% for 18O). An apparent trophic effect for δ2H and isotopic discrimination between water and protein for δ18O (c. 15 ‰) were identified. Our isotopic data and model revealed potential applications and cautions in using δ2H and δ18O measurements for ecological studies in aquatic food webs. Tissue δ2H values may be a complementary trophic tracer in aquatic food webs, but only when the main controlling mechanisms are properly accounted for (i.e., H isotopic exchange with water during protein synthesis and influence of metabolic water). Measurements of δ18O, on the other hand, reflect that of water and so can be used for predicting isotopic assignment to origin of aquatic organisms as there is no complicating trophic effect, but more δ18O field data and improved analytical precision may be required to better establish the strengths to ecological applications. © 2013 British Ecological Society.
Squires A.J., Dubé M.G., Rozon-Ramilo L.D. (2013). Assessing the sublethal effects of in-river concentrations of parameters contributing to cumulative effects in the athabasca river basin using a fathead minnow bioassay. Environmental Toxicology and Chemistry, 32(3) 662-672.

The Athabasca River basin, located in Alberta, Canada, covers 157, 000km2 and holds significant cultural and economic importance. Recent research assessed changes in several water quality and quantity parameters that have changed both spatially (along the river continuum) and temporally (pre-development and present day) in the Athabasca River Basin. In particular, parameters such as salinity and dissolved sulphate have changed significantly across the Athabasca River mainstem over the past five decades. Further laboratory testing has linked concentrations of these parameters to changes in fathead minnow reproduction. Research is required to determine whether these changes observed in the laboratory can be applied to actual in-river conditions. The objectives of the present study were to twofold: assess changes in fathead minnow response metrics (i.e., condition, liver and gonad size, egg production, and gill histology) associated with increasing concentrations of salinity and dissolved sulphate and determine whether sublethal effect thresholds established in laboratory experiments correspond to actual in-river concentrations using water from the mouth and headwaters of the Athabasca River. Three dose-response experiments (NaCl, SO4, and water sampled from the mouth of the Athabasca River) were conducted at Jasper National Park, Alberta, Canada. Significant increases in mean eggs per female per day occurred at the 50% treatment for the mouth experiment and thresholds previously developed in the laboratory were verified. Environ. Toxicol. Chem. 2013;32:662-672. © 2012 SETAC.
Tomie J.P.N., Cairns D.K., Courtenay S.C. (2013). How american eels Anguilla rostrata construct and respire in burrows. Aquatic Biology, 19(3) 287-296.

We investigated the burrowing behaviour of growth-phase (yellow) American eel Anguilla rostrata, a nocturnal fish that occupies the substrate during daylight hours and during winter. Eels formed burrows by forcing the head, then the body, into the substrate with rapid body undulations. Eels excavated from mud showed highly variable postures. In 10 of 15 experiments, the eel’s mouth was at or slightly above the surface. In the remaining experiments, the eel’s mouth was a mean of 3.5 cm below the surface, and an inhalation shaft ran from the surface to the mouth. Eels probably advance through mud by alternately pushing and anchoring the anterior and posterior parts of the body. Eel burrows observed in the lab and the field had up to 5 openings. Craters or mounds formed around some winter burrow openings due to head or tail movements or sediment erosion. Flat openings and openings in which the eel plugged the burrow entrance were found in both summer and winter. Dye trace experiments indicated that eels in mud and pebble burrows draw water from the water column into the mouth and exhale it through the gill openings. Because eels in burrows use water from the water column for respiration, the spread of anthro-pogenically induced anoxia and hypoxia in coastal waters poses an increasing conservation threat.
Woodward G., Gray C., Baird D.J. (2013). Biomonitoring for the 21st Century: New perspectives in an age of globalisation and emerging environmental threats. Limnetica, 32(2) 159-172.

As we move deeper into the Anthropocene, the scale and magnitude of existing and emerging anthropogenic threats to freshwater ecosystems become evermore apparent, yet we are still surprisingly poorly equipped to diagnose causes of adverse change in freshwater ecosystems. Our main aim in this perspectives and opinion piece is to suggest some new approaches to biomonitoring that could improve on the currently limited capabilities of existing schemes. We consider how biomonitoring might develop in the future as "Big Data" and next generation sequencing (NGS) approaches continue to revolutionize all branches of ecology, with a particular emphasis on the need to consider not just nodes in the food web, but their interactions too, and also to look beyond our current reliance on the Latin binomial system of describing biological entities as "species", when this concept is largely meaningless for many branches of the tree of life. We highlight the possible scope for enriching existing datasets to start assembling reasonable facsimiles of food webs, the need to collect and share more data more widely, and the value of metagenomics and metagenetics approaches to characterizing biodiversity in situ in a far more complete way than has been possible previously. Finally, we explore how these new approaches could provide a better marriage between structure and functioning than we have at present, but which is demanded increasingly by environmental legislation.
Yates A.G., Brua R.B., Culp J.M., Chambers P.A. (2013). Multi-scaled drivers of rural prairie stream metabolism along human activity gradients. Freshwater Biology, 58(4) 675-689.

1.Stream metabolism is increasingly used for monitoring and assessment of the biological condition of aquatic ecosystems. However, distal environmental drivers, such as land use, are typically not well connected to the proximate controls, such as stream chemistry, that are usually invoked as driving metabolism. This is particularly true for North American prairie streams and for grassland streams worldwide. 2.Stream metabolism was measured at the outflow of 19 subcatchments of the Red River in southern Manitoba, Canada. Subcatchments represented gradients of nutrient-producing human activities present in the region, that is, wastewater treatment (WWT), livestock production and crop cultivation. Stream metabolism was estimated at all sites using diel changes in dissolved oxygen (DO) concentration over 1week in the middle of summer. Environmental parameters hypothesised to control stream metabolism were sampled across three spatial scales (stream reach, stream segment and catchment). Model selection using Akaike's information criterion (AIC) was used to determine linkages between environmental parameters and measures of stream metabolism. 3.Estimated rates of metabolism were within the range of past studies of metabolism in prairie streams, although most streams had negative values of net ecosystem metabolism. However, production-to-respiration ratios were >0.5, at all but three sites suggesting that autochthonous production was an important source of organic matter. 4.The a priori model that best predicted gross primary production (GPP) was the intensity of nutrient-producing human activities (i.e. WWT, livestock and crop cultivation) measured at the catchment scale. Ecosystem respiration (ER) was best predicted by the a priori model comprised of GPP, total nitrogen (TN) and total phosphorus (TP). However, model averaging revealed that prediction of ER could be improved by including riparian cover and removing TP from the model. The positive association between GPP and ER suggested that heterotrophic compartments of the ecosystem were modest contributors to variation in respiration rates. 5.Overall, this study suggests that variation of metabolism in prairie streams of southern Manitoba is controlled by human activities occurring at the catchment scale, a finding consistent with current hierarchically structured riverine paradigms. Moreover, increased understanding of the hierarchical structure of stream metabolism drivers will help to ensure that assessment results can be used more effectively to inform management strategies for prairie ecosystems. © 2012 Crown.
Alfredsen K., Harby A., Linnansaari T., Ugedal O. (2012). Development of an inflow-controlled environmental flow regime for a norwegian river. River Research and Applications, 28(6) 731-739.

Hydropower produces 99% of the electricity in Norway, and a large number of rivers are regulated. Currently, static minimum flow regimes are used as a mitigation measure for most of these developments, usually having fixed values for winter and summer flow. Improved knowledge on the importance of variability in flow regimes has led to research on alternative solutions to the static minimum flow regimes. This paper describes the development of an environmental flow regime that is designed to follow the variation in natural inflow. The flow regime is designed using an adaptation of the building block methodology and linked to high, normal and low natural flow conditions. The work is focused on the river Daleelva in western Norway where Atlantic salmon is the key species. The paper also describes how the variable environmental flow regime can be implemented in practice as it pertains to current Norwegian legislation. © 2011 John Wiley & Sons, Ltd.
Armanini D.G., Monk W.A., Tenenbaum D.E., Peters D.L., Baird D.J. (2012). Influence of runoff regime type on a macroinvertebrate-based flow index in rivers of British Columbia (Canada). Ecohydrology, 5(4) 414-423.

Anthropogenic pressure on flow regimes has been recognized as a significant threat to the health of rivers in Canada and elsewhere. Yet while we know that the historical hydrological conditions prevailing at river sites can be assigned to runoff regime types, the implications of this hydrological structure on biological community composition have been poorly studied. Here we support the improvement of guidelines for flow management by exploring the relationship between biota and runoff regime types for selected rivers in British Columbia. One thousand six hundred biological samples were extracted from Environment Canada's Canadian Aquatic Biomonitoring Network (CABIN) database and a matching procedure was undertaken to associate biological samples to the long-term hydrometric monitoring stations stored in the HYDAT National Water Data Archive. A practical approach for spatial matching of hydrometric and biomonitoring sites was presented, which permitted matching of a sufficient number of samples to assess the structure of biological communities across the four regime types identified. By examining multivariate and univariate biological descriptors, including the recently developed Canadian Ecological Flow Index, differences in macroinvertebrate community composition between the runoff regimes were observed. In conclusion, we have developed a practical approach to match hydrological and biomonitoring data and we have forwarded guidelines on how to improve integration between hydrometric and biomonitoring networks. Moreover, we have provided the first ecological validation of runoff regime types in Canada, confirming the need to account for antecedent hydrological conditions in the assessment of ecological quality using biomonitoring data. © 2011 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.
Baird D.J., Hajibabaei M. (2012). Biomonitoring 2.0: A new paradigm in ecosystem assessment made possible by next-generation DNA sequencing. Molecular Ecology, 21(8) 2039-2044.

Biological monitoring has failed to develop from simple binary assessment outcomes of the impacted/unimpacted type, towards more diagnostic frameworks, despite significant scientific effort over the past fifty years. It is our assertion that this is largely because of the limited information content of biological samples processed by traditional morphology-based taxonomy, which is a slow, imprecise process, focused on restricted groups of organisms. We envision a new paradigm in ecosystem assessment, which we refer to as 'Biomonitoring 2.0'. This new schema employs DNA-based identification of taxa, coupled with high-throughput DNA sequencing on next-generation sequencing platforms. We discuss the transformational nature of DNA-based approaches in biodiversity discovery and ecosystem assessment and outline a path forward for their future widespread application. © 2012 Crown in the right of Canada.
Barata C., Fernández-San Juan M., Feo M.L., Eljarrrat E., Soares A.M.V.M., Barceló D., Baird D.J. (2012). Population growth rate responses of Ceriodaphnia dubia to ternary mixtures of specific acting chemicals: Pharmacological versus ecotoxicological modes of action. Environmental Science and Technology, 46(17) 9663-9672.

When considering joint toxic apical effects at higher levels of biological organization, such as the growth of populations, the so-called pharmacological mode of action that relies on toxicological mechanistic effects on molecular target sites may not be relevant. Such effects on population growth rate will depend on the extent to which juvenile and adult survival rates and production rates (juvenile developmental rates and reproduction) are affected by toxic exposure and also by the sensitivity of population growth rates to life-history changes. In such cases, the ecotoxicological mode of action, defined as the crucial life-history trait processes and/or xenobiotic-life-history trait interactions underlying a toxicological effect on population growth rate, should be considered. Life-table response experiments with the crustacean Ceriodaphnia dubia exposed to single and ternary mixtures of nine compounds were conducted to test the hypothesis that joint effects on population growth rates could be predicted from the mixture constituent ecotoxicological mode of action. Joint effects of mixtures containing pharmacologically dissimilar compounds (cadmium, λ-cyhalothrin, and chlorpyrifos) that differentially affected life-history traits contributing to population growth rates were accurately predicted by the independent-action concept. Conversely, the concentration-addition concept accurately predicted joint effects of two different mixtures: one containing pharmacologically similar acting pyrethroids that also affected similarly life-history traits, the other one that included pharmacologically dissimilar compounds (3,4-dichloroaniline, sodium bromide, and fenoxycarb) acting mainly on reproduction rates. These results indicate that when assessing combined effects on population growth rate responses, selection of mixture toxicity conceptual models based on the ecotoxicological mode of action of mixture constituents provided more accurate predictions than those based on the pharmacological mode of action. © 2012 American Chemical Society.
Benoy G.A., Sutherland A.B., Culp J.M., Brua R.B. (2012). Physical and ecological thresholds for deposited sediments in streams in agricultural landscapes. Journal of Environmental Quality, 41(1) 31-40.

Excessive sedimentation in streams and rivers remains a pervasive problem for the protection of aquatic habitat and the sustainability of aquatic communities. Whereas water quality criteria have been determined for suspended sediments in many jurisdictions across North America, comparably little has been done for deposited (also known as bedded) sediments. Through Canada's National Agri-Environmental Standards Initiative, assessment techniques and analytical tools were developed for estimating environmental thresholds for deposited sediments in agricultural watersheds in New Brunswick (NB) and Prince Edward Island (PEI) in the Atlantic Maritimes of Canada. Physical thresholds were developed through assessment of geomorphic metrics, which were then analyzed using y-intercept and 25th percentile approaches. For NB, there was strong agreement in physical thresholds for both analytical approaches (e.g., percent fines <2 mm were 7.5 for y-intercept and 6.9 for 25th percentile approaches). In contrast, physical thresholds for PEI differed considerably between approaches (e.g., percent fines <2 mm were 6.1 for y-intercept and 19.6 for 25th percentile approaches), likely due to a narrower range in agricultural land cover. Cross-calibration of our provisional physical thresholds for NB with ecological (i.e., benthic macroinvertebrate) assessments show that ecological thresholds, calculated as change-points in relationships between Ephemeroptera-Plecoptera-Trichoptera relative abundance or Modified Family Biotic Index and geomorphic criteria, were more liberal than physical thresholds. These results suggest that provisional thresholds developed using geomorphic criteria should demarcate change from the least disturbed condition and reduce the risk of sedimentation degrading benthic ecosystems. © 2012 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.
Beveridge D., A. Curry R., St-Hilaire A. (2012). Selecting hydrologic indices for the Prairie Provinces. River Research and Applications, 28(10) 1595-1608.

The large and accumulating body of evidence for both the controlling effect of the flow regime on river ecology and for the dependence of river health on the natural flow regime has led to the increasing use of hydrologic indices in instream flow studies. The myriad of collinear hydrologic indices present a daunting challenge to water managers trying to select a manageable number of indices for use in a hydrology-based environmental flow framework. In this study, a large number of hydrologic indices were calculated from gauging sites in the prairie provinces of Canada. Principal component analysis (PCA) and two rank-based non-parametric techniques are compared in their ability to select a small number of statistically informative indices. Despite the data being skewed and far from normal, PCA and the non-parametric technique called BioEnv+stepwise (BEST) both led to similar interpretations and could identify a small number of indices that capture a majority of the statistical variability. BEST selected indices more evenly from among conceptual categories of flow than PCA. © 2011 John Wiley & Sons, Ltd.
Beveridge D., St-Hilaire A., Ouarda T.B.M.J., Khalil B., Conly F.M., Wassenaar L.I., Ritson-Bennett E. (2012). A geostatistical approach to optimize water quality monitoring networks in large lakes: Application to Lake Winnipeg. Journal of Great Lakes Research, 38(SUPPL. 3) 174-182.

Water quality monitoring in lakes is often done by regularly sampling water quality variables of interest at fixed stations. Station location is a critical component of monitoring network design. Geostatistical methods were used to quantify redundancy in an intentionally dense network of lake stations on Lake Winnipeg, Canada. Water isotope samples (δ2H, δ18O) were collected approximately every 1-2km during research cruises in September-October 2009, for a total of 240 lakewide stations. Two statistical approaches were used to assess redundancy: 1) kriging, a spatial interpolation technique, was performed in a reduced multivariate space and kriging variance was used to assess the suitability of the sampled network configuration; and 2) Local Moran's I values were calculated. Moran's I identified clusters of stations that were similar or different. Good kriging models were developed for both δ2H and δ18O. When assessed individually, a large number of stations were identified as redundant but redundancy was based on the premise that all other stations remained in the network. When the analysis was performed on clusters of stations, within each cluster, up to four stations could be removed without significant loss of information. Relationships of redundancy were confirmed by Local Moran's I values. In combination, these techniques identified stations that were statistically important or redundant. This study emphasizes the importance of completing the evaluation of information provided by an individual station with information from clusters of stations within a network. © 2012 Elsevier B.V.
Borgå K., Kidd K.A., Muir D.C.G., Berglund O., Conder J.M., Gobas F.A.P.C., Kucklick J., Malm O., Powellkk D.E. (2012). Trophic magnification factors: Considerations of ecology, ecosystems, and study design. Integrated Environmental Assessment and Management, 8(1) 64-84.

Recent reviews by researchers from academia, industry, and government have revealed that the criteria used by the Stockholm Convention on persistent organic pollutants under the United Nations Environment Programme are not always able to identify the actual bioaccumulative capacity of some substances, by use of chemical properties such as the octanol-water partitioning coefficient. Trophic magnification factors (TMFs) were suggested as a more reliable tool for bioaccumulation assessment of chemicals that have been in commerce long enough to be quantitatively measured in environmental samples. TMFs are increasingly used to quantify biomagnification and represent the average diet-to-consumer transfer of a chemical through food webs. They differ from biomagnification factors, which apply to individual species and can be highly variable between predator-prey combinations. The TMF is calculated from the slope of a regression between the chemical concentration and trophic level of organisms in the food web. The trophic level can be determined from stable N isotope ratios (δ 15N). In this article, we give the background for the development of TMFs, identify and discuss impacts of ecosystem and ecological variables on their values, and discuss challenges and uncertainties associated with contaminant measurements and the use of δ 15N for trophic level estimations. Recommendations are provided for experimental design, data treatment, and statistical analyses, including advice for users on reporting and interpreting TMF data. Interspecies intrinsic ecological and organismal properties such as thermoregulation, reproductive status, migration, and age, particularly among species at higher trophic levels with high contaminant concentrations, can influence the TMF (i.e., regression slope). Following recommendations herein for study design, empirical TMFs are likely to be useful for understanding the food web biomagnification potential of chemicals, where the target is to definitively identify if chemicals biomagnify (i.e., TMF>or<1). 1). TMFs may be less useful in species- and site-specific risk assessments, where the goal is to predict absolute contaminant concentrations in organisms in relation to threshold levels. © 2011 SETAC.
Burkhard L.P., Cowan-Ellsberry C., Embry M.R., Hoke R.A., Kidd K.A. (2012). Bioaccumulation data from laboratory and field studies: Are they comparable? Integrated Environmental Assessment and Management, 8(1) 13-16.

Once they are released into the environment, a number of chemicals are known to bioaccumulate in organisms, sometimes to concentrations that may threaten the individual or their predators. However, use of physical or chemical properties or results from laboratory bioaccumulation tests to predict concentrations sometimes found in wild organisms remains a challenge. How well laboratory studies and field measurements agree or disagree, andthe cause of any discrepancies, is a subject of great interest and discussion from both ascientific and a regulatory perspective. A workshop sponsored by the ILSI Health and Environmental Sciences Institute, US Environmental Protection Agency, and the Society of Environmental Toxicology and Chemistry assembled scientists from academia, industry, and government to compare and contrast laboratory and field bioaccumulation data. The results of this workshop are summarized in a series of 5 articles published in this issue of Integrated Environmental Assessment and Management. The articles describe: 1) a weight-of-evidence approach that uses fugacity ratios to bring field measurements into the assessment of biomagnification potential for legacy chemicals; 2) a detailed comparison between laboratory and field data for the most commonly measured bioaccumulation endpoint, the biota-sediment accumulation factor; 3) a study that identifies and quantifies the differences between laboratory and field metrics of bioaccumulation for aquatic and terrestrial organisms; and 4) 2 reports on trophic magnification factors: the 1st addresses how trophic magnification factors are determined and interpreted and the 2nd describes how they could be used in regulatory assessments. Collectively, these articles present the workshop participants' current understanding and assessment of bioaccumulation science and make a number of recommendations on how to improve the collection and interpretation of bioaccumulation data. © 2011 SETAC.
Calhoun A.J.K., Gahl M.K., Baldwin R.F. (2012). Northeastern seasonal woodland pools. Wetland Habitats of North America Ecology and Conservation Concerns 135-148.
Chambers P.A., Culp J.M., Roberts E.S., Bowerman M. (2012). Development of environmental thresholds for streams in agricultural watersheds. Journal of Environmental Quality, 41(1) 1-6.

Global increases in consumption of chemical nutrients, application of pesticides, and water withdrawal to enhance agricultural yield have resulted in degraded water quality and reduced water availability. Efforts to safeguard or improve environmental conditions of agroecosystems have usually focused on managing on-farm activities to reduce materials loss and conserve habitat. Another management measure for improving environmental quality is adoption of environmental performance standards (also called outcome-based standards). This special collection of six papers presents the results of four years of research to devise scientifically credible approaches for setting environmental performance standards to protect water quantity and quality in Canadian agriculturally dominated watersheds. The research, conducted as part of Canada's National Agri-Environmental Standards Initiative, aimed to identify Ideal Performance Standards (the desired environmental state needed to maintain ecosystem health) and Achievable Performance Standards (the environmental conditions achievable using currently available and recommended best available processes and technologies). Overviews of the papers, gaps in knowledge, and future research directions are presented. As humans, livestock, and wildlife (both terrestrial and aquatic) experience greater pressures to share the same limited water resources, innovative research is needed that incorporates a landscape perspective, economics, farm practices, and ecology to advance the development and application of tools for protecting water resources in agricultural watersheds. © 2012 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.
Chambers P.A., McGoldrick D.J., Brua R.B., Vis C., Culp J.M., Benoy G.A. (2012). Development of environmental thresholds for nitrogen and phosphorus in streams. Journal of Environmental Quality, 41(1) 7-20.

Inputs of nutrients (P and N) to freshwaters can cause excessive aquatic plant growth, depletion of oxygen, and deleterious changes in diversity of aquatic fauna. As part of a "National Agri-Environmental Standards Initiative," the Government of Canada committed to developing environmental thresholds for nutrients to protect ecological condition of agricultural streams. Analysis of data from >200 long-term monitoring stations across Canada and detailed ecological study at ̃70 sites showed that agricultural land cover was associated with increased nutrient concentrations in streams and this, in turn, was associated with increased sestonic and benthic algal abundance, loss of sensitive benthic macroinvertebrate taxa, and an increase in benthic diatom taxa indicative of eutrophication. Chemical thresholds for N and P were defined by applying five approaches, employing either a predetermined percentile to a water chemistry data set or a relationship between water chemistry and land cover, to identify boundaries between minimally disturbed and impaired conditions. Comparison of these chemical thresholds with biological thresholds (derived from stressor-response relationships) produced an approach for rationalizing these two types of thresholds and deriving nutrient criteria. The resulting criteria were 0.01 to 0.03 mg L -1 total P and 0.87 -1.2 mg L -1 total N for the Atlantic Maritime, 0.02 mg L -1 total P and 0.21 mg L -1 total N for the Montane Cordillera, ̃0.03 mg L -1 total P and ̃1.1 mg L -1 total N for the Mixedwood Plains, and ̃0.10 mg L -1 total P and 0.39-0.98 mg L -1 total N for the interior prairies of Canada. Adoption of these criteria should result in greater likelihood of good ecological condition with respect to benthic algal abundance, diatom composition, and macroinvertebrate composition. © 2012 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.
Chandra K., Bosker T., Hogan N., Lister A., MacLatchy D., Currie S. (2012). Sustained high temperature increases the vitellogenin response to 17α-ethynylestradiol in mummichog (Fundulus heteroclitus). Aquatic Toxicology, 118-119 130-140.

Mummichog (. Fundulus heteroclitus), an estuarine fish of the western Atlantic, were acclimated to three salinities (0, 16 or 32. ppt) or three temperatures (10, 20 or 26. °C) and exposed to nominal 50 or 250. ng/L 17α-ethynylestradiol (EE2) for 14 days. In a separate experiment, fish were exposed to the same levels of EE2 and were subjected to a 1. h heat shock (20-30. °C) on the 14th day and allowed to recover for 20. h. We were interested in whether or not susceptibility to EE2 exposure, as indicated by increases in vitellogenin (. vtg) gene expression would change with high and low salinity, warm or cold temperature acclimation or acute heat shock. We also investigated the potential role of heat shock proteins (HSPs) under these conditions. Liver . vtg1 mRNA was significantly induced in male mummichog exposed to 50 and 250. ng/L EE2, but salinity acclimation or acute heat shock did not further affect this induction. Males acclimated to 26. °C and exposed to 250. ng/L EE2 induced 3.5-fold more . vtg1 mRNA than EE2 exposed males acclimated to 10. °C. HSP90 and HSP70 protein were largely unaffected by EE2 exposure. Our findings suggest that mummichog are more susceptible to EE2 under sustained temperature increases that may occur seasonally or with warming of coastal waters. © 2012 Elsevier B.V.
Chiang G., Munkittrick K.R., McMaster M.E., Tucca F., Saavedra M.F., Ancalaf A., Gavilán J.F., Unzueta L., Barra R. (2012). Seasonal changes in oocyte development, growth and population size distribution of Percilia gillissi and Trichomycterus areolatus in the Itata basin, Chile. Gayana, 76(2) 131-141.

There is scarce basic biological data on native freshwater fish species from Chile and next to zero on growth, gonad development and reproduction, which are critical for the purposes of the conservation of their natural populations. Seasonal analysis of sub-individual (oocyte development) and population (length frequency, growth rates) endpoints in Trichomycterus areolatus and Percilia gillissi were evaluated from February 2007 to January 2008. Oocyte development has a marked seasonality for P. gillissi, with mature eggs in October and declining frequency of mature oocytes into January. For T. areolatus we found some mature eggs in July, with highest number of mature eggs in October, coincident with previous data on maximum gonad size. Both species showed a multiple spawning reproductive strategy, with a long spawning season starting in spring to early summer. Increased numbers of juveniles were observed during mid-summer for P. gillissi,and during the end of the summer and beginning of autumn for T. areolatus. Juveniles had a higher growth coefficient (K) (0.56-0.38 mm month-1) than adults (0.29-0.15 mm month-1), and almost all juveniles in the population reached maturity before the spring (>50 mm for T areolatus and >40 mm for P. gillissi) and were incorporated into the population as a new recruitment cohort. Knowledge of the seasonal variability of these individual and population level responses can help better understand the biology of the species, and simultaneously improve the management and conservation of freshwater biota in Chile.
Chiang G., Munkittrick K.R., Urrutia R., Concha C., Rivas M., Diaz-Jaramillo M., Barra R. (2012). Liver ethoxyresorufin-O-deethylase and brain acetylcholinesterase in two freshwater fish species of South America; the effects of seasonal variability on study design for biomonitoring. Ecotoxicology and Environmental Safety, 86 147-155.

Responses at low levels of biological organization to evaluate environmental changes and water quality have been used for many years. South America is no different, and recently biochemical endpoints in fish have been used to assess the impacts of industrial and sewage effluents on wild fish populations. For Chilean native freshwater fish, basic biological data is scarce and data on 7-ethoxyresorufin-O-deethylase (EROD) and Acetylcholinesterase (AChE) activity is practically absent. Moreover, extensive variation in these two biochemical endpoints exists among species and seasons. In this article we evaluate seasonal variation in liver EROD and brain AChE activities in Trichomycterus areolatus and Percilia gillissi, two widely distributed native freshwater fish species in central Chile. We observed a marked seasonality in hepatic EROD activity in both species, with maximums for P. gillissi during winter months and sex differences in February, July, August and December. T. areolatus showed no sex differences, and peaks in EROD activity in the middle of summer, winter and late spring. Species differences in EROD activity were observed with activity being 1-2 orders of magnitude higher in P. gillissi compared to T. areolatus. Scarce seasonal variation and no sex related differences in brain AChE for both species were observed. Multivariate analysis (PCA) indicated that physical water quality parameters had some degree of responsibility for the seasonal responses found. The seasonal variability data of these biochemical endpoints were used to optimize study design for future monitoring programs, planning timing of sampling, increasing statistical power by collecting specific sample sizes required. © 2012 Elsevier Inc.
Culp J.M., Lento J., Goedkoop W., Power M., Rautio M., Christoffersen K.S., Gudbergsson G., Lau D., Liljaniemi P., Sandøy S., Svoboda M. (2012). Developing a circumpolar monitoring framework for Arctic freshwater biodiversity. Biodiversity, 13(3-4) 215-227.

Arctic freshwater ecosystems are facing unique challenges through the interaction of natural and human-induced stressors such as climate change and industrial development. Much is unknown about the biodiversity of Arctic freshwaters, although it is believed to have already been affected by climate change. A pan-Arctic monitoring strategy is critically needed to improve abilities to detect and understand ongoing and future changes in Arctic freshwater ecosystems. The challenging issues that Arctic freshwater monitoring must address include: the large diversity of Arctic freshwater ecosystems, varying levels of stressor impacts across the Arctic, lack of historical baseline research and monitoring coordination, and poor among-country standardization of sampling protocols. In response, the Arctic Council's Freshwater Expert Monitoring Group of the Circumpolar Biodiversity Monitoring Program (Conservation of Arctic Flora and Fauna) is developing a framework for monitoring Arctic freshwater biodiversity that will lead to regular reviews of the state of freshwater ecosystems across the circumpolar Arctic. The parameters of primary focus for the monitoring framework are classified by focal ecosystem components (FECs), which are biotic or abiotic factors that are ecologically pivotal, charismatic and/or sensitive to changes in biodiversity. FECs are placed in the context of expected ecosystem change through the development of testable impact hypotheses (or predictions) that outline a cause-effect framework regarding how change in environmental and anthropogenic stressors is expected to affect FECs. These prediction statements provide both guidelines for future scientific data collection and a focus for management decision-making. Here we discuss the design of a proposed monitoring framework and the development of impact hypotheses that focus on climate change effects. We emphasise the connectivity between science, monitoring and management necessary to implement the framework across the Arctic. © 2012 Copyright Taylor and Francis Group, LLC.
Curry C.J., Curry R.A., Baird D.J. (2012). The contribution of riffles and riverine wetlands to benthic macroinvertebrate biodiversity. Biodiversity and Conservation, 21(4) 895-913.

Benthic macroinvertebrates collected in biomonitoring programs are a potentially valuable source of biodiversity information for conservation planning in river ecosystems. Biomonitoring samples often focus on riffles; however, we have only partially assessed the extent to which riffle biodiversity patterns reflect those of other river habitats, particularly riverine wetlands. Using a standard biomonitoring protocol, we assessed the richness, composition and magnitude of variation of macroinvertebrate assemblages in riffles across 18 sites in the Nashwaak river catchment, and compared these to samples from adjacent riverine wetlands. Despite containing on average fewer taxa per site than riffles, riverine wetlands demonstrated similar levels of taxon richness at the catchment scale. There was strong assemblage separation between habitat types, and riverine wetlands displayed significantly greater assemblage variation than riffles. Riffles and riverine wetlands did not demonstrate significant correlations in terms of taxon richness or assemblage variation, though this may be partially due to the scale at which we collected observations. Principal component analysis with vector fitting suggested that (log) sub-catchment area was an important factor structuring riffle assemblages, while depth was potentially important for riverine wetland assemblages. We discuss the implications of these results for the use of biomonitoring data in systematic conservation planning, and identify future research that will improve our understanding of the role riverine wetlands play in maintaining catchment biodiversity and ecosystem processes. © 2012 Springer Science+Business Media B.V.
Curry C.J., Zhou X., Baird D.J. (2012). Congruence of biodiversity measures among larval dragonflies and caddisflies from three Canadian rivers. Freshwater Biology, 57(3) 628-639.

Scientists tasked with collecting taxon richness and assemblage variation data for conservation purposes have identified biomonitoring studies as potential sources of information. This approach assumes that biodiversity patterns revealed by biomonitoring reflect those of the wider community, an assumption not thoroughly tested in riverine ecosystems. We compared patterns of taxon richness and assemblage variation in an important biomonitoring group (Trichoptera) with a group with high conservation significance (Odonata) at 34 sites across three fifth-order catchments. We also explored the effect of abundance on observed patterns by rarefying the larval Trichoptera data set. Our results indicate that Trichoptera do not fully reflect site-scale taxon richness or assemblage variation in Odonata. The magnitude of odonate assemblage variation was much greater than that of Trichoptera for one of the catchments. Odonata and Trichoptera richness was moderately correlated in two catchments, while assemblage variation was strongly correlated in another pair of catchments. However, comparisons based on rarefied data eliminated differences in the magnitude of assemblage variation and strengthened correlations in richness and assemblage variation, suggesting the lack of congruence in these measures might be due to differences in abundance among groups. Further, incomplete taxonomy may mask additional assemblage variation, particularly in Trichoptera. Conservation planning in riverine ecosystems based on proxies derived from biomonitoring data should proceed cautiously until we understand how well the resulting information reflects biodiversity patterns in under-sampled taxa and habitats. Future studies of biodiversity congruence should consider both richness and assemblage variation as each provides valuable information for conservation-related decisions. The taxonomic resolution and relative abundance of comparison groups can potentially impact the strength, direction and statistical significance of patterns. Researchers should employ species-level taxonomy and account for differences in abundance among groups through rarefaction where at all possible and DNA-based taxonomy methods can support this. © 2011 Blackwell Publishing Ltd and Her Majesty the Queen in Right of Canada.
Denslow N.D., Griffitt R.J., Martyniuk C.J. (2012). Advancing the Omics in aquatic toxicology: SETAC North America 31st Annual Meeting. Ecotoxicology and Environmental Safety, 76(1) 1-2.
Deslauriers D., Kieffer J.D. (2012). Swimming performance and behaviour of youngof- the-year shortnose sturgeon (Acipenser brevirostrum) under fixed and increased velocity swimming tests. Canadian Journal of Zoology, 90(3) 345-351.

Swimming performance and behaviour in fish has been shown to vary depending on the investigation method. In this study, an endurance swimming curve was generated for young-of-the-year shortnose sturgeon (Acipenser brevirostrum LeSueur, 1818) (~7 cm total length, ~2 g) and compared with values determined in a separate incremental swimming (critical swimming, U <inf>crit</inf>) test. Using video, tail-beat frequency (TBF) was quantified and compared for fish swimming under both swimming tests. From the endurance-curve analysis, it was found that sturgeon did not display a statistically significant burst swimming phase. Maximum sustainable swimming speed (calculated to be 18.00 cm s -1) from the endurance curve occurred at ~80% of U <inf>crit</inf> (22.30 cm s -1). TBF was similar at all speeds for both swimming tests, except at speeds approaching U <inf>crit</inf>, where fish displayed TBFs of 4.29 Hz for the endurance protocol and 2.26 Hz for the U <inf>crit</inf> protocol. TBF was more variable between individuals swimming at the same speed within the U <inf>crit</inf> compared with the endurance protocol. Finally, a significant negative correlation was found between TBF and U <inf>crit</inf> in individual fish, suggesting that station-holding may be an important energy saving strategy during swimming in this size class of sturgeon.
Deslauriers D., Kieffer J.D. (2012). The effects of temperature on swimming performance of juvenile shortnose sturgeon (Acipenser brevirostrum). Journal of Applied Ichthyology, 28(2) 176-181.

The swimming performance of juvenile shortnose sturgeon (∼16cm TL, ∼20g), Acipenser brevirostrum, was quantified with regards to temperature (5 to 25°C) using both increased (U <inf>crit</inf>) and fixed velocity (endurance) tests in a laboratory setting. Sturgeons were found to show reduced U <inf>crit</inf> values at 5 and 10°C (25.99 and 28.86cms -1 respectively), with performance beginning to plateau at 15°C through 25°C (33.99 cms -1). For the endurance protocol, fish were tested at speeds of 35, 40 and 45cms -1 at 5, 15 and 25°C. Performance within a single speed was similar at all temperatures, indicating the usage of anaerobic metabolism to fuel locomotion at these higher velocities. Overall, shortnose sturgeon demonstrated high tolerance towards a wide range of temperatures but showed few differences between performance levels at colder or warmer water conditions. © 2012 Blackwell Verlag, Berlin.
Duro D.C., Franklin S.E., Dubé M.G. (2012). Multi-scale object-based image analysis and feature selection of multi-sensor earth observation imagery using random forests. International Journal of Remote Sensing, 33(14) 4502-4526.

The random forest (RF) classifier is a relatively new machine learning algorithm that can handle data sets with large numbers and types of variables. Multi-scale object-based image analysis (MOBIA) can generate dozens, and sometimes hundreds, of variables used to classify earth observation (EO) imagery. In this study, a MOBIA approach is used to classify the land cover in an area undergoing intensive agricultural development. The information derived from the elevation data and imagery from two EO satellites are classified using the RF algorithm. Using a wrapper feature selection algorithm based on the RF, a large initial data set consisting of 418 variables was reduced by ~60%, with relatively little loss in the overall classification accuracy. With this feature-reduced data set, the RF classifier produced a useable depiction of the land cover in the selected study area and achieved an overall classification accuracy of greater than 90%. Variable importance measures produced by the RF algorithm provided an insight into which object features were relatively more important for classifying the individual land-cover types. The MOBIA approach outlined in this study achieved the following: (i) consistently high overall classification accuracies (>85%) using the RF algorithm in all models examined, both before and after feature reduction; (ii) feature selection of a large data set with little expense to the overall classification accuracy; and (iii) increased interpretability of classification models due to the feature selection process and the use of variable importance scores generated by the RF algorithm. © 2012 Copyright Taylor and Francis Group, LLC.
Freedman J.A., Curry R.A., Munkittrick K.R. (2012). Stable isotope analysis reveals anthropogenic effects on fish assemblages in a temperate reservoir. River Research and Applications, 28(10) 1804-1819.

Effluent from anthropogenic inputs can affect fish assemblages in aquatic ecosystems by altering species richness, diversity and trophic structure. To investigate the effects of a bleached kraft pulp mill effluent (PME) and municipal sewage treatment plant (STP) discharge on fish assemblages in a temperate reservoir, we combined standard ecological methodologies with stable isotope analysis of δ13C and δ15N. Total catch, species richness, diversity and coefficient of community loss indicated lower species richness and diversity at sites exposed to PME, whereas sewage-exposed assemblages had intermediate richness and diversity relative to reference sites. Stable isotope analysis of δ13C and δ15N revealed that many species fed at higher relative trophic positions in the presence of both effluents and showed shifts towards increased reliance on littoral-derived and benthic-derived carbon at sites downstream of the PME discharge. Fishes at PME-influenced sites had also generally higher condition factor whereas fishes at STP-influenced sites were more variable in condition factor. These differences may, in part, be due to decreased species diversity at these sites and to nutrient enrichment manifest from the effluent discharge. While standard fisheries and ecological methodologies and stable isotope analysis have been separately used in other studies of anthropogenic effects on fishes, their integration in this study provides greater resolution than either could alone. © 2011 John Wiley & Sons, Ltd.
Gahl M.K., Longcore J.E., Houlahan J.E. (2012). Varying Responses of Northeastern North American Amphibians to the Chytrid PathogenBatrachochytrium dendrobatidis. Conservation Biology, 26(1) 135-141.

Chytridiomycosis, caused byBatrachochytrium dendrobatidis(Bd), is widespread among amphibians in northeastern North America. It is unknown, however, whetherBdhas the potential to cause extensive amphibian mortalities in northeastern North America as have occurred elsewhere. In the laboratory, we exposed seven common northeastern North American amphibian species toBdto assess the likelihood of population-level effects from the disease. We exposed larval wood frogs (Lithobates sylvaticus) and postmetamorphic frogs of six other species to two different strains ofBd,a northeastern strain (JEL404) and a strain that caused die-offs of amphibians in Panama (JEL423), under ideal in vitro growth conditions forBd. Exposed American toads (Anaxyrus americanus) all died; thus, this species may be the most likely to die fromBd-caused disease in the wild. BothBdstrains were associated with mortalities of wood frogs, although half the metamorphs survived. TheBdstrain from Panama killed metamorphic green frogs (L. clamitans), whereas the northeastern strain did not, which means novel strains ofBdmay lead to death even when local strains may not. No mortality was observed in four species (bullfrogs [L. catesbeianus], northern leopard frogs [L. pipiens], spring peepers [Pseudacris crucifer], and blue-spotted salamanders [Ambystoma laterale]) and in some individuals of green frogs and wood frogs that we exposed. This finding suggests these six species may beBdvectors. Our results show that systematic exposures of amphibian species toBdin the laboratory may be a good first step in the identification of species susceptible toBd-caused declines and in directing regional conservation efforts aimed at susceptible species. © 2011 Society for Conservation Biology.
Gautreau M.D., Curry R.A. (2012). Ecology and status of the redbreast sunfish, lepomis auritus, in Yoho Lake, New Brunswick. Northeastern Naturalist, 19(4) 653-664.

In Canada, Lepomis auritus (Redbreast Sunfish) is only found in southwestern New Brunswick, which is the northern limit for the species. In 1989, The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) listed it as a species of special concern due to its limited distribution, and changed the status to data deficient in 2008. The purpose of our study is to begin to build a database of ecological information for the Redbreast Sunfish in New Brunswick. The most northern population occurs in Yoho Lake. Population estimates averaged 386 from 2005 to 2007. The average total length and weight were 12.5 ± 3.1 cm and 42.6 ± 27.3 g, respectively. The length-frequency distributions were consistent over the years, suggesting a stable population structure. Most adult and juvenile sunfish were observed in areas of dense vegetation and large woody debris. Snorkeling surveys were conducted from late June to early July 2005-2007 to assess timing and habitat preference of spawning Redbreast Sunfish. The nests averaged 52.4 ± 10.1 cm in diameter and were 43.9 ± 12.2 cm deep. Nest substrate was sandy with small gravel, and only 33% of the nests were associated with a physical structure in the water column. Overall, the population of Redbreast Sunfish in Yoho Lake appears to be healthy and stable.
Hobson K.A., Anderson R.C., Soto D.X., Wassenaar L.I. (2012). Isotopic Evidence That Dragonflies (Pantala flavescens) Migrating through the Maldives Come from the Northern Indian Subcontinent. Plos One, 7(12).

Large numbers of the Globe Skimmer dragonfly (Pantala flavescens) appear in the Maldives every October-December. Since they cannot breed on these largely waterless islands, it has recently been suggested that they are "falling out" during a trans-oceanic flight from India to East Africa. In addition, it has been suggested that this trans-oceanic crossing is just one leg of a multi-generational migratory circuit covering about 14,000-18,000 km. The dragonflies are presumed to accomplish this remarkable feat by riding high-altitude winds associated with the Inter-tropical Convergence Zone (ITCZ). While there is considerable evidence for this migratory circuit, much of that evidence is circumstantial. Recent developments in the application of stable isotope analyses to track migratory dragonflies include the establishment of direct associations between dragonfly wing chitin δ2H values with those derived from long-term δ2H precipitation isoscapes. We applied this approach by measuring wing chitin δ2H values in 49 individual Pantala flavescens from the November-December migration through the Maldives. Using a previously established spatial calibration algorithm for dragonflies, the mean wing δ2H value of -117±16 ‰ corresponded to a predicted mean natal ambient water source of -81 ‰, which resulted in a probabilistic origin of northern India, and possibly further north and east. This strongly suggests that the migratory circuit of this species in this region is longer than previously suspected, and could possibly involve a remarkable trans-Himalayan high-altitude traverse. © 2012 Hobson et al.
Hogan N.S., Gallant M.J., van den Heuvel M.R. (2012). Exposure to the pesticide linuron affects androgen-dependent gene expression in the three-spined stickleback (Gasterosteus aculeatus). Environmental Toxicology and Chemistry, 31(6) 1391-1395.

Previous research demonstrated that exposure to exogenous androgens and effluents with androgenic activity can induce spiggin mRNA production in the kidney of the three-spined stickleback (Gasterosteus aculeatus). In the present study, we determine whether a short-term exposure to a known antiandrogenic pesticide, linuron (LN), suppresses spiggin mRNA in male stickleback and in androgenized female stickleback. Primers were designed from previously characterized sequences for each androgen receptor (AR) isoform in stickleback, arα and arβ, to assess whether these receptors are differentially regulated by androgen or antiandrogen exposure. Fish were exposed for 72h to one of four treatments: control, LN (250μg/L), 17α-methyltestosterone (MT, 500ng/L), and an LN-MT mixture at those same concentrations. There was no effect of LN on spiggin and arβ mRNA levels in male kidney, while levels of arα were significantly increased twofold. Exposure to LN significantly inhibited MT-induced spiggin RNA production in female kidney with no effect on expression of arα and arβ. The present study is the first to demonstrate the antiandrogenic effect of LN at the transcript level and to examine androgenic/antiandrogenic responsiveness of the two ARs in the stickleback. From the present study, it was determined that measurement of spiggin RNA is a reliable and sensitive screening tool for the detection of both androgenic and antiandrogenic compounds. © 2012 SETAC.
Jardine T.D., Kidd K.A., Rasmussen J.B. (2012). Aquatic and terrestrial organic matter in the diet of stream consumers: Implications for mercury bioaccumulation. Ecological Applications, 22(3) 843-855.

The relative contribution of aquatic vs. terrestrial organic matter to the diet of consumers in fluvial environments and its effects on bioaccumulation of contaminants such as mercury (Hg) remain poorly understood. We used stable isotopes of carbon and nitrogen in a gradient approach (consumer isotope ratio vs. periphyton isotope ratio) across temperate streams that range in their pH to assess consumer reliance on aquatic (periphyton) vs. terrestrial (riparian vegetation) organic matter, and whether Hg concentrations in fish and their prey were related to these energy sources. Taxa varied in their use of the two sources, with grazing mayflies (Heptageniidae), predatory stoneflies (Perlidae), one species of water strider (Metrobates hesperius), and the fish blacknose dace (Rhinichthys atratulus) showing strong connections to aquatic sources, while Aquarius remigis water striders and brook trout (Salvelinus fontinalis) showed a weak link to in-stream production. The aquatic food source for consumers, periphyton, had higher Hg concentrations in low-pH waters, and pH was a much better predictor of Hg in predatory invertebrates that relied mainly on this food source vs. those that used terrestrial C. These findings suggest that stream biota relying mainly on dietary inputs from the riparian zone will be partially insulated from the effects of water chemistry on Hg availability. This has implications for the development of a whole-system understanding of nutrient and material cycling in streams, the choice of taxa in contaminant monitoring studies, and in understanding the fate of Hg in stream food webs. © 2012 by the Ecological Society of America.
Karami A., Christianus A., Bahraminejad B., Gagné F., Courtenay S.C. (2012). Artificial neural network modeling of biomarkers to infer characteristics of contaminant exposure in Clarias gariepinus. Ecotoxicology and Environmental Safety, 77 28-34.

This study examined the potential of artificial neural network (ANN) modeling to infer timing, route and dose of contaminant exposure from biomarkers in a freshwater fish. Hepatic glutathione S-transferase (GST) activity and biliary concentrations of BaP, 1-OH BaP, 3-OH BaP and 7,8D BaP were quantified in juvenile Clarias gariepinus injected intramuscularly or intraperitoneally with 10-50. mg/kg benzo[. a]pyrene (BaP) 1-3. d earlier. A feedforward multilayer perceptron (MLP) ANN resulted in more accurate prediction of timing, route and exposure dose than a linear neural network or a radial basis function (RBF) ANN. MLP sensitivity analyses revealed contribution of all five biomarkers to predicting route of exposure but no contribution of hepatic GST activity or one of the two hydroxylated BaP metabolites to predicting time of exposure and dose of exposure. We conclude that information content of biomarkers collected from fish can be extended by judicious use of ANNs. © 2011 Elsevier Inc.
Karami A., Christianus A., Ishak Z., Shamsuddin Z.H., Masoumian M., Courtenay S.C. (2012). Use of intestinal Pseudomonas aeruginosa in fish to detect the environmental pollutant benzo[a]pyrene. Journal of Hazardous Materials, 215-216 108-114.

This study examined the potential of . Pseudomonas aeruginosa abundance in the intestines of fish as an indicator of exposure to benzo[. a]pyrene (BaP). . P. aeruginosa populations were enumerated in juvenile African catfish (. Clarias gariepinus) injected intramuscularly three days previous with 0, 10, 30, 40, 50 or 70. mg/kg of BaP. Hepatic EROD and GST activities and biliary fluorescent aromatic compounds (FACs) 1-OH BaP, 3-OH BaP, 7,8-D BaP and BaP were quantified to investigate agreements between the new indicator and established fish biomarkers. The shape of bacterial population (logarithm of colony-forming unit) dose-response curve generally matched those of biliary FACs concentrations. Conversely, the EROD and GST dose-response curves were generally the mirror images of the bacterial population curve. Changes in intestinal . P. aeruginosa population appear to be an indirect effect of BaP exposure because exposure to 0-100. μg/ml BaP had no effect on . P. aeruginosa populations grown on agar plates containing BaP. Using intestinal . P. aeruginosa population of fish as a universal indicator of BaP pollution in aquatic environments is discussed.Conversely, the EROD and GST dose-response curves were generally the mirror images of the bacterial population curve. © 2012 Elsevier B.V.
Karami A., Syed M.A., Christianus A., Willett K.L., Mazzeo J.R., Courtenay S.C. (2012). Two-stage bile preparation with acetone for recovery of fluorescent aromatic compounds (FACs). Journal of Hazardous Materials, 223-224 84-93.

In this study we sought to optimize recovery of fluorescent aromatic compounds (FACs) from the bile of African catfish (Clarias gariepinus) injected with 10. mg/kg benzo[a]pyrene (BaP). Fractions of pooled bile were hydrolyzed, combined with ten volumes of methanol, ethanol, acetonitrile, or acetone, centrifuged and supernatants were analyzed by high-performance liquid chromatography with fluorescent detection (HPLC/FL). As well, to test whether FACs were being lost in solids from the centrifugation, pellets were resuspended, hydrolyzed and mixed with six volumes of the organic solvent that produced best FAC recovery from the supernatant, and subjected to HPLC/FL. Highest FAC concentrations were obtained with 2000. μl and 1250. μl acetone for supernatants and resuspended pellets respectively. FACs concentrations were negatively correlated with biliary protein content but were unaffected by addition of bovine serum albumin (BSA) followed by no incubation indicating that the presence of proteins in the biliary mixture does not simply interfere with detection of FACs. In another experiment, efficiency of acetone addition was compared to two different liquid-liquid extractions (L-LEs). Acetone additions provided significantly higher biliary FACs than the L-LE methods. The new two-stage bile preparation with acetone is an efficient, inexpensive and easily performed method. © 2012 Elsevier B.V.
Keppel E.A., Scrosati R.A., Courtenay S.C. (2012). Ocean acidification decreases growth and development in American lobster (Homarus americanus) larvae. Journal of Northwest Atlantic Fishery Science, 44 61-66.

Ocean acidification resulting from the global increase in atmospheric CO2 concentration is emerging as a threat to marine species, including crustaceans. Fisheries involving the American lobster (Homarus americanus) are economically important in eastern Canada and United States. Based on ocean pH levels predicted for 2100, this study examined the effects of reduced seawater pH on the growth (carapace length) and development (time to molt) of American lobster larvae throughout stages I-III until reaching stage IV (postlarvae). Each stage is reached after a corresponding molt. Larvae were reared from stage I in either acidified (pH = 7.7) or control (pH = 8.1) seawater. Organisms in acidified seawater exhibited a significantly shorter carapace length than those in control seawater after every molt. Larvae in acidified seawater also took significantly more time to reach each molt than control larvae. In nature, slowed progress through larval molts could result in greater time in the water column, where larvae are vulnerable to pelagic predators, potentially leading to reduced benthic recruitment. Evidence was also found of reduced survival when reaching the last stage under acidified conditions. Thus, from the perspective of larval ecology, it is possible that future ocean acidification may harm this important marine resource. © Her Majesty the Queen in right of Canada, 2012.
Kidd K.A., Muir D.C.G., Evans M.S., Wang X., Whittle M., Swanson H.K., Johnston T., Guildford S. (2012). Biomagnification of mercury through lake trout (Salvelinus namaycush) food webs of lakes with different physical, chemical and biological characteristics. Science of the Total Environment, 438 135-143.

Mercury (Hg) biomagnification in aquatic ecosystems remains a concern because this pollutant is known to affect the health of fish-eating wildlife and humans, and the fish themselves. The "rate" of mercury biomagnification is being assessed more frequently using stable nitrogen isotope ratios (δ15N), a measure of relative trophic position of biota within a food web. Within food webs and across diverse systems, log-transformed Hg concentrations are significantly and positively related to δ15N and the slopes of these models vary from one study to another for reasons that are not yet understood. Here we compared the rates of Hg biomagnification in 14 lake trout lakes from three provinces in Canada to understand whether any characteristics of the ecosystems explained this among-system variability. Several fish species, zooplankton and benthic invertebrates were collected from these lakes and analyzed for total Hg (fish only), methyl Hg (invertebrates) and stable isotopes (δ15N; δ13C to assess energy sources). Mercury biomagnification rates varied significantly across systems and were higher for food webs of larger (surface area), higher nutrient lakes. However, the slopes were not predictive of among-lake differences in Hg in the lake trout. Results indicate that among-system differences in the rates of Hg biomagnification seen in the literature may be due, in part, to differences in ecosystem characteristics although the mechanisms for this variability are not yet understood. © 2012 Elsevier B.V.
Kruitbos L.M., Tetzlaff D., Soulsby C., Buttle J., Carey S.K., Laudon H., McDonnell J.J., McGuire K., Seibert J., Cunjak R., Shanley J. (2012). Hydroclimatic and hydrochemical controls on Plecoptera diversity and distribution in northern freshwater ecosystems. Hydrobiologia, 693(1) 39-53.

Freshwater ecosystems in the mid- to upper-latitudes of the northern hemisphere are particularly vulnerable to the impact of climate change as slight changes in air temperature can alter the form, timing, and magnitude of precipitation and consequent influence of snowmelt on streamflow dynamics. Here, we examine the effects of hydro-climate, flow regime, and hydrochemistry on Plecoptera (stonefly) alpha (α) diversity and distribution in northern freshwater ecosystems. We characterized the hydroclimatic regime of seven catchments spanning a climatic gradient across the northern temperate region and compared them with estimates of Plecoptera genera richness. By a space-for-time substitution, we assessed how warmer temperatures and altered flow regimes may influence Plecoptera alpha diversity and composition at the genus level. Our results show wide hydroclimatic variability among sites, including differences in temporal streamflow dynamics and temperature response. Principal component analysis showed that Plecoptera genera richness was positively correlated with catchment relief (m), mean and median annual air temperature (°C), and streamflow. These results provide a preliminary insight into how hydroclimatic change, particularly in terms of increased air temperature and altered streamflow regimes, may create future conditions more favorable to some Plecopteras in northern catchments. © 2012 Springer Science+Business Media B.V.
LeBlanc H.M.K., Culp J.M., Baird D.J., Alexander A.C., Cessna A.J. (2012). Single versus combined lethal effects of three agricultural insecticides on larvae of the freshwater insect Chironomus dilutus. Archives of Environmental Contamination and Toxicology, 63(3) 378-390.

Pesticides are currently regulated individually but are present in aquatic systems as mixtures of toxicants. In this study, the lethal effects of three agricultural insecticides- chlorpyrifos, imidacloprid and dimethoate-on Chironomus dilutus larvae were examined. Ninety-six- hour static bioassays were performed using single, binary, and ternary toxicant mixtures. The effects of the binary mixtures were investigated using the MIXTOX model to determine if the mixtures behaved additively, synergistically, or antagonistically. Dimethoate was much less toxic than chlorpyrifos or imidacloprid. Chlorpyrifos and dimethoate were not additive in mixture despite their common mode of action (MOA) and resulted in opposing effects (synergism and antagonism, respectively) when combined with imidacloprid. Synergism was observed in the ternary mixture. These results suggest that current mixture models based on MOA alone may not always be adequate in describing mixture effects, as in the current situation of mixtures with relatively few components. Other factors, such as water solubility, secondary MOA, and mechanisms of toxicity, should also be considered in future investigations of multichemical-mixture effects. © Springer Science+Business Media, LLC 2012.
Lento J., Dillon P.J., Somers K.M. (2012). Evaluating long-term trends in littoral benthic macroinvertebrate communities of lakes recovering from acid deposition. Environmental Monitoring and Assessment, 184(12) 7175-7187.

The Mann-Kendall test has been proposed as a nonparametric method to evaluate trends in long-term water quality datasets with missing values, serial correlation, and non-normality. However, this test has rarely been used to evaluate long-termtrends in biological data. In this study, we used the Mann-Kendall test to evaluate trends in 15 years of data on benthic macroinvertebrate communities from17 Precambrian Shield lakes.We also used the van Belle and Hughes test of trend homogeneity to assess whether common among-lake temporal trends existed.We assumed that evidence of a common regional trend among lakes would support the hypothesis of longterm biological recovery from past acidification. We found decreasing proportions of Chironomidae and increasing proportions of Ephemeroptera, Plecoptera, and Trichoptera (EPT) in both single-lake and multi-lake trend analysis. Moreover, six of the nine lakes with significant trends in more than one benthos metric displayed a significant decrease in Chironomidae and increase in EPT concurrently, indicating a shift towards more acid-sensitive taxa. Weak trends in several of the biological metrics indicated that recovery in these lakes has been impeded. Results of this study indicate that the Mann-Kendall and van Belle and Hughes trend tests are useful statistical tools to evaluate long-term patterns in biological data. © Springer Science+Business Media B.V. 2011.
Martyniuk C.J., Alvarez S., Denslow N.D. (2012). DIGE and iTRAQ as biomarker discovery tools in aquatic toxicology. Ecotoxicology and Environmental Safety, 76(1) 3-10.

Molecular approaches in ecotoxicology have greatly enhanced mechanistic understanding of the impact of aquatic pollutants in organisms. These methods have included high throughput Omics technologies, including quantitative proteomics methods such as 2D differential in-gel electrophoresis (DIGE) and isobaric tagging for relative and absolute quantitation (iTRAQ). These methods are becoming more widely used in ecotoxicology studies to identify and characterize protein bioindicators of adverse effect. In teleost fish, iTRAQ has been used successfully in different fish species (e.g. fathead minnow, goldfish, largemouth bass) and tissues (e.g. hypothalamus and liver) to quantify relative protein abundance. Of interest for ecotoxicology is that many proteins commonly utilized as bioindicators of toxicity or stress are quantifiable using iTRAQ on a larger scale, providing a global baseline of biological effect from which to assess changes in the proteome. This review highlights the successes to date for high throughput quantitative proteomics using DIGE and iTRAQ in aquatic toxicology. Current challenges for the iTRAQ method for biomarker discovery in fish are the high cost and the lack of complete annotated genomes for teleosts. However, the use of protein homology from teleost fishes in protein databases and the introduction of hybrid LTQ-FT (Linear ion trap-Fourier transform) mass spectrometers with high resolution, increased sensitivity, and high mass accuracy are able to improve significantly the protein identification rates. Despite these challenges, initial studies utilizing iTRAQ for ecotoxicoproteomics have exceeded expectations and it is anticipated that the use of non-gel based quantitative proteomics will increase for protein biomarker discovery and for characterization of chemical mode of action. © 2011 Elsevier Inc.
Martyniuk C.J., Alvarez S., Lo B.P., Elphick J.R., Marlatt V.L. (2012). Hepatic protein expression networks associated with masculinization in the female fathead minnow (Pimephales promelas). Journal of Proteome Research, 11(8) 4147-4161.

Endocrine disruptors that act via the androgen receptor (AR) are less well studied than environmental estrogens, and there is evidence that treatment with AR agonists can result in masculinization of female fish. In this study, female fathead minnows (FHM) were exposed to the model nonaromatizable androgen 5-alpha dihydrotestosterone (DHT) (100 μg/L), the ureic-based herbicide linuron (LIN) (100 μg/L), and a mixture of DHT and LIN (100 μg/L each) to better characterize androgen action in females. LIN was used because of reports that this chemical has an antiandrogenic mode of action in fish. After 21d, DHT and LIN treatments resulted in a significant depression of plasma vitellogenin (Vtg) and DHT and DHT + LIN increased the prevalence of nuptial tubercles in female FHMs indicating masculinization. Using iTRAQ and an LTQ Orbitrap Velos, ∼2000 proteins were identified in the FHM liver and the number of proteins quantified after exposures was >1200. Proteins that significantly and consistently changed in abundance across biological replicates included prostaglandin E synthase 3, programmed cell death 4a, glutathione S transferases, canopy, selenoprotein U, and ribosomal proteins. Subnetwork enrichment analysis identified that interferon and epidermal growth factor signaling were regulated by DHT and LIN, suggesting that these signaling pathways are correlated to depressed plasma vitellogenin. These data provide novel insight into hepatic protein networks that are associated with the process of masculinization in teleosts. © 2012 American Chemical Society.
Martyniuk C.J., Denslow N.D. (2012). Exploring androgen-regulated pathways in teleost fish using transcriptomics and proteomics. Integrative and Comparative Biology, 52(5) 695-704.

In the environment, there are aquatic pollutants that disrupt androgen signaling in fish. Laboratory and field-based experiments have utilized omics technologies to characterize the molecular mechanisms underlying androgen-receptor agonism/antagonism. Transcriptomics and proteomics studies with 17β-trenbolone, a growth-promoting pharmaceutical found in water systems surrounding cattle feed lots, and androgens such as 17α- methyltestosterone and 17α-methyldihydrotestosterone, have been conducted in ovary and liver of fish that include the fathead minnow (FHM) (Pimephales promelas), common carp (Cyprinus carpio), Qurt medaka (Oryzias latipes), and zebrafish (Danio rerio). In this mini-review, we survey recent omics studies in fish and reveal that, despite the diversity of species and tissues examined, there are common cellular responses that are observed with waterborne androgenic treatments. Recurring themes in gene ontology include apoptosis, transport and oxidation of lipids, synthesis and transport of hormones, immune response, protein metabolism, and cell proliferation. However, we also discuss other mechanisms other than androgen receptor (AR) activation, such as responses to toxicant stress, estrogen receptor agonism, aromatization of androgens into estrogens, and inhibitory feedback mechanisms by high levels of androgens that may also explain molecular responses in fish. To further explore androgen-responsive protein networks, a sub-network enrichment analysis was performed on protein data collected from the livers of female FHMs exposed to 17β-trenbolone. We construct a putative AR-regulated protein/cell process network in the liver that includes B-lymphocyte differentiation, xenobiotic clearance, low-density lipoprotein oxidation, proliferation of smooth muscle cells, and permeability of blood vessels. We demonstrate that construction of protein networks can offer insight into cell processes that are potentially regulated by androgens. © 2012 The Author. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved.
Martyniuk C.J., Popesku J.T., Chown B., Denslow N.D., Trudeau V.L. (2012). Quantitative proteomics in teleost fish: Insights and challenges for neuroendocrine and neurotoxicology research. General and Comparative Endocrinology, 176(3) 314-320.

Neuroendocrine systems integrate both extrinsic and intrinsic signals to regulate virtually all aspects of an animal's physiology. In aquatic toxicology, studies have shown that pollutants are capable of disrupting the neuroendocrine system of teleost fish, and many chemicals found in the environment can also have a neurotoxic mode of action. Omics approaches are now used to better understand cell signaling cascades underlying fish neurophysiology and the control of pituitary hormone release, in addition to identifying adverse effects of pollutants in the teleostean central nervous system. For example, both high throughput genomics and proteomic investigations of molecular signaling cascades for both neurotransmitter and nuclear receptor agonists/antagonists have been reported. This review highlights recent studies that have utilized quantitative proteomics methods such as 2D differential in-gel electrophoresis (DIGE) and isobaric tagging for relative and absolute quantitation (iTRAQ) in neuroendocrine regions and uses these examples to demonstrate the challenges of using proteomics in neuroendocrinology and neurotoxicology research. To begin to characterize the teleost neuroproteome, we functionally annotated 623 unique proteins found in the fish hypothalamus and telencephalon. These proteins have roles in biological processes that include synaptic transmission, ATP production, receptor activity, cell structure and integrity, and stress responses. The biological processes most represented by proteins detected in the teleost neuroendocrine brain included transport (8.4%), metabolic process (5.5%), and glycolysis (4.8%). We provide an example of using sub-network enrichment analysis (SNEA) to identify protein networks in the fish hypothalamus in response to dopamine receptor signaling. Dopamine signaling altered the abundance of proteins that are binding partners of microfilaments, integrins, and intermediate filaments, consistent with data suggesting dopaminergic regulation of neuronal stability and structure. Lastly, for fish neuroendocrine studies using both high-throughput genomics and proteomics, we compare gene and protein relationships in the hypothalamus and demonstrate that correlation is often poor for single time point experiments. These studies highlight the need for additional time course analyses to better understand gene-protein relationships and adverse outcome pathways. This is important if both transcriptomics and proteomics are to be used together to investigate neuroendocrine signaling pathways or as bio-monitoring tools in ecotoxicology. © 2011 Elsevier Inc.
McNeill S.A., Arens C.J., Hogan N.S., Köllner B., van den Heuvel M.R. (2012). Immunological impacts of oil sands-affected waters on rainbow trout evaluated using an in situ exposure. Ecotoxicology and Environmental Safety, 84 254-261.

Rainbow trout were exposed in situ to oil sands-affected waters for 21. d, either with or without an immune stimulation using inactivated Aeromonas salmonicida. Three aquatic systems were utilized for the experiment: a pond containing oil sands tailings capped with approximately 3. m of natural surface water, a second pond where unextracted oil sands materials were deposited in the watershed, and a reservoir receiving Athabasca River water as a reference caging location. The three systems showed a gradient of oil sands-related compounds, most notably, total naphthenic acids were highest in the system containing tailings (13. mg/L), followed by the system influenced by unextracted oil sands (4. mg/L), followed by the reference cage location (1. mg/L). Biochemical and chemical measures of exposure in rainbow trout showed the same trend, with the tailings-influenced system having the highest hepatic EROD activity and elevated bile fluorescence measured at phenanthrene wavelengths. Trout caged in the tailings-influenced location had significantly fewer leukocytes and smaller spleens as compared to the reference fish, though liver size and condition factor were unaffected. Fish in the tailings-influenced waters also demonstrated increased fin erosion, indicative of opportunistic infection. The trout exposed to tailing-influenced waters also showed a significantly decreased ability to produce antibodies to the inactivated A. salmonicida. Given the complexity of the exposure conditions, exact causative agents could not be determined, however, naphthenic acids, polycyclic aromatic hydrocarbons and pH correlate with the immunotoxic effects while elevated salinity or metals seem unlikely causes. © 2012 Elsevier Inc.
Mehinto A.C., Martyniuk C.J., Spade D.J., Denslow N.D. (2012). Applications of next-generation sequencing in fish ecotoxicogenomics. Frontiers in Genetics, 3(APR).

The new technologies for next-generation sequencing (NGS) and global gene expression analyses that are widely used in molecular medicine are increasingly applied to the field of fish biology. This has facilitated new directions to address research areas that could not be previously considered due to the lack of molecular information for ecologically relevant species. Over the past decade, the cost of NGS has decreased significantly, making it possible to use non-model fish species to investigate emerging environmental issues. NGS technologies have permitted researchers to obtain large amounts of raw data in short periods of time. There have also been significant improvements in bioinformatics to assemble the sequences and annotate the genes, thus facilitating the management of these large datasets.The combination of DNA sequencing and bioinformatics has improved our abilities to design custom microarrays and study the genome and transcriptome of a wide variety of organisms. Despite the promising results obtained using these techniques in fish studies, NGS technologies are currently underused in ecotoxicogenomics and few studies have employed these methods. These issues should be addressed in order to exploit the full potential of NGS in ecotoxicological studies and expand our understanding of the biology of non-model organisms. © 2012 Mehinto, Martyniuk, Spade and Denslow.
Melvin S.D., Houlahan J.E. (2012). Tadpole mortality varies across experimental venues: Do laboratory populations predict responses in nature? Oecologia, 169(4) 861-868.

Laboratory experiments are widely used to study how populations in nature might respond to various biological interactions, but the relevance of experiments in artificial venues is not known. We compiled mortality and growth data from 424 anuran populations carried out under laboratory, mesocosm, field enclosure, and field settings to determine if major differences exist amongst experimental venues and how this might influence experimental responses of tadpoles amongst venues. Our results show that there are fundamental differences in survival amongst venues, with the highest mortality occurring in field populations and the lowest in laboratory populations. Separation of mesocosm and field enclosure data based on the possibility of predatory interactions indicates that predation is an important factor leading to increased mortality in natural populations. Comparisons of size distributions across venues (although size data were limited for field populations) suggest that variation in tadpole size is low in natural populations compared to populations in artificial venues. We infer from this that mortality has a homogenizing effect on size in nature, resulting in natural populations that are not a random sample of hatched individuals. This finding suggests that populations reared under controlled laboratory conditions in the absence of predation (and other selective pressures) may not be representative of natural populations. © 2012 Springer-Verlag.
Melvin S.D., Trudeau V.L. (2012). Toxicity of naphthenic acids to wood frog tadpoles (Lithobates sylvaticus). Journal of Toxicology and Environmental Health Part A Current Issues, 75(3) 170-173.

Increased incidences of mortality and adverse effects have been described for wildlife exposed to oil-sands-process-affected waters (OSPW). Naphthenic acids (NA) were identified as a primary toxic component of OSPW, yet little information exists regarding NA-induced toxicity in aquatic vertebrates. Amphibian larvae may be particularly susceptible to exposure to OSPW in groundwater surrounding oil sands regions, and increased frequency of mortality and adverse developmental effects were noted in exposed tadpoles. Despite this, there are no published studies investigating the effects of NA exposure on developing tadpoles. LC<inf>50</inf> values of 4.76 mg/L NA were found for tadpoles at an early developmental stage (Gosner stage 28), and even greater toxicity with more developed tadpoles at 96 h, with an LC<inf>50</inf> value of 3.04 mg/L in Gosner stage 36 tadpoles. These values are well below NA concentrations found in OSPW tailing ponds and similar to levels identified in groundwater in the Athabasca Oil Sands region. © 2012 Copyright Taylor and Francis Group, LLC.
Monk W.A., Peters D.L., Baird D.J. (2012). Assessment of ecologically relevant hydrological variables influencing a cold-region river and its delta: The Athabasca River and the Peace-Athabasca Delta, northwestern Canada. Hydrological Processes, 26(12) 1827-1839.

Natural and anthropogenically driven changes in upstream watershed conditions strongly influence the hydrological, geomorphological and ecological processes within downstream riverine and deltaic ecosystems. The goal of our study was to examine temporal trends and spatial patterns in ecologically relevant hydrological variables within the Athabasca River watershed and the downstream Peace-Athabasca Delta (PAD), located in northwestern Canada. Temporal trends for a suite of indicators of hydrologic alteration, appropriate for cold regions environments, were explored using non-parametric Mann-Kendall trend analysis. Results in the Lower Athabasca River (LAR) watershed were placed in a watershed-scale context. Across the two study periods (A - 1958-2009 and B - 1974-2009), results indicated decreasing trends in several key drivers of deltaic system hydrology, including short-term and long-term maximum and minimum runoff. In addition, an increasing trend in hydrograph variability was observed within the watershed. A spatially discrete pattern was apparent from the data, with a greater number of significant trends noted within the headwater region as compared with other areas of the watershed. Although earlier dates of annual freeze-up were observed across the watershed, there were few observable patterns in ice-on/ice-off conditions on the river. If these historical trends in freeze-up continue on the LAR, water levels in the PAD channels and inland wetlands could be affected, leading to reduced habitat diversity and altered ecosystem productivity. The study illustrates significant natural variability in the hydrological regime within the LAR that should be considered in future water management frameworks to ensure the preservation and maintenance of this Ramsar wetland site, particularly in the context of projected climate change and the increased water demands arising from upstream development associated with the Alberta Oil Sands. © 2012 John Wiley & Sons, Ltd.
Monk W.A., Wood P.J., Hannah D.M., Extence C.A., Chadd R.P., Dunbar M.J. (2012). How does macroinvertebrate taxonomic resolution influence ecohydrological relationships in riverine ecosystems. Ecohydrology, 5(1) 36-45.

The taxonomic resolution of macroinvertebrate community data needs careful consideration, to ensure that research objectives in pure and applied freshwater scientific research are met. The level of taxonomy used may be driven by time and financial restrictions associated with the increasing resources and effort needed to identify organisms to a lower taxonomic resolution. This paper aims to assess the influence of taxonomic resolution on the understanding of long-term (1985-2006) benthic macroinvertebrate community response to changes in the hydrological regime. There were marked differences in the number of taxa included in the analysis when comparing 'species'- and 'family'-level data used to derive lotic-invertebrate index for flow evaluation (LIFE) scores, particularly among species rich orders, such as Ephemeroptera, Plecoptera, Trichoptera and Coleoptera. The performance of the partial least squares (PLS) regression models of hydrological variables and the LIFE scores derived for different taxonomic levels were compared. Coefficients of determination were higher for species-level LIFE data than for the same data resolved to family level. Results demonstrate that the species-level LIFE data produced significant model components while those derived from family-level data were not; although both models indicated the dominance of hydrological indices quantifying the duration and magnitude of the hydrological events. We conclude that there is a growing need to resolve faunal data to species level to adequately fulfil operational and legislative obligations for river management and conservation purposes. © 2011 John Wiley & Sons, Ltd.
Ou C., St-Hilaire A., Ouarda T.B.M.J., Conly F.M., Armstrong N., Khalil B., Proulx-Mcinnis S. (2012). Coupling geostatistical approaches with PCA and fuzzy optimal model (FOM) for the integrated assessment of sampling locations of water quality monitoring networks (WQMNs). Journal of Environmental Monitoring, 14(12) 3118-3128.

The assessment of the adequacy of sampling locations is an important aspect in the validation of an effective and efficient water quality monitoring network. Two geostatistical approaches (e.g., kriging and Moran's I) are presented to assess multiple sampling locations. A flexible and comprehensive framework was developed for the selection of multiple sampling locations of multiple variables which was accomplished by coupling geostatistical approaches with principal component analysis (PCA) and fuzzy optimal model (FOM). The FOM was used in the integrated assessment of both multiple principal components and multiple geostatistical approaches. These integrated methods were successfully applied to the assessment of two independent water quality monitoring networks (WQMNs) of Lake Winnipeg, Canada, which respectively included 14 and 30 stations from 2006 to 2010. © The Royal Society of Chemistry 2012.
Palmer L.J., Hogan N.S., Van den Heuvel M.R. (2012). Phylogenetic analysis and molecular methods for the detection of lymphocystis disease virus from yellow perch, Perca flavescens (Mitchell). Journal of Fish Diseases, 35(9) 661-670.

Lymphocystis disease is a prevalent, non-fatal disease that affects many teleost fish and is caused by the DNA virus lymphocystis disease virus (LCDV). Lymphocystis-like lesions have been observed in yellow perch, Perca flavescens (Mitchell), in lakes in northern Alberta, Canada. In an effort to confirm the identity of the virus causing these lesions, DNA was extracted from these lesions and PCR with genotype generic LCDV primers specific to the major capsid protein (MCP) gene was performed. A 1357-base pair nucleotide sequence corresponding to a peptide length of 452 amino acids of the MCP gene was sequenced, confirming the lesions as being lymphocystis disease lesions. Phylogenetic analysis of the generated amino acid sequence revealed the perch LCDV isolate to be a distinct and novel genotype. From the obtained sequence, a real-time PCR identification method was developed using fluorgenic LUX primers. The identification method was used to detect the presence/absence of LCDV in yellow perch from two lakes, one where lymphocystis disease was observed to occur and the other where the disease had not been observed. All samples of fin, spleen and liver tested negative for LCDV in the lake where lymphocystis disease had not been observed. The second lake had a 2.6% incidence of LCD, and virus was detected in tissue samples from all individuals tested regardless of whether they were expressing the disease or not. However, estimated viral copy number in spleen and liver of symptomatic perch was four orders of magnitude higher than that in asymptomatic perch. © 2012 Blackwell Publishing Ltd.
Peters D.L., Baird D.J., Monk W.A., Armanini D.G. (2012). Establishing standards and assessment criteria for ecological instream flow needs in agricultural regions of Canada. Journal of Environmental Quality, 41(1) 41-51.

Agricultural land use can place heavy demands on regional water resources, strongly influencing the quantity and timing of water flows needed to sustain natural ecosystems. The effects of agricultural practices on streamflow conditions are multifaceted, as they also contribute to the severity of impacts arising from other stressors within the river ecosystem. Thus, river scientists need to determine the quantity of water required to sustain important aquatic ecosystem components and ecological services, to support wise apportionment of water for agricultural use. It is now apparent that arbitrarily defined minimum flows are inadequate for this task because the complex habitat requirements of the biota, which underpin the structure and function of a river ecosystem, are strongly influenced by predictable temporal variations in flow. We present an alternative framework for establishing a first-level, regional ecological instream flow needs standard based on adoption of the Indicators of Hydrologic Alteration/Range of Variability Approach as a broadly applicable hydrological assessment tool, coupling this to the Canadian Ecological Flow Index which assesses ecological responses to hydrological alteration. By explicitly incorporating a new field-based ecological assessment tool for small agricultural streams, we provide a necessary verification of altered hydrology that is broadly applicable within Canada and essential to ensure the continuous feedback between the application of flow management criteria and ecological condition. © 2012 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.
Popesku J.T., Martyniuk C.J., Trudeau V.L. (2012). Meta-type analysis of dopaminergic effects on gene expression in the neuroendocrine brain of female goldfish. Frontiers in Endocrinology, 3(NOV).

Dopamine (DA) is a major neurotransmitter important for neuroendocrine control and recent studies have described genomic signaling pathways activated and inhibited by DA agonists and antagonists in the goldfish brain. Here we perform a meta-type analysis using microarray datasets from experiments conducted with female goldfish to characterize the gene expression responses that underlie dopaminergic signaling. Sexually mature, pre-spawning [gonadosomatic index (GSI)=4.5±1.3%] or sexually regressing (GSID=3±0.4%) female goldfish (15-40 g) injected intraperitoneally with either SKF 38393, LY 171555, SCH 23390, sulpiride, or a combination of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and a-methyl-ptyrosine. Microarray meta-type analysis identified 268 genes in the telencephalon and hypothalamus as having reciprocal (i.e., opposite between agonism and antagonism/depletion) fold change responses, suggesting that these transcripts are likely targets for DA-mediated regulation. Noteworthy genes included ependymin, vimentin, and aromatase, genes that support the significance of DA in neuronal plasticity and tissue remodeling. Sub-network enrichment analysis (SNEA) was used to identify common gene regulators and binding proteins associated with the differentially expressed genes mediated by DA. SNEA analysis identified gene expression targets that were related to three major categories that included cell signaling (STAT3, SP1, SMAD, Jun/Fos), immune response (IL-6, IL-1β, TNFs, cytokine, NF-<inf>k</inf>B), and cell proliferation and growth (IGF1, TGFβ1). These gene networks are also known to be associated with neurodegenerative disorders such as Parkinsons' disease, well-known to be associated with loss of dopaminergic neurons. This study identifies genes and networks that underlie DA signaling in the vertebrate CNS and provides targets that may be key neuroendocrine regulators. The results provide a foundation for future work on dopaminergic regulation of gene expression in fish model systems. © 2012 Popesku, Martyniuk and Trudeau.
Páez Y.C., Betancourt C.A., González-Sansón G., Kidd K.A., Munkittrick K.R., Curry R.A. (2012). Increased mercury and body size and changes in trophic structure of Gambusia puncticulata (poeciliidae) along the Almendares River, Cuba. Archives of Environmental Contamination and Toxicology, 63(4) 523-533.

The Almendares River is the largest river draining the area around Havana City, Cuba. The watershed is heavily populated and industrialized, which has had a significant impact on the flow and water quality of the river. The main goal of this study was to analyze the spatial variability in dietary habits, nutrient flow (using stable isotope ratios δ15N and δ13C), and mercury (Hg) levels along the Almendares River upstream and downstream of point-source discharges using localized fish Gambusia puncticulata. Stomach contents of G. puncticulata were similar among these sites. However, mean δ15N values ranged from 6 to 18 % across sites and were lower in fish from downstream than upstream sites, suggesting localized influences of nutrient inputs along the river. δ13C values were between -22 and -25 %, except at a mid-basin site (- 26 to -27%), indicating that fish relied on similar carbon sources at most sites. Total mercury concentrations ranged from 0.04 to 0.49 lg/g wet weight whole body and were unrelated to the among-site differences in δ15N, but Hg exceeded the threshold considered to be protective of fish health (0.2 lg/g ww whole body) in the majority of fish from all sites but one. Results of this study indicate that although the dietary habits of this species do not vary across sites, tissue differences in δ15N, δ13C and Hg show little movement of this species among sites. Localized effects of human activities on nutrients and metals may be affecting the health of this species and posing a risk to other consumers in the ecosystem. © Springer Science+Business Media, LLC 2012.
Riazanov A., Hindle M.M., Goudreau E.S., Martyniuk C.J., Baker C.J.O. (2012). Ecotoxicology data federation with SADI semantic web services. Ceur Workshop Proceedings, 952.

Biologists and biotechnologists need to draw information from numerous distributed and heterogeneous resources, such as online biomedical databases, nomenclatures and specialised bioinformatics tools. These tasks can benefit significantly from semantic data federation with SADI Semantic Web services where multiple resources exposed through SADI services are accessed as a single virtual SPARQL-queriable database. We provide evidence in support of this premise by creating and testing a kit of public SADI services for a number of bioinformatics databases and programs, and by demonstrating how it can be used to serve real information needs of ecotoxicology researchers, by using the services to answer some model queries.
Ribeiro R., Baird D.J., Soares A.M.V.M., Lopes I. (2012). Contaminant driven genetic erosion: A case study with Daphnia longispina. Environmental Toxicology and Chemistry, 31(5) 977-982.

Natural populations exposed to pollutants are predicted to experience a loss of genetic diversity, especially through genetic drift, gene flow (emigration), and/or selection (as sensitive genotypes may be lost). In the present study, the authors discuss the use of selectable markers and neutral markers to evaluate a contaminant-driven loss of genetic diversity and possible implications of genetic erosion on populations' viability. Viability could be reduced by altering life history parameters, especially due to fitness costs associated with the acquisition of resistance and/or by compromising the resilience and adaptation to future environmental changes. This discussion aims at an integrated and critical analysis of this topic; it is illustrated by several independent studies (each with its own specific objectives) that were carried out at the same location with Daphnia longispina populations. To the best of the authors' knowledge, this is the most extensively documented case study on genetic erosion of a natural zooplankton population. Directional selection has been found to be a main factor of microevolution; therefore, genetic erosion was detected by monitoring suitable phenotypic markers. Genetic drift was found to be probably irrelevant or masked by other factors, especially gene flow. Although the acquisition of resistance apparently did not entail genetically determined fitness costs under uncontaminated conditions, the present case study suggests the possibility of a further loss of genotypes due to some negative linkages between the sensitivity to potential ulterior toxicants. © 2012 SETAC.
Rubach M.N., Baird D.J., Boerwinkel M.C., Maund S.J., Roessink I., Van Den Brink P.J. (2012). Species traits as predictors for intrinsic sensitivity of aquatic invertebrates to the insecticide chlorpyrifos. Ecotoxicology, 21(7) 2088-2101.

Ecological risk assessment (ERA) has followed a taxonomy-based approach, making the assumption that related species will show similar sensitivity to toxicants, and using safety factors or species sensitivity distributions to extrapolate from tested to untested species. In ecology it has become apparent that taxonomic approaches may have limitations for the description and understanding of species assemblages in nature. Therefore it has been proposed that the inclusion of species traits in ERA could provide a useful and alternative description of the systems under investigation. At the same time, there is a growing recognition that the use of mechanistic approaches in ERA, including conceptual and quantitative models, may improve predictive and extrapolative power. Purposefully linking traits with mechanistic effect models could add value to taxonomy-based ERA by improving our understanding of how structural and functional system facets may facilitate inter-species extrapolation. Here, we explore whether and in what ways traits can be linked purposefully to mechanistic effect models to predict intrinsic sensitivity using available data on the acute sensitivity and toxicokinetics of a range of freshwater arthropods exposed to chlorpyrifos. The results of a quantitative linking of seven different endpoints and twelve traits demonstrate that while quantitative links between traits and/or trait combinations and process based (toxicokinetic) model parameters can be established, the use of simple traits to predict classical sensitivity endpoints yields little insight. Remarkably, neither of the standard sensitivity values, i.e. the LC<inf>50</inf> or EC50, showed a strong correlation with traits. Future research in this area should include a quantitative linking of toxicodynamic parameter estimations and physiological traits, and requires further consideration of how mechanistic trait-process/parameter links can be used for prediction of intrinsic sensitivity across species for different substances in ERA. © The Author(s) 2012.
Schein A., Courtenay S.C., Crane C.S., Teather K.L., van den Heuvel M.R. (2012). The Role of Submerged Aquatic Vegetation in Structuring the Nearshore Fish Community Within an Estuary of the Southern Gulf of St. Lawrence. Estuaries and Coasts, 35(3) 799-810.

Artificial fertilizers are contributing to the replacement of eelgrass (Zostera marina) by sea lettuce (Ulva lactuca) in estuaries of Prince Edward Island (PEI), Canada. In this study, we found that the nearshore fish community differed between areas dominated by these two vegetations within an estuary in every month sampled (April-August). Adult northern pipefish (Syngnathus fuscus), threespine stickleback (Gasterosteus aculeatus), blackspotted stickleback (Gasterosteus wheatlandi), and Atlantic silverside (Menidia menidia) were most strongly associated with eelgrass, while mummichog (Fundulus heteroclitus), ninespine stickleback (Pungitius pungitius), and American eel (Anguilla rostrata) were often more numerous in sea lettuce. Sea lettuce stations tended to have more young-of-the-year mummichog, fourspine stickleback (Apeltes quadracus), and Gasterosteus sp. than eelgrass stations but fewer young-of-the-year northern pipefish and Atlantic silverside. Fish richness and abundance were significantly lower in the sea lettuce than eelgrass habitat during August when benthic hypoxia occurred. We conclude that the loss of eelgrass from PEI estuaries will result in significant declines in fish biodiversity. © 2011 Coastal and Estuarine Research Federation.
Skinner M.A., Courtenay S.C., Parker W.R., Curry R.A. (2012). Stable isotopic assessment of site fidelity of mummichogs, Fundulus heteroclitus, exposed to multiple anthropogenic inputs. Environmental Biology of Fishes, 94(4) 695-706.

The goals of the study were: (1) to evaluate stable isotopic analysis (SIA) in determining the site fidelity of mummichogs, Fundulus heteroclitus, along a smaller spatial scale (~10 km) in homogenous habitat type relative to previous SIA studies; and (2) to cross-validate SIA results with mark-recapture results from a study conducted concurrently at the same sites in the upper Miramichi River estuary (MRE), New Brunswick, Canada influenced by two pulp mills and three municipal wastewater facilities. Mummichogs sampled at 9 sites along the upper MRE (n = 198) had overall mean (± SD) ratios of -21. 03 ± 1. 45 ‰ δ 13C and 11. 37 ± 1. 02 ‰ δ 15N. Mean δ 13C and δ 15N ratios were significantly different among sites with mean δ 13C increasing in a downstream direction and distinct δ 15N group signatures along the northern and southern shores. Multivariate analyses detected seven distinct groups out of nine sites sampled and these differences appear to be related to wastewater treatment influences, thus demonstrating the utility of SIA as a method to determine the site-specificity of organisms on a relatively small spatial scale within homogenous habitat within an estuary. These results, in addition to the scarcity of statistical outliers (3 %) during examination of isotopic ratios within sites support the results of a previous mark-recapture study that demonstrated very few mummichogs (3. 4 %) in the upper MRE move more than 200 m. © 2012 Springer Science+Business Media B.V.
St-Hilaire A., Ouarda T.B.M.J., Bargaoui Z., Daigle A., Bilodeau L. (2012). Daily river water temperature forecast model with a k-nearest neighbour approach. Hydrological Processes, 26(9) 1302-1310.

Water temperature is a key abiotic variable that modulates both water chemistry and aquatic life in rivers and streams. For this reason, numerous water temperature models have been developed in recent years. In this paper, a k-nearest neighbour model (KNN) is proposed and validated to simulate and eventually produce a one-day forecast of mean water temperature on the Moisie River, a watercourse with an important salmon population in eastern Canada. Numerous KNN model configurations were compared by selecting different attributes and testing different weight combinations for neighbours. It was found that the best model uses attributes that include water temperature from the two previous days and an indicator of seasonality (day of the year) to select nearest neighbours. Three neighbours were used to calculate the estimated temperature, and the weighting combination that yielded the best results was an equal weight on all three nearest neighbours. This nonparametric model provided lower Root Mean Square Errors (RMSE = 1·57 °C), Higher Nash coefficient (NTD = 0·93) and lower Relative Bias (RB = - 1·5%) than a nonlinear regression model (RMSE = 2·45 °C, NTD = 0·83, RB = - 3%). The k-nearest neighbour model appears to be a promising tool to simulate of forecast water temperature where long time series are available. © 2011 John Wiley & Sons, Ltd..
Sumith J.A., Hansani P.L.C., Weeraratne T.C., Munkittrick K.R. (2012). Seasonal exposure of fish to neurotoxic pesticides in an intensive agricultural catchment, Uma-oya, Sri Lanka: Linking contamination and acetylcholinesterase inhibition. Environmental Toxicology and Chemistry, 31(7) 1501-1510.

The annual cultivation pattern in the Uma-oya catchment in Sri Lanka is characterized by Yala and Maha rainfall periods and associated cropping. Two cultivation seasons were compared for pesticide residues: base flow, field drainage, and the runoff and supplementary sediment data for three sites in the catchment. Organophosphate and N-methyl carbamate pesticide analysis confirmed a higher concentration in the Yala season with low-flow conditions. Acetylcholinesterase (AChE) activity was measured by standard spectrometry in the brain, muscle, and eye tissues of three freshwater cyprinid fishes, Garra ceylonensis, Devario malabaricus, and Rasbora daniconius from three study sites during months overlapping two seasons in 2010 (December) and 2011 (July). Baseline AChE data were measured from fish samples from a forested reserve in the Knuckles. A 73% inhibition in muscle AChE activity in G. ceylonensis was associated with intense pesticide exposure months in the Yala season. The AChE inhibition more than 70% in G. ceylonensis eyes in both Yala (76%) and Maha (72.5%) seasons indicates particular sensitivity of eye tissue to inhibitors. The less dramatic AChE inhibition in the eye tissues in D. malabaricus and R. daniconius in both seasons indicates exemplary protective capacity of muscle AChE in fish. The highest inhibition of AChE (up to 60% in brain and up to 56% in muscle AChE activity in R. daniconius and up to 47.8% in brain and up to 64.6% in muscle AChE activity in D. malabaricus) occurred during the Yala season. Tissue AChE activity and physiological activity in fish were correlated. The results collectively indicate that AChE is a consistent biomarker for diffused contaminant exposure in agricultural catchments. © 2012 SETAC.
Sutherland A.B., Culp J.M., Benoy G.A. (2012). Evaluation of deposited sediment and macroinvertebrate metrics used to quantify biological response to excessive sedimentation in agricultural streams. Environmental Management, 50(1) 50-63.

The objective of this study was to evaluate which macroinvertebrate and deposited sediment metrics are best for determining effects of excessive sedimentation on stream integrity. Fifteen instream sediment metrics, with the strongest relationship to land cover, were compared to riffle macroinvertebrate metrics in streams ranging across a gradient of land disturbance. Six deposited sediment metrics were strongly related to the relative abundance of Ephemeroptera, Plecoptera and Trichoptera and six were strongly related to the modified family biotic index (MFBI). Few functional feeding groups and habit groups were significantly related to deposited sediment, and this may be related to the focus on riffle, rather than reach-wide macroinvertebrates, as reach-wide sediment metrics were more closely related to human land use. Our results suggest that the coarse-level deposited sediment metric, visual estimate of fines, and the coarse-level biological index, MFBI, may be useful in biomonitoring efforts aimed at determining the impact of anthropogenic sedimentation on stream biotic integrity. © 2012 Springer Science+Business Media, LLC.
Trudeau V.L., Martyniuk C.J., Zhao E., Hu H., Volkoff H., Decatur W.A., Basak A. (2012). Is secretoneurin a new hormone? General and Comparative Endocrinology, 175(1) 10-18.

Numerous small potentially bioactive peptides are derived from the selective processing of the ~600 amino acid secretogranin II (SgII) precursor, but only the 31-42 amino acid segment termed secretoneurin (SN) is well-conserved from sharks to mammals. Both SNa and SNb paralogs have been identified in some teleosts, likely arising as a result of the specific genome duplication event in this lineage. Only one copy of the putative lamprey SgII (188 amino acids) could be identified which gives rise to a divergent agnathan SN that contains the signature YTPQ-X-LA-X<inf>7</inf>-EL sequence typical of the central core of all known SN peptides. In rodent models, SN has regulatory effects on neuroinflammation and neurotransmitter release, and possesses therapeutic potential for the induction of angiogenesis. The wide distribution of SN in neuroendocrine neurons and pituitary cells suggests important endocrine roles. The clearest example of the endocrine action of SN is the stimulatory effects on pituitary luteinizing hormone release from goldfish pituitary and mouse LβT2 gonadotroph cells, indicative of an important role in reproduction. Several lines of evidence suggest that the SN receptor is most likely a G-protein coupled protein. Microarray analysis of SN effects on dispersed goldfish pituitary cells in vitro reveals novel SN actions that include effects on genes involved in notch signaling and the guanylate cyclase pathway. Intracerebroventricular injection of SN increases feeding and locomotory behaviors in goldfish. Given that SgII appeared early in vertebrate evolution, SN is an old peptide with emerging implications as a new multifunctional hormone. © 2011 Elsevier Inc.
Van den Heuvel M.R., Hogan N.S., Roloson S.D., Van Der Kraak G.J. (2012). Reproductive development of yellow perch (Perca flavescens) exposed to oil sands-affected waters. Environmental Toxicology and Chemistry, 31(3) 654-662.

In similar experiments conducted in 1996 and 2009, yellow perch (Perca flavescens) were stocked into two experimental systems: a demonstration lake where oil sands fine tailings were capped with natural water and a lake in a watershed containing bitumen-bearing sodic clays. In both experiments, yellow perch were captured in May from a nearby reservoir and released into the experimental ponds. Perch were recaptured in the experimental systems, the source lake, and two reference lakes in late September and lethally sampled to examine reproductive parameters. In the 1996 experiment, gonad size and steroid hormones were not affected in either pond environment. In the 2009 experiment, male perch in the water-capped tailings pond showed a significant reduction in the testicular development and reductions in circulating testosterone and 11-ketotestosterone, while no reductions were seen in the second experimental pond. No changes were observed in ovarian size or circulating steroid levels in female perch. In the pond containing tailings, the release of water from underlying tailings caused approximately a twofold increase in salinity, alkalinity, and naphthenic acids, and a pH increase from 8.4 to 9.4 over the 13-year period of the study. In the pond influenced by unextracted oil sands materials, total dissolved solids, major ions, and pH did not change substantially. However, naphthenic acids in this system dropped more than twofold post-watershed reclamation. Because the selective reproductive effect observed in male perch in the experimental end-pit lake were accompanied by increases in naphthenic acids, alkalinity, and pH, a specific cause cannot be determined. The present study adds to the evidence, suggesting the presence of endocrine-disrupting substances in oil sands. © 2011 SETAC.
Webb J.M., Jacobus L.M., Funk D.H., Zhou X., Kondratieff B., Geraci C.J., DeWalt R.E., Baird D.J., Richard B., Phillips I., Hebert P.D.N. (2012). A DNA barcode library for North American ephemeroptera: Progress and prospects. Plos One, 7(5).

DNA barcoding of aquatic macroinvertebrates holds much promise as a tool for taxonomic research and for providing the reliable identifications needed for water quality assessment programs. A prerequisite for identification using barcodes is a reliable reference library. We gathered 4165 sequences from the barcode region of the mitochondrial cytochrome c oxidase subunit I gene representing 264 nominal and 90 provisional species of mayflies (Insecta: Ephemeroptera) from Canada, Mexico, and the United States. No species shared barcode sequences and all can be identified with barcodes with the possible exception of some Caenis. Minimum interspecific distances ranged from 0.3-24.7% (mean: 12.5%), while the average intraspecific divergence was 1.97%. The latter value was inflated by the presence of very high divergences in some taxa. In fact, nearly 20% of the species included two or three haplotype clusters showing greater than 5.0% sequence divergence and some values are as high as 26.7%. Many of the species with high divergences are polyphyletic and likely represent species complexes. Indeed, many of these polyphyletic species have numerous synonyms and individuals in some barcode clusters show morphological attributes characteristic of the synonymized species. In light of our findings, it is imperative that type or topotype specimens be sequenced to correctly associate barcode clusters with morphological species concepts and to determine the status of currently synonymized species. © 2012 Webb et al.
Yates A.G., Culp J.M., Chambers P.A. (2012). Estimating nutrient production from human activities in subcatchments of the Red River, Manitoba. Journal of Great Lakes Research, 38(SUPPL. 3) 106-114.

Human activities in the subcatchments of Lake Winnipeg's contributing basins are hypothesized to be an important cause of the increased nutrient loadings intensifying eutrophication processes in Lake Winnipeg, Manitoba, Canada. This study used a geographic information system (GIS) and available human activity data to describe the types and extents of nutrient producing human activities in subcatchments of the Red River Valley, Manitoba. The goal of the study was to estimate variation in the relative amount of nitrogen and phosphorus produced by human activities and thus potentially available for release to aquatic environments. Estimates of nutrient production indicated that agricultural activities, particularly through synthetic fertilizer application, were by far the largest potential source of anthropogenic nutrients to aquatic ecosystems in most subcatchments. Residential sources in these subcatchments contributed less than 1% of the total amount of nutrients produced. Assessment of spatial variation in nutrient production demonstrated that estimated nutrient production from fertilizer application in subcatchments on the west side of the Red River Valley was up to two orders of magnitude higher than that found in subcatchments on the east side. In contrast, high livestock densities in several eastern subcatchments of the Red River Valley produced more than five times the annual areal mass of nitrogen and phosphorus of most western subcatchments. Our findings demonstrate the importance of quantifying, a priori, the potential sources of nutrients to river tributaries so that future sampling sites can be stratified to include catchments where different nutrient producing activities are most extensive. © 2011.
Zubair S.N., Peake S.J., Hare J.F., Anderson W.G. (2012). The effect of temperature and substrate on the development of the cortisol stress response in the lake sturgeon, Acipenser fulvescens, Rafinesque (1817). Environmental Biology of Fishes, 93(4) 577-587.

Lake sturgeon, Acipenser fulvescens, are considered threatened or endangered throughout most of their North American Range. Current hatchery rearing for re-stocking programs utilise conventional methods with little to no understanding of the relationship between rearing conditions and the development of the hypothalamic-pituitary-interrenal (HPI) stress axis. In the present study we examined the effects of substrate type and temperature on the development of the HPI stress axis in prolarval and larval lake sturgeon. Lake sturgeon raised over either gravel or no substrate did not consistently show an increase in whole body cortisol at the prolarval stage. However, after the onset of exogenous feeding a consistent increase in whole body cortisol following a stress was evident. Lake sturgeon larvae raised in gravel substrate demonstrated a sustained increase in whole body cortisol for at least 240 min post stress whereas whole body cortisol in larvae raised in no substrate returned to baseline within 240 min post stress. Lake sturgeon larvae raised at 9, 12 and 15°C exhibited markedly different cortisol responses with baseline whole body cortisol being, 38. 6 ± 3, 5. 67 ± 0. 41 and 25. 38 ± 2. 84 ng. g -1 respectively. Furthermore, the chase induced increases in whole body cortisol at the larval stage were significantly different for each temperature treatment. These experiments demonstrate that physical environment has a significant impact on the development of the HPI stress axis in lake sturgeon. © 2011 Springer Science+Business Media B.V.
Allain R.N., Moriyasu M., Crawford B.D., Courtenay S.C. (2011). Lipofuscin quantification as a potential tool for age estimation in snow crabs, Chionoecetes opilio (O. Fabricius, 1788) (Decapoda, Oregoniidae). Crustaceana, 84(12-13) 1441-1463.

Lipofuscin levels were investigated in snow crabs (Chionoecetes opilio) to assess the applicability of lipofuscin quantification as an age determining tool for this species. Localization and quantification of lipofuscin granules in the olfactory lobe cell mass (OLCM) of the brain were conducted by confocal microscopy and image analysis. The majority of immature crabs had no detectable lipofuscin. Crabs with a dirty carapace condition (an indication of greater age) had more lipofuscin (in terms of granule density, area fraction, and mean granule size) than crabs with a clean carapace condition; however, the amount of lipofuscin was much lower than that in more temperate species. Lipofuscin content was positively correlated with carapace size among crabs with a clean carapace but not among crabs with a dirty carapace. No correlation was observed between average lipofuscin granule fluorescent intensity and carapace width. OLCM neuron characteristics were also investigated. An inverse relationship was observed between neuron density and carapace width although it is unknown if this density reduction is due to a loss of neurons, an increase in size of the structures, or both. Furthermore, a positive relationship was observed between neuron size and carapace width. The range of neuron size also increased in larger crabs, suggesting the presence of mitotically active cells in the OLCM. Although lipofuscin levels were higher in dirty carapace condition (presumably older) crabs than in clean carapace crabs and increased with size (in mature, clean carapace snow crabs), the lack of detectable lipofuscin in most immature crabs, generally low levels of lipofuscin in mature crabs, and lack of increase with size in older (dirty carapace) crabs limits the applicability of this age estimation tool for this species. © 2011 BRILL.
Allainu R., Mikio M., Crawford B., Courtenay S. (2011). Technical development and calibration of lipofuscin quantification for the potential use as an age estimate in snow crabs Chionoecetes opilio (Decapoda: Oregoniidae). Cahiers De Biologie Marine, 52(2) 203-215.

This study demonstrated the presence of lipofuscin granules in the olfactory lobe cell mass (OLCM) of snow crab Chionoecetes opilio and examined whether granule quantification results are subject to methodological bias. Lipofuscin quantification in histological sections of the OLCM were compared between: 1) snow crab categories (sex and two indicators of age: size and condition of carapace (evaluated by the coloration of the carapace, presence/absence of scars and epizootic and epiphytic growth); 2) sample preparation methods; and 3) microscopic image collection parameters. No significant difference was observed in lipofuscin levels between mature males and females of similar size and carapace condition. Lipofuscin was more abundant in crabs with a decalcifying (presumably, older) carapace condition. However, larger clean-shell males did not have higher lipofuscin levels than smaller old-decalcify trig-shell males. Autoflu ore scent intensity of granules was significantly higher in brain samples post-fixed in decalcifying solution compared to formalin fixed samples; however, lipofuscin levels did not differ. Increased exposure times to laser light of up to 120 seconds significantly decreased autofluorescent intensity of lipofuscin granules. No significant differences wrere observed in lipofuscin levels when varying optical section thickness or when comparing single confocal planes and stacks. Lipofuscin granule size frequency histograms showed possible image analysis limitations in terms of minimum lipofuscin granule size. These results raised concerns regarding the applicability of histological lipofuscin quantification in the OLCM of snow crabs.
Arciszewski T.J., Kidd K.A., Munkittrick K.R. (2011). Comparing responses in the performance of sentinel populations of stoneflies (Plecoptera) and slimy sculpin (Cottus cognatus) exposed to enriching effluents. Ecotoxicology and Environmental Safety, 74(7) 1844-1854.

Programs in Canada that assess the effects of wastewater discharges on organisms, such as Environmental Effects Monitoring (EEM), primarily focus on fish populations and benthic invertebrate communities. Although these methods are widely accepted, there are many situations where fish monitoring is difficult and benthic community data is difficult to interpret; in these instances alternative approaches should be used. There are, however, few alternative methods available. One potential alternative is to use invertebrate population endpoints to determine effects in the receiving environment. In this study we examined effects of sewage and pulp mill effluents in the Saint John River, New Brunswick, on two stonefly genera (Plecoptera, Perlidae, Acroneuria spp. and Paragnetina spp.) and compared the responses to those of a small-bodied fish, the slimy sculpin (Cottus cognatus). Stonefly measurements included condition, developmental stage, gonad weight, and size upstream and downstream of sewage and a pulp mill discharge. Condition, developmental stage, and absolute gonad weight were greater in Paragnetina spp. downstream of the sewage discharge. Acroneuria spp. showed persistence of the late developmental stage downstream of the sewage inputs. Slimy sculpin exposed to sewage effluents also showed increased condition, but the impacts downstream of the pulp mill effluent were inconsistent in both sculpin and Paragnetina spp. Our findings suggest that stonefly populations and slimy sculpin respond to effluents in similar ways and that the responses of large long-lived invertebrate populations, such as stoneflies, may be a viable alternative to fish population monitoring in environmental assessments of point source discharges. © 2011 Elsevier Inc.
Armanini D.G., Horrigan N., Monk W.A., Peters D.L., Baird D.J. (2011). Development of a benthic macroinvertebrate flow sensitivity index for Canadian rivers. River Research and Applications, 27(6) 723-737.

Widespread alteration of flow regimes requires guidelines for the protection of river ecosystems based on sound science. Preservation of the biodiversity within river ecosystems and sustaining natural ecological functions are key aspects of their management. However, the relationship between the biota and flow-related phenomena is poorly understood and, as a consequence, over-simplistic hydrology-based guidelines for river management have been adopted without establishing clear indicators of success. In the present paper, we aim to support the improvement of guidelines for flow (current velocity) management by developing a flow sensitivity index based on macroinvertebrates for Canadian rivers. Using benthic macroinvertebrate (BMI) samples collected by the Canadian Aquatic Biomonitoring Network (CABIN), current velocity preferences for the 55 most common invertebrate taxa across a range of reference and potential reference sites were derived. A Canadian Ecological Flow Index (CEFI) was developed based on these preferences. By testing the index against independent data, CEFI was found to respond mainly to changes in hydraulic conditions, and was minimally influenced by confounding factors (e.g. stream type, organic enrichment). The index was further validated using two independent data sets from the west and east of Canada, suggesting countrywide applicability of the method. In conclusion, we have developed a practical approach to evaluate relationships between hydrological regime and an important component of the river biota, permitting the development of an index which has good potential as an indicator for the effects of flow alteration. Moreover, we outline how the CEFI could be used as a tool for the development of holistic guidelines for the estimation of riverine flow needs. © 2010 Crown in the right of Canada and John Wiley & Sons, Ltd.
Baird D.J., Baker C.J.O., Brua R.B., Hajibabaei M., McNicol K., Pascoe T.J., de Zwart D. (2011). Toward a knowledge infrastructure for traits-based ecological risk assessment. Integrated Environmental Assessment and Management, 7(2) 209-215.

The trait approach has already indicated significant potential as a tool in understanding natural variation among species in sensitivity to contaminants in the process of ecological risk assessment. However, to realize its full potential, a defined nomenclature for traits is urgently required, and significant effort is required to populate databases of species-trait relationships. Recently, there have been significant advances in the area of information management and discovery in the area of the semantic web. Combined with continuing progress in biological trait knowledge, these suggest that the time is right for a reevaluation of how trait information from divergent research traditions is collated and made available for end users in the field of environmental management. Although there has already been a great deal of work on traits, the information is scattered throughout databases, literature, and undiscovered sources. Further progress will require better leverage of this existing data and research to fill in the gaps.We review and discuss a number of technical and social challenges to bringing together existing information and moving toward a new, collaborative approach. Finally, we outline a path toward enhanced knowledge discovery within the traits domain space, showing that, by linking knowledge management infrastructure, semantic metadata (trait ontologies), andWeb 2.0 and 3.0 technologies, we can begin to construct a dedicated platform for TERA science. © 2010 SETAC.
Baird D.J., Pascoe T.J., Zhou X., Hajibabaei M. (2011). Building freshwater macroinvertebrate DNA-barcode libraries from reference collection material: Formalin preservation vs specimen age. Journal of the North American Benthological Society, 30(1) 125-130.

As part of its ongoing work in biomonitoring, Environment Canada's Canadian Aquatic Biomonitoring Network (CABIN) program has assembled an expert-verified reference collection of 3864 specimens of 604 species of Canadian freshwater macroinvertebrates. Such collections are a key resource for developing a deoxyribonucleic acid (DNA) barcode library to facilitate molecular identification of biomonitoring samples. We examined the problems encountered in using such legacy material to obtain reference barcodes. We focused on the influence of specimen age and preservation history. To supplement work on the reference collection, we determined the time-dependent effects of formalin preservation on DNA-barcode integrity in 4 common arthropod taxa by controlled exposure of fresh material obtained from laboratory cultures. Specimens in the reference collection were preserved with short-term fixation in formalin followed by prolonged preservation in 70% ethanol. Only 19 caddisfly larval specimens out of the total of 650 analyzed returned full-length sequences. In contrast, formalin preservation of freshly collected material for up to 20 d yielded good sequencing success and high-quality sequences. Freshly collected material clearly provides the best basis for the future development of DNA-barcode libraries, and formalin preservation should be avoided where possible to ensure that DNA integrity is maximized. © 2011 The North American Benthological Society.
Baird D.J., Sweeney B.W. (2011). Applying DNA barcoding in benthology: The state of the science. Journal of the North American Benthological Society, 30(1) 122-124.

The application of deoxyribonucleic acid (DNA) barcoding in benthic ecology is proceeding rapidly, and a special session held at the 2009 North American Benthological Society Annual Meeting in Grand Rapids, Michigan, USA, brought together benthic scientists working in areas varying from taxonomy to biomonitoring to present the state of the science. The papers arising from this meeting are grouped in this special series of papers. Here, we present a brief introduction to this emerging area of benthic science, highlight the contributions of previous researchers, and provide an overview of these latest contributions to this highly active field. Paper topics include the development of DNA libraries for identification of material from field studies, application of DNA-based taxonomy in the discovery of new faunas, and the use of DNA-based identification in field biomonitoring studies, present and future. In addition, a critique is presented of the use of DNA barcoding in benthology and the potential pitfalls facing researchers who seek to use this method in their future research. © 2011 The North American Benthological Society.
Barrett T.J. (2011). Computations using analysis of covariance. Wiley Interdisciplinary Reviews Computational Statistics, 3(3) 260-268.

Although analysis of covariance (ANCOVA) was introduced long ago, it is not well understood by many researchers and is frequently misused. ANCOVA is an extension of analysis of variance (ANOVA) with the inclusion of one or more covariates. Its benefits compared to ANOVA include (1) increased power and (2) a reduction in biases caused by differences in experimental units [the covariate(s)] among groups. ANCOVA can be presented using an adjusted means procedure (testing for differences in means adjusted for the covariate), but the procedure can be easily understood using a multiple linear regression method using indicator variables to represent groups. Statistical software packages use general linear models to perform ANCOVA which are identical to the multiple linear regression models. Failure to meet assumptions of ANCOVA can lead to misinterpretation of results. Failing to meet the assumption of parallel group regression slopes is common in many data sets and methods are available to analyze these data sets (e.g., the Johnson-Neyman technique). Although ANCOVA is robust to violations of some assumptions (e.g., normality and equality of variances) when sample sizes are equal, many nonparametric tests based on ranks are available as nonparametric alternatives to ANCOVA. © 2011 John Wiley & Sons, Inc.
Barth C.C., Gary Anderson W., Henderson L.M., Peake S.J. (2011). Home range size and seasonal movement of juvenile lake sturgeon in a large river in the Hudson Bay drainage basin. Transactions of the American Fisheries Society, 140(6) 1629-1641.

Development of rehabilitation strategies and accurate assessment of anthropogenic impacts relies on a thorough understanding of a species' life history. In the case of the lake sturgeon Acipenser fulvescens, a better understanding of the juvenile life history stages is needed to improve conservation efforts for this imperiled species. Home range size and seasonal movement of juvenile lake sturgeon in the Winnipeg River, Manitoba, were examined using markrecapture and acoustic telemetry. Over a 30-month period (May 2006-October 2008), 5,671 juvenile lake sturgeon (213-879 mm fork length [FL]) were marked with Floy tags and the movements of 23 juvenile lake sturgeon (364-505 mm FL) were monitored by means of acoustic transmitters. Despite the potential for movement over 49 km of naturally connected riverine habitat, the results indicated that juvenile lake sturgeon exhibited strong site fidelity. As determined from the mark-recapture data set, 90.8% of recaptured fish were recaptured less than 2.0 river kilometers (rkm) from their original capture location. Similarly, acoustic telemetry data indicated that 50% of the tagged fish moved 1.5 rkm or less from their initial release locations. Finally, the results of both methodologies indicated that juvenile lake sturgeon rarely move through rapids characterized by high water velocities (>1.5 m/s), complex turbulent flows, boulder and bedrock substrates, and various cross-sectional water depths ranging from 1.0 m to approximately 15.0 m in either an upstream or downstream direction. These results suggest that the year-round habitat requirements for juvenile lake sturgeon can be met in relatively short sections of a large river. Furthermore, owing to strong site fidelity and a lack of movement through rapids, macroscale habitat use in juvenile lake sturgeon occupying large rivers may be dependent on dispersal at either the larval or young of the year life history stages. © American Fisheries Society 2011.
Bethea D.M., Carlson J.K., Hollensead L.D., Papastamatiou Y.P., Graham B.S. (2011). A comparison of the foraging ecology and bioenergetics of the early life-stages of two sympatric hammerhead sharks. Bulletin of Marine Science, 87(4) 873-889.

Juvenile scalloped hammerhead sharks, Sphyrna lewini (Griffith and Smith, 1834), were collected in northwest Florida to examine foraging ecology, bioenergetics, and trophic level [30-60 cm fork length (FL ); mean FL = 41.5 cm; n = 196]. Diet analysis was performed using single and compound measures of prey quantity, as well as seven broad diet categories. Diet composition and estimated daily ration were compared to previously published information on bonnethead sharks, Sphyrna tiburo (Linnaeus, 1758). Diet overlap was low between species. Juvenile S. lewini feed on relatively small (85% of prey items < 5% shark length) teleosts (mostly bothids and sciaenids) and shrimps, whereas juvenile S. tiburo has been documented to feed mostly on crustaceans and plant material. Plant material contributed little to the diet of S. lewini. Estimated daily ration was significantly lower for S. lewini than for S. tiburo, regardless of whether plant material was included in the model. Trophic level was calculated at 4.0 for S. lewini and 2.6 for S. tiburo. Stable isotope analysis showed S. lewini had significantly higher ä15N values and significantly lower ä13C values than S. tiburo, consistent with the difference observed in calculated trophic level. These results provide evidence that juvenile hammerhead species coexist in coastal northwest Florida by feeding at separate trophic levels. © 2011 Rosenstiel School of Marine and Atmospheric Science of the University of Miami.
Bosman S.H., Methven D.A., Courtenay S.C., Hanson J.M. (2011). Fish assemblages in a north Atlantic coastal ecosystem: Spatial patterns and environmental correlates. Estuarine Coastal and Shelf Science, 92(2) 232-245.

Analyses of six years of bottom trawl data collected from Northumberland Strait, southern Gulf of St. Lawrence revealed four major fish assemblages, two of which occurred in the same two geographic areas each year. One of the two persistent assemblages occurred in deeper water off northwestern Prince Edward Island and consisted mostly of demersal fishes. The other persistent assemblage contained a mixture of demersal and pelagic fishes and occurred primarily in shallow water of central Northumberland Strait. Analyses of abiotic (depth, bottom temperature, substratum type) and biotic (presence of American lobster Homarus americanus, northern lady crab Ovalipes ocellatus) factors revealed bottom temperature and catches of lady crab correlate best with the fish assemblage structure each year, but correlation values were low (ρ<inf>w</inf> ≤ 0.48). Combinations of all abiotic and biotic variables only marginally improved the strength of the correlations in four of six years (2002, 2003, 2005, 2006). Changes observed in the Northumberland Strait ecosystem over the six years included an increase in the ratio of pelagic to demersal fishes, disappearance of one of the four assemblages, and increased spatial overlap between the two persistent assemblages, which coincided with an increase in bottom temperature. The increasing importance of pelagic fishes, relative to demersal fishes, suggests a shift in food web structure may be occurring in Northumberland Strait. © 2011.
Breau C., Cunjak R.A., Peake S.J. (2011). Behaviour during elevated water temperatures: Can physiology explain movement of juvenile Atlantic salmon to cool water? Journal of Animal Ecology, 80(4) 844-853.

Temperature governs most physiological processes in animals. Ectotherms behaviourally thermoregulate by selecting habitats with temperatures regulating their body temperature for optimal physiological functioning. However, ectotherms can experience temperature extremes forcing the organisms to seek temperature refuge. Fish actively avoid potentially lethal temperatures by moving to cool-water sites created by inflowing tributaries and groundwater seeps. Juvenile Atlantic salmon (Salmo salar) of different age classes exhibit different behavioural responses to elevated temperatures (>23°C). Yearling (1+) and 2-year-old (2+) Atlantic salmon often cease feeding, abandon territorial behaviour and swim continuously in aggregations in cool-water sites; whereas young-of-the-year (0+) fish continue defending territories and foraging. This study determined whether the behavioural shift in older individuals (2+) occurred when basal metabolic rate, driven by increasing water temperature, reached the maximum metabolic rate such that anaerobic pathways were recruited to provide energy to support vital processes. Behaviour (feeding and stress responses), oxygen consumption, muscle lactate and glycogen, and circulating blood lactate and glucose concentrations were measured in wild 0+ and 2+ Atlantic salmon acclimated to water temperatures between 16 and 28°C. Results indicate that oxygen consumption of the 2+ fish increased with temperature and reached a plateau at 24°C, a temperature that corresponded to cessation of feeding and a significant increase in muscle and blood lactate levels. By contrast, oxygen consumption in 0+ fish did not reach a plateau, feeding continued and muscle lactate did not increase, even at the highest temperatures tested (28°C). To conclude, the experiment demonstrated that the 0+ and 2+ fish had different physiological responses to the elevated water temperatures. The results suggest that wild 2+ Atlantic salmon employ behavioural responses (e.g. movement to cool-water sites) at elevated temperatures in an effort to mitigate physiological imbalances associated with an inability to support basal metabolism through aerobic metabolic processes. © 2011 The Authors. Journal of Animal Ecology © 2011 British Ecological Society.
Brua R.B., Culp J.M., Benoy G.A. (2011). Comparison of benthic macroinvertebrate communities by two methods: Kick- and U-net sampling. Hydrobiologia, 658(1) 293-302.

The assessment of benthic invertebrate community condition is an integral component of freshwater biomonitoring and water quality determination. Several sampling devices have been developed to collect benthic macroinvertebrates, including qualitative, semi-quantitative, and quantitative methods. In this study, we compared several benthic macroinvertebrate metrics and community assemblage measures calculated from data obtained from two sampling methods, namely the Kick- and U-net sampling devices. We reasoned that if the two methods produced similar values for benthic metrics and community composition, then samples collected by these methods should be able to be combined to build larger data sets for use in regional bioassessment analyses. No statistical differences between Kick- and U-net methods were found among standard benthic macroinvertebrate metrics, except for Kicknets collecting more Chironomidae. Invertebrate assemblages were very similar between collection methods, although slightly greater taxonomic richness was found in U-net samples. Bray-Curtis similarity was typically [75% between methods within a stream, while classification strengthsampling- method comparability, an approach for analyzing differences in similarity between groups, indicated invertebrate assemblage similarity between collection methods was virtually identical at approximately 100%. Since these two methods produce similar results, we conclude that benthic macroinvertebrate data collected by these methods can be combined for data analysis and bioassessments with the caveat that mesh size of the sample nets is similar. In addition, if the primary study objective is to assess macroinvertebrate biodiversity, then the U-net sampling device may be more appropriate, despite the slightly greater time needed to complete field sample collection, as it tended to collect a greater diversity of species. © Springer Science+Business Media B.V. 2010.
Chambers P.A., Benoy G.A., Brua R.B., Culp J.M. (2011). Application of nitrogen and phosphorus criteria for streams in agricultural landscapes. Water Science and Technology, 64(11) 2185-2191.

Efforts to control eutrophication of water resources in agriculturally dominated ecosystems have focused on managing on-farm activities to reduce nutrient loss; however, another management measure for improving water quality is adoption of environmental performance criteria (or 'outcome-based standards'). Here, we review approaches for setting environmental quality criteria for nutrients, summarize approaches developed in Canada for setting 'ideal' and 'achievable' nutrient criteria for streams in agricultural watersheds, and consider how such criteria could be applied. As part of a 'National Agri-Environmental Standards Initiative', the Government of Canada committed to the development of non-regulatory environmental performance standards that establish total P (TP) and total N (TN) concentrations to protect ecological condition of agricultural streams. Application of four approaches for defining ideal standards using only chemistry data resulted in values for TP and TN spanning a relatively narrow range of concentrations within a given ecoregion. Cross-calibration of these chemically derived standards with information on biological condition resulted in recommendations for TP and TN that would likely protect aquatic life from adverse effects of eutrophication. Non-point source water quality modelling was then conducted in a specific watershed to estimate achievable standards, i.e. chemical conditions that could be attained using currently available and recommended management practices. Our research showed that, taken together, short-term achievable standards and ultimate ideal standards could be used to set policy targets that should, if realized, lower N and P concentrations in Canadian agricultural streams and improve biotic condition. © Environment Canada 2011.
Chiang G., Mcmaster M.E., Urrutia R., Saavedra M.F., Gavilán J.F., Tucca F., Barra R., Munkittrick K.R. (2011). Health status of native fish (Percilia gillissi and Trichomycterus areolatus) downstream of the discharge of effluent from a tertiary-treated elemental chlorine-free pulp mill in Chile. Environmental Toxicology and Chemistry, 30(8) 1793-1809.

Few data exist on the possible effects of pulp and paper effluent discharge on native fish populations in the Southern Hemisphere, relative to the research done in the Northern Hemisphere. The present research examined two native fish species (Trichomycterus areolatus and Percilia gillissi) for effects at both the molecular and individual level due to the discharge of effluent from a tertiary treated elemental chlorine-free pulp mill into a fluvial system in Central Chile over three seasons (February 2007, October 2007, January 2008). Different responses were observed between species and between sexes. There was an increase in the production of gonadal 17β-estradiol in the females of both species but a drop in 11-ketotestosterone production in P. gillissi males. Female gonadal size was increased, especially during the summer period, with corresponding increases the frequency of advanced oocyte development, and in the oocyte diameter in both species. Hepatic ethoxyresorufin-O-deethylase (EROD) activity was elevated for both species downstream of the discharge point, although overall it was higher in P. gillissi than T. areolatus. Decreases in the frequency of smaller-sized fish for both species, as well as a drop in the size of the adults downstream of the discharge point, were observed. The present study is the first evidence of endocrine disruption in native freshwater fish associated with modern pulp mills in South America. This study establishes possible links in the reproductive alterations observed at the subindividual and individual levels that could explain the changes observed at the population level. © 2011 SETAC.
Chiang G., Munkittrick K.R., Saavedra M.F., Tucca F., McMaster M.E., Urrutia R., Tetreault G., Barra R. (2011). Seasonal changes in reproductive endpoints in Trichomycterus areolatus (Siluriformes: Trichomycteridae) and Percilia gillissi (Perciformes, Perciliidae), and the consequences for environmental monitoring. Studies on Neotropical Fauna and Environment, 46(3) 185-196.

As protection of the natural reproductive pattern is necessary to ensure adequate conservation of natural populations, we examined some typical reproductive endpoints throughout a reproductive season in two Chilean species that lack this baseline information. Trichomycterus areolatus and Percilia gillissi both have maximum gonad development for an austral spring spawning period beginning in October/November. Trichomycterus areolatus appears to spawn many times, as there was no significant correlation between gonad size and body size, a characteristic of asynchronous spawners. Percilia gillissi appears to be a multiple spawner, with larger individuals spawning into January, although most fish completed spawning by December. To design a study for monitoring purposes with these species, the best sampling periods would be late fall (June) and spring (October) for P. gillissi, as power analysis indicated a target sample size of 20 females in June and 34 in October; the sample size in October could be reduced to 12 by selecting females > 50 mm in length, thereby reducing the variability. Trichomycterus areolatus gonadal variability was much higher, requiring a sample size in excess of 80 individuals for adequate statistical power. An understanding of these basic reproductive and metabolic patterns in South American freshwater fishes will help ensure better management of the water resources. © 2011 Copyright Taylor and Francis Group, LLC.
Corriveau J., Chambers P.A., Yates A.G., Culp J.M. (2011). Snowmelt and its role in the hydrologic and nutrient budgets of prairie streams. Water Science and Technology, 64(8) 1590-1596.

Small watersheds in the Canadian Prairies are characterized by seasonally disconnected hydrologic networks whereby stream channels are hydrologically connected during snowmelt but have disconnected reaches throughout the remainder of the year. Snowmelt is the most significant hydrological event in the Canadian Prairies, yet few studies have investigated the role of snowmelt in the nutrient budget of prairie streams. We quantified hydrologic and nutrient dynamics during snowmelt for ten agricultural subwatersheds distributed along a gradient of human activity in the Red River Valley, Canada, to evaluate the timing of nitrogen (N) and phosphorus (P) export. Elevated concentrations of total P (TP) and total N (TN) were observed during the snowmelt peak, with maximum concentrations reaching 3.23 mg TP L -1 and 18.50 mg TN L -1. Dissolved P and N dominated the total nutrient pool throughout snowmelt, likely due to reduced erosion and sediment transport resulting from the combination of the flat topography, frozen soil and stream banks, and gradual snow cover melt. Significant correlations were observed between snowmelt N load (r = 0.91; p < 0.05) and both agricultural land cover and fertilizer usage, with a weaker correlation between snowmelt P load (r = 0.81; p < 0.05) and agricultural area. Our results showed that snowmelt plays a key role in nutrient export to prairie aquatic ecosystems and this may have serious impacts on downstream ecosystems. Land use management practices need to consider the snowmelt period to control nutrient loads to Lake Winnipeg and other waterbodies in the Great Plains. © IWA Publishing 2011.
Culp J.M., Armanini D.G., Dunbar M.J., Orlofske J.M., LeRoy Poff N., Pollard A.I., Yates A.G., Hose G.C. (2011). Incorporating traits in aquatic biomonitoring to enhance causal diagnosis and prediction. Integrated Environmental Assessment and Management, 7(2) 187-197.

The linkage of trait responses to stressor gradients has potential to expand biomonitoring approaches beyond traditional taxonomically based assessments that identify ecological effect to provide a causal diagnosis. Traits-based information may have several advantages over taxonomically based methods. These include providing mechanistic linkages of biotic responses to environmental conditions, consistent descriptors or metrics across broad spatial scales, more seasonal stability compared with taxonomic measures, and seamless integration of traits-based analysis into assessment programs. A traits-based biomonitoring approach does not require a new biomonitoring framework, because contemporary biomonitoring programs gather the basic siteby-species compositionmatrices requiredtolink communitydata to the traitsdatabase. Impediments tothe adoption of traits-based biomonitoring relate to the availability, consistency, and applicability of existing trait data. For example, traits generalizationsamong taxa across biogeographical regions are rare, andnoconsensus exists relative tothe requiredtaxonomic resolutionandmethodology for traits assessment. Similarly, we must determine if traits form suites that are related to particular stressor effects, and whether significant variation of traits occurs among allopatric populations. Finally, to realize the potential of traits-based approaches in biomonitoring, a concerted effort to standardize terminology is required, along with the establishment of protocols to ease the sharing and merging of broad, geographical trait information. © 2010 SETAC.
Daigle A., St-Hilaire A., Beveridge D., Caissie D., Benyahya L. (2011). Multivariate analysis of the low-flow regimes in eastern Canadian rivers. Hydrological Sciences Journal, 56(1) 51-67.

A characterization of the low-flow regimes of 175 eastern Canadian rivers based on multivariate analysis of hydrological indices (HIs) is presented. Principal component analysis (PCA) was used to identify eight highly informative and low-correlated HIs amongst 67 low-flow HIs reported in the literature, and to test their ability to describe regional characteristics and differences among low-flow regimes at the 175 stations. It was found that eight HIs can provide a regional description of the main low-flow characteristics almost equivalent to using all HIs related to low flows. The PCA also identified regional similarities and differences among the geographical and hydrological regions within the Province of Quebec, as well as between the Atlantic provinces of Canada. Multivariate analysis proved to be an efficient tool that can complement expert knowledge in the selection of criteria for instream flow assessments in eastern Canada, by quantitatively indicating indices carrying high information, and by ensuring low redundancy in the selected subset of variables (HIs). © 2011 IAHS Press.
Danielescu S., MacQuarrie K.T.B. (2011). Nitrogen loadings to two small estuaries, Prince Edward Island, Canada: A 2-year investigation of precipitation, surface water and groundwater contributions. Hydrological Processes, 25(6) 945-957.

In this research the dissolved inorganic nitrogen (DIN) loadings from direct precipitation, stream flow and groundwater discharge to two small estuaries located in Prince Edward Island (PEI), Canada, were quantified over a 2-year period. The two estuaries, like many around the world, exhibit deteriorating conditions that are believed to be related to excessive nitrogen transport from adjacent catchments. The significance of the groundwater transport pathway and the temporal variability of the loadings have not been previously investigated. The wet fraction of the atmospheric loading was quantified using available precipitation and DIN concentration records. Stream water entering the estuaries and the discharge from numerous shoreline springs, the predominate form of groundwater discharge, were monitored periodically during the study. The annual DIN loads delivered to both estuaries were dominated by streams, although groundwater discharge provided significant contributions of approximately 15-18%. Temporal variability of DIN loading was large, with monthly loads varying by a factor of 5; this variability was found to be primarily related to the variability of freshwater discharge. Concentrations of nitrate in stream water discharging to the estuaries and shoreline groundwater springs were similar in each catchment, suggesting that there was minimal differential attenuation during transport via these two pathways. The McIntyre Creek estuary had one of the highest normalized loads reported in the literature (1700 kg NO<inf>3</inf>-N/ha estuary/year), more than four-fold that of the Trout River estuary, and this result appears to be related to the larger percentage of land area used for potato production in the catchment. This study demonstrates that direct groundwater discharge to estuaries in PEI should not be ignored and that seasonal variations in loading may be important for managing DIN delivery to such estuaries. Copyright © 2010 John Wiley & Sons, Ltd.
Deslauriers D., Kieffer J.D. (2011). The influence of flume length and group size on swimming performance in shortnose sturgeon Acipenser brevirostrum. Journal of Fish Biology, 79(5) 1146-1155.

The main objectives of this study were to determine optimal methodologies to assess the general swimming performance of juvenile shortnose sturgeon Acipenser brevirostrum. Swimming densities (group v. individual swimming) and flume length (2 v. 1 m) were altered to verify if any of those variables affected performance (i.e. time to fatigue) during critical swimming (U <inf>crit</inf>) and endurance tests. Results for both U <inf>crit</inf> and endurance swimming were not significantly different between fish swum in groups of five or fish swum individually. The U <inf>crit</inf> values, however, were c. 22% higher for fish swum in a longer flume. Although swimming fish in groups did not improve swimming performance, group swimming lowered the variance of the data. Results also reveal that juvenile A. brevirostrum may not possess an ability to swim at high speeds (i.e. burst phase) for long periods. © 2011 The Authors. Journal of Fish Biology © 2011 The Fisheries Society of the British Isles.
Doperalski N.J., Martyniuk C.J., Prucha M.S., Kroll K.J., Denslow N.D., Barber D.S. (2011). Cloning and expression of the translocator protein (18kDa), voltage-dependent anion channel, and diazepam binding inhibitor in the gonad of largemouth bass (Micropterus salmoides) across the reproductive cycle. General and Comparative Endocrinology, 173(1) 86-95.

Cholesterol transport across the mitochondrial membrane is rate-limiting for steroidogenesis in vertebrates. Previous studies in fish have characterized expression of the steroidogenic acute regulatory protein, however the function and regulation of other genes and proteins involved in piscine cholesterol transport have not been evaluated. In the current study, mRNA sequences of the 18. kDa translocator protein (tspo; formerly peripheral benzodiazepine receptor), voltage-dependent anion channel (vdac), and diazepam binding inhibitor (dbi; also acyl-CoA binding protein) were cloned from largemouth bass. Gonadal expression was examined across reproductive stages to determine if expression is correlated with changes in steroid levels and with indicators of reproductive maturation. In testis, transcript abundance of tspo and dbi increased with reproductive maturation (6- and 23-fold maximal increase, respectively) and expression of tspo and dbi was positively correlated with reproductive stage, gonadosomatic index (GSI), and circulating levels of testosterone. Testis vdac expression was positively correlated with reproductive stage and GSI. In females, gonadal tspo and vdac expression was negatively correlated with GSI and levels of plasma testosterone and 17β-estradiol. Ovarian dbi expression was not correlated with indicators of reproductive maturation. These studies represent the first investigation of the steroidogenic role of tspo, vdac, and dbi in fish. Findings suggest that cholesterol transport in largemouth bass testis, but not in ovary, may be transcriptionally-regulated, however further investigation will be necessary to fully elucidate the role of these genes in largemouth bass steroidogenesis. © 2011 Elsevier Inc.
Doyle M.A., Bosker T., Munkittrick K.R. (2011). The potential use of Atlantic silverside (Menidia menidia) for monitoring estuarine pollution. Journal of Environmental Monitoring, 13(11) 3168-3177.

Monitoring chronic impacts of nearshore pollution on fish in Atlantic marine systems is challenging due to the mobility and seasonal nature of most habitat use. We evaluated Atlantic silverside (Menidia menidia) as a potential indicator of pollution across a gradient of contaminated sites in the Saint John River Estuary, New Brunswick, Canada. Fish returning from offshore in the spring showed no differences in length, weight, or condition factor between sites, but a graded response in condition factor appeared gradually, consistent with levels of contamination. Gonad size peaked in early June, however no differences in GSI were found among sites. By September, most fish collected were young of the year, with a significant bias towards female juveniles at the exposed site. These results indicate that Atlantic silverside are locally resident during their onshore period, and demonstrates their potential as a sentinel species. Sampling should focus on early June prior to the full moon to ensure maximal exposure periods before spawning, or in late October to evaluate growth as fish grow rapidly prior to offshore movement. © The Royal Society of Chemistry 2011.
Edge C.B., Gahl M.K., Pauli B.D., Thompson D.G., Houlahan J.E. (2011). Exposure of juvenile green frogs (Lithobates clamitans) in littoral enclosures to a glyphosate-based herbicide. Ecotoxicology and Environmental Safety, 74(5) 1363-1369.

The majority of studies on the toxicity of glyphosate-based herbicides to amphibians have focused on larval life stages exposed in aqueous media. However, adult and juvenile amphibians may also be exposed directly or indirectly to herbicides. The potential for such exposures is of particular interest in the littoral zone surrounding wetlands as this is preferred habitat for many amphibian species. Moreover, it may be argued that potential herbicide effects on juvenile or adult amphibians could have comparatively greater influence on overall recruitment, reproductive potential and thus stability of local populations than effects on larvae. In this experiment, juvenile green frogs (Lithobates clamitans) were exposed to two concentrations (2.16 and 4.27kga.e./ha) of a glyphosate-based herbicide formulation (VisionMax®), which were based on typical application scenarios in Canadian forestry. The experimental design employed frogs inhabiting in situ enclosures established at the edge of small naturalized wetlands that were split in half using an impermeable plastic barrier. When analyzed using nominal target application rates, exposure to the glyphosate-based herbicide had no significant effect on survival, body condition, liver somatic index or the observed rate of Batrachochytrium dendrobatidis infection. However, there were marginal trends in both ANOVA analysis and post-hoc regressions regarding B. dendrobatidis infection rates and liver somatic index in relation to measured exposure estimates. Results from this study highlight the importance of field research and the need to include multiple endpoints when examining potential effects of a contaminant on non-target organisms. © 2011 Elsevier Inc.
Gahl M.K., Pauli B.D., Houlahan J.E. (2011). Effects of chytrid fungus and a glyphosate-based herbicide on survival and growth of wood frogs (Lithobates sylvaticus). Ecological Applications, 21(7) 2521-2529.

Anthropogenic-derived stressors in the environment, such as contaminants, are increasingly considered important cofactors that may decrease the immune response of amphibians to pathogens. Few studies, however, have integrated amphibian disease and contaminants to test this multiple-stressor hypothesis for amphibian declines. We examined whether exposure to sublethal concentrations of a glyphosate-based herbicide and two strains of the pathogenic chytrid fungus, Batrachochytrium dendrobatidis (Bd) could: (1) sublethally affect wood frogs (Lithobates sylvaticus) by altering the time to and size at metamorphosis, and (2) directly affect survivability of wood frogs after metamorphosis. Neither Bd strain nor herbicide exposure alone significantly altered growth or time to metamorphosis. The two Bd strains did not differ in their pathogenicity, and both caused mortality in post-metamorphic wood frogs. There was no evidence of an interaction between treatments, indicating a lack of herbicide-induced susceptibility to Bd. However, the trends in our data suggest that exposure of wood frogs to a high concentration of glyphosate-based herbicide may reduce Bd-caused mortality compared to animals exposed to Bd alone. These results exemplify the complexities inherent when populations are coping with multiple stressors. In this case, the perceived stressor, glyphosate-based herbicide, appeared to affect the pathogen more than the host's immune system, relieving the host from disease-caused effects. This suggests caution when invoking multiple stressors as a cause for increased disease susceptibility and indicates that the effects of multiple stressors on disease outcome depend on the interrelationships of stressors to both the pathogen and the host. © 2011 by the Ecological Society of America.
Gielen G.J.H.P., Clinton P.W., Van den Heuvel M.R., Kimberley M.O., Greenfield L.G. (2011). Influence of sewage and pharmaceuticals on soil microbial function. Environmental Toxicology and Chemistry, 30(5) 1086-1095.

Although sewage effluent application to land is a common approach to recycle water and provide nutrients to plants, bioactive pharmaceuticals contained in sewage may change soil quality by affecting soil microbial communities. Establishing causal effects, however, is difficult, because trace levels of pharmaceuticals are confounded with other effluent constituents. Therefore, two originally similar soil microbial communities, one irrigated in situ with sewage effluent for 12 years and another nonirrigated, were exposed to high levels of acetaminophen, aspirin, carbamazepine, chlorpromazine, and tetracycline. The objectives of the current study were to determine the influence of high levels of pharmaceuticals on several soil microbial properties, the effect that prolonged effluent irrigation with ambient levels of pharmaceuticals had on soil microbial function, and how this effect would change in response to pharmaceutical exposure. Several pharmaceuticals, at high exposure levels, imposed stress on the soil microbial community as judged by increased CO<inf>2</inf> respiration, decreased biomass carbon, and altered substrate utilization affinities. Prolonged effluent irrigation, which altered the genetic fingerprint of the microbial community, also mitigated the response that exposure to pharmaceuticals had on the microbial community and enabled degradation of the antimicrobial salicylic acid after aspirin exposure. In conclusion, prolonged irrigation with sewage effluent containing pharmaceuticals at ambient levels influenced the microbial community so that they were able to better cope with sudden exposure to high levels of pharmaceuticals. © 2011 SETAC.
Guillemette N., St-Hilaire A., Ouarda T.B.M.J., Bergeron N. (2011). Statistical tools for thermal regime characterization at segment river scale: Case study of the Ste-Marguerite River. River Research and Applications, 27(8) 1058-1071.

Suitable thermal fish habitats are constrained by both maximum and minimum temperature tolerances. A multivariate and geostatistical approach was developed to estimate stream thermal characteristics at the river segment scale. Data from 22 temperature-monitoring stations during summer 2007 were used to estimate monthly maximum temperature as well as thermal characteristics such as the number of events, the cumulative degree-days and the associated duration over specific temperature thresholds of 19 and 21°C. The probability of exceeding these temperature thresholds has also been interpolated. The methodology relies on the construction of a multivariate space using physiographic and hydrological characteristics of gauging stations as inputs in a canonical correlation analysis (CCA). A geostatistical interpolation technique, ordinary kriging, was subsequently used to perform interpolation in the physiographical space constructed using CCA. Results from this study were obtained for thermal characteristics estimated into two different interpolation spaces: (1) a 7 metrics space, and (2) an 8 metrics space. Cross-validation technique has been performed and satisfactory results were obtained. Kriging thermal characteristics (magnitude and duration) into the 7 metric space for a 19°C threshold exceedance leads to best results with Relative Root Mean Square Error (RRMSE) ranging between 9.66 and 15.08%. The study shows that kriging in a multivariate space is a promising tool for water resources managers, especially in cases where risk mapping for lethal or sub-lethal temperature thresholds may be required for a specific fish species. © 2010 John Wiley & Sons, Ltd.
Hajibabaei M., Shokralla S., Zhou X., Singer G.A.C., Baird D.J. (2011). Environmental barcoding: A next-generation sequencing approach for biomonitoring applications using river benthos. Plos One, 6(4).

Timely and accurate biodiversity analysis poses an ongoing challenge for the success of biomonitoring programs. Morphology-based identification of bioindicator taxa is time consuming, and rarely supports species-level resolution especially for immature life stages. Much work has been done in the past decade to develop alternative approaches for biodiversity analysis using DNA sequence-based approaches such as molecular phylogenetics and DNA barcoding. On-going assembly of DNA barcode reference libraries will provide the basis for a DNA-based identification system. The use of recently introduced next-generation sequencing (NGS) approaches in biodiversity science has the potential to further extend the application of DNA information for routine biomonitoring applications to an unprecedented scale. Here we demonstrate the feasibility of using 454 massively parallel pyrosequencing for species-level analysis of freshwater benthic macroinvertebrate taxa commonly used for biomonitoring. We designed our experiments in order to directly compare morphology-based, Sanger sequencing DNA barcoding, and next-generation environmental barcoding approaches. Our results show the ability of 454 pyrosequencing of mini-barcodes to accurately identify all species with more than 1% abundance in the pooled mixture. Although the approach failed to identify 6 rare species in the mixture, the presence of sequences from 9 species that were not represented by individuals in the mixture provides evidence that DNA based analysis may yet provide a valuable approach in finding rare species in bulk environmental samples. We further demonstrate the application of the environmental barcoding approach by comparing benthic macroinvertebrates from an urban region to those obtained from a conservation area. Although considerable effort will be required to robustly optimize NGS tools to identify species from bulk environmental samples, our results indicate the potential of an environmental barcoding approach for biomonitoring programs. © 2011 Hajibabaei et al.
Hindle M.M., Riazanov A., Goudreau E.S., Martyniuk C.J., Baker C.J.O. (2011). Leveraging SADI semantic web services to exploit fish ecotoxicology data. Ceur Workshop Proceedings, 774 19-33.

In order to interpret experimental Omics-data, ecotoxicologists are faced with an array of disconnected bioinformatics databases and algorithms. These include tools for microarray analysis, gene annotation, functional gene set enrichment, and network analysis. Drawing together these Web tools and resources is a frequently labour-consuming technical exercise in identifying links across database records and the connecting input and output formats of tools. Interpreting experimental Omics-data in the context of the current available knowledge and methodologies from a single query platform with explicit semantics would be a valuable asset for toxicology in the analysis of DNA, transcriptomics, proteomic, and metabolomic experimental data. Methods: We have created 30+ SADI semantic Web Services, resources and tools pertinent to the interpretation of Omics toxicological data. These services encompass a wide range of algorithms, domains and databases, including sequence alignment and protein domain finding tools (e.g. BLAST, HMMR3, and InterProScan), databases containing experimentally validated protein functions (e.g. ZFIN and MGI), and central repositories of sequence and microarray data (e.g. ArrayExpress and NCBI-RefSeq). All these services can be leveraged through SPARQL queries submitted to the SHARE query engine. This paradigm provides a single access-point on the Web for a toxicologist to submit semantically rich queries that are resolved using the relevant databases and tools. This frees the ecotoxicologist from learning unnecessary details concerning tool interfaces and the semantic idiosyncrasies of databases. Results: We present a series of example queries for ecotoxicology, which facilitate the interpretation of transcriptomics data in the context of public knowledge and current tools. These queries include common tasks, specific to a user's experimental data set, such as gene ontology annotation of probes on a custom microarray experiment for an aquatic species of interest.
Jardine T.D., Kidd K.A. (2011). Low concentrations of selenium in stream food webs of eastern Canada. Science of the Total Environment, 409(4) 785-791.

Herbivorous and predatory invertebrates and two species of fish (brook trout and blacknose dace) were collected from 49 streams in New Brunswick, Canada to determine whether concentrations of selenium (Se) in the biota were affected by a point source (a coal-fired power plant), and stream water chemistry (pH, sulphate, conductivity, and total organic carbon), and to determine the trophic transfer of Se through these food webs. Total Se concentrations in the biota were generally low (0.2 to 4.8μgg-1 dry weight) across sites and there was no relationship between distance from the coal-fired power plant and Se concentrations in invertebrates or fishes. Water chemistry was an equally poor predictor of Se concentrations in invertebrates and fish. Trophic position (determined using δ15N) was a significant predictor of Se concentrations in only five of the stream food webs, and two of these had negative slopes, indicating little or no trophic magnification across most systems; many fishes had lower concentrations than their invertebrate prey and trophic transfer was higher at sites with low invertebrate Se concentrations. Variability in Se concentrations in fishes was explained more by site of capture than microhabitat use within the site (as measured with δ13C), suggesting among-site differences in geological sources of Se. Because concentrations were below known toxicity thresholds for fish and other consumers, these results suggest that Se is not an environmental issue in New Brunswick streams that do not receive direct inputs from mining activities. © 2010 Elsevier B.V.
Karami A., Christianus A., Ishak Z., Syed M.A., Courtenay S.C. (2011). The effects of intramuscular and intraperitoneal injections of benzo[a]pyrene on selected biomarkers in Clarias gariepinus. Ecotoxicology and Environmental Safety, 74(6) 1558-1566.

This study investigated the dose-dependent and time-course effects of intramuscular (i.m.) and intraperitoneal (i.p.) injection of benzo[. a]pyrene (BaP) on the biomarkers EROD activity, GST activity, concentrations of BaP metabolites in bile, and visceral fat deposits (Lipid Somatic Index, LSI) in African catfish (Clarias gariepinus). Intraperitoneal injection resulted in 4.5 times higher accumulation of total selected biliary FACs than i.m. injection. Hepatic GST activities were inhibited by BaP via both injection methods. Dose-response relationships between BaP injection and both biliary FAC concentrations and hepatic GST activities were linear in the i.p. injected group but nonlinear in the i.m. injected fish. Hepatic EROD activity and LSI were not significantly affected by BaP exposure by either injection route. We conclude that i.p. is a more effective route of exposure than i.m. for future ecotoxicological studies of PAH exposure in C. gariepinus. © 2011 Elsevier Inc.
Karami A., Christianus A., Zokaeifar H., Saad K.Z., Imraan F.T.J., Shakibazadeh S., Negarestan H., Courtenay S.C. (2011). Ovaprim treatment promotes oocyte development and milt fertilization rate in diploid and triploid African catfish (Clarias gariepinus). Aquaculture International, 19(6) 1025-1034.

Triploid fish are increasingly used in aquaculture because they are generally unable to reproduce successfully. Energy is channeled into somatic growth rather than gonadal development, and in the event of escape, the animals are unlikely to breed successfully among themselves or with wild conspecifics. This study tested the ability of recently matured triploid African catfish (Clarias gariepinus) to produce and fertilize eggs with and without ovaprim treatment. Triploid females did not show the increase in ovary size observed in diploid members of the same cohort between 8 and 9 months of age, or the coincident decrease in visceral fat deposits, and this was unaffected by up to 5 weekly i.m. injections of 0.5 ml kg-1 Ovaprim. However, we observed advanced vitellogenin (Vtg) sequestration in oocytes of triploid females, albeit to a lesser degree and with lesser cortical alveoli, compared to oocytes from diploid cohort members. Histological sections revealed a positive trend of oocyte development up to the third weekly ovaprim injection followed by a negative gonadal development in weeks four and five. Milt from triploid males injected 9-12 h earlier with 0.25 ml kg-1 ovaprim i. m. fertilized more diploid eggs than milt from untreated triploid males (30 vs. 20%), but none of the developing embryos of triploid paternity survived to hatch. In contrast, milt of diploid males fertilized 49% of eggs, and 20% of the developing embryos hatched successfully. These rates were improved in ovaprim-injected diploid males to 70% fertilization and 33% hatch. This study demonstrates potential of overcoming non-viability of eggs from triploid female African catfish, and enhancing the ability of triploid milt to fertilize eggs. © 2011 Springer Science+Business Media B.V.
Kidd K., Clayden M., Jardine T. (2011). Bioaccumulation and Biomagnification of Mercury through Food Webs. Environmental Chemistry and Toxicology of Mercury 453-499.
Larsson S., Linnansaari T., Vatanen S., Serrano I., Haikonen A. (2011). Feeding of wild and hatchery reared Atlantic salmon (Salmo salar L.) smolts during downstream migration. Environmental Biology of Fishes, 92(3) 361-369.

In general, hatchery salmonid smolts experience higher mortality during migration than wild smolts, which is suggested to be due to domestication effects and that hatchery fish lack experience of the natural environment. However, possible differences in feeding during smolt migration between hatchery and wild smolts have rarely been addressed. We compared the number of feeding smolts and stomach fullness among wild Atlantic salmon smolts, hatchery-reared smolts released as 1-year-old parr, and hatchery-reared smolts released as 2-year-old smolts during their descent to sea in River Tornionjoki. In addition, estimations of prey selection among the smolt groups were conducted. A high proportion of wild smolts and smolts stocked as parr actively fed during the smolt migration. A lower proportion of smolts stocked as smolts was feeding and their stomach fullness were much reduced in comparison with the two other groups. The study also indicated that the feeding of migrating smolts is selective rather than opportunistic. In conclusion, this study suggests that stocked 2-year-old smolts may enter sea with an inferior foraging behaviour and it is a possibility that this may contribute to the observed low post-smolt survival in the Baltic Sea. © 2011 Springer Science+Business Media B.V.
Lopes I., Moreira-Santos M., Rendón-von Osten J., Baird D.J., Soares A.M.V.M., Ribeiro R. (2011). Suitability of five cladoceran species from Mexico for in situ experimentation. Ecotoxicology and Environmental Safety, 74(1) 111-116.

Although they are highly suited for site-specific risk assessment, little attention has been given to in situ ecotoxicological experimentation in tropical regions. This study intended to assess the suitability of five freshwater cladocerans from Mexico for in situ experiments. Juveniles of Ceriodaphnia cornuta, Macrothrix triserialis group, Simocephalus vetulus, Diaphanosoma birgei, and Pseudosida cf. ramosa, from two populations, were used to perform seven day laboratory and in situ experiments. Pseudosida cf. ramosa was very sensitive to handling and was discarded from further evaluations. Ceriodaphnia cornuta reproduced significantly more neonates, with smaller coefficients of variation, than M. triserialis and S. vetulus. Also due to its worldwide distribution in the tropics, C. cornuta is suggested to be highly suitable for in situ experiments. © 2010 Elsevier Inc.
Martel P.H., Kovacs T.G., O'Connor B.I., Semeniuk S., Hewitt L.M., MacLatchy D.L., McMaster M.E., Parrott J.L., Van Den Heuvel M.R., Van Der Kraak G.J. (2011). Effluent monitoring at a bleached kraft mill: Directions for best management practices for eliminating effects on fish reproduction. Journal of Environmental Science and Health Part A Toxic Hazardous Substances and Environmental Engineering, 46(8) 833-843.

A long-term monitoring study was conducted on effluents from a bleached kraft pulp and paper mill located in Eastern Canada. The study was designed to gain insights into temporal effluent variability with respect to fish reproduction as it related to production upsets, mill restarts and conditions affecting biological treatment performance. Final effluent quality was monitored between February 2007 and May 2009 using biochemical and chemical oxygen demand, total suspended solids, resin and fatty acids, a gas chromatographic profiling index, and the presence of methyl substituted 2-cyclopentenones. Selected effluent samples were evaluated for effects on fish reproduction (egg production) using a shortened version of the adult fathead minnow reproductive test. The events relating to negative effects on fish reproduction were upsets of the pulping liquor recovery system resulting in black liquor losses, operational upsets of the hardwood line resulting in the loss of oxygen delignification filtrates, and conditions that reduced the performance of biological treatment (e.g., mill shutdown and low ambient temperatures). The reductions in egg production observed in fathead minnow were associated with biochemical oxygen demand values > 20 mg/L, GC profiling indices > 1.2 and the presence of methyl-substituted 2-cyclopentenones at concentrations > 100 μg/L. This study demonstrated the importance of both in-plant measures for controlling the loss of organics as well as the optimum operation of biological effluent treatment for eliminating effluent-related effects on fish reproduction (egg production) in the laboratory. Copyright © Taylor & Francis Group, LLC.
Martyniuk C.J., Spade D.J., Blum J.L., Kroll K.J., Denslow N.D. (2011). Methoxychlor affects multiple hormone signaling pathways in the largemouth bass (Micropterus salmoides) liver. Aquatic Toxicology, 101(3-4) 483-492.

Methoxychlor (MXC) is an organochlorine pesticide that has been shown to have estrogenic activity by activating estrogen receptors and inducing vitellogenin production in male fish. Previous studies report that exposure to MXC induces changes in mRNA abundance of reproductive genes in the liver and testes of largemouth bass (Micropterus salmoides). The objective of the present study was to better characterize the mode of action of MXC by measuring the global transcriptomic response in the male largemouth liver using an oligonucleotide microarray. Microarray analysis identified highly significant changes in the expression of 37 transcripts (p< 0.001) (20 induced and 17 decreased) in the liver after MXC injection and a total of 900 expression changes (p< 0.05) in transcripts with high homology to known genes. Largemouth bass estrogen receptor alpha (esr1) and androgen receptor (ar) were among the transcripts that were increased in the liver after MXC treatment. Functional enrichment analysis identified the molecular functions of steroid binding and androgen receptor activity as well as steroid hormone receptor activity as being significantly over-represented gene ontology terms. Pathway analysis identified c-fos signaling as being putatively affected through both estrogen and androgen signaling. This study provides evidence that MXC elicits transcriptional effects through the estrogen receptor as well as androgen receptor-mediated pathways in the liver. © 2010 Elsevier B.V.
Minns C.K., Randall R.G., Smokorowski K.E., Clarke K.D., Vélez-Espino A., Gregory R.S., Courtenay S., LeBlanc P. (2011). Direct and indirect estimates of the productive capacity of fish habitat under Canada's Policy for the Management of Fish Habitat: Where have we been, where are we now, and where are we going? Canadian Journal of Fisheries and Aquatic Sciences, 68(12) 2204-2227.

No net loss of productive capacity (PC) of fish habitat has been the central concept guiding Canadian fish habitat management policy since 1986. The purpose of this paper is to describe the concept of PC, to review the history and application of the fish habitat management policy in Canada, and to provide a critical review of the range of potential approaches to estimating PC. The approaches were grouped by their central focus: habitat, individual, population, and community- ecosystem. A set of case studies is used to illustrate the use of some approaches drawn from freshwater and marine contexts. Ten components to assessing no net loss of PC were developed and used in the review of approaches for evaluating potential limitations. The review also highlighted the likely future direction of method development, with increasing emphasis on dynamic models integrating population responses to habitat supply characteristics. More work needs to be done to turn research- based metrics of PC into practical operational management assessment tools and to better quantify the link between habitat structure and function and fisheries productivity. The evolving approaches to measure PC reinforce the ties that fish habitat management has to the emerging practices in ecosystem-based management.
Monk W.A., Peters D.L., Allen Curry R., Baird D.J. (2011). Quantifying trends in indicator hydroecological variables for regime-based groups of Canadian rivers. Hydrological Processes, 25(19) 3086-3100.

As a key contribution to Canada's Ecosystem Status and Trends (ESTR) national assessment, the goal of our study was to utilize available flow data as a surrogate of habitat suitability for aquatic ecological communities, and examine temporal trends in hydroecological variables over the 1970-2005 period. Daily flow data were extracted from the Reference Hydrological Basin Network, and an agglomerative hierarchical classification method was used to identify homogenous regions with similar seasonality of the flow regime. Six regime regions were identified reflecting the timing of the annual peaks and low flows in addition to the patterns in the rising and falling limbs. For each of the gauging station sites, the magnitude, duration, timing, frequency, and rate of change of annual hydrological events were quantified through 32 ecologically important hydrological variables. Long-term patterns in the hydroecological variables were quantified using the nonparametric Mann-Kendall trend statistic. The results revealed more trends than would be expected to occur by chance for most variables. Clear regional trend patterns were observed within individual regime groups demonstrating the often differing response to environmental variability within the different regions. Results at the national scale were highly variable, but trends towards increased variability in river flows were observed with a predominant increasing trend in the number of flow reversals over the water year and decreasing trend in the annual low-flow indices. The identified river regime regions offer an initial framework for scientific investigation of hydroecological patterns and an opportunity to move towards a more predictive approach to environmental flows assessment in sustainable resource management and planning. © 2011 John Wiley & Sons, Ltd.
Mower B.F., Munkittrick K.R., McMaster M.E., Van Beneden R.J. (2011). Response of white sucker (Catostomus commersoni) to pulp and paper mill effluent in the Androscoggin River, Maine, USA. Environmental Toxicology and Chemistry, 30(1) 142-153.

Adverse effects of pulp and paper mill effluent on fish populations have been well documented in many countries over the last two decades. Some of the initial studies were at mills with conventional chlorine bleaching and no secondary effluent treatment. Following installation of secondary treatment, changes in bleaching technology to elemental chlorine-free bleaching, and other process changes, adverse effects on fish were reduced or eliminated at some mills. Because no two mills are exactly alike, it is difficult to predict adverse impacts of any given mill on fish populations. In 1994, a study of female white sucker (Catostomus commersoni) in the Androscoggin River, Maine, USA, showed induction of mixed function oxidase, reductions in gonad size and plasma estradiol, and an increase in plasma testosterone in fish downstream of discharges from three large bleached kraft pulp and paper mills, and host community municipal sewage treatment plants (STP). After all three mills switched to elemental chlorine-free bleaching in the late 1990s, studies from 2001 to 2003 found that the pattern of reproductive impacts on white sucker populations measured in 1994 was not repeated. In addition, population estimates of white sucker from 2002 to 2003 using mark-recapture techniques found that densities and biomass were well within the range of those of a reference population, and of those reported in the literature for unimpacted populations. Detailed studies immediately above and below each mill/sewage treatment plant showed no evidence of reproductive effects. However, a clear pattern of eutrophication was noted, which increased cumulatively downstream below each mill/STP. © 2010 SETAC.
Newbury R., Bates D., Alex K.L. (2011). Restoring habitat hydraulics with constructed riffles. Geophysical Monograph Series, 194 353-366.

Riffles and rapids may be added to channels for a variety of purposes, including increasing hydraulic complexity, stabilizing mobile bed streams, increasing aquatic habitat, or restoring fish passage. To increase hydraulic complexity, there are several options for introducing locally varied hydraulic conditions through the creation of riffles, rapids, runs, and pools. This involves increasing the frequency of transitions between several conditions of uniform, gradually varied and rapidly varied flow. To improve fish passage, riffles and rapids are normally designed as fish-passable hydraulic structures, often replacing traditional fixed drop structures or low dams in channelized streams. The provision of more diverse hydraulics and fish access may be a project objective, but the intricacies of specific aquatic habitat types are beyond commonly used one-dimensional open channel hydraulic equations. Consequently, reliance is placed on mimicking the hydraulics of preferred habitats surveyed in natural reference streams. The hydraulics observed in several preferred aquatic habitat types are broadly summarized, and a design method for riffles, runs, and pools with six project examples is presented. Copyright © 2011 by the American Geophysical Union.
Shaw J.L., Curry A.A. (2011). Ontogenetic divergence of growth among rainbow smelt morphotypes. Environmental Biology of Fishes, 92(2) 217-227.

Multiple, sympatric morphotypes of rainbow smelt (Osmerus mordax) are known in Lake Utopia, New Brunswick. The largest, 'giant' form is predominantly a piscivore, the smaller, 'dwarf' form are predominantly planktivores, and there is an intermediate body-sized form. The forms exhibit some genetic variability, but it is body size that best defines morphotypes, trophic status, and spawning behaviour. We compared egg size, spawning date, incubation time, size at hatching, and daily and annual growth to determine when divergence in body size occurs among morphotypes. Giant form larvae hatched earlier and grew faster during their first year. Dwarf and intermediate form larvae displayed inter-annual variability in degree of overlap and divergence in growth which occurred in their first growing season or at age 1+ or 2+. We conclude that earlier hatching, early growth trajectories, and later niche shifting are linked to the persistence of morphotypes, i. e., the process is controlled by the environment and sustained to some degree by spawning segregation. © 2011 Springer Science+Business Media B.V.
Smedley R.A., Curry R.A., Gray M.A. (2011). Testing the severity of ill effects model for predicting fish abundance and condition. North American Journal of Fisheries Management, 31(3) 419-426.

We tested the severity of ill effects (SEV) model as a predictor of the potential impacts of suspended sediment in small streams in an agricultural region of New Brunswick. Proposed by Newcombe and Jensen, the SEV uses the concentration of suspended sediment and the duration of exposure to predict the impacts on fish. In 2007, eight streams with brook trout Salvelinus fontinalis and slimy sculpin Cottus cognatus were usedtotest the SEV model. Total suspended solids measured from May to August were used to calculate the SEV index using two different methods. Our analyses indicated poor correlations between the SEV index and measures of fish densities and condition factor. A survey of an additional eight streams in the region over 2 years indicated that local habitat and landscape features and temperature were better predictors of fish density and species occurrence. These results demonstrate the complexity of interpreting stressor impacts and the challenges inherent in developing indices of stress for fish in natural streams. © American Fisheries Society 2011.
Smokorowski K.E., Bergeron N., Boisclair D., Clarke K., Cooke S., Cunjak R., Dawson J., Eaton B., Hicks F., Higgins P., Katopodis C., Lapointe M., Legendre P., Power M., Randall R., Rasmussen J., Rose G., Saint-Hilaire A., Sellars B., Swanson G., Winfield N., Wysocki R., Zhu D. (2011). NSERC's HydroNet: A National Research Network to Promote Sustainable Hydropower and Healthy Aquatic Ecosystems. Fisheries, 36(10) 480-488.

NSERC's HydroNet is a collaborative national fiveyear research program initiated in 2010 involving academic, government, and industry partners. The overarching goal of HydroNet is to improve the understanding of the effects of hydropower operations on aquatic ecosystems, and to provide scientifically defensible and transparent tools to improve the decision-making process associated with hydropower operations. Multiple projects are imbedded under three themes: 1) Ecosystemic analysis of productive capacity of fish habitats (PCFH) in rivers, 2) Mesoscale modelling of the productive capacity of fish habitats in lakes and reservoirs, and 3) Predicting the entrainment risk of fish in hydropower reservoirs relative to power generation operations by combining behavioral ecology and hydraulic engineering. The knowledge generated by HydroNet is essential to balance the competing demands for limited water resources and to ensure that hydropower is sustainable, maintains healthy aquatic ecosystems and a vibrant Canadian economy. © copyright 2011 Periodicals postage paid at Bethesda.
Sumith J.A., Munkittrick K.R. (2011). Study design considerations for assessing the health of fish populations impacted by agriculture in developing countries: A Sri Lankan case study. Journal of Environmental Monitoring, 13(8) 2105-2123.

Studies on the use of indigenous or endemic fish species for the assessment of agricultural impacts on fish populations are lacking in tropical South and Southeast Asia. This paper describes the steps involved in developing an agricultural impacts assessment program focused on river health, using recent studies on wild fish in Sri Lanka. The assessment methodology includes the selection of fish species for monitoring, and development of a strategy for sample timing, sample size requirements, and selection of appropriate reference site(s). Preliminary fish sampling data from several tributaries of the Uma-oya and the Amban-ganga (Knuckles streams) from the Mahaweli River basin were evaluated and temporal patterns of gonadal recruitment were investigated for three common species: Garra ceylonensis, Devario malabaricus, and Rasbora daniconius. The data on reproductive development were statistically incorporated to evaluate appropriate sample timing and sample size requirements. For this study, we proposed a cluster gradient design with a range of assessment endpoints and suitable statistical methods; an alternate assessment in different agricultural catchments would facilitate verification. The review and preliminary data support provide a template for study design considerations for agricultural impact assessments in South and SE Asian countries. © 2011 The Royal Society of Chemistry.
Sumith J.A., Munkittrick K.R., Athukorale N. (2011). Fish assemblage structure of two contrasting stream catchments of the Mahaweli River Basin in Sri Lanka: Hallmarks of human exploitation and implications for conservation. Open Conservation Biology Journal, 5(1) 25-44.

Patterns of fish community composition in the Mahaweli ichthyological region of Sri Lanka were examined in agricultural tributaries of the Uma-oya catchment of the upper Mahaweli River in comparison to more pristine streams in a nature reserve in the Amban-ganga catchment. The Uma-oya catchment shows characteristics commonly observed in extensive agricultural exploitation such as impaired water quality and altered riparian vegetation. The most abundant fish species in the two regions were Garra ceylonensis, Devario malabaricus, and Rasbora daniconius, although their relative abundance differed between sites. G. ceylonensis and Neomacheilus notostigma were the only endemic fish species in common but the latter has been extremely depauperate. Endemism is higher in the reference sites (62.5%) than agricultural sites (ca. 25%); some of the reference streams showed greater diversity with unique fish species and a few species that have not been recorded previously in the catchment. The ichthyofaunal similarity between two catchments was 39% and fish species diversity was negatively correlated with stream gradients (Pearson correlation (-0.630); r2 = 39.6% p = 0.028). Species density and biomass of G. ceylonensis and D. malabaricus were positively associated with some water quality parameters. The presence of exotic fish species were amongst the primary discriminants between human exploited and least-exploited (reference) streams. The possible negative impact of exotic Oreochromis niloticus (Nile tilapia) on indigenous G. ceylonensis is highlighted. This paper provides impetus for making several hypotheses for sustainability of stream fish assemblages in highly exploited agricultural catchments in Sri Lanka. © Sumith et al.
Swanson H., Gantner N., Kidd K.A., Muir D.C.G., Reist J.D. (2011). Comparison of mercury concentrations in landlocked, resident, and sea-run fish (Salvelinus spp.) from Nunavut, Canada. Environmental Toxicology and Chemistry, 30(6) 1459-1467.

Mercury concentrations ([Hg]) in Arctic food fish often exceed guidelines for human subsistence consumption. Previous research on two food fish species, Arctic char (Salvelinus alpinus) and lake trout (Salvelinus namaycush), indicates that anadromous fish have lower [Hg] than nonanadromous fish, but there have been no intraregional comparisons. Also, no comparisons of [Hg] among anadromous (sea-run), resident (marine access but do not migrate), and landlocked (no marine access) life history types of Arctic char and lake trout have been published. Using intraregional data from 10 lakes in the West Kitikmeot area of Nunavut, Canada, we found that [Hg] varied significantly among species and life history types. Differences among species-life history types were best explained by age-at-size and C:N ratios (indicator of lipid); [Hg] was significantly and negatively related to both. At a standardized fork length of 500mm, lake trout had significantly higher [Hg] (mean 0.17μg/g wet wt) than Arctic char (0.09μg/g). Anadromous and resident Arctic char had significantly lower [Hg] (each 0.04μg/g) than landlocked Arctic char (0.19μg/g). Anadromous lake trout had significantly lower [Hg] (0.12μg/g) than resident lake trout (0.18μg/g), but no significant difference in [Hg] was seen between landlocked lake trout (0.21μg/g) and other life history types. Our results are relevant to human health assessments and consumption guidance and will inform models of Hg accumulation in Arctic fish. © 2011 SETAC.
Swanson H.K., Kidd K.A., Reist J.D. (2011). Quantifying importance of marine prey in the diets of two partially anadromous fishes. Canadian Journal of Fisheries and Aquatic Sciences, 68(11) 2020-2028.

The importance of marine prey sources for partially anadromous fishes has received little study and is complicated by considerable plasticity in life history. We determined proportional contributions of marine, freshwater benthic, and freshwater pelagic prey to anadromous and resident Arctic char (Salvelinus alpinus) and lake trout (Salvelinus namaycush) from several partially anadromous populations in the Canadian Arctic. Bayesian mixing models (MixSIR) applied to d34S and d13C ratios in lake-specific models indicated that marine prey accounted for 90%-91% of anadromous Arctic char diet and 60%-66% of anadromous lake trout diet. When these estimates were combined with proportion of anadromous individuals in partially anadromous populations, marine food sources accounted for 31%-44% of Arctic char population productivity and 16%-26% of lake trout population productivity. Although future research is needed to refine and quantify variability around these estimates, our results will allow better predictions of the effects of anthropogenic stressors on partially anadromous fishes.
Titley-O'Neal C.P., Munkittrick K.R., MacDonald B.A. (2011). The effects of organotin on female gastropods. Journal of Environmental Monitoring, 13(9) 2360-2388.

Female masculinisation (FM) in gastropods (imposex, intersex and ovo-testis) has been documented in > 260 species globally. Biomonitoring studies use FM to indirectly assess the presence of tributyltin (TBT), a once popular biocide in antifouling paint, which has since been regulated. Laboratory studies confirm that FM in gastropods can be induced not only by TBT, but other tin (Sn) compounds, Sn "cocktails", steroids, and other contaminants such as Aroclor 1260. Even though FM in gastropods in the field has been attributed to TBT from boating activity, there is evidence that imposex occurred prior to the advent use of TBT in the 1960s, and for some species imposex occurs naturally. There are roughly 42 species that do not elicit a FM response even if they are exposed to TBT under laboratory conditions, collected sympatrically with other species displaying FM, and/or have TBT in their tissues. A geographic analysis of field studies in four regions indicates that the bulk of studies were conducted in Europe > Asia and Oceania > North America > Latin America. More data are needed regarding FM in Africa, the Middle East, and Latin America since data regarding the masculinisation of female gastropods in these areas are lacking. The most studied gastropod species used in TBT biomonitoring studies is the dogwhelk, Nucella lapillus. This review summarizes the progression of the literature from 1962 to 2009 outlining how the terminology, science, and theories have evolved over time. © 2011 The Royal Society of Chemistry.
Van den Brink P.J., Alexander A.C., Desrosiers M., Goedkoop W., Goethals P.L.M., Liess M., Dyer S.D. (2011). Traits-based approaches in bioassessment and ecological risk assessment: Strengths, weaknesses, opportunities and threats. Integrated Environmental Assessment and Management, 7(2) 198-208.

We discuss the application of traits-based bioassessment approaches in retrospective bioassessment as well as in prospective ecological risk assessments in regulatory frameworks. Both approaches address the interaction between species and stressors and their consequences at different levels of biological organization, but the fact that a specific species may be less abundant in a potentially impacted site compared with a reference site is, regrettably, insufficient to provide diagnostic information. Species traits may, however, overcome the problems associated with taxonomy-based bioassessment. Trait-based approaches could provide signals regarding what environmental factors may be responsible for the impairment and, thereby, provide causal insight into the interaction between species and stressors. For development of traits-based (TBA), traits should correspond to specific types of stressors or suites of stressors. In this paper, a strengths, weaknesses, opportunities, and threats (SWOT) analysis of TBA in both applications was used to identify challenges and potentials. This paper is part of a series describing the output of the TERA (Traits-based ecological risk assessment: Realising the potential of ecoinformatics approaches in ecotoxicology) Workshop held between 7 and 11 September, 2009, in Burlington, Ontario, Canada. The recognized strengths were that traits are transferrable across geographies, add mechanistic and diagnostic knowledge, require no new sampling methodology, have an old tradition, and can supplement taxonomic analysis.Weaknesses include autocorrelation, redundancy, and inability to protect biodiversity directly. Automated image analysis, combined with genetic and biotechnology tools and improved data analysis to solve autocorrelation problems were identified as opportunities, whereas low availability of trait data, their transferability, their quantitative interpretation, the risk of developing nonrelevant traits, low quality of historic databases, and their standardization were listed as threats. © 2011 SETAC.
Van den Brink P.J., Rubach M.N., Culp J.M., Pascoe T., Maund S.J., Baird D.J. (2011). Traits-based ecological risk assessment (TERA): Realizing the potential of ecoinformatics approaches in ecotoxicology. Integrated Environmental Assessment and Management, 7(2) 169-171.
Barrett T.J., Lowell R.B., Tingley M.A., Munkittrick K.R. (2010). Effects of pulp and paper mill effluent on fish: A temporal assessment of fish health across sampling cycles. Environmental Toxicology and Chemistry, 29(2) 440-452.

The Canadian environmental effects monitoring (EEM) program is a regulated, cyclical, industry-funded program designed to determine whether receiving water impacts exist when a mill is in compliance with its discharge limits. The results from three cycles of the fish monitoring program (1992 to 2004) are available from over 200 surveys of fish compared between sites located upstream and downstream of pulp and paper mill effluent outfalls. Previous meta-analyses have shown a national average response pattern across cycles characterized by an increase in endpoints measuring energy storage and growth and a decrease in a reproductive endpoint, consistent with a response of nutrient enrichment in combination with some form of metabolic disruption. Although the national average pattern of effects was temporally consistent, there was some variability in the magnitude of effects among cycles. Questions were raised as to whether the intercycle variability was due to changes in effluent quality or due, at least in part, to other factors. The present study compares responses over the first three cycles, and shows that the choice of sentinel species is likely to be a major contributing factor to the variability in observed effects. Subset analyses using studies from mills that used the same sentinel species across cycles reveal fairly uniform responses and little evidence of significant improvements in overall fish health from cycles one to three. However, a metaanalysis using 1991 data collected from 10 mills before the implementation of the EEM program and data from the same mills collected during cycles one to three of the program reveal significantly reduced effects on relative liver weight and potential improvements in other endpoints. © 2009 SETAC.
Barrett T.J., Tingley M.A., Munkittrick K.R., Lowell R.B. (2010). Dealing with heterogeneous regression slopes in analysis of covariance: New methodology applied to environmental effects monitoring fish survey data. Environmental Monitoring and Assessment, 166(1-4) 279-291.

Analysis of covariance (ANCOVA) is a powerful statistical method which incorporates one or more covariates into the analysis to reduce error associated with measurement. ANCOVA (modeling response as a function of fish size) is frequently used to analyze environmental effects monitoring (EEM) fish survey data. In approximately 12% of fish survey data sets taken from cycles 1 to 3 of Environment Canada's EEM database for pulp and paper mills, the standard assumption of parallel regression slopes is not met. For the first three cycles of the EEM program, these data sets were classified as indicating a mill effect, but for the most part were excluded from subsequent analyses aimed at quantifying the effect. We present two different methods for initially dealing with data sets that exhibit heterogeneous slopes so that they can be analyzed using the parallel slope model. The first method identifies data sets where heterogeneous slopes are forced by a few high-influence observations. The second approach identifies data sets where a model with heterogeneous slopes is statistically, but not practically, significant: with a high coefficient of determination for the parallel slope model. These new methodologies are applied to EEM pulp and paper data sets and about 55% of cases with heterogeneous slopes can be described by a parallel slope model. We also discuss a third method that can be used to describe mill effects when regression slopes remain heterogeneous even after applying the above two methods, enabling comparison with a critical effect size. These new methodologies could benefit the EEM program by enabling more data sets to be incorporated into meta-analyses and be used to make more equitable mill monitoring decisions in the future. © 2009 Springer Science+Business Media B.V.
Blanar C.A., MacLatchy D.L., Kieffer J.D., Munkittrick K.R. (2010). Exposure to a mixture of zinc and copper decreases survival and fecundity of discocotyle sagittata (Leuckart) Parasitizing juvenile atlantic Salmon, Salmo salar L. Bulletin of Environmental Contamination and Toxicology, 84(6) 692-697.

We assessed the effects of zinc and copper on freshwater monogenean ectoparasites (Discocotyle sagittata Leuckart) infecting juvenile Atlantic salmon (Salmo salar L.). Exposure to 47 μg/L zinc and 3 μg/L copper reduced survival and fecundity of adult D. sagittata, while egg hatching success was only reduced at high exposure concentrations (2704 μg/L zinc and 164 μg/L copper). Parasitized salmon had decreased plasma chloride, but this was negated in infected fish exposed to metals. No other effects on Atlantic salmon survival and physiology (plasma osmolality, hematocrit) were noted, suggesting that D. sagittata may be more susceptible to metal toxicity than its host fish. © 2010 Springer Science+Business Media, LLC.
Bosker T., Mark Hewitt L., Doyle M.A., Maclatchy D.L. (2010). Effects of neutral sulfite semichemical pulp mill effluent in the mummichog (Fundulus heteroclitus) adult fish reproductive test. Water Quality Research Journal of Canada, 45(2) 201-208.

Short-term adult fish reproductive tests using freshwater species have demonstrated negative impacts on egg production in fish exposed to complex pulp and paper mill effluents. In an effort to address the ability of laboratory tests to predict effects on wild fish, mummichog (Fundulus heteroclitus) were exposed in saltwater conditions for 21 days to 3 and 30% final effluent of a neutral sulfite semi-chemical pulp mill that discharges into an estuarine environment in eastern Canada. Although no effects on gonad size, liver size, or condition factor were found, egg production was significantly increased by 31% and decreased by 30% when fish were exposed to 3 and 30% final effluent, respectively. This study i) is the first to demonstrate a decrease in egg production when fish are exposed to complex effluents under estuarine conditions and ii) provides the first linkage of effects on gonad size in wild fish to egg production from laboratory testing in the same species. I n so doing, this study also demonstrates the utility of egg production measurements to further investigate the causes and solutions to the effects of mill effluents in both freshwater and marine wild fish. © 2010, CAWQ.
Bosker T., Mark Hewitt L., Munkittrick K.R., MacLatchy D.L. (2010). Validation of a refined short-term adult fish reproductive test with improved power for mummichog (Fundulus heteroclitus) to test complex effluents. Ecotoxicology and Environmental Safety, 73(7) 1596-1601.

Short-term adult fish reproductive tests are widely used to assess the toxicity of chemicals and waste streams. However, these tests often have low power to detect differences in egg production among treatments, due to high variance and small sample sizes, limiting their effectiveness for informing regulatory decisions. A protocol for a fish reproductive test using mummichog (Fundulus heteroclitus) was refined to increase statistical power. Three studies using the original protocol were compared with three studies using the refined protocol. Tank pre-selection and sample size increased the a priori power from 11.2% to 85.7%. After exposure, average power levels were 62.0%, a more than five-fold increase compared to studies that used the original protocol (power of 15.0%). There was a high level of consistency compared to the original protocol; differences >33% in female and male gonad size and egg production could be detected among treatments. This study demonstrates that a refinement process can address shortcomings in short-term adult fish reproductive protocols, creating a solid foundation for further standardization and possible regulatory use. © 2010 Elsevier Inc.
Bosker T., Munkittrick K.R., MacLatchy D.L. (2010). Challenges and opportunities with the use of biomarkers to predict reproductive impairment in fishes exposed to endocrine disrupting substances. Aquatic Toxicology, 100(1) 9-16.

Biomarkers are commonly used as signposts to evaluate the potential of contaminants to disrupt the endocrine system. However, the relationship between responses in these biomarkers and whole organism endpoints that directly affect population status is not clearly understood. In this study, the relationship between egg production (a whole-organism endpoint which has been directly linked to population-level responses) and biomarkers (sex steroids, vitellogenin (VTG) and gonad size) is examined. Data were collected from short-term reproductive tests in which a wide variety of fish species were exposed to a suite of contaminants with known or unknown modes/mechanisms of action (MOA). The potential to use biomarkers as signposts was evaluated by determining the occurrence of false negatives (i.e., an effect in egg production was not accompanied by a biomarker response) and false positives (i.e., an effect in biomarkers was not followed by an effect in egg production). The quantitative relationships between biomarkers and egg production, and the ability to use these quantitative relationships to predict population-level responses based on modeling was also assessed. A suite of female biomarkers resulted in a relatively low occurrence of both false positives and negatives, indicating the potential for their use as signposts for reproductive effects via endocrine disruption. Egg production in short-term adult fish reproductive tests showed significant relationships to 17β-estradiol (E<inf>2</inf>), changes in female VTG levels, and relative female gonad size (gonadosomatic index; GSI). Weaker significant relationships were found between egg production and both VTG levels and GSI in males. However, use of these quantitative relationships to predict population-level effects are cautioned because of high levels of uncertainty. This study demonstrates that there are qualitative and quantitative relationships among biomarkers, regardless of fish species used or the MOA of contaminants and concludes that a suite of female reproductive biomarkers can be used as effective signposts to screen chemicals and assess waste streams for endocrine disrupting substances with different MOA. © 2010 Elsevier B.V.
Chiang G., Munkittrick K.R., Orrego R., Barra R. (2010). Monitoring of the environmental effects of pulp mill discharges in chilean rivers: Lessons learned and challenges. Water Quality Research Journal of Canada, 45(2) 111-122.

Environmental monitoring activities in Chile are relatively new and have traditionally relied on physicochemical measurements. The pulp mill industry in Chile is highly competitive in the global market and several new large mills have recently opened. Early studies on fish in the receiving environments revealed lower species richness and an increase in the abundance of introduced species relative to native ones near pulp mill discharges. Even though changes were observed, their relationship with the discharges was unclear. Several diffi culties related to small body sizes and the unavailability of basic biological data for native Chilean fish species were found during initial field studies. One of the main challenges is the standardization of monitoring methods (including fish species selection, sampling sizes, indicators, reference sites, etc.) and consensus about the responses that should be considered in a river monitoring program in the Chilean context. This paper summarizes major findings from a series of studies looking at impacts on fish at different levels of biological organization and the current approach used in Chile for monitoring impacts of pulp mill effluents on wild fish populations. © 2010, CAWQ.
Clément M., Cunjak R.A. (2010). Physical injuries in juvenile Atlantic salmon, slimy sculpin, and blacknose dace attributable to electrofishing. North American Journal of Fisheries Management, 30(3) 840-850.

Juvenile Atlantic salmon Salmo salar captured by electrofishing were X-rayed and dissected to determine rates of electrofishing-induced spinal injuries and hemorrhages. This study showed a low incidence of spinal injuries (11%) in electrofished wild parr captured alive and thereafter sacrificed. A negligible hemorrhage rate (2%) was observed. All of the spinal injuries observed were rated class 1 (minor injury), except for a class 2 injury in one parr. Larger, older wild parr (≥ age 2) showed a higher incidence of spinal injuries (17%) than age-1 parr (4%). Parr captured with two or more electrofishing sweeps had a spinal injury rate of 20%, compared with 6% when captured with a single electrofishing sweep. Among the mortalities, 8% of the parr had spinal injuries (class 1 except for one class 3) and 5% had hemorrhages. Spinal injury was observed in 6% of the mortalities of slimy sculpin Cottus cognatus and blacknose dace Rhinichthys atratulus; no hemorrhages were observed in these fish. This study showed that electrofishing produced a low incidence of injuries in juvenile Atlantic salmon, slimy sculpin, and blacknose dace. Nonetheless, caution is advised when conducting electrofishing surveys because sublethal effects other than physical injuries remain largely unknown. © American Fisheries Society 2010.
Curry A.A., Bernatchez L., Whoriskey F., Audet C. (2010). The origins and persistence of anadromy in brook charr. Reviews in Fish Biology and Fisheries, 20(4) 557-570.

We synthesized the results of a coordinated study examining the spatial and temporal movements, genetic structure, and physiological characteristics of sympatric populations of resident and sea-run brook charr across eastern Canada. Our goal was to critically evaluate three working hypotheses that may explain anadromous behaviour in brook charr: (1) resident and anadromous forms have different phylogenic origins; (2) anadromy emerges from freshwater residents; and (3) freshwater residency emerges from anadromous individuals. Our synthesis is consistent with the conclusion that freshwater residency emerging from anadromous individuals is most probable. Overall, anadromy in brook charr is poorly developed and the tactic of sea-running may be described as partial, facultative anadromy if the species must be described in terms of anadromy. The sea-run tactic most probably results from the species' propensity to move and disperse, the over-production of juveniles, an archetypical physiological ability to tolerate saline environments, and the persistence of critical habitats. When the spatial and temporal physical environments permit, the anadromous behaviour is expressed. The tactic creates an apparent fitness advantages related to growth, but it is not necessarily the only evolutionary stable strategy for a river. Most populations with sea-run forms are declining and successful conservation of sea-run forms will depend on managing harvests and more importantly, protection of the temporally and spatially complexity of critical habitats. © 2010 Springer Science+Business Media B.V.
Daigle A., St-Hilaire A., Peters D., Baird D. (2010). Multivariate modelling of water temperature in the okanagan watershed. Canadian Water Resources Journal, 35(3) 237-258.

Initiatives for the protection of river ecosystems must include the monitoring of key flow and water quality variables, as well as clear and quantifiable management goals. One variable which strongly influences water quality is water temperature, and its modification arising from human activity should be incorporated into ecosystem protection guidelines. This work, conducted as part of the Canadian National Agri-Environmental Standards Initiative (NAESI) program, presents a preliminary study investigating statistical regression methods and a geostatistical approach to model key water temperature characteristics that could assist in the development of standards. Water temperature time series recorded at 16 sites in the Okanagan watershed were used to develop the models. Monthly maxima were modelled for the period of April-September 2007 using four predictors: the site longitude, the drainage basin maximum altitude, the local slope at the station, and the log of the mean substrate diameter. Four types of multivariate regressions of monthly maxima were produced, and a leave-one-out resampling approach was used to validate the models. Relative Bias, Root Mean Square Errors (RMSE) and a corrected Akaike Information Criterion (AICc) were calculated for each month. Models gave RMSE values between 0.9°C and 2.1°C for the monthly maxima. All models generally performed best between May and July. Geostatistical interpolation of maxima was also performed in a multivariate physiographic space reduced to two orthogonal dimensions using canonical correlation analysis (CCA). Examples of interpolated maps show that the approach can be used to discriminate between warm and cool streams. © 2010 Canadian Water Resources Association.
Doherty C.A., Curry R.A., Munkittrick K.R. (2010). Spatial and temporal movements of white sucker: Implications for use as a sentinel species. Transactions of the American Fisheries Society, 139(6) 1818-1827.

White suckers Catostomus commersonii are widely distributed in rivers of North America and often used in environmental monitoring. The species' value as a sentinel has been questioned because some populations are known to travel long distances during spawning migrations and therefore can be exposed to multiple environments. The movements of white suckers in a 65-km reach of the Saint John River, New Brunswick, were studied from 2001 to 2003 using radio and acoustic tracking and analyses of stable isotope ratios. Individuals maintained small home ranges in the river from summer to late winter, averaging 2.6 river kilometers [rkm] or less each year. During the spring spawning season, upstream and downstream movements to three tributaries occurred. Distances traveled were up to 40 rkm and averaged 9.2 rkm (SD = 11.0). Two males used separate tributaries within a spawning period, and there was evidence that spawning may not take place every year. Stable isotope results confirmed that white suckers maintained a high fidelity to well-defined reaches in the main river outside the spawning period. These results indicate the importance of distinct, limited habitats and connectivity of habitats for white suckers in large rivers and support the hypothesis that white suckers reflect localized environmental conditions and can be used as a sentinel. © by the American Fisheries Society 2010.
Graham B.S., Koch P.L., Newsome S.D., McMahon K.W., Aurioles D. (2010). Using isoscapes to trace the movements and foraging behavior of top predators in oceanic ecosystems. Isoscapes Understanding Movement Pattern and Process on Earth Through Isotope Mapping 299-318.

The stable isotope composition of animal tissues can provide intrinsic tags to study the foraging and migratory ecology of predators in the open ocean. Chapter 13 (this volume) demonstrated that by comparing the isotope values of an animal and its local prey or environment, the animal's movements can be estimated, given that isotopic variation exists between habitats. The utility of using geographical variations in stable isotopes values, or isoscapes to study the movements of marine predators has been limited because of our lack of knowledge on the spatial variation of the carbon, nitrogen, and oxygen isotope values in the open ocean. In this chapter, we review the spatial patterns in the carbon and nitrogen values of primary producers in the oceans and broadly discuss mechanisms that set the isotopic composition at the base of marine food webs. We then discuss how spatial patterns in baseline and predator isotope values can be used to examine the movements and foraging behavior in two groups of marine predators, pinnepids and tropical tuna. These two case studies demonstrate that ocean isoscapes are a promising tool to investigate population-level movements and foraging behavior of elusive predators, but this method has limitations and will not achieve the fine-spatial resolution obtained with electronic tags and instrumentation. Furthermore, the construction and application of ocean isoscapes is still in its early development and requires knowledge about the physiology and behavior of the predator, an understanding of the temporal and spatial stability of the isotopic baseline, and validation with independent datasets. © 2010 Springer Science+Business Media B.V.
Hogan N.S., Currie S., LeBlanc S., Hewitt L.M., MacLatchy D.L. (2010). Modulation of steroidogenesis and estrogen signalling in the estuarine killifish (Fundulus heteroclitus) exposed to ethinylestradiol. Aquatic Toxicology, 98(2) 148-156.

Previous studies have shown that mummichog (. Fundulus heteroclitus; a lunar, asynchronous-spawning killifish of the western Atlantic) exposed to 17α-ethynylestradiol (EE2) exhibit decreased plasma reproductive steroid levels, decreased gonadal steroid production, increased plasma vitellogenin, decreased fecundity and impaired fertilization. The objective of this study was to determine the potential mechanisms by which EE2 depresses gonadal steroidogenesis and influences estrogen signalling in the mummichog. Adult recrudesced fish were exposed to the potent synthetic estrogen, ethinylestradiol (EE2; 0-270. ng/L) for 14 days. Following exposure, gonadal tissue was removed and incubated for 24. h with stimulators of steroidogenesis, including forskolin; 25-OH cholesterol; or pregnenolone. Testosterone production was decreased in basal, forskolin-stimulated and pregnenolone-stimulated EE2-exposed males, indicating effects on the steroidogenic pathway both at and downstream of cholesterol mobilization to P450 side-chain cleavage (P450scc) and/or P450scc conversion of cholesterol to pregnenolone. Hepatic transcript levels of estrogen receptor alpha (ERα) and vitellogenin were increased in EE2-treated males compared to control recrudescing males and females confirming an estrogenic response. Hepatic heat shock protein 90 (Hsp90), a chaperoning molecule involved in estrogen signalling, was not affected by EE2 exposure at either the transcript or protein level. However, higher levels of Hsp90 observed in the membrane fractions of female fish raise interesting questions regarding the influence of gender on Hsp90's role in estrogen signalling. These results demonstrate that EE2 can alter steroid production at specific sites within the steroidogenic pathway and can stimulate hepatic estrogen signalling, providing important information regarding the molecular mechanisms underlying the endocrine response of the mummichog to exogenous estrogen. © 2010 Elsevier B.V.
Hogan N.S., Lee K.S., Köllner B., van den Heuvel M.R. (2010). The effects of the alkyl polycyclic aromatic hydrocarbon retene on rainbow trout (Oncorhynchus mykiss) immune response. Aquatic Toxicology, 100(3) 246-254.

The objective of this study was to examine the immune toxicity of the alkyl polycyclic aromatic hydrocarbon (PAH) retene (7-isopropyl-1-methyl phenanthrene) in rainbow trout. Retene is a common alkyl PAH associated with combustion of terrestrial plants or industrial effluents. Rainbow trout were injected intraperitoneally with a single dose of 0, 1, or 10. mg/kg of retene and sampled at 21. d. Within each retene treatment, co-injection of formalin-killed Aeromonas salmonicida or a phosphate buffered saline sham was used to stimulate the trout immune system. At the highest retene dose (10. mg/kg) there was an increase in total blood leukocyte counts but only in the A. salmonicida-injected group. This result was paralleled by an increase in leukocytes in differential blood cell counts. There was an overall increase in A. salmonicida-specific antibody titre due to the antigen injection and there was also a significant stimulation of antibody production response at the 10. mg/kg retene dose. At the tissue level, immunohistochemistry revealed a greater density of B-lymphocytes at the highest retene dose in spleen and head kidney. A number of immune specific transcripts including the Th2 marker CD4, TCR, MHCII TNFα, and the Th1 marker CD8, INFγ were examined by quantitative RT-PCR in spleen and head kidney. There was no influence of the A. salmonicida antigen on the expression of Th1 related genes in either tissue but increased production of Th2 related CD4 co-receptor transcripts was observed in spleen at both retene concentrations. Retene appeared to be mildly immunostimulatory, either on its own, or in combination with an inactivated A. salmonicida immune challenge and these data suggest that exposures of fishes to retene may not pose significant risk of eliciting immunotoxic effects. © 2010 Elsevier B.V.
Imre I., Grant J.W.A., Cunjak R.A. (2010). Density-dependent growth of young-of-the-year Atlantic salmon (Salmo salar) revisited. Ecology of Freshwater Fish, 19(1) 1-6.

The length of individual young-of-the-year (YOY) Atlantic salmon (Salmo salar) in Catamaran Brook decreases with increasing population density following a negative power curve. Because most of this decrease in growth rate occurs at low densities (<1 fish·m-2), (Imre et al. 2005; Journal of Animal Ecology, 74: 508-516) suggested that exploitation competition for drifting prey rather than space limitation might be responsible for this pattern. Recently, (Ward et al. 2007; Journal of Animal Ecology, 76: 135-138) showed that the negative power curve of growth rate versus density can be caused by other mechanisms and suggested that Imre et al.'s evidence for density-dependent growth would have been stronger if we had analysed final size versus initial density rather than final density. We examined (i) whether the negative power curve of size versus density was also apparent in an analysis of final size versus initial density and tested two predictions that emerge from Ward et al.'s model, (ii) the variance in body size increases with population density, and (iii) the maximum fish size at a site is density-independent. The final size of YOY salmon decreased with increasing initial density following a negative power curve. Our data did not provide strong support for the above predictions emerging from Ward et al.'s model. Our analyses of different years, sites and seasons were consistent with the hypothesis of density-dependent growth of YOY salmon. © 2009 John Wiley & Sons A/S.
Karami A., Christianus A., Ishak Z., Courtenay S.C., Syed M.A., Azlina M.N., Noorshinah H. (2010). Effect of triploidization on juvenile African catfish (Clarias gariepinus). Aquaculture International, 18(5) 851-858.

Triploid African catfish (Clarias gariepinus) produced through cold shock 3 min post fertilization were compared to diploid offspring of the same parentage at 66 days of age. Triploid fish were significantly shorter (11%) and weighed less (18%) than diploids but showed no significant difference in mortality or cannibalism, which can be an important source of losses under aquaculture conditions. Erythrocytes of triploid fish were more oval shaped than the normal spherical shape of diploid erythrocytes, were significantly larger (38%) and had nuclei that were significantly larger (25%) than observed in diploid fish. Erythrocyte morphological characteristics show potential as an indicator for the detection of triploidy in African catfish. © 2009 Springer Science+Business Media B.V.
Kieffer J.D. (2010). Perspective - Exercise in fish: 50+ years and going strong. Comparative Biochemistry and Physiology A Molecular and Integrative Physiology, 156(2) 163-168.

Swimming in fish has garnered the attention of researchers for more than 50 years. Research has focused on the mechanisms that fish utilize during exercise, fuel use patterns, recovery dynamics and the effects of abiotic and biotic factors on fish exercise physiology. Research direction has been influenced both by technology (e.g., availability of telemetry devices and access to swim flumes) and environmental changes (e.g., global warming and pollution). In addition, researchers have begun to examine the interplay between swimming physiology and behaviour. As part of the 50th Anniversary of Comparative Physiology and Biochemistry, this perspective examines the history of fish exercise research, and some of the individuals who have made significant contributions. © 2010 Elsevier Inc. All rights reserved.
Landman M.J., Bleackley N.A., Ling N., ven derHeuvel M.R. (2010). Physiological health of common bully (Gobiomorphus cotidianus) in the Tarawera and Rangitaiki Rivers of New Zealand: Evidence of diminished ecological effects of pulp and paper effluents in wild fish populations. Water Quality Research Journal of Canada, 45(2) 223-233.

This study examined the comparative physiological health of the endemic New Zealand common bully (Gobiomorphus cotidianus) in the Tarawera and Rangitaiki Rivers. Bully were sampled downstream of pulp and paper effluent inputs in the Tarawera River and compared with a similar inland population in the Rangitaiki River. Condition factor and liver somatic index did not differ between populations, but Tarawera River bullies possessed larger gonads. Haematological assessments found smaller erythrocytes with reduced haemoglobin content, and increased leukocyte concentrations in Tarawera River females. Male and female Tarawera River bullies had significantly induced hepatic ethoxyresorufin-O-deethylase (EROD) activity.Greater ovarian follicular steroid production was also found for Tarawera River females. Microscopic analysis of ovariantissue samples found no histopathological abnormalities in either population and indicated a slightly advanced vitellogenic stage of development in the Tarawera River population. It is concluded that the difference in steroid production between populations was most likely linked to gonad size and developmental status. In line with the disappearance of physiological effects in recent controlled laboratory and mesocosm pulp and paper effluent exposures, this study further demonstrates that, with the exception of EROD induction, characteristic pulp and paper effluent effects are not obvious in wild Tarawera fish. © 2010, CAWQ.
Linnansaari T., Cunjak R.A. (2010). Patterns in apparent survival of Atlantic salmon (Salmo salar) parr in relation to variable ice conditions throughout winter. Canadian Journal of Fisheries and Aquatic Sciences, 67(11) 1744-1754.

Apparent within-site survival of Atlantic salmon (Salmo salar) parr, individually tagged with passive integrated transponders, was not constant throughout the winter period in a 3-year study (2003-2006) in Catamaran Brook, New Brunswick, Canada. Highest decline in apparent survival (19.4%-33.3% of the study population) occurred prior to any ice formation and coincided with early winter acclimatization period (dynamic temperature and discharge regime). Stream discharge and parr maturity were identified to be relevant factors explaining emigration prior to ice formation. Apparent survival was improved during the period affected by subsurface ice and considerably better when surface ice was prevailing, with a decline in population size between 0% and 15.4%. Overall, observed within-site winter mortality was low (4.4%), and the majority of the loss of tagged salmon parr occurred because of emigration. On average, the within-site population of tagged salmon parr declined by 31.7% over the whole winter (November-April). Our data suggest that anthropogenic impacts, like climate change or river regulation, are likely to affect the apparent survival rate and distribution of juvenile Atlantic salmon because of their effects on natural ice regime in streams.
Maclatchy D.L., Milestone C., Shaughnessy K.S., Belknap A.M., Dubé M.G., Mark Hewitt L. (2010). Reproductive steroid responses in fish exposed to pulp mill condensates: An investigation of cause case study. Water Quality Research Journal of Canada, 45(2) 163-173.

An investigation of cause (IOC) approach integrating artificial stream exposures and laboratory bioassays has been used to identify waste stream sources of contaminants at the Irving Pulp & Paper Ltd. mill, in Saint John, New Brunswick, Canada. Chemical recovery condensates have shown the greatest potential for reducing circulating steroids in mummichog (Fundulus heteroclitus), an endemic fish species. A solid phase extraction (SPE) technique was developed to isolate hormonally active substances from the condensates, and a toxicity identification evaluation approach was used to gain a better understanding of the chemical characteristics of the active substances. Extracts were fractionated by high performance liquid chromatography (HPLC) and the fractions were used in a seven-day bioassay. Dose-response experiments indicated that steroid reductions in male mummichog were observed consistently after a 4% (vol/vol) exposure. At 4% (vol/vol), however, steroid reductions were not observed in fractions of the active SPE extract generated by HPLC. Some fractions actually induced increases in plasma testosterone. Recent work has focused on understanding what methodologies must be used to handle the semivolatile condensates to ensure 100% chemical recovery and retention of biological activity. Results are sum marized in the context of developing an industry-wide IOC framework. © 2010, CAWQ.
Martyniuk C.J., Kroll K.J., Doperalski N.J., Barber D.S., Denslow N.D. (2010). Genomic and proteomic responses to environmentally relevant exposures to dieldrin: Indicators of neurodegeneration? Toxicological Sciences, 117(1) 190-199.

Dieldrin is a persistent organochlorine pesticide that induces neurotoxicity in the vertebrate central nervous system and impairs reproductive processes in fish. This study examined the molecular events produced by subchronic dietary exposures to 2.95 mg dieldrin/kg feed in the neuroendocrine brain of largemouth bass, an apex predator. Microarrays, proteomics, and pathway analysis were performed to identify genes, proteins, and cell processes altered in the male hypothalamus. Fifty-four genes were induced, and 220 genes were reduced in steady-state levels (p < 0.001; fold change greater than ± 1.5). Functional enrichment analysis revealed that the biological gene ontology categories of stress response, nucleotide base excision repair, response to toxin, and metabolic processes were significantly impacted by dieldrin. Using isobaric tagging for relative and absolute quantitation, 90 proteins in the male hypothalamus were statistically evaluated for changes in protein abundance. Several proteins altered by dieldrin are known to be associated with human neurodegenerative diseases, including apolipoprotein E, microtubule-associated tau protein, enolase 1, stathmin 1a, myelin basic protein, and parvalbumin. Proteins altered by dieldrin were involved in oxidative phosphorylation, differentiation, proliferation, and cell survival. This study demonstrates that a subchronic exposure to dieldrin alters the abundance of messenger RNAs and proteins in the hypothalamus that are associated with cell metabolism, cell stability and integrity, stress, and DNA repair. © The Author 2010. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved.
McMullin V.A., Munkittrick K.R., Methven D.A. (2010). Spatial Variability of Reproductive and Size Characteristics of the Northern Mummichog (Fundulus heteroclitus macrolepidotus) Collected Near Municipal Wastewater Discharges. Water Quality Research Journal of Canada, 45(1) 25-34.

Northern mummichog (Fundulus heteroclitus macrolepidotus) have been widely considered to be suitable for environmental effects monitoring despite concerns of spatial variability observed in energy reserves and reproductive indices. In this study, temporal and spatial variability in gonadosomatic index (GSI), liversomatic index (LSI), and condition factor (K) were examined across two sites in 2006 and 10 sites (four sites exposed to wastewater discharge; six reference sites) in 2007. In 2006 GSI, LSI, and K appeared highly variable and significantly different for both males and females. In 2007, female K and gonad weight were significantly different among all sites. For males, significant differences in K and liver weight were observed among sites. Extensive spatial variation in GSI, LSI, and K observed between reference sites suggests current standardized Canadian Environmental Effects Monitoring (EEM) methods, including effect size and duration of sampling, should not be adopted for use with the northern mummichog F. h. macrolepidotus. © 2010, CAWQ.
Menezes S., Baird D.J., Soares A.M.V.M. (2010). Beyond taxonomy: A review of macroinvertebrate trait-based community descriptors as tools for freshwater biomonitoring. Journal of Applied Ecology, 47(4) 711-719.

Species traits have been frequently used in ecological studies in an attempt to develop a general ecological framework linking biological communities to habitat pressures. The trait approach offers a mechanistic alternative to traditional taxonomy-based descriptors. This review focuses on research employing traits as biomonitoring tools for freshwater ecosystems, although the lessons learned have wider application in the assessment of other ecosystem types. We review the support from ecological theory to employ species traits for biomonitoring purposes (e.g. the habitat templet concept, landscape filtering hypothesis), and the subsequent studies that test the hypotheses arising from these theories, and apply this knowledge under real freshwater biomonitoring scenarios. We also include studies that deal with more specific issues such as trait trade-offs and trait syndromes. We highlight the functional trait approach as one of the most promising tools emerging for biomonitoring freshwater ecosystems. Several technical issues are addressed and solutions are proposed. We discuss the need for: a broader unified trait biomonitoring tool; a more accurate understanding of the natural variation of community patterns of trait expression; approaches to diminish the effects of trait trade-offs and trait syndromes; additional life history and ecological requirement studies; and the detection of specific impacts under multiple stressor scenarios. Synthesis and applications. This review provides biologists with the conceptual underpinning for the use of species traits as community descriptors and for freshwater biomonitoring and management. We expect that the functional trait approach will ultimately improve communication to managers and legislators of the importance of protecting freshwater ecosystem functions. © 2010 The Authors. Journal compilation © 2010 British Ecological Society.
Munkittrick K.R., Barrett T.J., McMaster M.E. (2010). Guidance for site-specifically assessing the health of fish populations with emphasis on Canada's environmental effects monitoring program. Water Quality Research Journal of Canada, 45(2) 209-221.

Techniques have been developed over the past two decades to site-specifically assess effects of contaminants on the health of fish populations using a sentinel species approach. National environment effects monitoring (EEM) programs have been implemented in Canada for pulp and paper effluents since 1992 and liquid metal mining effluents since 2002 to monitor effects of these discharges on the health of fish populations. The major criticisms of past EEM fish population surveys can be separated into concerns about the adequacy of the reference sites, the potential impacts of confounding factors, the ecological relevance of endpoints used, the influences of natural variability, concerns over statistical design issues, and potential genetic influences on species characteristics. This paper provides input to deal with these issues and guidance on the selection of sentinel species, timing of sampling, and nonlethal sampling methods to evaluate the health of fish populations. Sample size requirements, effect sizes, and power analysis are also discussed as well as data analysis guidance needed to obtain reliable results. © 2010, CAWQ.
Ouellet V., Mingelbier M., Saint-Hilaire A., Morin J. (2010). Frequency analysis as a tool for assessing adverse conditions during a massive Fish Kill in the St. Lawrence River, Canada. Water Quality Research Journal of Canada, 45(1) 47-57.

During the summer of 2001, the largest fish kill in the recorded history of the St. Lawrence River occurred. More than 25,000 dead carp were recovered. Preliminary analyses suggested hydroclimatic factors may have triggered the fish kill. Long time series of hydroclimatic variables were available upstream and downstream from the study area. In order to investigate if hydroclimatic conditions were extreme during the summer of 2001, frequency analyses were performed on time series of air and water temperature, water level, and solar radiation. During this period, the daily maximum water temperature was abnormally high (return period of 47 years) relative to other years. Air temperature was also high (return period of 22 years) and water level was very low (return period of 67 years). Results showed that hydroclimatic forcings were acting at two different time scales. First, short-term extremes are more likely to have direct impacts on ecosystems, such as lethal stress caused by oxygen depletion in shallow areas. Long-term extremes have indirect effects, which are more difficult to detect, such as immunosuppression. These results reiterate the importance of water temperature in aquatic habitat, particularly in the present context of global warming and climate change. © 2010, CAWQ.
Parrott J.L., Mark Hewitt L., Kovacs T.G., Maclatchy D.L., Martel P.H., ven den Heuvel M.R., van der Kraak G.J., McMaster M.E. (2010). Responses in a fathead minnow (pimephales promelas) lifecycle test and in wild white sucker (catostomus commersoni) exposed to a canadian bleached kraft mill effluent. Water Quality Research Journal of Canada, 45(2) 187-200.

To evaluate currently available bioassays for their use in investigating the causes of pulp and paper mill effluent effects on fish reproduction, the responses of wild white sucker (Catostomus commersoni) collected from the receiving environment at the bleached kraft mill at La Tuque, Quebec, were compared with responses of fathead minnow (Pimephales promelas) exposed to effluent in a laboratory lifecycle test. White sucker collected at effluent exposed sites had increased liver size but none of the reproductive effects that had been documented in earlier field studies at this site. Exposure to 1, 3, 10, 30, and 100% bleached kraft mill effluent (BKME) in the lab led to significantly decreased length, but increased weight and liver size in male fathead minnow. Female length was also decreased and liver size was increased at high effluent exposures. Most effluent concentrations (1 to 30%) significantly increased egg production compared with controls. The fathead minnow lifecycle assay mirrored the effects seen in wild fish captured downstream of the BKME discharge. These results will be used to select shortterm fish tests for investigating the causes of and solutions to the effects of mill effluents on fish reproduction. © 2010, CAWQ.
Pestana J.L.T., Loureiro S., Baird D.J., Soares A.M.V.M. (2010). Pesticide exposure and inducible antipredator responses in the zooplankton grazer, Daphnia magna Straus. Chemosphere, 78(3) 241-248.

Risk assessment of toxic substances under ecologically-relevant scenarios which include the presence of natural stressors is essential to understand their indirect toxic effects and to improve prediction of the impacts of contamination on community structure and ecosystem function. Here, we study the effects of the pesticide imidacloprid on the responses of Daphnia magna to a combination of predator-release kairomones from trout and alarm cues from conspecifics, simulating different levels of perceived predation risk. The joint effects of simultaneous exposure to both types of stressors were assessed both by traditional analysis of variance and by employing conceptual models for the evaluation of contaminant mixture exposures. Results demonstrated that pesticide exposure can significantly increase the costs of inducible antipredator defences and impair life-history responses of daphnids to fish predation pressure. Since trait-mediated effects are well-known to play a key role in population dynamics, the combined direct and indirect effects of sub-lethal concentrations of pesticides could induce maladaptive responses in zooplankton populations in the field, reducing their long-term viability. © 2009 Elsevier Ltd.
Peters R.E.M., Courtenay S.C., Hewitt L.M., MacLatchy D.L. (2010). Effects of 17α-ethynylestradiol on early-life development, sex differentiation and vitellogenin induction in mummichog (Fundulus heteroclitus). Marine Environmental Research, 69(3) 178-186.

Fertilized mummichog eggs retrieved from 17α-ethynylestradiol (EE<inf>2</inf>) exposed adult fish were raised in concentrations of EE<inf>2</inf> ranging from 0 to 100 ng/L (100 ng/L EE<inf>2</inf> estimated to have actual average exposure concentrations of 30% of nominal; 0.1-10 ng/L were below detect throughout 24-h exposure period) for 61 weeks post-hatch. Eggs exposed at 100 ng/L hatched sooner, the larvae were longer, and survival of juvenile fish from hatch to study termination was greater than all other treatments, though fewer hatched at this treatment. Sex ratios were skewed (>80% female phenotype) at 100 ng/L EE<inf>2</inf>, and some gonadal male fish displayed female secondary sex characteristics. Condition factor, gonadosomatic index (GSI), and liver somatic index (LSI) were found to decrease in both sexes between 52 and 61 weeks post-hatch. Female fish had increased hepatic vitellogenin (VTG) at 52 weeks post-hatch. When exposed to 1, 10 and 100 ng/L EE<inf>2</inf>, female fish had a higher proportion of vitellogenic follicles in the ovarian tissue. Males exposed at 100 ng/L may have had disruption at some endpoints (GSI, VTG) that is masked due to reduced sample size compared to other treatments. Fish exposed to concentrations of EE<inf>2</inf> at or below 10 ng/L showed inconsistent effects on development and reproductive potential. This study indicates the potential for population-level effects at the high range of environmental EE<inf>2</inf> at concentrations equivalent to those at which consistent effects in fecundity in the adult mummichog reproductive test have been measured. This work demonstrates that chronic EE<inf>2</inf> exposure causes developmental effects at concentrations similar to those which cause effects in the shorter-term adult mummichog reproductive test. Effects are at higher concentrations than have been noted for freshwater model species. Whether this is because of species sensitivity or due to differences between freshwater and saltwater availability of EE<inf>2</inf> or its uptake requires further study. © 2009 Elsevier Ltd. All rights reserved.
Rubach M.N., Ashauer R., Maund S.J., Baird D.J., Van Den Brink P.J. (2010). Toxicokinetic variation in 15 freshwater arthropod species exposed to the insecticide chlorpyrifos. Environmental Toxicology and Chemistry, 29(10) 2225-2234.

Recent advances in modeling the processes of the toxicity of chemicals-toxicokinetics (TK) and toxicodynamics (TD)-are improving environmental risk assessment (ERA) through prediction of effects from time-varying exposure. This has been achieved by linking chemical fate and toxicological effects mechanistically, based on internal concentrations, through the tissue residue approach. However, certain questions remain: for example, how do TK and TD differ among species and how does this relate to differences in species sensitivity? In a series of experiments, we studied the TK of [14C]chlorpyrifos in 15 freshwater arthropod species, two of which were studied in juvenile and adult life stages. Uptake (k<inf>in</inf>) and elimination (k<inf>out</inf>) rate constants were fitted using a one-compartment single first-order kinetic model. The application of two complementary parameter estimation methods facilitated the calculation of bioconcentration factors (BCF) with prediction intervals and 95% depuration times (t<inf>95</inf>) for all tested species. Extremely slow elimination was observed in some species as well as high overall variation in k<inf>in</inf>, k<inf>out</inf>, BCF, and t<inf>95</inf> across the tested aquatic arthropod species. This variation has implications for the development of TKTD approaches in ERA, including assessing fluctuating exposure concentrations and the interpretation of observed toxicity responses in the laboratory and in the field. © 2010 SETAC.
Rubach M.N., Baird D.J., Van Den Brink P.J. (2010). A new method for ranking mode-specific sensitivity of freshwater arthropods to insecticides and its relationship to biological traits. Environmental Toxicology and Chemistry, 29(2) 476-487.

The problem of how to deal with species sensitivity differences to toxic substances has been addressed successfully with the species sensitivity distribution (SSD), yet this has not increased understanding about the underlying mechanisms of sensitivity. Other researchers have identified the mode of action of chemicals and also biological traits of species as determinants for sensitivity, yet no systematic approach combines these factors. To achieve this, first existing data on organophosphate, carbamate, and pyrethroid toxicity and mode of action and also species trait information were mined. Second, we linked taxon sensitivity to their traits at the family level to generate empirical and mechanistic hypotheses about sensitivity-trait relationships. In this way, a mode-specific sensitivity (MSS) ranking method was developed, and tested at the taxonomic level of family and genus. The application of several quality criteria indicated overall confidence in rankings, but confidence in exact taxon rank was less certain, due to data insufficiency for certain groups. The MSS rankings were found to be applicable for trait-based approaches and were successfully linked to existing trait data to identify traits with predictive potential. Although this empirical analysis cannot test causality relationships between traits and sensitivity, testable hypotheses were generated, for further experimental investigation. Single traits as well as combinations of traits can be used to predict laboratory sensitivity to the substances tested, although associations were not as strong as in previous studies. We conclude that existing trait data are not suitable for every trait-based research question and that important traits remain to be identified and quantified in relation to the processes of toxicity, i.e., the toxicokinetics and toxicodynamics. © 2009 SETAC.
Sutherland A.B., Culp J.M., Benoy G.A. (2010). Characterizing deposited sediment for stream habitat assessment. Limnology and Oceanography Methods, 8(1) 30-44.

Numerous techniques are used to measure deposited sediment and quantify substrate quality in streams. We evaluated the relationship between land disturbance and stream habitat by comparing 25 commonly used deposited sediment parameters to watershed, riparian, and local-scale drivers. We also tested whether land use regressions were improved by accounting for geomorphic setting (measures of slope and channel incision) and how visual versus measurement-based estimations of percent fines and embeddedness were related to each other and to percent agriculture. Of the 16 metrics significantly related to watershed agriculture, subsurface percent fines was the best indicator of land use. Subsurface fines were more strongly related to both watershed and riparian percent agriculture than surface sediment metrics. The second best-performing parameter was the visual assessment of percent fines <2 mm. Surface particle counts also performed moderately well. Sediment percentiles (d<inf>50</inf>, d<inf>84</inf>) and stability indices were among the weakest indicators of watershed land use. All measures of local percent agriculture were poor predictors of deposited sediment parameters. Mean slope within the entire stream network was nearly as good of a predictor of deposited sediment as watershed percent agriculture. This suggests that we may improve our ability to predict deposited sediment by considering land use within the appropriate geomorphic context.
Sutherland A.B., Culp J.M., Benoy G.A. (2010). Characterizing deposited sediment for stream habitat assessment. Limnology and Oceanography Methods, 8(JAN) 30-44.

Numerous techniques are used to measure deposited sediment and quantify substrate quality in streams. We evaluated the relationship between land disturbance and stream habitat by comparing 25 commonly used deposited sediment parameters to watershed, riparian, and local-scale drivers. We also tested whether land use regressions were improved by accounting for geomorphic setting (measures of slope and channel incision) and how visual versus measurement-based estimations of percent fines and embeddedness were related to each other and to percent agriculture. Of the 16 metrics significantly related to watershed agriculture, subsurface percent fines was the best indicator of land use. Subsurface fines were more strongly related to both watershed and riparian percent agriculture than surface sediment metrics. The second best-performing parameter was the visual assessment of percent fines <2mm. Surface particle counts also performed moderately well. Sediment percentiles (d<inf>50</inf>, d<inf>84</inf>) and stability indices were among the weakest indicators of watershed land use. All measures of local percent agriculture were poor predictors of deposited sediment parameters. Mean slope within the entire stream network was nearly as good of a predictor of deposited sediment as watershed percent agriculture. This suggests that we may improve our ability to predict deposited sediment by considering land use within the appropriate geomorphic context. © 2010, by the American Society of Limnology and Oceanography, Inc.
Swanson H.K., Kidd K.A. (2010). Mercury concentrations in arctic food fishes reflect the presence of anadromous arctic charr (Salvelinus alpinus), species, and life history. Environmental Science and Technology, 44(9) 3286-3292.

Single-spawning (semelparous) anadromous fishes are known to transport contaminants from marine to freshwater habitats, but little research has been conducted on contaminant biotransport by multiple-spawning (iteroparous) anadromous fishes. We examined the effect of iteroparous, anadromous Arctic charr (Salvelinus alpinus) on mercury concentrations ([Hg]) in freshwater biota and compared [Hg] between species and life history types of Arctic charr and lake trout (Salvelinus namaycush). Data from six lakes and one coastal marine area in the Arctic territory of Nunavut, Canada, indicated that 1) lake trout had significantly lower [Hg] in lakes where anadromous Arctic charr were present; 2) [Hg] was significantly lower in recently discovered anadromous lake trout than in resident lake trout; and 3) regardless of life history, Arctic charr had significantly lower [Hg] than lake trout. These differences were explained by fish condition, age-at-size, and C:N. Biomagnification of Hg, measured as log<inf>10</inf>[Hg]-δ15N slopes, did not differ between lakes with and without anadromous Arctic charr but was significantly higher in freshwater food webs (∼0.2) than in the marine food web (0.08). Some biomagnification estimates were affected by correction for fish age and size. In contrast to semelparous anadromous species, biotransport of Hg by anadromous Arctic charr appears to be offset by increased growth of freshwater fishes. © 2010 American Chemical Society.
Swanson H.K., Kidd K.A., Babaluk J.A., Wastle R.J., Yang P.P., Halden N.M., Reist J.D. (2010). Anadromy in Arctic populations of lake trout (Salvelinus namaycush): Otolith microchemistry, stable isotopes, and comparisons with Arctic char (Salvelinus alpinus). Canadian Journal of Fisheries and Aquatic Sciences, 67(5) 842-853.

In the family Salmonidae, lake trout (Salvelinus namaycush) are considered the least tolerant of salt water. There are, however, sporadic reports of lake trout in coastal, brackish habitats in the Canadian Arctic. Otolith microchemistry analyses conducted on lake trout and Arctic char (Salvelinus alpinus) from four Arctic lakes in the West Kitikmeot region of Nunavut, Canada, revealed that 37 of 135 (27%) lake trout made annual marine migrations. Anadromous lake trout were in significantly better condition (K = 1.17) and had significantly higher C:N ratios (3.71) than resident lake trout (K = 1.05 and C:N = 3.34). Anadromous lake trout also had significantly higher δ15N (mean = 16.4%), δ13C (mean = -22.3%), and δ34S (mean = 13.43%) isotope ratios than resident lake trout (means = 12.84%, -26.21%, and 1.93% for δ15N, δ13C, and δ34S, respectively); results were similar for Arctic char and agree with results from previous studies. Mean age of first migration for lake trout was 13 years, which was significantly older than that for Arctic char (5 years). This could be a reflection of size-dependent salinity tolerance in lake trout, but further research is required. These are the first detailed scientific data documenting anadromy in lake trout.
Swanson H.K., Kidd K.A., Reist J.D. (2010). Effects of partially anadromous Arctic charr (Salvelinus alpinus) populations on ecology of coastal Arctic lakes. Ecosystems, 13(2) 261-274.

Little research has been conducted on effects of iteroparous anadromous fishes on Arctic lakes. We investigated trophic ecology, fish growth, and food web structure in six lakes located in Nunavut, Canada; three lakes contained anadromous Arctic charr (Salvelinus alpinus) whereas three lakes did not contain Arctic charr. All lakes contained forage fishes and lake trout (Salvelinus namaycush; top predator). Isotope ratios (δ13C, δ15N) of fishes and invertebrates did not differ between lakes with and without anadromous Arctic charr; if anadromous Arctic charr deliver marine-derived nutrients and/or organic matter to freshwater lakes, these inputs could not be detected with δ13C and/or δ15N. Lake trout carbon (C):nitrogen (N) and condition were significantly higher in lakes with Arctic charr (C:N = 3.42, K = 1.1) than in lakes without Arctic charr (C:N = 3.17, K = 0.99), however, and ninespine stickleback (Pungitius pungitius) condition was significantly lower in lakes with Arctic charr (K = 0.58) than in lakes without Arctic charr (K = 0.64). Isotope data indicated that pre-smolt and resident Arctic charr may be prey for lake trout and compete with ninespine stickleback. Linear distance metrics applied to isotope data showed that food webs were more compact and isotopically redundant in lakes where Arctic charr were present. Despite this, lake trout populations in lakes with Arctic charr occupied a larger isotope space and showed greater inter-individual isotope differences. Anadromous Arctic charr appear to affect ecology and feeding of sympatric freshwater species, but effects are more subtle than those seen for semelparous anadromous species. © 2010 Springer Science+Business Media, LLC.
Tramblay Y., Saint-Hilaire A., Ouarda T.B.M.J., Moatar F., Hecht B. (2010). Estimation of local extreme suspended sediment concentrations in California Rivers. Science of the Total Environment, 408(19) 4221-4229.

The total amount of suspended sediment load carried by a stream during a year is usually transported during one or several extreme events related to high river flow and intense rainfall, leading to very high suspended sediment concentrations (SSCs). In this study quantiles of SSC derived from annual maximums and the 99th percentile of SSC series are considered to be estimated locally in a site-specific approach using regional information. Analyses of relationships between physiographic characteristics and the selected indicators were undertaken using the localities of 5-km radius draining of each sampling site. Multiple regression models were built to test the regional estimation for these indicators of suspended sediment transport. To assess the accuracy of the estimates, a Jack-Knife re-sampling procedure was used to compute the relative bias and root mean square error of the models. Results show that for the 19 stations considered in California, the extreme SSCs can be estimated with 40-60% uncertainty, depending on the presence of flow regulation in the basin. This modelling approach is likely to prove functional in other Mediterranean climate watersheds since they appear useful in California, where geologic, climatic, physiographic, and land-use conditions are highly variable. © 2010 Elsevier B.V.
van den Heuvel M.R. (2010). Recent progress in understanding the causes of endocrine disruption related to pulp and paper mill effluents. Water Quality Research Journal of Canada, 45(2) 137-144.

Reproductive impairment in fishes exposed to pulp and paper effluent has been observed in the wild for three decades. Despite intense research, identification of causative agents, if indeed the changes are strictly chemically mediated, has yet to be achieved. This review examines the body of research developed over the last six years that was directed at understanding the mechanisms of reproductive dysfunction in fishes associated with pulp mill effluent exposures. Research has continued to show diminishing effects of effluent exposure on fish reproductive physiology. Observations of exposure to androgens and estrogens continue to be observed and new evidence suggests that antiestrogens may be present. The presence of androgenic steroids remains a consistent observation, and those androgens appear to be native to wood. Recent studies have also suggested a number of alternate mechanisms beyond androgens or estrogens. One such possibility is that neuroactive substances are interfering with endocrine balance critical to reproduction. A second possibility is that some reproductive effects in the field may be due to nutritional factors, and thus reproductive impacts are caused by indirect effects of pulp mill effluent exposure. Ongoing mechanistic studies, particularly with paired field-lab components, are required to make further progress. © 2010, CAWQ.
van den Heuvel M.R., Martel P.H., Kovacs T.G., Maclatchy D.L., van der Kraak G.J., Parrott J.L., McMaster M.E., O'Connor B.I., Melvin S.D., Mark Hewitt L. (2010). Evaluation of short-term fish reproductive bioassays for predicting effects of a Canadian bleached kraft mill effluent. Water Quality Research Journal of Canada, 45(2) 175-186.

Under the Canadian Environmental Effects Monitoring (EEM) program for pulp and paper effluents, the observation of a national response pattern of decreased gonad size and increased fish condition and liver size has triggered a centralized multiagency investigation of cause (IOC) of reproductive impacts in fishes. The purpose of the component of the IOC study presented here is to compare a number of fish bioassays for determining reproductive and reproductive-endocrine effects of a bleached kraft mill effluent. The bleached kraft mill chosen for this study had demonstrated the national response pattern in previous EEM cycles. The bioassays employed to examine reproduction were fathead minnow (Pimephales promelas) 5- and 21-d, mummichog (Fundulus heteroclitus) 25-d, and zebrafish (Danio rerio) 7-d tests, all of which had egg production as the primary reproductive endpoint. Additional bioassays examining reproductive-endocrine endpoints included a 7-d mummichog test, a 7- and a 21-d threespine stickleback (Gasterosteus aculeatus) test, a rainbow trout (Oncorhynchus mykiss) 7-d test, and in vitro sex steroid receptor and plasma protein binding bioassays. The zebrafish and fathead minnow reproductive tests showed significant suppression of egg production at the 100% effluent concentration. Endocrine data derived from the tests showed that this effluent did not impact steroidogenic endpoints at any concentration. Bioassays showed that this effluent i) was capable of eliciting cytochrome P4501A induction at as low as 10% vol/vol effluent, ii) was weakly androgenic at 10% vol/vol, and iii) showed no evidence of in vivo estrogenicity. These results were consistent with in vitro receptor binding assays showing a highly variable level of androgenic equivalents over six months of effluent testing, with little evidence of estrogenic activity. Bioassay results were consistent in that the overall conclusion was that this effluent has only a weak potential to cause reproductive impairment and would likely not do so at environmentally relevant concentrations. Field studies and a fathead minnow lifecycle study conducted concurrently were in agreement with reproductive bioassay results as white sucker exposed in the receiving environment no longer had significantly reduced gonadal development. Overall, this study provided evidence that the laboratory assays evaluated for various reproductive endpoints have potential application for future IOC work. © 2010, CAWQ.
van den Heuvel M.R., Slade A.H., Landman M.J. (2010). Summary of a decade of research on the effects of a New Zealand pulp and paper millon reproduction in fishes. Water Quality Research Journal of Canada, 45(2) 123-135.

The effluent of the Tasman pulp and paper mill (Kawerau, New Zealand) has been intensively studied for its effects on the health of fishes between 1998 and present. This review summarizes peer-reviewed scientific literature on the reproductive effects of the Tasman Mill effluent on fishes. In the 1990s there was an emerging body of literature from around the world showing that exposure to pulp and paper effluent could cause subtle reproductive alterations in exposed fishes. Locally, the Tarawera River had proved to be a difficult environment to conduct field studies. To overcome some of the difficulties with studying fish populations in the Tarawera River, initial studies on the reproductive health of fishes were focused on mesocosm and laboratory bioassays. During the later part of this period of study, wild fish population sampling was conducted in river to assess the cumulative impact of multiple discharges. The initial mesocosm studies were conducted with rainbow trout exposures over an entire reproductive development cycle. The Tasman Mill effluent was initially observed to cause reductions in gonad size in females corresponding with lower circulating sex steroid hormones and reduced egg and larval sizes. This result was not observed again in the two subsequent long-term exposures conducted after 2001. Laboratory studies initially found the effluent to have a masculinizing effect on female mosquitofish (Gambusia affinis). This mosquito fish masculinization response disappeared after 2001 and was also not seen in effluent-exposed wild populations. Upstream and downstream populations of the native common bully (Gobiomorphus cotidianus) showed different reproductive timing, and investigation revealed that genetic differences were a potential reason for these differences. Subsequent investigation compared the Tarawera River bully to genetically similar Rangitiki River bully and found no evidence of reproductive alterations. The entire body of published data was assessed with regards to changes at the mill and chemical profiles of the effluent. It was evident that continuing effort on the part of the mill has resulted in gradual improvement in effluent quality over the duration of the studies. However, the disappearance of reproductive effects as assessed by multiple bioassays corresponds to one major change: screen room closure in the pulp mill. This change would have resulted in wood extractives being shunted from the treatment system to the recovery boiler, resulting in a net reduction in compounds derived from wood. © 2010, CAWQ.
Weir L.K., Breau C., Hutchings J.A., Cunjak R.A. (2010). Multiple paternity and variance in male fertilization success within Atlantic salmon Salmo salar redds in a naturally spawning population. Journal of Fish Biology, 77(3) 479-493.

The incidence and magnitude of multiple paternity were estimated for a natural, unmanipulated spawning population of Atlantic salmon Salmo salar. Egg nests were surveyed in the autumn and sub-samples were excavated the following spring. Parentage data derived from microsatellite DNA revealed an unexpectedly high level of multiple paternity. Within a single redd, females may mate with as many as 16 different males, including small mature male parr and large anadromous males. Multiple paternity was most pronounced in areas of highest redd density, corresponding with increased abundances of mature male parr. In addition, there was considerable variation in success among males, although this variability did not depend upon the number of males participating in spawning. This work underscores the value of undertaking genetic studies on the mating systems of fishes in unmanipulated, natural environments. © 2010 The Authors. Journal compilation © 2010 The Fisheries Society of the British Isles.
Wyn B., Kidd K.A., Burgess N.M., Curry R.A., Munkittrick K.R. (2010). Increasing Mercury in Yellow Perch at a Hotspot in Atlantic Canada, Kejimkujik National Park. Environmental Science and Technology, 44(23) 9176-9181.

In the mid-1990s, yellow perch (Perca flavescens) and common loons (Gavia immer) from Kejimkujik National Park and National Historic Site (KNPNHS), Nova Scotia, Canada, had among the highest mercury (Hg) concentrations across North America. In 2006 and 2007, we re-examined 16 lakes to determine whether there have been changes in Hg in the loon's preferred prey, yellow perch. Total Hg concentrations were measured in up to nine perch in each of three size classes (5-10 cm, 10-15 cm, and 15-20 cm) consumed by loons. Between 1996/97 and 2006/07, polynomial regressions indicated that Hg in yellow perch increased an average of 29% in ten lakes, decreased an average of 21% in three, and were unchanged in the remaining three lakes. In 2006/07, perch in 75% of the study lakes had Hg concentrations (standardized to 12-cm fish length) equal to or above the concentration (0.21 μg·g-1ww) associated with a 50% reduction in maximum productivity of loons, compared with only 56% of these lakes in 1996/97. Mercury contamination currently poses a greater threat to loon health than a decade ago, and further reductions in anthropogenic emissions should be considered to reduce its impacts on ecosystem health. © 2010 American Chemical Society.
Allen P.J., Barth C.C., Peake S.J., Abrahams M.V., Anderson W.G. (2009). Cohesive social behaviour shortens the stress response: The effects of conspecifics on the stress response in lake sturgeon Acipenser fulvescens. Journal of Fish Biology, 74(1) 90-104.

An examination was made of whether social interactions can have a beneficial effect through the attenuation of the stress response in a social species. In the first experiment, one larger (mean ± s.e. 194.0 ± 12.5 g) and seven smaller (32.0 ± 2.6 g) juvenile lake sturgeon Acipenser fulvescens were placed in tanks to determine whether a classic dominance effect would be established based on body size (n = 6). Large fish did not establish a territory or aggressively interact with smaller fish, as there were no significant differences in nearest-neighbour distances and an absence of aggressive behaviour (biting, chasing and pushing). In the second experiment, it was hypothesized that the presence of conspecifics would have a beneficial effect through an attenuation of the stress response. Fish in groups or isolation were stressed by a brief aerial exposure (30 s), and blood plasma was measured at regular time intervals (0, 20, 40, 60, 120 and 240 min) following the stressor via an implanted cannula (n = 9-11). The presence of conspecifics did not affect the peak cortisol response, however, the overall cortisol response was shorter in duration compared to fish in isolation. Furthermore, secondary stress variables (plasma ions and glucose) showed differences between fish in groups and isolation. The results of these experiments suggest that social interaction plays an important and beneficial role in regulating the stress response in cohesive social species such as A. fulvescens. © 2008 The Authors.
Allen P.J., Webb M.A.H., Cureton E., Bruch R.M., Barth C.C., Peake S.J., Anderson W.G. (2009). Calcium regulation in wild populations of a freshwater cartilaginous fish, the lake sturgeon Acipenser fulvescens. Comparative Biochemistry and Physiology A Molecular and Integrative Physiology, 154(4) 437-450.

Lake sturgeon, Acipenser fulvescens, are one of a few species of cartilaginous fishes that complete their life cycle entirely in freshwater. Sturgeons maintain very low concentrations of circulating calcium (Ca2+) compared with other vertebrates, and therefore, face unique challenges in regard to Ca2+ regulation, which are likely to be magnified during vitellogenic stages of the reproductive cycle. In the present study, Ca2+ concentrations and associated hormones of female and male lake sturgeon were examined in two wild populations, and were related to reproductive stage. In both populations, free, bound and total Ca2+ were low, peaking in mid-late vitellogenic females. Internal Ca2+ and phosphate (PO<inf>4</inf>3-) concentrations were inversely related to environmental concentrations, suggesting that these ions are preferentially retained and that mechanisms for mobilization are up-regulated under diminished environmental concentrations. Plasma 17β-estradiol, 11-ketotestosterone and testosterone, peaked in mid-late vitellogenic females, while the androgens peaked in spawning males. Urine Ca2+ was more tightly regulated than other divalent ions and decreased in spawning fish. Therefore, the increases in free plasma Ca2+, the very low circulating concentrations of free and total Ca2+, and the increase in PO<inf>4</inf>3- and bound Ca2+ in low Ca2+ environments indicate unique adaptations to Ca2+ regulation in the lake sturgeon. © 2009 Elsevier Inc.
Aubry E., Methven D.A., Hurlbut T. (2009). Length-depth relations of enchelyopus cimbrius fourbeard rockling (gadiformes: Phycidae) from the southern gulf of st lawrence and cabot strait in relation to abiotic factors. Journal of the Marine Biological Association of the United Kingdom, 89(8) 1643-1653.

Research vessel survey data collected by Fisheries and Oceans Canada in the southern Gulf of St Lawrence (1971-2002) and Cabot Strait (1994-1997) were analysed to determine if Enchelyopus cimbrius the fourbeard rockling, distributed itself with larger individuals occurring in deeper water. A positive size-depth relationship was first observed for the European plaice, Pleuronectes platessa in the North Sea and has been reported for other fish. Positive relationships were found between the total length of E. cimbrius and depths where it occurred in this study. However, the biological relationship was not significant since the linear regression slopes were very weak, explaining less than approximately five per cent of the variance observed. Data were analysed further to determine the water depth, temperature and salinity ranges where the fourbeard rockling was most abundant. Enchelyopus cimbrius occurred throughout the depth-ranges sampled with highest catches occurring at 25-50m (southern Gulf of St Lawrence) and deeper than 200m (southern Gulf of St Lawrence and Cabot Strait). Low catches at intermediate depths (̃50-100m) in the southern Gulf of St Lawrence may have been due to the lack of suitable mud substrate and colder bottom temperatures in the Magdalen Shallows, a large central region of the southern Gulf. Enchelyopus cimbrius was mostly caught at relatively narrow temperature and salinity ranges of 4-6°C and 34-34.9 ppt in both regions, and only occurred in areas with a mud substratum, predominantly in the eastern Northumberland Strait, Baie des Chaleurs and in the deeper water of the Cape Breton Trough, Laurentian Channel and Cabot Strait. Enchelyopus cimbrius was caught throughout the day and night, contradicting a previous study that characterized it as being nocturnal in shallow coastal waters off Newfoundland. Copyright © 2009 Marine Biological Association of the United Kingdom.
Barth C.C., Peake S.J., Allen P.J., Anderson W.G. (2009). Habitat utilization of juvenile lake sturgeon, acipenser fulvescens, in a large Canadian river. Journal of Applied Ichthyology, 25(SUPPL. 2) 18-26.

An increased understanding of the juvenile life history stage of the lake sturgeon, Acipenser fulvescens, has been recognized as a key requirement for improving conservation efforts for this once abundant species. The objectives of the current study were to develop an effective methodology for capturing juvenile lake sturgeon in a large riverine environment; to describe the physical habitat characteristics (depth, water velocity and substrate) associated with the areas where juvenile lake sturgeon were captured; and to determine basic population parameters (length, body mass and condition factor) for juvenile lake sturgeon captured in those areas. Gillnets (mesh sizes 25-108 mm) were used to sample the Winnipeg River, a large river in the northern extent of the species range, from 12 June to 6 November 2006. A total of 2154 juvenile (<530 mm FL) lake sturgeon were captured, which represented over 74% of the total fish catch. Moderate (51-108 mm) and small (25 mm) mesh gill nets were found to be efficient for sampling juvenile lake sturgeon, with the former capturing a wider range of sizes and the latter capturing fewer fish but resulting in decreased mortality. Juvenile lake sturgeon were captured at high densities in discrete areas characterized by water depths >13.7 m, detectable water velocities >0.20 m s-1, and various substrate types. © 2009 Blackwell Verlag GmbH.
Blanar C.A., Munkittrick K.R., Houlahan J., MacLatchy D.L., Marcogliese D.J. (2009). Pollution and parasitism in aquatic animals: A meta-analysis of effect size. Aquatic Toxicology, 93(1) 18-28.

Numerous studies have indicated that aquatic pollution affects parasite populations and communities. However, the responses of individual taxa and functional groups to specific contaminants, and their effect sizes, have yet to be assessed quantitatively. We began by summarizing general trends in the literature, and found that reports of significant changes in parasitism were most commonly observed in response to eutrophication and metal contamination. Among parasite taxa, significant changes were most commonly reported for acanthocephalans, digeneans and microparasites. We then conducted a quantitative meta-analysis of the effects of pollution on parasitism in aquatic animals. We calculated signed standardized effect sizes (as Cohen's d) for all published studies that provided the necessary descriptive statistics, and compared them among major contaminant types (pesticides, hydrocarbons, polychlorinated biphenyls, pulp mill effluent, metals, sewage, eutrophication, and acidification) and parasite taxa (Acanthocephala, Cestoda, Digenea, Monogenea, Nematoda and microparasites). Effect sizes were not significantly different from zero for many parasite/contaminant interactions, and tended to be highly variable within individual taxa. However, consistently strong, significant negative effects were noted in Digenea and Monogenea, especially in response to metal pollution. Significant effect sizes were typically negative, indicating that pollutants have negative effects on parasite populations. Contaminants also had a slightly negative effect on community richness. When parasites were grouped into heteroxenous (with >1 obligatory host in life cycle) vs. monoxenous (1 obligatory host in life cycle) taxa, the latter were more susceptible to a wide range of pollutants. Similarly, directly exposed (external parasites and the free-living transmission stages of internal parasites) and freshwater taxa were more susceptible to a wider range of pollutants than indirectly exposed (internal parasites) and marine taxa. This meta-analysis represented a first attempt to consider the size of the effect of pollution on parasites, and highlighted the potential of susceptible parasite taxa, communities, and functional groups for use in the biological assessment of pollution. For instance, our results indicate that freshwater monogeneans and digeneans are good candidates as potential biological indicators of pollution in aquatic ecosystems. © 2009 Elsevier B.V.
Bosker T., Hewitt L.M., Munkittrick K.R., Melvin S.D., MacLatchy D.L. (2009). The effects of final treated effluent and in-mill waste streams from a Canadian thermomechanical pulp and paper mill on mummichog (Fundulus heteroclitus) reproduction. Water Quality Research Journal of Canada, 44(4) 333-344.

The effect on fish reproduction of final treated effluent from a thermomechanical pulp mill in Saint John, New Brunswick, Canada, was studied using mummichog (Fundulus heteroclitus), an endemic fish species of the Atlantic coast of North America. A 1997 artificial stream study at the same mill showed a reduction in gonad sizes in mummichog after a 28-day exposure to 3% final treated effluent. In 2005, we reevaluated final treated effluent, and conducted a toxicity source evaluation to identity waste stream sources within the mill that may cause reproductive effects. Relative to reference, no significant differences in gonad size, plasma levels of gonadal sex steroids, egg production, or stage of egg development were observed in fish exposed to 1, 3, 10, 30, and 100% final treated effluent or in-mill waste streams. Unlike the previous study in 1997, these data indicate a low potential for an effect of final effluent on fish reproduction. Since the 1997 study there were no major process changes that could explain the differences in the results. However, there was high variability in gonad size, egg production, and endocrine endpoints measured in the more recent test, which resulted in low power to detect differences. This has prompted research to refine the current reproductive test by optimizing study design. © 2009, CAWQ.
Bosker T., Munkittrick K. (2009). Often overlooked: Biological QA/QC. Integrated Environmental Assessment and Management, 5(3) 489-491.
Bosker T., Munkittrick K.R., Maclatchy D.L. (2009). Challenges in current adult fish laboratory reproductive tests: Suggestions for refinement using a mummichog (fundulus heteroclitus) case study. Environmental Toxicology and Chemistry, 28(11) 2386-2396.

Concerns about screening endocrine-active contaminants have led to the development of a number of short-term fish reproductive tests. A review conducted, of 62 published adult fish reproductive papers using various fish species found, low samples sizes (mean of 5.7 replicates with a median of 5 replicates) and high variance (an average coefficient of variance of 43.8%). The high variances and low sample sizes allow only relatively large differences to be detected with the current protocols; the average significant difference detected was a 68.7% reduction in egg production, while only differences above 50% were detected with confidence. This result indicates low power to detect more subtle differences and a high probability of type II errors in interpretation. The present study identifies several ways to increase the power of the adult fish reproductive test in the mummichog (Futidulus lieteroclitus). By identifying the peak timing of egg production (before and after the new moon), extending the duration of the experiment (increased from 7 to 14 d), and. determining that a sample size of eight replicate tanks per treatment accurately predicts variance in the sample population (based on pre-exposure variation calculations of replicate tanks), the power of the test has been significantly increased. The present study demonstrates that weaknesses in the current adult fish reproductive tests can easily be addressed by focusing on improved understanding of the reproductive behavior of the test species and developing study designs that include calculating desired variability levels and increasing replicates. © 2009 SETAC.
Boudreau M., Sweezey M.J., Lee K., Hodson P.V., Courtenay S.C. (2009). Toxicity of Orimulsion-400® to early life stages of Atlantic herring (Clupea harengus) and mummichog (Fundulus heteroclitus). Environmental Toxicology and Chemistry, 28(6) 1206-1217.

The toxicity of Orimulsion-400® (PDVSA-BITOR), an emulsion of 70% bitumen in 30% water, was tested during the embryonic development of Atlantic herring (Clupea harengus) and mummichog (Fundulus heteroclitus) in duplicate experiments. Air injection and different salinities were included in the herring assays to examine their effects on Orimulsion-400 toxicity. Water-accommodated fractions (WAFs) of no. 6 fuel oil were tested in the mummichog assays to compare Orimulsion-400 toxicity with that of a heavy fuel oil. Concentrations of Orimulsion-400 as low as 0.001% (v/v) were harmful to both species. In herring, the more sensitive of the two species, this concentration produced 100% abnormal larvae. Similar abnormalities, including pericardial edema and spinal deformities, the same signs of toxicity caused by heavy fuel oils and polycyclic aromatic hydrocarbons (PAH5), were produced in both herring and mummichog. Fish exposed to Orimulsion-400 also suffered from increased mortality, reduced heart rates, premature hatch, and reduced lengths compared to control fish. Orimulsion-400 was approximately 300-fold more toxic than the WAFs of no. 6 fuel oil. Salinity had few clear effects on Orimulsion-400 toxicity, but aeration of test solutions greatly reduced toxicity by causing bitumen to coalesce and float. Aeration also removed toxic chemicals such as PAHs. The present study suggests that in the event of a spill, Orimulsion-400 could impair fish recruitment, but that strong wave action would reduce toxicity by accelerating the removal of emulsified bitumen from the water column. © 2009 SETAC.
Bowron L.K., Munkittrick K.R., McMaster M.E., Tetreault G., Hewitt L.M. (2009). Responses of white sucker (Catostomus commersoni) to 20 years of process and waste treatment changes at a bleached kraft pulp mill, and to mill shutdown. Aquatic Toxicology, 95(2) 117-132.

The impacts of pulp mill effluents on white sucker (Catostomus commersoni) have been studied at Jackfish Bay, ON, Canada since the late 1980s. The site receives effluent from a large bleached kraft pulp mill which is the only source of chemical contamination in the area. Many laboratory studies have looked at the toxicological consequences of pulping process changes, but the benefit of these changes have not been looked at in wild fish. Jackfish Bay white sucker showed impacts on sexual maturity, gonad size, secondary sexual characteristics and circulating steroids hormone levels in the early years of the studies, and impacts were evaluated after installation of secondary treatment (1989), major pulping process changes (1995) and after the mill ceased pulp production and effluent release (2006). The addition of secondary treatment resulted in minor improvements in wild fish health, and the conversion to elemental chlorine free (ECF) bleaching at the mill was associated with more recovery in liver and gonad size. While some impacts persist at the exposure site, reproductive parameters showed further improvement during the mill shutdown period demonstrating that biologically active chemicals are still being discharged from modernized mills. © 2009 Elsevier B.V.
Clément M., St-Hilaire A., Caissie D., Chlasson A., Courtenay S., Hardie P. (2009). An evaluation of mitigation measures to reduce impacts of peat harvesting on the aquatic habitat of the East Branch Portage River, New Brunswick, Canada. Canadian Water Resources Journal, 34(4) 441-452.

The evaluation of impacts of peat harvesting on riverine ecosystems is essential to the implementation of adequate mitigation measures. The objective of the present study was to determine the potential impacts of peat harvesting on the physical (e.g., flow, suspended sediment concentration (SSC), water temperature) and biological (fish abundance) parameters of the East Branch Portage River, New Brunswick. This study was initiated in 2005 and a before and after study design was used to assess impacts. When the operational activities were initiated (spring 2007), 19 ha of peatland (15% of the total area scheduled for harvesting) was drained. The exploited area was drained through a network of ditches which emptied into a sedimentation pond. Drained water subsequently flowed into a 250 m vegetated buffer zone and discharged into the East Branch Portage River. Drained water did not diffuse throughout the buffer zone as expected. Rather, water tended to concentrate in a natural depression (channel) in the buffer zone, thus connecting the outflow of the sedimentation pond directly to the river. Two main results deserve attention. First, elevated SSC events were recorded in the East Branch Portage River downstream of the confluence of the channel formed in the buffer zone and the river. Periods of elevated SSC could be attributed to poor maintenance of the sedimentation pond. However, elevated SSC events were also recorded after pond maintenance and were concurrent with the timing of ditching activities within the peatland. Secondly, fish abundance was lower in 2007 compared to 2006 (pre-development period). However, potential impacts of peatland development on fish abundance should be interpreted with caution at this stage of the study. © 2009 Canadian Water Resources Association.
Daigle A., St-Hilaire A., Ouellet V., Corriveau J., Ouarda T.B.M.J., Bilodeau L. (2009). Diagnostic study and modeling of the annual positive water temperature onset. Journal of Hydrology, 370(1-4) 29-38.

A data-driven model is designed using artificial neural networks (ANN) to predict the average onset for the annual water temperature cycle of North-American streams. The data base is composed of daily water temperature time series recorded at 48 hydrometric stations in Québec (Canada) and northern US, as well as the geographic and physiographic variables extracted from the 48 associated drainage basins. The impact of individual and combined drainage area characteristics on the stream annual temperature cycle starting date is investigated by testing different combinations of input variables. The best model allows to predict the average temperature onset for a site, given its geographical coordinates and vegetation and lake coverage characteristics, with a root mean square error (RMSE) of 5.6 days. The best ANN model was compared favourably with parametric approaches. © 2009 Elsevier B.V. All rights reserved.
Danielescu S., MacQuarrie K.T.B., Faux R.N. (2009). The integration of thermal infrared imaging, discharge measurements and numerical simulation to quantify the relative contributions of freshwater inflows to small estuaries in Atlantic Canada. Hydrological Processes, 23(20) 2847-2859.

Nutrient fluxes from developed catchments are often a significant factor in the declining water quality and ecological functioning in estuaries. Determining the relative contributions of surface water and groundwater discharge to nutrient-sensitive estuaries is required because these two pathways may be characterized by different nutrient concentrations and temporal variability, and may thus require different remedial actions. Quantifying the volumetric discharge of groundwater, which may occur via diffuse seepage or springs, remains a significant challenge. In this contribution, the total discharge of freshwater, including groundwater, to two small nutrient-sensitive estuaries in Prince Edward Island (Canada) is assessed using a unique combination of airborne thermal infrared imaging, direct discharge measurements in streams and shoreline springs, and numerical simulation of groundwater flow. The results of the thermal infrared surveys indicate that groundwater discharge occurs at discrete locations (springs) along the shoreline of both estuaries, which can be attributed to the fractured sandstone bedrock aquifer. The discharge measured at a sub-set of the springs correlates well with the area of the thermal signal attributed to each discharge location and this information was used to determine the total spring discharge to each estuary. Stream discharge is shown to be the largest volumetric contribution of freshwater to both estuaries (83% for Trout River estuary and 78% for McIntyre Creek estuary); however, groundwater discharge is significant at between 13% and 18% of the total discharge. Comparison of the results from catchment-scale groundwater flow models and the analysis of spring discharge suggest that diffuse seepage to both estuaries comprises only about 25% of the total groundwater discharge. The methods employed in this research provide a useful framework for determining the relative volumetric contributions of surface water and groundwater to small estuaries and the findings are expected to be relevant to other fractured sandstone coastal catchments in Atlantic Canada. Copyright © 2009 John Wiley & Sons, Ltd.
Finley M.A., Courtenay S.C., Teather K.L., van den Heuvel M.R. (2009). Assessment of northern mummichog (Fundulus heteroclitus macrolepidotus) as an estuarine pollution monitoring species. Water Quality Research Journal of Canada, 44(4) 323-332.

The use of multiple spawning fishes in environmental effects monitoring programs has proven difficult for a number of reasons including the inability to predict reproductive investment and ensure synchronous sampling of reference and impacted populations. The estuarine resident northern mummichog (Fundulus heteroclitus macrolepidotus) has been successfully used as a sentinel for effects of pulp and paper mill effluents in Atlantic Canada and has been proposed for monitoring other anthropogenic impacts. This study investigated the spatial and temporal variability of the somatic parameters used to describe fish performance, specifically measures of energy use and storage, in estuaries located in Prince Edward Island, Canada. Three sites with varying levels of agricultural input were studied. Fish at all sites depleted their energy reserves over winter, as reflected in depressed condition, liver size, and gonad size, but then quickly replenished them in May. These population parameters were highly variable throughout the reproductive season and within an estuary. Spawning was continuous at all sites without indication of lunar or other periodicity. We conclude that repeated sampling is required to assess reproductive output in the northern mummichog and densities of adults and young-of-the-year deserve further investigation as a potentially less logistically demanding indicator of eutrophication. © 2009, CAWQ.
Gielen G.J.H.P., Heuvel M.R.v.d., Clinton P.W., Greenfield L.G. (2009). Factors impacting on pharmaceutical leaching following sewage application to land. Chemosphere, 74(4) 537-542.

Sewage effluent application to land is a treatment technology that requires appropriate consideration of various design factors. Soil type, level of sewage pre-treatment and irrigation rate were assessed for their influence on the success of soil treatment in removing pharmaceuticals remaining after conventional sewage treatment. A large scale experimental site was built to assess treatment performance in a realistic environment. Of the factors investigated, soil type had the biggest impact on treatment performance. In particular, carbamazepine was very efficiently removed (>99%) when irrigated onto a volcanic sandy loam soil. This was in contrast to irrigation onto a sandy soil where no carbamazepine removal occurred after irrigation. Differences were likely caused by the presence of allophane in the volcanic soil which is able to accumulate a high level of organic matter. Carbamazepine apparent adsorption distribution coefficients (K<inf>d</inf>) for both soils when irrigated with treated sewage effluent were determined as 25 L kg-1 for the volcanic soil and 0.08 L kg-1 for the sandy soil. Overall, a volcanic soil was reasonably efficient in removing carbamazepine while soil type was not a major factor for caffeine removal. Removal of caffeine, however, was more efficient when a partially treated rather than fully treated effluent was applied. Based on the investigated pharmaceuticals and given an appropriate design, effluent irrigation onto land, in conjunction with conventional sewage treatment may be considered a beneficial treatment for pharmaceutical removal. © 2008 Elsevier Ltd. All rights reserved.
Herrell A.M., Methven D.A. (2009). Annual and monthly variation in species composition and catches of fishes from the tabusintac river estuary in the Southern Gulf of St. Lawrence. Canadian Field Naturalist, 123(1) 48-67.

A total of 7130 fish from 13 taxa were collected during summer and autumn, 2002-2005 using box traps at two sites in the Tabusintac River Estuary, New Brunswick, Canada. The objective was to determine seasonal change in species composition and catches, and to access change in annual returns of Atlantic Salmon, an important recreational fishery during autumn on the Tabusintac, Miramichi and neighboring rivers. Taxa richness and composition varied annually and from trap to trap. Richness ranged from 8-10 taxa annually and catches were usually highest in the trap closest to the ocean despite its slightly smaller size. Taxa contributing greater than one percent of the total catch during the four years of sampling included six diadromous taxa: Blueback Herring and Alewife (41.65%), Striped Bass (21.54%), Atlantic Salmon (3.98%), Tomcod (2.95%), Brook Trout (1.05%), American Eel (5.27%); one freshwater species, White Sucker (11.96%); one marine species, Winter Flounder and one resident estuarine species, Smooth Flounder which together account for 11.19% of the total catch. The remaining five species (American Smelt, Northern Pipefish, White Perch, Cunner, Sea Lamprey) contributed 0.39% of the total catch. The fish fauna 14-15 km up the Tabusintac River was not species rich, due in large part to the limited sampling time each year and due to fishing with just one sampling gear, a stationary box trap. Additional species would have been collected if smaller mesh sampling gear were used. Comparisons were made with other studies and the phenology of the dominant species on the Tabusintac and Miramichi River Estuaries during the ice free season is established. Most catches appear to be related to pre- or post-spawning movements of anadromous fishes.
Irving E.C., Baird D.J., Culp J.M. (2009). Cadmium toxicity and uptake by mats of the freshwater diatom: Navicula pelliculosa (bréb) hilse. Archives of Environmental Contamination and Toxicology, 57(3) 524-530.

Contaminant uptake by algae, and its subsequent toxicity, has important ramifications for aquatic biomonitoring and environmental risk assessment. To study the effects of cadmium on diatom mats, a series of experiments was undertaken. These investigated the sensitivity of Navicula pelliculosa mats to cadmium, uptake of cadmium across a range of exposure concentrations, influence of mat biomass and thickness on uptake, and cadmium uptake by mats over time. Diatom mat formation proved to be sensitive to cadmium exposure, with a 96-h EC<inf>50</inf> of 31 μg/L. The rapid uptake of cadmium over 15 min was a linear function of exposure concentration and was not significantly affected by mat thickness. Cadmium uptake over time was also a linear function of exposure concentration for time periods up to 5 h. Linear uptake was likely due to the availability of algal binding sites as cadmium ions diffused through the diatom mats. Internal high-pH microenvironments may also have influenced uptake, through cadmium precipitation or enhanced adsorption within the mats. The lack of a significant relationship between mat biomass and uptake could be explained by the static water exposure conditions. Other studies have shown that cadmium uptake by algal mats was only significantly affected by biomass under flowing water conditions. Flowing water appeared to facilitate the diffusion of cadmium ions through the algal mats. Our research demonstrates the propensity of diatom mats to adsorb cadmium to achieve concentrations that could inhibit macroinvertebrate grazing. Overall, these findings contribute to a greater understanding of cadmium bioavailability in aquatic ecosystems and to the further development of benthic algae as an effective biomonitoring tool. © 2009 Springer Science+Business Media, LLC.
Jardine T.D., Kidd K.A., Cunjak R.A. (2009). An evaluation of deuterium as a food source tracer in temperate streams of eastern Canada. Journal of the North American Benthological Society, 28(4) 885-893.

Stable H isotope ratios (D/H, expressed as δD) hold promise as an additional tool for elucidating food sources for consumers in aquatic ecosystems. We tested the applicability of δD as a food source tracer in streams of New Brunswick, Canada. First, we analyzed δD and δ13C in biofilm and terrestrial leaves and compared signal-to-noise ratios (variability within sources vs variability between sources) between the 2 elements. Signal-to-noise ratios were roughly similar, and 23 of the 31 sites had isotopically distinct food sources based on δD compared to 20 of 31 based on δ13C. Second, we used mixing models to estimate % aquatic H and % aquatic C for benthic invertebrates at a subset of sites. Of 16 samples, only 1 had δ13C that was outside the range of the 2 food sources (yielding % aquatic C > 100%), but 12 of the 16 samples had δD outside the range of the food sources, a result suggesting confounding effects of water and lipids on total body H content. Last, we analyzed δD in laboratory-reared consumers (brook trout and water striders) and in their diet before and after lipid extraction to estimate diet-tissue fractionation. Large differences between consumer and diet were apparent before lipid extraction, but no significant differences were found after lipid extraction. All of these measures indicate that δD could serve as a complementary, but not alternative, isotopic method for estimating food sources for consumers in streams. Further laboratory trials are needed to explore the influence of lipids on δD values. © 2009 by The North American Benthological Society.
Jardine T.D., Kidd K.A., Cunjak R.A., Arp P.A. (2009). Factors affecting water strider (Hemiptera: Gerridae) mercury concentrations in lotic systems. Environmental Toxicology and Chemistry, 28(7) 1480-1492.

Water striders (Hemiptera: Gerridae) have been considered as a potential sentinel for mercury (Hg) contamination of freshwater ecosystems, yet little is known about factors that control Hg concentrations in this invertebrate. Striders were collected from 80 streams and rivers in New Brunswick, Canada, in August and September of 2004 through 2007 to assess the influence of factors such as diet, water chemistry, and proximity to point sources on Hg concentrations in this organism. Higher than average Hg concentrations were observed in the southwest and Grand Lake regions of the province, the latter being the location of a coal-fired power plant that is a source of Hg (∼100 kg annually), with elevated Hg concentrations in the lichen Old Man's Beard (Usnea spp.) in its immediate vicinity. Across all streams, pH and total organic carbon of water were relatively weak predictors of strider Hg concentrations. Female striders that were larger in body size than males had significantly lower Hg concentrations within sites, suggestive of growth dilution. There was no relationship between percent aquatic carbon in the diet and Hg concentrations in striders. For those striders feeding solely on terrestrial carbon, Hg concentrations were higher in animals occupying a higher trophic level. Mercury concentrations were highly variable in striders collected monthly over two growing seasons, suggesting short-term changes in Hg availability. These measurements highlight the importance of considering both deposition and postdepositional processes in assessing Hg bioaccumulation in this species. They also suggest that striders may be more appropriate as a terrestrial rather than an aquatic Hg sentinel, underscoring the importance of understanding the origin of food for organisms used in contaminant studies. © 2009 SETAC.
Khalil B., Ouarda T.B.M.J., St-Hilaire A. (2009). Reconstitute information about discontinued water quality variables in the nile delta monitoring network using two record extension techniques. World Academy of Science Engineering and Technology, 33 598-606.

The world economic crises and budget constraints have caused authorities, especially those in developing countries, to rationalize water quality monitoring activities. Rationalization consists of reducing the number of monitoring sites, the number of samples, and/or the number of water quality variables measured. The reduction in water quality variables is usually based on correlation. If two variables exhibit high correlation, it is an indication that some of the information produced may be redundant. Consequently, one variable can be discontinued, and the other continues to be measured. Later, the ordinary least squares (OLS) regression technique is employed to reconstitute information about discontinued variable by using the continuously measured one as an explanatory variable. In this paper, two record extension techniques are employed to reconstitute information about discontinued water quality variables, the OLS and the Line of Organic Correlation (LOC). An empirical experiment is conducted using water quality records from the Nile Delta water quality monitoring network in Egypt. The record extension techniques are compared for their ability to predict different statistical parameters of the discontinued variables. Results show that the OLS is better at estimating individual water quality records. However, results indicate an underestimation of the variance in the extended records. The LOC technique is superior in preserving characteristics of the entire distribution and avoids underestimation of the variance. It is concluded from this study that the OLS can be used for the substitution of missing values, while LOC is preferable for inferring statements about the probability distribution.
Kieffer J.D., Arsenault L.M., Litvak M.K. (2009). Behaviour and performance of juvenile shortnose sturgeon Acipenser brevirostrum at different water velocities. Journal of Fish Biology, 74(3) 674-682.

Critical swimming speeds (mean ± s.e.) for juvenile shortnose sturgeon Acipenser brevirostrum were 34.4 cm s-1 ± 1.7 (2.18 ± 0.09 body lengths, BL s-1). Swimming challenges at 10, 20 and 30 cm s-1 revealed that juvenile A. brevirostrum are relatively poor swimmers, and that the fish did not significantly modify their swimming behaviour, although they spent more time substratum skimming (i.e. contact with flume floor) at 30 cm s-1 relative to 10 cm s-1. When present, these behavioural responses are probably related to morphological features, such as flattened rostrum, large pectoral fins, flattened body shape and heterocercal tail, and may be important to reduce the costs of swimming. © 2009 The Authors.
Kieffer J.D., Cooke S.J. (2009). Physiology and Organismal Performance of Centrarchids. Centrarchid Fishes Diversity Biology and Conservation 207-263.
Kieffer J.D., Wakefield A.M. (2009). Oxygen consumption, ammonia excretion and protein use in response to thermal changes in juvenile Atlantic salmon Salmo salar. Journal of Fish Biology, 74(3) 591-603.

Experiments were designed to examine the effects of various temperature challenges on oxygen consumption and ammonia excretion rates and protein utilization in juvenile Atlantic salmon Salmo salar. Fish acclimated to 15°C were acutely and abruptly exposed to either 20 or 25°C for a period of 3 h. To simulate a more environmentally relevant temperature challenge, a third group of fish was exposed to a gradual increase in temperature from 15 to 20°C over a period of 3 h (c. 1.7°C h-1). Oxygen consumption and ammonia excretion rates were monitored before, during and after the temperature shift. From the ammonia excretion and oxygen consumption rates, protein utilization rates were calculated. Acute temperature changes (15-20°C or 15-25°C) caused large and immediate increases in the oxygen consumption rates. When the temperature was gradually changed (i.e. 1.7°C h-1), however, the rates of oxygen consumption and ammonia excretion were only marginally altered. When fish were exposed to warmer temperatures (i.e. 15-20°C or 15-25°C) protein use generally remained at pre-exposure (15°C) levels. A rapid transfer back to 15°C (20-15°C or 25-15°C) generally increased protein use in S. salar. These results indicate that both the magnitude and the rate of temperature change are important in describing the physiological response in juvenile salmonids. © 2009 The Authors.
Kullman M.A., Kidd K.A., Podemski C.L., Paterson M.J., Blanchfield P.J. (2009). Assimilation of freshwater salmonid aquaculture waste by native aquatic biota. Canadian Journal of Fisheries and Aquatic Sciences, 66(11) 1965-1975.

An experimental finfish aquaculture farm was operated in a small lake at the Experimental Lakes Area in northwestern Ontario, Canada. In this study, we used the distinct and enriched carbon and nitrogen isotope ratios (δ13C and δ15N) of rainbow trout (Oncorhynchus mykiss) feed and waste to determine whether the operation provided a novel source of energy for native biota. For 1 year prior to and for 3 years during the cage culture, we collected littoral, pelagic, and profundal invertebrates and minnows from the experimental and reference lakes. In both the second and third years of aquaculture, there was a significant increase in δ15N of all organisms sampled in the experimental lake; mean δ15N values of littoral, pelagic, and profundal invertebrates and minnows shifted towards the signature of the fish feed by up to 4.2%. Significant increases in δ13C of up to 2.6% were observed in Mysis, profundal chironomids, and minnows but not in littoral invertebrates or zooplankton. Aquaculture waste became a progressively more important component of minnow diets over the course of this study. The dissolved and (or) particulate wastes of the cage operation became a novel source of energy for the native biota in this experimental lake.
Linnansaari T., Alfredsen K., Stickler M., Arnekleiv J.V., Harby A., Cunjak R.A. (2009). Does ice matter? site fidelity and movements by Atlantic salmon (Salmo salar l.) parr during winter in a substrate enhanced river reach. River Research and Applications, 25(6) 773-787.

In-stream habitat enhancement is a common remedial action in rivers where degradation/lack of suitable fish habitat can be diagnosed. However, post-project monitoring to assess the response of the biota to modification is rare particularly during winter. We conducted in situ monitoring during the winters of 2004-2006 in the regulated Dalåa River, central Norway, in order to determine if winter habitat requirements of Atlantic salmon (Salmo salar L.) parr were realized in an enhanced (substrate and mesohabitat modification) reach. In total, 140 parr were marked with passive integrated transponder (PIT) tags and the fish were followed by carrying out active tracking surveys under variable ice conditions throughout the winter. Highest emigration (44%) occurred before ice formation started. Emigration was reduced after ice formed and was largely offset by parr re-entering the enhanced area. Dispersal into the non-enhanced, small substrate control area was observed only when the study reach was ice covered, and no parr were subsequently encountered in the control section after ice had melted. In the enhanced area, declining water temperature and surface ice conditions did not affect the spatial distribution of the resident salmon parr at the studied scale. Areas with 'solid' anchor ice precluded access for salmon parr whilst areas with 'patchy' anchor were used throughout the winter. Our results indicate that surface ice creates conditions that allow salmon parr to use stream habitats that otherwise provide only a limited amount of in-stream cover. Ice processes should be taken into consideration when habitat enhancement projects are carried out and subsequently assessed for effectiveness. © 2008 John Wiley & Sons, Ltd.
Lopes I., Martins N., Baird D.J., Ribeiro R. (2009). Genetic erosion and population resilience in daphnia longispina o.f. müller under simulated predation and metal pressures. Environmental Toxicology and Chemistry, 28(9) 1912-1919.

This study investigated the effects of nonselective predation (culling) and metal toxicity on the genetic diversity of laboratory populations of the cladoceran Daphnia longispina. Populations, comprising five clones differing in their sensitivity to lethal concentrations of a metal-rich mine drainage effluent, were subjected to all possible combinations of three levels (absent, weak, and strong) of each stressor. Observed population densities were compared to those expected from a life history experiment, and clone frequencies were determined by allozyme profiling. Culling did not affect population density, although clonal diversity was higher than the control. Populations stressed by mine drainage recovered to their initial densities within 12 days, though the most sensitive genotypes disappeared under both weak and strong metal stress levels. Because the surviving resistant clones were shown to be the most sensitive ones to other chemicals (Cd and H+), it is suggested that successive inputs of partially lethal concentrations of different chemicals can lead to the disappearance of the population, even if the time between inputs is large enough to allow density recovery. These results suggest that changes in abundance are not enough to evaluate ecological effects of chemicals on the environment and information on co-tolerance and multiple tolerance within populations is highly valuable to prevent their extinction. Moreover, populations exposed to low levels of both stressors showed clonal diversity levels identical to controls, highlighting the importance of low level effects of nonselective stressors in the maintenance of high clonal diversity levels in Daphnia populations, and thus further supporting the intermediate disturbance hypothesis. © 2009 SETAC.
Lorrain A., Graham B., Ménard F., Popp B., Bouillon S., Van Breugel P., Cherel Y. (2009). Nitrogen and carbon isotope values of individual amino acids: A tool to study foraging ecology of penguins in the Southern Ocean. Marine Ecology Progress Series, 391 293-306.

We determined the δ15N and δ13C values of individual amino acids (AAs) isolated from chick blood of 4 penguin species that forage in different oceanic regions (from the subtropics of the Indian Ocean to Antarctica) to test if: (1) the δ15N values of phenylalanine (δ15N<inf>phe</inf>) revealed different foraging areas among the species; (2) the difference between glutamic acid and phenylalanine δ15N values (δδ15N <inf>glu-phe</inf>) accurately predicted trophic levels; and (3) the δ13C value of AAs could resolve species foraging locations, similar to bulk δ13C values. The δ13C values of all AAs decreased with latitude, were positively correlated with bulk δ13C data, and, therefore, tracked the isotopic baseline. However, we were not able to discern additional ecological information from these δ13C values. In contrast, the δ15N values of AAs distinguished the isotopic value of the nitrogen at the base of the food web from the trophic level of the consumer, providing new insight for the study of the trophic ecology of seabirds. The difference in the bulk δ15N values of northern and southern rockhopper penguins Eudyptes chrysocome ssp. was due to both a difference in their foraging location (different δ15N<inf>phe</inf>) and their trophic levels (different Δδ15N<inf>glu-phe</inf>). The δ15N<inf>phe</inf> values of king Aptenodytes patagonicus and Adélie penguins Pygoscelis adeliae were higher than those of rockhoppers, which could reflect a foraging on mesopelagic prey for king penguins and, in the highly productive Antarctic shelf waters, for Adelie penguins. The Δδ15N<inf>glu-phe</inf> accurately reflected the relative trophic level of penguins, but further work is required to determine the trophic enrichment factors for compound-specific isotope analysis.
McMullin V.A., Munkittrick K.R., Methven D.A. (2009). Latitudinal variability in lunar spawning rhythms: Absence of a lunar pattern in the northern mummichog Fundulus heteroclitus macrolepidotus. Journal of Fish Biology, 75(4) 885-900.

In this study, the natural spawning season of the northern mummichog Fundulus heteroclitus macrolepidotus was examined from May to July in the lower St John River, New Brunswick, Canada (45° N), through measurements of gonado-somatic index (I<inf>G</inf>), liver-somatic index (I<inf>L</inf>) and condition factor (K). I<inf>G</inf> increased during the prespawning phase (mean ±s.e. 5.49 ± 0.20%), peaked during the spawning phase (14.68 ± 0.51%) and dropped during the regression phase (3.23 ± 0.29%). A single peak of spawning was observed in F. h. macrolepidotus, contrasting with multiple peaks observed in studies south of 41° N in North America. Within the prespawning phase, there were significant differences between sampling dates in female body mass, gonad mass, liver mass and K. On the basis of results from this study, water temperature is believed to be the predominant factor controlling initiation of spawning in F. h. macrolepidotus. © 2009 The Fisheries Society of the British Isles.
Melvin S.D., Munkittrick K.R., Bosker T., Maclatchy D.L. (2009). Detectable effect size and bioassay power of mummichog (Fundulus heteroclitus) and fathead minnow (Pimephales promelas) adult reproductive tests. Environmental Toxicology and Chemistry, 28(11) 2416-2425.

Although multiple reproductive tests have been developed, in small-bodied fish to determine the effects of endocrinedisrupting substances, few direct comparisons have been made among the available tests. Side-by-side reproductive tests with mummichog (Fundulus heteroclitus) and fathead minnow (FHM; Pimephales promelas) were conducted with 0, 3, 10, and 30% effluent from a bleached, kraft pulp mill in Saint John, New Brunswick, Canada. Egg production was significantly increased in mummichog exposed to 3% combined mill effluent, but no difference was observed in FHM. No differences were found in whole-body testosterone or estradiol, levels in mummichog, and whole-body 11-ketotestosterone levels in males were increased in 3% exposed fish compared to those in 10% effluent. Male FHM exposed to 30% effluent had increased, whole-body testosterone levels, and female FHM in 30% effluent had decreased, testosterone. No differences in estradiol or 11-ketotestosterone were observed, in FHM. Relatively limited response occurred in other endpoints. A comparison of the results of the present study to other published studies suggests that current reproductive bioassays are only sensitive for detecting magnitudes of change of greater than 50% and that differences exist in the sensitivities offish. Future research should address methods of reducing variability within test populations and focus on understanding the comparative responses among species commonly used for endocrine-disrupting substance testing. © 2009 SETAC.
Munkittrick K.R. (2009). Ubiquitous criticisms of ecological field studies. Human and Ecological Risk Assessment, 15(4) 647-650.
Munkittrick K.R., Arens C.J., Lowell R.B., Kaminski G.P. (2009). A review of potential methods of determining critical effect size for designing environmental monitoring programs. Environmental Toxicology and Chemistry, 28(7) 1361-1371.

The effective design of field studies requires that sample size requirements be estimated for important endpoints before conducting assessments. This a priori calculation of sample size requires initial estimates for the variability of the endpoints of interest, decisions regarding significance levels and the power desired, and identification of an effect size to be detected. Although many programs have called for use of critical effect sizes (CES) in the design of monitoring programs, few attempts have been made to define them. This paper reviews approaches that have been or could be used to set specific CES. The ideal method for setting CES would be to define the level of protection that prevents ecologically relevant impacts and to set a warning level of change that would be more sensitive than that CES level to provide a margin of safety; however, few examples of this approach being applied exist. Program-specific CES could be developed through the use of numbers based on regulatory or detection limits, a number defined through stakeholder negotiation, estimates of the ranges of reference data, or calculation from the distribution of data using frequency plots or multivariate techniques. The CES that have been defined often are consistent with a CES of approximately 25%, or two standard deviations, for many biological or ecological monitoring endpoints, and this value appears to be reasonable for use in a wide variety of monitoring programs and with a wide variety of endpoints. © 2009 SETAC.
Palace V.P., Evans R.E., Wautier K.G., Mills K.H., Blanchfield P.J., Park B.J., Baron C.L., Kidd K.A. (2009). Interspecies differences in biochemical, histopathological, and population responses in four wild fish species exposed to ethynylestradiol added to a whole lake. Canadian Journal of Fisheries and Aquatic Sciences, 66(11) 1920-1935.

Efforts to understand the effects of environmental estrogens on fish have shifted away from biochemical indicators towards population-level impacts. Ethynylestradiol (EE2) was added to a whole lake at environmentally relevant concentrations for 3 consecutive years to examine links between vitellogenin (VTG) induction, histopathological impacts, and population decline in four species of fish. VTG induction and histopathological effects in tissues were most severe in fathead minnow (Pimephales promelas) and pearl dace (Margariscus margarita). VTG was induced to a similar extent in lake trout (Salvelinus namaycush) but less so in white sucker (Catostomus commersonii). There were no histopathological effects in tissues of the two latter species. Population decline occurred in fathead minnows in the second year of EE2 additions and there were some indications of population decline in pearl dace during the third year. White suckers were not affected but lake trout declined in year 3. Habitat selection probably altered EE2 exposure and the different effects in each species likely also reflect differing sensitivities. It appears that VTG induction is not sufficient to predict effects of xenoestrogens on fish populations. However, stronger predictions can be made when VTG induction is assessed in conjunction with histopathological evidence of liver, kidney, and gonad tissue damage.
Pavey B., Courtenay S., St-Hilaire A., Ourda T. (2009). Sediment deposition rates downstream of harvested and natural peat bogs in New Brunswick, Canada. Advances in Geosciences Volume 11 Hydrological Science Hs 207-221.

Peat harvesting is an important industry in many countries, including Canada. To harvest peat, bogs are drained and drainage water is evacuated toward neighboring rivers, estuaries, or coastal waters. Previous research in New Brunswick (Canada) has demonstrated that suspended solids in this drainage water can compromise fish habitat where it settles out and smothers the benthos. The objectives of this study were to quantify the particle size distribution and organic content of deposited sediments in addition to determining deposition rates. Results show that most of the material settling immediately downstream of harvested bogs is inorganic. Grain sizes were different between the reference and harvested sites, with the former showing a greater percentage of sand than the latter. Deposition rates are significantly higher at harvested sites than at the reference, unperturbed bog.
Pestana J.L.T., Alexander A.C., Culp J.M., Baird D.J., Cessna A.J., Soares A.M.V.M. (2009). Structural and functional responses of benthic invertebrates to imidacloprid in outdoor stream mesocosms. Environmental Pollution, 157(8-9) 2328-2334.

Structural and functional responses of a benthic macroinvertebrate assemblage to pulses of the insecticide imidacloprid were assessed in outdoor stream mesocosms. Imidacloprid pulses reduced invertebrate abundance and community diversity in imidacloprid-dosed streams compared to control streams. These results correlated well with effects of imidacloprid on leaf litter decomposition and feeding rates of Pteronarcys comstocki, a stonefly, in artificial streams. Reductions in oxygen consumption of stoneflies exposed to imidacloprid were also observed in laboratory experiments. Our findings suggest that leaf litter degradation and single species responses can be sensitive ecotoxicological endpoints that can be used as early warning indicators and biomonitoring tools for pesticide contamination. The data generated illustrates the value of mesocosm experiments in environmental assessment and how the consideration of functional and structural endpoints of natural communities together with in situ single species bioassays can improve the evaluation and prediction of pesticide effects on stream ecosystems. © 2009 Elsevier Ltd.
Pestana J.L.T., Loureiro S., Baird D.J., Soares A.M.V.M. (2009). Fear and loathing in the benthos: Responses of aquatic insect larvae to the pesticide imidacloprid in the presence of chemical signals of predation risk. Aquatic Toxicology, 93(2-3) 138-149.

The influence of interactions between pesticide exposure and perceived predation risk on the lethal and sub-lethal responses of two aquatic insects was investigated using the pesticide imidacloprid, and a combination of predator-release kairomones from trout and alarm substances from conspecifics. Laboratory experiments examined feeding and respiration rates of the caddisfly Sericostoma vittatum as well as the growth, emergence and respiration rates of the midge Chironomus riparius, exposed to sub-lethal concentrations of imidacloprid. The effects of the two stressors on burrowing behaviour of both species were also assessed. The results show significant effects of environmentally relevant concentrations of imidacloprid on all endpoints studied. Perceived predation risk also elicited sub-lethal effects in C. riparius and S. vittatum, the latter species being less responsive to predation cues. The effects of simultaneous exposure to both types of stressors were assessed using two different approaches: analysis of variance and conceptual models [concentration addition (CA) and independent action (IA)] normally used for the evaluation of contaminant mixture exposure. Both statistical approaches showed no significant interactions on responses in simultaneous exposures in the majority of parameters assessed with only a signification deviation from the reference CA and IA models being found for C. riparius respiration data contrary to the ANOVA results. Exposure to imidacloprid also compromised antipredator behavioural responses of both insect species, with potential negative consequences in terms of mortality from predation in the field. The results obtained demonstrate that natural and anthropogenic stressors can be treated within the same framework providing compatible data for modelling. For an improved interpretation of ecological effects it will be important to expand the mechanistic study of effects of combined exposure to pesticides and perceived predation risk by measuring different endpoints over a wider range of pesticide concentrations. © 2009 Elsevier B.V.
Pooley K.E., Blessing M., Schmidt T.C., Haderlein S.B., Macquarrie K.T.B., Prommer H. (2009). Aerobic biodegradation of chlorinated ethenes in a fractured bedrock aquifer: Quantitative assessment by compound-specific isotope analysis (CSIA) and reactive transport modeling. Environmental Science and Technology, 43(19) 7458-7464.

A model-based analysis of concentration and isotope data was carried out to assess natural attenuation of chlorinated ethenes in an aerobic fractured bedrock aquifer. Tetrachloroethene (PCE) concentrations decreased downgradient of the source, but constant δ13C signatures indicated the absence of PCE degradation. In contrast, geochemical and isotopic data demonstrated degradation of trichloroethene (TCE) and cis-1,2-dichloroethene (DCE) under the prevailing oxic conditions. Numerical modeling was employed to simulate isotopic enrichment of chlorinated ethenes and to evaluate alternative degradation pathway scenarios. Existing field information on groundwater flow, solute transport, geochemistry, and δ13C signatures of the chlorinated ethenes was integrated via reactive transport simulations. The results provided strong evidence for the occurrence of aerobic TCE and DCE degradation. The chlorinated ethene concentrations together with stable carbon isotope data allowed us to reliably constrain the assessment of the extent of biodegradation at the site and plume simulations quantitatively linked aerobic biodegradation with isotope signatures in the field. Our investigation provides the first quantitative assessment of aerobic biodegradation of chlorinated ethenes in a fractured rock aquifer based on compound specific stable isotope measurements and reactive transport modeling. © 2009 American Chemical Society.
Satapornvanit K., Baird D.J., Little D.C. (2009). Laboratory toxicity test and post-exposure feeding inhibition using the giant freshwater prawn Macrobrachium rosenbergii. Chemosphere, 74(9) 1209-1215.

A bioassay was developed using post-larvae of freshwater prawn Macrobrachium rosenbergii (length 9-10 mm) in order to determine the toxicity of profenofos, dimethoate, chlorpyrifos, carbendazim and zinc. This was the first study in the tropics with M. rosenbergii, particularly at the post-larvae stage (9-10 mm) on lethal (LC<inf>50</inf>) and sublethal (EC<inf>50</inf>) effects of toxic substances using post-exposure feeding rate as end point. Median lethal concentrations (LC<inf>50</inf> at 24 and 48 h) were respectively estimated as 11.6 and 9.8 μg L-1 for profenofos, 142.1 and 102.7 μg L-1 for dimethoate, 0.7 and 0.3 μg L-1 for chlorpyrifos, and 439.7 and 329 μg L-1 for zinc. Effects of carbendazim could not be estimated because carbendazim exposure needs more than 24 h exposure period to produce observable effects at the concentrations used. The EC<inf>50</inf> using post-exposure feeding rates determined for profenofos, dimethoate, chlorpyrifos and zinc were 6.023, 269.3, 0.293 and 109.01 μg L-1, respectively, at 24 h of exposure. Only chlorpyrifos and zinc had LC<inf>50</inf> concentrations greater than the post-exposure feeding EC<inf>50</inf> concentrations. This study demonstrated that the M. rosenbergii could also be used as a test animal to detect the effects of different chemical contaminants in aquatic environments. © 2008 Elsevier Ltd. All rights reserved.
Wartman C.A., Hogan N.S., Hewitt L.M., McMaster M.E., Landman M.J., Taylor S., Kovacs T.G., van den Heuvel M.R. (2009). Androgenic effects of a Canadian bleached kraft pulp and paper effluent as assessed using threespine stickleback (Gasterosteus aculeatus). Aquatic Toxicology, 92(3) 131-139.

The presence of unidentified estrogens and androgens in effluents from pulp and paper mills is well documented. However, their role in effluent effects on fish reproduction remains unclear. The objective of this study was to investigate the hypothesis that reproductive impacts of a modern pulp mill effluent are mediated by androgens and/or estrogens in the effluent. Male and female threespine stickleback were exposed to biologically treated Canadian bleached kraft mill effluent under flow-through conditions in the laboratory at 0, 1, 10 and 100% (v/v) dilutions. After 7 and 21 d of exposure, steroidogenesis was assessed using in vitro incubations of gonadal tissue in both males and females. mRNA expression of the estrogen-regulated gene vitellogenin, and the androgen-responsive gene spiggin were assessed using quantitative RT-PCR in the livers of male and posterior kidneys of female stickleback, respectively. Hepatic 7-ethoxyresorufin-O-deethylase (EROD) activity was assessed in both sexes. Effluent extracts were examined for estrogenic and androgenic bioactivity using receptor binding bioassays, and were screened for pulp and paper related extractives and steroidal androgens using GC-MS. This effluent up-regulated spiggin mRNA in the kidney of female stickleback at 10% and 100% (v/v) effluent at 21 d, but not at 7 d of exposure. This change at the mRNA expression of the gene was associated with an increase in cell height in kidney proximal tubule epithelial cells at 100% effluent after both 7 and 21 d. Liver vitellogenin mRNA in male stickleback was not induced at either 7 or 21 d. EROD was induced at 10 and 100% after 21 d of exposure in both sexes, but not after 7 d of exposure. Despite evidence of exposure to androgens, there was no reduction in steroidogenic capacity at any effluent dilution. Effluent extracts were capable of eliciting the displacement of androgens and estrogens from receptors, but androgenic potency was 4-fold greater. A screen of more than 30 androgenic androstane steroids showed no detections. Hence, the androgenic constituents in this particular effluent remain unknown. © 2009 Elsevier B.V.
Whitfield P.H., St-Hilaire A., Van Der Kamp G. (2009). Improving hydrological predictions in peatlands. Canadian Water Resources Journal, 34(4) 467-478.

Peatlands form an important part of the Canadian landscape and of many Canadian drainage basins. While there is a considerable body of literature and existing research on peatlands, this paper presents a discussion of areas that should be considered in the future to improve hydrological predictions for drainage basins that contain a significant proportion of peatlands. The critical hydrological issues concern evapotranspiration from peatlands and the water storage and water transmission properties of peatlands as influenced by the structure and composition of peat. The transient surface and subsurface exchange of peatland water with adjacent peatlands and with the surrounding uplands is also important but difficult to characterize. A related area of research is determining how organic matter decomposes and accumulates and changes through time creating the shallow aquifer-aquitard system that is a peatland. The resulting structural differences lead to hydrological, chemical, and ecological differences that reflect the diversity and complexity of peatlands across Canada. This synthesis was informed by the contents of the present volume and the opinions of a cross-section of our colleagues. © 2009 Canadian Water Resources Association.
Whitfield P.H., Van Der Kamp G., St-Hilaire A. (2009). Introduction to peatlands special issue: Improving hydrological prediction in canadian peatlands. Canadian Water Resources Journal, 34(4) 303-310.

Following from a session on the topic of peatland hydrology held at the 2008 conference of the Canadian Water Resources Association, this special issue collates papers on research dealing with water in peatlands in Canada. Tnis introduction paper presents a brief overview of the importance of peatlands in Canada, the main characteristics of peatland from a water perspective, and provides the background on the main differences between bogs and fens. Recent peatland research is summarized, covering the breadth of physical hydrology of peatlands, peatland water chemistry, the effects of changes in water balance, the characteristics of marginal transition zones, bog restoration, the potential impacts of climate change, and the needs for future research. © 2009 Canadian Water Resources Association.
Wrona F.J., Culp J.M., Prowse T.D. (2009). Basin Management Approaches used in a High-Latitude Northern Catchment - The Mackenzie River Basin. Handbook of Catchment Management 477-500.
Wyn B., Kidd K.A., Burgess N.M., Allen Curry R. (2009). Mercury biomagnification in the food webs of acidic lakes in Kejimkujik National Park and National Historic Site, Nova Scotia. Canadian Journal of Fisheries and Aquatic Sciences, 66(9) 1532-1545.

Mercury (Hg) concentrations in fish from acidic lakes (pH < 6.0) are typically elevated above those from nearneutral systems. It is unknown whether high biomagnification rates through the supporting food web can explain elevated Hg concentrations in top predators from low pH lakes. To investigate this, we collected yellow perch (Perca flavescens), brown bullhead (Ameiurus nebulosus), banded killifish (Fundulus diaphanous), golden shiner (Notemigonus crysoleucas), and littoral and pelagic invertebrates from four acidic lakes in Kejimkujik National Park and Historic Site (KNPNHS), Nova Scotia, Canada, and analyzed them for total Hg and methyl Hg (MeHg), and δ13C and δ15N to determine sources of energy and trophic position, respectively. Mercury biomagnification rates (slopes of log Hg versus δ15N) varied significantly among the four lakes but did not explain the among-lake differences in perch Hg; these slopes were also within the range published for nearneutral systems. Rather, Hg concentrations in yellow perch (i.e., predatory fish) in KNPNHS were higher in lakes with higher MeHg in lower-trophic-level organisms and suggest that processes influencing Hg uptake at the base of the food web are more important than rates of food web biomagnification for understanding the variation in concentrations of this contaminant among top predators.
Aguilar C., González-Sansón G., Faloh I., Curry R.A. (2008). Spatial variation in stable isotopes (δ13C and δ 15N) in marine fish along the coast of Havana City: Evidence of human impacts from harbor and river waters. Journal of Coastal Research, 24(5) 1281-1288.

We examined the hypothesis that nutrients from land sources are enhancing the food supply for fish in coastal reefs of northwestern Cuba. Spatial variation in stable isotope ratios (δ13C and δ15N) was investigated at two sites heavily impacted by mixed pollution sources in Havana City, Cuba, and two reference sites. Significant differences in isotope signatures were found among sites for territorial species, e.g., δ15N was consistently enriched at impacted sites. The most plausible explanation is enriched nitrogen and carbon sources in the food web derived from organic pollution of the coastal zone by human wastewaters. This supports earlier findings that fish were larger in the vicinity of the harbor because of nutrient additions due to sewage that can increase ecosystem productivity and enhance growth of fish. It is also evidence of the direct land-to-water linkage in coastal zone food webs and illustrates how additional nutrients may affect marine food web functions.
Alexander A.C., Heard K.S., Culp J.M. (2008). Emergent body size of mayfly survivors. Freshwater Biology, 53(1) 171-180.

1. Employing field-deployed mesocosms, we examined the effects of 12-h pulse and 20-day press (continuous) exposures of the common agricultural insecticide, imidacloprid, on nymph abundance, emergence patterns and adult body size of Epeorus spp. (Heptageniidae) and Baetis spp. (Baetidae). 2. In press exposures, reduced nymph density was driven by reduced survivorship; in pulse exposures, reduced nymph density may reflect increased emergence because of stress. 3. Once exposed to imidacloprid, Epeorus and Baetis mayflies developed less and emerged smaller than their control counterparts. Concentrations as low as 0.1 μg L-1 (12-h pulse) reduced head length in Baetis and thorax length in Epeorus. 4. In all of the Baetis and Epeorus examined, effects were only found in males. Male survivorship and body size can affect population dynamics. Sublethal doses of this widely applied agricultural insecticide have the potential to reduce reproductive success of mayfly populations. © 2007 The Authors.
Baird D.J., Rubach M.N., Van Den Brink P.J. (2008). Trait-based ecological risk assessment (TERA): The new frontier? Integrated Environmental Assessment and Management, 4(1) 2-3.

Traits describe the physical characteristics, ecological niche, and functional role of species within ecosystems, and traitbased approaches are now being introduced into the field of Ecological Risk Assessment (ERA). The costs and benefits arising from the adoption of these approaches in the assessment of risks from toxic substances are described, and the path forward for this new frontier in risk assessment science is presented. In particular, the necessity for more open collaboration and webbased data-sharing to facilitate the development of these exciting new tools is stressed, and the role of scientific organizations such as SETAC as promoters of this ambitious program is highlighted © 2008 SETAC.
Baker D.W., Peake S.J., Kieffer J.D. (2008). The effect of capture, handling, and tagging on hematological variables in wild adult lake sturgeon. North American Journal of Fisheries Management, 28(1) 296-300.

We measured hematocrit and plasma osmolality, cortisol, lactate, glucose, and chloride in wild lake sturgeon Acipenser fulvescens after gill-net capture (24-h sets) and multiple bouts of brief (2-3-min) air exposure during removal from nets and again during measurement and tagging procedures. Our objective was to evaluate the physiological consequences associated with capture, handling, and tagging activities commonly employed during mark-recapture studies and to determine whether blood chemistry values moved toward a resting state after a 3-d recovery period. Lake sturgeon that were caught during spring tagging activities showed plasma cortisol, glucose, lactate, osmolality, and chloride levels similar to those exhibited by maximally stressed lake sturgeon in published laboratory studies. After the 3-d recovery period, all physiological stress indicators had approached a nonstressed state and the values were similar to those previously reported for resting lake sturgeon. It appears that capture-mark-recapture programs that subject lake sturgeon to stressors similar to those applied here do not pose a significant threat to this often legislatively protected species. © Copyright by the American Fisheries Society 2008.
Couillard C.M., Courtenay S.C., Macdonald R.W. (2008). Chemical-environment interactions affecting the risk of impacts on aquatic organisms: A review with a Canadian perspective -interactions affecting vulnerability. Environmental Reviews, 16 19-44.

Environmental change can increase the vulnerability of aquatic species to toxic chemicals by challenging an organism's aptitude to respond to chemicals or to repair toxic injury or by modifying animal behaviours like migration or predation. On the other hand, xenobiotics may affect the capacity of aquatic species to adapt to environmental challenges that come with change (e.g., pathogens, temperature). Across Canada we have identified a number of circumstances where chemicals and environmental variability have likely worked together to affect vulnerability of aquatic organisms. For example in the Maritimes, exposure to municipal wastewater or bleached kraft pulp mill effluent altered immune function in bivalves and increased their risk of developing haemocytic neoplasia, a disease known to cause high mortality. Northwest Atlantic cod stocks have experienced large-scale changes in environment and exhibit marked seasonal cycles in energy reserves. The risk associated with subsequent redistribution of persistent chemicals in the body together with nutritional deficiency is presently under evaluation since it could affect the recovery of these endangered stocks. In the Great Lakes, the introduction of an invasive fish species, the alewife, modified the diet of salmonids, which led to a deficiency of the vitamin thiamine in eggs causing early mortality. Contaminants may interact with thiamine deficiency and thus critically impair recruitment of salmonids. Viewing the risks presented by toxic chemicals from the point of view of species vulnerability, offers managers opportunities to mitigate such risks, for example, through habitat, ocean and fisheries management. Further research is needed to develop biomarkers of vulnerability, identify most vulnerable life stages and populations, to understand the interactions between global environmental changes, nutritional status, pathogens and toxic chemicals, and to develop integrated approaches to manage vulnerability of aquatic ecosystems to toxic chemicals. © 2008 NRC Canada.
Couillard C.M., Macdonald R.W., Courtenay S.C., Palace V.P. (2008). Chemical-environment interactions affecting the risk of impacts on aquatic organisms: A review with a Canadian perspective -interactions affecting exposure. Environmental Reviews, 16 1-17.

As a consequence of human activity, the variability and range of environmental conditions is increasing. We review how the interactions between toxic chemicals and environmental change may affect exposure of aquatic organisms to stressful conditions and therefore alter the risk of deleterious impacts. Even in the absence of new inputs of contaminants, changing environmental conditions alters the transport, transformation and distribution of contaminants and their bioavailability. Conversely, some toxic chemicals modify the exposure of aquatic species to other stressors by affecting species distribution, behaviour or habitat. Across Canada there are a number of specific examples where interactions between contaminants and environmental change are probably harming aquatic species. In the Arctic, change in foraging brought on by change in ice regime, is a plausible mechanism to explain the marked recent increase in mercury concentrations in Beaufort Sea beluga whales. On the Pacific coast, chemical exposure by itself or in combination with other environmental factors, is a leading suspect for altered migration timing of some salmon stocks in the Fraser River leading to massive prespawning mortality. In the North Atlantic, short-term exposure of Atlantic salmon to endocrine-disrupting substances in their freshwater natal environments later leads to detectable effects at the time of their migration to saltwater. In Alberta, biotic and abiotic characteristics of the habitat dramatically affect exposure pathways and the risk of toxic effects of selenium in early life stages of trout. A better understanding of the interactions between toxic chemicals and environmental factors is a fundamental requirement for efficient management and protection of aquatic ecosystems. © 2008 NRC Canada.
Dubé M.G., Munkittrick K.R., Mark Hewitt L. (2008). Case study: Pulp and paper mill impacts. Toxicology of Fishes 933-970.

Examination of the environmental effects of effiuent discharges from pulp and paper mills provides an interesting case study in fish toxicology (Figure 24.1). The effects of pulp mill effiuents (PMEs) on aquatic environments have been examined for over 40 years, and extensive studies have been conducted since the mid-1980s. During this period, environmental effects have been observed, regulations have been implemented, and the industry has responded to these regulations, resulting in significant reductions in environmental effects. In the 1970s, many effiuents received no secondary treatment, and environmental concerns were associated with oxygen demand, suspended solids, and nutrient and organic loading (Owens, 1991). These concerns shifted in the mid-1980s when a series of Swedish field studies documented that PMEs induced toxic responses in fish at very low concentrations (Södergren, 1989). Over the next few years, supporting data were obtained in Canada (Hodson et al., 1992; McMaster et al., 1991; Munkittrick et al., 1991, 1992a, b; Servos et al., 1992), the United States (Adams et al., 1992), and New Zealand (Sharples and Evans, 1996; Sharples et al., 1994) confirming that effiuent from some discharges was capable of affecting fish at concentrations lower than previously suspected. It has since become clear that some PMEs impact the reproductive health of fish, yet the factors determining which mills will cause effects are unknown (Environment Canada, 2003; Lowell et al., 2004; Sandström, 1996).
Dunlop J.E., Horrigan N., McGregor G., Kefford B.J., Choy S., Prasad R. (2008). Effect of spatial variation on salinity tolerance of macroinvertebrates in Eastern Australia and implications for ecosystem protection trigger values. Environmental Pollution, 151(3) 621-630.

Salinisation of freshwater has been identified as a serious environmental issue in Australia and around the world. Protective concentrations (trigger values) for salinity can be used to manage salinity impacts, though require locally relevant salinity tolerance information. 72-h acute salinity tolerance values were determined for 102 macroinvertebrates collected from 11 locations in four biologically distinct freshwater bio-regions in Northeast Australia and compared with sensitivities observed in Southeast Australia. The salinity tolerance of individual taxa was consistent across Northeast Australia and between Northeast and Southeast Australia. However, two distinct communities were identified in Northeast Australia using distributions of the acute tolerance values and a calculated index of salinity sensitivity. Salinity trigger values should therefore be representative of local or regionally relevant communities and may be adequately calculated using sensitivity values from throughout Eastern Australia. The results presented provide a basis for assessing salinity risk and determining trigger values for salinity in freshwater ecosystems at local and regional scales in Eastern Australia. Crown Copyright © 2007.
Ginn B.K., Grace L.C., Cumming B.F., Smol J.P. (2008). Tracking anthropogenic- and climatic-related environmental changes in the remaining habitat lakes of the endangered Atlantic whitefish (Coregonus huntsmani) using palaeolimnological techniques. Aquatic Conservation Marine and Freshwater Ecosystems, 18(7) 1217-1226.

1. Atlantic whitefish (Coregonus huntsmani) is a critically endangered species whose remaining habitat is restricted to three lakes near Bridgewater, Nova Scotia, Canada. Other lakes in this region have been affected by a variety of environmental changes over the past 150 years (e.g. acidic deposition, eutrophication, and climatic changes); however, the extent of the impact on these remaining Atlantic whitefish lakes, and how the current limnological conditions compare with pre-industrial conditions, is not known. 2. Given the lack of long-term monitoring data, palaeolimnological techniques were used to track environmental changes in these three lakes to infer historic limnological conditions. 3. Results of this study show that acidic deposition has had no significant impact on these lakes (diatominferred lakewater pH has changed little over time), nor has the nutrient status of these lakes changed as the sediment profiles have been consistently dominated by oligotrophic diatom taxa. 4. Changes in the dominance of diatom assemblages since ∼1850, from Aulacoseira distans to Cyclotella stelligera, are correlated with climatic warming (r = 0:48-0.89, P <0:05). 5. Contrary to initial concerns, these only remaining habitats of the Atlantic whitefish have not yet been affected by acidic precipitation. However, other potential stressors, such as climatic warming and associated limnological changes, may now be affecting the habitat of this endangered species. Copyright © 2008 John Wiley & Sons, Ltd.
Guildford S.J., Muir D.C.G., Houde M., Evans M.S., Kidd K.A., Whittle D.M., Drouillard K., Wang X., Anderson M.R., Bronte C.R., Devault D.S., Haffner D., Payne J., Kling H.J. (2008). PCB concentrations in lake trout (Salvelinus namaycush) are correlated to habitat use and lake characteristics. Environmental Science and Technology, 42(22) 8239-8244.

This study considers the importance of lake trout habitat as a factor determining persistent organochlorine (OC) concentration. Lake trout is a stenothermal, cold water species and sensitive to hypoxia. Thus, factors such as lake depth, thermal stratification, and phosphorus enrichment may determine not only which lakes can support lake trout but may also influence among-lake variability in lake trout population characteristics including bioaccumulation of OCs. A survey of 23 lakes spanning much of the natural latitudinal distribution of lake trout provided a range of lake trout habitat to test the hypothesis that lake trout with greater access to littoral habitat for feeding will have lower concentrations of OCs than lake trout that are more restricted to pelagic habitat. Using the δ13C stable isotope signature in lake trout as an indicator of influence of benthic littoral feeding, we found a negative correlation between lipid-corrected δ13C and ΣPCB concentrations supporting the hypothesis that increasing access to littoral habitat results in lower OCs in lake trout. The prominence of mixotrophic phytoplankton in lakes with more contaminated lake trout indicated the pelagic microbial food web may exacerbate the biomagnification of OCs when lake trout are restricted to pelagic feeding. A model that predicted ΣPCB in lake trout based on lake area and latitude (used as proximate variables for proportion of littoral versus pelagic habitat and accessibility to littoral habitat respectively) explained 73% of the variability in ΣPCBs in lake trout in the 23 lakes surveyed. © 2008 American Chemical Society.
Harris R., Kidd K., Shanley J. (2008). Bridging the knowledge gaps on the sources, speciation, fate and bioaccumulation of mercury in aquatic and terrestrial environments. Environmental Pollution, 154(1) 1-2.
Hewitt L.M., Kovacs T.G., Dubé M.G., MacLatchy D.L., Martel P.H., McMaster M.E., Paice M.G., Parrott J.L., Van Den Heuvel M.R., Van Der Kraak G.J. (2008). Altered reproduction in fish exposed to pulp and paper mill effluents: Roles of individual compounds and mill operating conditions. Environmental Toxicology and Chemistry, 27(3) 682-697.

For the last 20 years, studies conducted in North America, Scandinavia, and New Zealand have shown that pulp and paper mill effluents affect fish reproduction. Despite the level of effort applied, few leads are available regarding the factors responsible. Effluents affect reproduction in multiple fish species, as evidenced by decreased gonad size, decreased circulating and gonadal production of reproductive steroids, altered expression of secondary sex characteristics, and decreased egg production. Several studies also have shown that effluent constituents are capable of accumulating in fish and binding to sex steroid receptors/binding proteins. Studies aimed at isolating biologically active substances within the pulping and papermaking process have provided clues about their source, and work has progressed in identifying opportunities for in-mill treatment technologies. Following comparisons of manufacturing processes and fish responses before and after process changes, it can be concluded that effluent from all types of mill processes are capable of affecting fish reproduction and that any improvements could not be attributed to a specific process modification (because mills normally performed multiple modifications simultaneously). Improved reproductive performance in fish generally was associated with reduced use of molecular chlorine, improved condensate handling, and liquor spill control. Effluent biotreatment has been effective in reducing some effects, but biotreated effluents also have shown no difference or an exacerbation of effects. The role of biotreatment in relation to effects on fish reproduction remains unclear and needs to be resolved. © 2008 SETAC.
Hogan N.S., Wartman C.A., Finley M.A., van der Lee J.G., van den Heuvel M.R. (2008). Simultaneous determination of androgenic and estrogenic endpoints in the threespine stickleback (Gasterosteus aculeatus) using quantitative RT-PCR. Aquatic Toxicology, 90(4) 269-276.

A method to evaluate the expression of three hormone responsive genes, vitellogenin (estrogens), spiggin (androgens), and an androgen receptor (ARβ) using real-time PCR in threespine stickleback is presented. Primers were designed from previously characterised spiggin and ARβ sequences, while a homology cloning strategy was used to isolate a partial gene sequence for stickleback vitellogenin (Vtg). Spiggin mRNA was significantly higher in kidneys of field-caught males compared to females by greater than five orders of magnitude while ARβ levels were only 1.4-fold higher in males. Female fish had four order of magnitude higher liver Vtg expression than wild-captured males. To determine the sensitivity of these genes to induction by hormones, male and female sticklebacks were exposed to 1, 10 and 100 ng/L of methyltestosterone (MT) or estradiol (E2) in a flow-through exposure system for 7 days. Spiggin induction in females, and Vtg induction in males were both detectable at 10 ng/L of MT and E2, respectively. MT exposure did not induce ARβ expression in the kidneys of female stickleback. In vitro gonadal steroid hormones production was measured in testes and ovaries of exposed stickleback to compare gene expression endpoints to an endpoint of hormonal reproductive alteration. Reduction in testosterone production in ovaries at all three MT exposure concentrations, and ovarian estradiol synthesis at the 100 ng/L exposure were the only effects observed in the in vitro steroidogenesis for either hormone exposure. Application of these methods to assess both androgenic, estrogenic, and anti-steroidogenic properties of environmental contaminants in a single fish species will be a valuable tool for identifying compounds causing reproductive dysfunction in fishes. © 2008 Elsevier B.V. All rights reserved.
Horrigan N., Baird D.J. (2008). Trait patterns of aquatic insects across gradients of flow-related factors: A multivariate analysis of Canadian national data. Canadian Journal of Fisheries and Aquatic Sciences, 65(4) 670-680.

Large-scale comparisons of aquatic bioassessment metrics based on taxonomic composition are currently constrained by the biogeographic limitations of taxon occurrence. The use of species trait patterns offers a possibility to overcome this constraint. We examine the assertion that the trait composition of aquatic insect communities changes in a consistent manner along similar environmental disturbance gradients by evaluating relationships between traits and three flow-related variables (velocity, water temperature, and dissolved oxygen) in 13 independently collected Canadian data sets. Certain trait states such as low crawling rate, common occurrence in drift, short adult life span, erosional rheophily, medium size at maturity, and cold or cool thermal preference were consistently sensitive to all three flowrelated factors, velocity in particular, despite biogeographic differences in faunal composition. Trait modalities exhibiting the highest mean correlation with velocity, temperature, and dissolved oxygen were identified, and the potential confounding effect of trait "syndromes" was addressed by restricting the selection of flow-sensitive traits to those with high evolutionary lability. The results of the study provide a basis for the future development of flow bioassessment metrics at the national Canadian scale and potentially at the international scale. © 2008 NRC.
Houde M., Muir D.C.G., Kidd K.A., Guildford S., Drouillard K., Evans M.S., Wang X., Whittle D.M., Haffner D., Kling H. (2008). Influence of lake characteristics on the biomagnification of persistent organic pollutants in lake trout food webs. Environmental Toxicology and Chemistry, 27(10) 2169-2178.

The biomagnification of polychlorinated biphenyls (PCBs) and major organochlorine pesticides (OCPs) was studied using lake trout (Salvelinus namaycush) and other food web organisms collected from 17 lakes in Canada and the northeastern United States between 1998 and 2001. Whole lake trout (n = 357) concentrations of the sum (Σ) of 57 PCB congeners ranged between 1.67 and 2,890 ng/g wet weight (median 61.5 ng/g wet wt). Slimy sculpin had the highest mean concentrations of ΣPCB of all forage fish (32-73 ng/g wet wt). Positive relationships between log (lipid wt) concentrations of PCB congener 153, PCB congener 52, p, p′-dichlorodiphenyldichloroethylene, hexachlorobenzene, cis-chlordane, trans-nonachlor, or dieldrin and trophic level (determined using stable nitrogen isotope ratios) were found for most of the 17 food webs, indicating biomagnification of these PCBs and OCPs. The p, p′-dichlorodiphenyldichloroethylene had the highest trophic magnification factors (TMFs) of the 14 individual compounds studied, averaging 4.0 ±1.8 across the 17 lakes, followed by trans-nonachlor (3.6 ± 1.5) and PCB congener 153 (3.4 ± 1.2). Average TMFs for 14 individual PCBs or OCPs were significantly correlated with log octanol-water partition coefficient, implying that the rate of accumulation along the food web is dependent on hydrophobicity and recalcitrance. Significant correlations (p < 0.05) were found between TMFs of ΣPCBs, hexachlorobenzene, α- hexachlorocyclohexane, and lindane and lake area, latitude, and longitude, but not for 11 other PCBs or OCPs. Overall, the results of the present study show that biomagnification of PCBs and most OCPs, as measured by TMFs, is only weakly influenced by such factors as latitude and longitude. Exceptions are hexachlorocyclohexane isomers and hexachlorobenzene, which had generally greater TMFs in northern lakes, possibly due to lower rates of elimination and biotransformation in the food web. © 2008 SETAC Printed in the USA.
Irving E.C., Lowell R.B., Culp J.M., Liber K., Xie Q., Kerrich R. (2008). Effects of arsenic speciation and low dissolved oxygen condition on the toxicity of arsenic to a lotic mayfly. Environmental Toxicology and Chemistry, 27(3) 583-590.

The influence of site-specific conditions on contaminant bioavailability and toxicity to benthic invertebrates is a key consideration in the environmental risk assessment process. This is particularly relevant for contaminants with complex speciation chemistries, such as arsenic. The present study addressed uncertainties regarding arsenic toxicity to a mayfly (Baetis tricaudatus) under low dissolved oxygen (DO) conditions characteristic of many contaminated sites. Arsenic toxicity (arsenite, As(III); arsenate, As(V)) to mayfly nymphs was assessed under two DO scenarios (68 and 84% saturation). Arsenic speciation ratios were determined during testing to confirm the nature of arsenic exposure. The present study found that As(III) was more lethal and bioaccumulated to a greater degree in B. tricaudatus compared to As(V), but the sublethal toxicities of the two arsenic species were similar. Nymph growth and development were significantly inhibited after 12 d of exposure to both 1 mg/L of As(III) and As(V). Exposure to arsenic under low DO conditions (6.5 mg/L, 68% saturation) did not significantly affect As(III) or As(V) toxicity and bioaccumulation over 12 d. The DO level of 6.5 mg/L, however, appeared to be marginally lethal to B. tricaudatus. Results indicate that the Canadian arsenic criterion for the protection of aquatic life (5 μg/L) is protective of B. tricaudatus and is low enough to accommodate differences in arsenic toxicity because of the interconversions between As(III) and As(V). These findings provide insight regarding the toxicity and speciation of arsenic under DO conditions considered to be low for this lotie mayfly species and representative of existing conditions at mine sites in northern Canada. © 2008 SETAC.
Jardine T.D., Chernoff E., Curry R.A. (2008). Maternal transfer of carbon and nitrogen to progeny of sea-run and resident brook trout (Salvelinus fontinalis). Canadian Journal of Fisheries and Aquatic Sciences, 65(10) 2201-2210.

Early-life history characteristics of sea-run and resident salmonid fishes that co-exist in sympatry are poorly understood. To assess differences in characteristics of offspring of these two strategies following their emergence to the stream, stable isotope ratios (δ13C and δ15N) were used to identify the progeny of resident and sea-run female brook trout (Salvelinus fontinalis) in a tributary of the Miramichi River, New Brunswick, Canada. Upon emergence, sea-run progeny captured in emergence traps were longer, heavier, and had higher carbon to nitrogen ratios (C/N, an indicator of lipid content) than resident progeny, but did not have a higher body condition. After some feeding and growth in the stream, sea-run progeny (still identifiable by their δ13C and δ15N) captured in dip-nets became longer, heavier, had higher C/N, and had higher condition than resident progeny. The proportion of fish caught in dip nets at sites where the two forms coexisted was dominated by offspring of sea-run females (sea-run = 56%, resident = 19%, unknown = 25%). These analyses suggest that offspring of sea-run, female trout benefit from maternally derived energy reserves gained at sea and thus have potential adaptive advantages over offspring of residents. © 2008 NRC.
Jardine T.D., Kidd K.A., Polhemus J.T., Cunjak R.A. (2008). An elemental and stable isotope assessment of water strider feeding ecology and lipid dynamics: Synthesis of laboratory and field studies. Freshwater Biology, 53(11) 2192-2205.

1. Despite the ubiquity and abundance of water striders (Hemiptera: Gerridae) in temperate streams and rivers and their potential usefulness as sentinels in contaminant studies, little is known about their feeding ecology and lipid dynamics. 2. In this study we used stable isotopes of carbon (δ13C) and nitrogen (δ15N) and elemental carbon to nitrogen ratios (C/N) to assess dietary habits and lipid content, respectively, for water striders. 3. To determine diet-tissue fractionation factors, nymphs of the most common species in New Brunswick, Canada, Aquarius remigis were reared in the laboratory for 73 days and exhibited rapid isotopic turnover in response to a switch in diet (C half-life = 1.5 days, N half-life = 7.8 days). Their lipid content increased towards the end of the growing season and resulted in lower δ13C values. Diet-tissue fractionation factors were established after correction of δ13C data for the confounding effect of de novo lipid synthesis (strider δ 13C<inf>adj</inf>- diet δ13C<inf>adj</inf> = 0.1‰, strider δ15N - diet δ15N = 2.7‰). 4. Water striders from the majority of 45 stream sites (83%) in New Brunswick had less than 50% contribution of aquatic carbon to their diets but showed a gradual increase in the contribution of this carbon source to their diet with increasing stream size. 5. These data indicate that striders exhibit a strong connection to terrestrial carbon sources, making them important users of energy subsidies to streams from the surrounding catchment. However, this dependence on terrestrial organic matter may limit their utility as indicators of contamination of aquatic systems by heavy metals and other pollutants. © 2008 The Authors.
Jeffries K.M., Jackson L.J., Peters L.E., Munkittrick K.R. (2008). Changes in population, growth, and physiological indices of longnose dace (Rhinichthys cataractae) in the Red Deer River, Alberta, Canada. Archives of Environmental Contamination and Toxicology, 55(4) 639-651.

The Red Deer River, Alberta, Canada is a prairie river that is impacted by the point-source input of Red Deer's municipal wastewater effluent and non-point- source agricultural runoff. We used population, growth, and physiological performance end points in longnose dace (Rhinichthys cataractae), an endemic and abundant minnow, to evaluate changes in fish health over a 220 km section of the Red Deer River. Longnose dace immediately downstream of Red Deer had elevated catch per unit effort with larger body and liver sizes compared to upstream of Red Deer sites, likely due to elevated riverine productivity from Red Deer's wastewater effluent. Longnose dace immediately downstream of Red Deer showed depressed testosterone production capacity and elevated ethoxyresorufin-O-deethylase (EROD) activity, which is consistent with exposure to endocrine-disrupting compounds and aromatic hydrocarbons, respectively. Longnose dace 150-180 km downstream of Red Deer had reduced liver and gonad sizes, elevated EROD, and increased 11-ketotestosterone production capacity compared to upstream of Red Deer sites, possibly related to a non-point-source agricultural influence on water quality. Longnose dace populations at the most downstream sites were missing the oldest age classes and might reach sexual maturity faster than at upstream sites, which is consistent with a younger age structure. Our results highlight the importance of assessing multiple performance end points to reveal physiological or reproductive effects in natural fish populations. We have demonstrated how longnose dace populations change over a river impacted by municipal wastewater and agricultural runoff; further studies are required to determine if these changes will influence the long-term viability of longnose dace in the Red Deer River. © 2008 Springer Science+Business Media, LLC.
Klassen C.N., Peake S.J. (2008). Effect of diet switch timing and food source on survival and growth of lake sturgeon. Journal of Applied Ichthyology, 24(5) 527-533.

Studies were conducted to determine the effects of diet switch timing and food source on hatchery survival and growth of lake sturgeon (Acipenser fulvescens) during a 7- and 6-week period in 2004 and 2005, respectively. Diet transitions to bloodworm (Diptera: Chironomidae) and black fly (Diptera: Simuliidae) larvae were undertaken 1, 2, 3 or 4 weeks after an initial diet of brine shrimp (Artemia spp.) in 2004, and 2 or 4 weeks after initiation of feeding in 2005. In 2004, mean (±SE) final survival was significantly lower following early (week 1, 50.8 ± 8.3%) vs late (week 4, 83.3 ± 3.9%) diet switches, regardless of diet type; however, rearing lake sturgeon on black fly larvae led to significantly higher mean survival rates (78.7 ± 3.3%) in comparison to bloodworm diets (56.5 ± 6.5%). Fish reared in 2005 on black fly larvae showed no significant differences in mean (±SE) final survivals when switched early (week 2, 96.7 ± 1.0%) vs late (week 4, 97.6 ± 0.5%), but those groups transitioned to bloodworm did significantly worse following the early diet switch (week 2, 91.9 ± 1.7%; week 4, 99.0 ± 1.0%). Final mean (±SE) mass was significantly higher for lake sturgeon reared on black fly larvae (0.63 ± 0.02 g) vs bloodworm (0.53 ± 0.02 g) at the end of the 2004 study period, despite having received fewer daily feedings; however, this difference was not observed the following year (bloodworm, 1.48 ± 0.07 g; black fly larvae, 1.43 ± 0.07 g). While there was no significant difference in final mean mass (±SE) of fish among the various diet switch points in 2004 (week 1, 0.54 ± 0.05 g; week 2, 0.57 ± 0.03 g; week 3, 0.60 ± 0.01 g; week 4, 0.59 ± 0.03 g), there was a significant advantage to transitioning fish early in 2005, regardless of food type (week 2, 1.60 ± 0.03 g; week 4, 1.31 ± 0.02 g). Given our results from both years, we conclude that transitioning larval lake sturgeon to black fly larvae following 2 weeks on an initial diet of brine shrimp can maximize survival rates without sacrificing final sizes, while reducing effort and cost associated with culturing brine shrimp and feeding bloodworm. © 2008 Blackwell Verlag, Berlin.
Knapp C.W., Findlay D.L., Kidd K.A., Graham D.W. (2008). A comparative assessment of molecular biological and direct microscopic techniques for assessing aquatic systems. Environmental Monitoring and Assessment, 145(1-3) 465-473.

Molecular techniques have clear value for community characterization; however, almost all previous datasets are based upon non-molecular measurements and it is hard to compare "old" data with "new" data because few correlations have been made. Therefore, the purpose of this evaluation was to simultaneously use molecular and non-molecular methods within the same sampling program to determine how data compare. Three methods were used for characterizing microbial populations in Lake 260 (L260) at Experimental Lakes Area (Ontario, Canada) during a whole-lake exposure study. Methods included whole-cell microscopic counts (for bacteria, cyanobacteria, algae and zooplankton), chlorophyll a, and small sub-unit (ssu)-rRNA hybridization using EUB-338, EUB-785, CYAN-785-a/b, EUCA-1379 and UNIV-1390 gene probes. Strong correlations were found between the EUB-785 probe signal and "bacteria minus cyanobacteria" direct counts, and the EUB-338 probe signal and "bacteria plus cyanobacteria" counts. Furthermore, the difference in probe signal between EUB-338 and EUB-785 (a presumptive signature for cyanobacteria and plastids) correlated with cyanobacterial direct counts and also with chlorophyll a. However, EUCA-1379 probe signal did not correlate with algae counts, and UNIV-1390 probe signal only correlated with total bacteria counts. Results suggest that, although ssu-rRNA methods are fast, reproducible, and specifically detect "viable" organisms, their use may be limited to non-eukaryotic populations unless new probes are developed that are more specific. © Springer Science+Business Media B.V. 2007.
Landman M.J., Taylor S., van den Heuvel M.R. (2008). Carotenoid depletion and ovarian dysfunction in common bully exposed to a New Zealand pulp mill effluent. Aquatic Toxicology, 87(4) 303-309.

In a previous cumulative impacts assessments of fish populations along the Waikato River, New Zealand, reduced ovary pigmentation was observed in the common bully (Gobiomorphus cotidianus) with an associated reduction in recruitment in the pulp mill-impacted Kopakorahi Arm of Lake Maraetai compared to an upstream reference site. Carotenoid pigments are typically responsible for the yellow to red colouration of fish eggs and a number of functions for these pigments such as pro-vitamins and antioxidants have been proposed. The purpose of the current study was first to quantify the observed pigment reduction and then to establish possible consequences of carotenoid deficiency. Significantly lower levels of all measured carotenoids were observed in the ovaries of fish from below the mill outfall compared to the reference site. Using in vitro incubations of ovarian follicles, it was also found that these fish had a significantly reduced ability to produce the sex steroids testosterone and estradiol. This study demonstrates changes in ovarian carotenoids associated with pulp mill effluent exposure. Significantly reduced biosynthetic capacity of ovarian follicles demonstrates reproductive endocrine disruption potential associated with exposure to this particular effluent. These results may provide an important link between reproductive dysfunction, oxidative stress and food chain modifications in pulp mill-impacted systems. © 2008 Elsevier B.V. All rights reserved.
Linnansaari T., Cunjak R.A., Newbury R. (2008). Winter behaviour of juvenile Atlantic salmon Salmo salar L. in experimental stream channels: Effect of substratum size and full ice cover on spatial distribution and activity pattern. Journal of Fish Biology, 72(10) 2518-2533.

Activity and choice of areas offering different cover (substratum or surface ice) for juvenile Atlantic salmon Salmo salar were studied in experimental stream channels during winter. Channels were completely ice covered between December and March. During this period, the ice thickness increased from 50 to 300 mm after which 50% of the ice was experimentally removed and followed by c. 2·5-fold increase in discharge to simulate the effects of spring flood. Large substrata provided preferred habitats but areas with small substratum sizes were also used when full surface ice provided above-stream cover and the stream discharge was relatively low. The fish remained nocturnal throughout the study but the level of day activity significantly increased as the surface ice became thicker. Maximum movement distance during a 24 h period and homing-at-dawn behaviour remained at a constant level throughout the main winter, but significantly changed during the simulated spring flood (mean ±s.e. maximum extent of movements within 24 h increased from 1·1 ± 0·1 to 3·0 ± 0·5 m; homing behaviour decreased from the highest level of 89·3 to 34·6% during spring flood). Overwinter survival was high (92·9%). Relative mass increase during the study ranged from -8·3 to 28·5%, and 84% of the juvenile Atlantic salmon gained mass. The highest rates of mass increase were associated with frequent movements between areas of different substratum size. The results indicate that during winter: (1) Atlantic salmon parr preferred large substratum cover compared with surface ice cover at the fish densities studied here, (2) juvenile Atlantic salmon were predominantly nocturnal but diurnal activity increased as surface ice became thicker and (3) increase in water discharge during spring altered the behaviour of juvenile Atlantic salmon and may have caused additional habitat shifts. © 2008 The Fisheries Society of the British Isles.
Logan J.M., Jardine T.D., Miller T.J., Bunn S.E., Cunjak R.A., Lutcavage M.E. (2008). Lipid corrections in carbon and nitrogen stable isotope analyses: Comparison of chemical extraction and modelling methods. Journal of Animal Ecology, 77(4) 838-846.

1. Lipids have more negative δ13C values relative to other major biochemical compounds in plant and animal tissues. Although variable lipid content in biological tissues alters results and conclusions of δ13C analyses in aquatic food web and migration studies, no standard correction protocol exists. 2. We compared chemical extraction and mathematical correction methods for freshwater and marine fishes and aquatic invertebrates to better understand impacts of correction approaches on carbon (δ13C) and nitrogen (δ15N) stable isotope data. 3. Fish and aquatic invertebrate tissue δ13C values increased significantly following extraction for almost all species and tissue types relative to nonextracted samples. In contrast, δ15N was affected for muscle and whole body samples from only a few freshwater and marine species and had a limited effect for the entire data set. 4. Lipid normalization models, using C : N as a proxy for lipid content, predicted lipid-corrected δ13C for paired data sets more closely with parameters specific to the tissue type and species to which they were applied. 5. We present species- and tissue-specific models based on bulk C : N as a reliable alternative to chemical extraction corrections. By analysing a subset of samples before and after lipid extraction, models can be applied to the species and tissues of interest that will improve estimates of dietary sources using stable isotopes. © 2008 The Authors.
Loomer H.A., Kidd K.A., Vickers T., McAslan A. (2008). Swimming in sewage: Indicators of faecal waste on fish in the saint john harbour, new brunswick. Water Quality Research Journal of Canada, 43(4) 283-290.

Despite increased recognition of the risks to the health of humans and the environment, untreated municipal wastewaters are still discharged into waterways worldwide. One of the primary concerns related to its discharge into surface waters is the risk to human health through the transmission of pathogens associated with faecal matter. Saint John, New Brunswick, is one of the few Canadian cities that still releases untreated sewage into its urban waterways and harbour. Water faecal coliform levels, an indicator of faecal waste and associated pathogens, are well above recreational guidelines in some of these areas. Although it is not encouraged by the municipality, recreational fishing occurs in these areas and this raises concerns regarding the potential for disease transmission during the handling of these fish. To investigate the potential for fish to be a vehicle of pathogen transmission to humans, the skin of wild fishes (smelt, Osmerus mordax, and mummichog, Fundulus heteroclitus) and caged mummichog was sampled for faecal coliforms from several sites in Saint John between August and November of 2005. Water faecal coliform levels at sites used for caging studies and wild fish collections, and the duration of caging were compared with the number of faecal coliforms on the surface of the fish. Skin samples from the two fish species collected from the wild indicated elevated levels of fecal coliforms in some locations. Both wild and caged fish showed that the amount of faecal coliform on fish skin is influenced by the water faecal coliform levels. Copyright © 2008, CAWQ.
Macquarrie K.T.B., Al T.A. (2008). The influence of seasonal temperature variation and other factors on the occurrence of dissolved manganese during river bank filtration. IAHS AISH Publication(324) 467-474.

The water quality from production wells used by the City of Fredericton is generally good, with the exception of elevated dissolved Mn. This occurrence has been attributed to the flux of dissolved organic carbon (DOC) that enters the aquifer during river water infiltration, and the subsequent creation of in situ conditions suitable for reductive dissolution of Mn-oxides. A geochemical investigation near a well that induces river water infiltration indicates a potential seasonal dependence of the redox conditions that may be governed by water temperature, although elevated Mn persists at depth and adjacent to the production well. It has also been speculated that Mn-oxide mineral depletion will eventually occur in the aquifer sediments, and that this occurrence could be followed by elevated dissolved Fe in the extracted water. In this contribution, reactive transport modelling is applied to assess the impact of seasonally-varying river water temperature on dissolved Mn, and to investigate the factors controlling Mn-oxide depletion. Employing an empirical function for temperature-dependent reaction rate, and using the measured time series for river water temperature, produces simulated spatial and temporal patterns of dissolved Mn that are similar to the observed data. The long-term persistence of elevated Mn is shown to be strongly controlled by the travel time from the river to the well, and by the initial pyrolusite content of the aquifer sediments. Copyright © 2008 IAHS Press.
Michel C., Hicks B.J., Stölting K.N., Clarke A.C., Stevens M.I., Tana R., Meyer A., Van Den Heuvel M.R. (2008). Distinct migratory and non-migratory ecotypes of an endemic New Zealand eleotrid (Gobiomorphus cotidianus) - Implications for incipient speciation in island freshwater fish species. BMC Evolutionary Biology, 8(1).

Background. Many postglacial lakes contain fish species with distinct ecomorphs. Similar evolutionary scenarios might be acting on evolutionarily young fish communities in lakes of remote islands. One process that drives diversification in island freshwater fish species is the colonization of depauperate freshwater environments by diadromous (migratory) taxa, which secondarily lose their migratory behaviour. The loss of migration limits dispersal and gene flow between distant populations, and, therefore, is expected to facilitate local morphological and genetic differentiation. To date, most studies have focused on interspecific relationships among migratory species and their non-migratory sister taxa. We hypothesize that the loss of migration facilitates intraspecific morphological, behavioural, and genetic differentiation between migratory and non-migratory populations of facultatively diadromous taxa, and, hence, incipient speciation of island freshwater fish species. Results. Microchemical analyses of otolith isotopes (88Sr, 137Ba and 43Ca) differentiated migratory and non-migratory stocks of the New Zealand endemic Gobiomorphus cotidianus McDowall (Eleotridae). Samples were taken from two rivers, one lake and two geographically-separated outgroup locations. Meristic analyses of oculoscapular lateral line canals documented a gradual reduction of these structures in the non-migratory populations. Amplified fragment length polymorphism (AFLP) fingerprints revealed considerable genetic isolation between migratory and non-migratory populations. Temporal differences in reproductive timing (migratory = winter spawners, non-migratory = summer spawners; as inferred from gonadosomatic indices) provide a prezygotic reproductive isolation mechanism between the two ecotypes. Conclusion. This study provides a holistic look at the role of diadromy in incipient speciation of island freshwater fish species. All four analytical approaches (otolith microchemistry, morphology, spawning timing, population genetics) yield congruent results, and provide clear and independent evidence for the existence of distinct migratory and non-migratory ecotypes within a river in a geographically confined range. The morphological changes within the non-migratory populations parallel interspecific patterns observed in all non-migratory New Zealand endemic Gobiomorphus species and other derived gobiid taxa, a pattern suggesting parallel evolution. This study indicates, for the first time, that distinct ecotypes of island freshwater fish species may be formed as a consequence of loss of migration and subsequent diversification. Therefore, if reproductive isolation persists, these processes may provide a mechanism to facilitate speciation. © 2008 Michel et al; licensee BioMed Central Ltd.
Monk W.A., Wood P.J., Hannah D.M. (2008). Examining the Influence of Flow Regime Variability on Instream Ecology. Hydroecology and Ecohydrology Past Present and Future 165-184.
Monk W.A., Wood P.J., Hannah D.M., Wilson D.A. (2008). Macroinvertebrate community response to inter-annual and regional river flow regime dynamics. River Research and Applications, 24(7) 988-1001.

Spatio-temporal variability in river flow is a fundamental control on instream habitat structure and riverine ecosystem biodiversity and integrity. However, long-term riverine ecological time-series to test hypotheses about hydrology-ecology interactions in a broader temporal context are rare, and studies spanning multiple rivers are often limited in their temporal coverage to less than five years. To address this research gap, a unique spatio-temporal hydroecological analysis was conducted of long-term instream ecological responses (1990-2000) to river flow regime variability at 83 sites across England and Wales. The results demonstrate clear hydroecological associations at the national scale (all data). In addition, significant differences in ecological response are recorded between three 'regions' identified (RM1-3*) associated with characteristics of the flow regime. The effect of two major supra-seasonal droughts (1990-1992 and 1996-1997) on inter-annual (IA) variability of the LIFE scores is evident with both events showing a gradual decline before and recovery of LIFE scores after the low flow period. The instream community response to high magnitude flow regimes (1994 and 1995) is also apparent, although these associations are less striking. The results demonstrate classification of rivers into flow regime regions offers a way to help unravel complex hydroecological associations. The approach adopted herein could easily be adapted for other geographical locations, where datasets are available. Such work is imperative to understand flow regime-ecology interactions in a longer term, wider spatial context and so assess future hydroecological responses to climate change and anthropogenic modification of riverine ecosystems. Copyright © 2008 John Wiley & Sons, Ltd.
Peake S.J. (2008). Behavior and passage performance of northern pike, walleyes, and white suckers in an experimental raceway. North American Journal of Fisheries Management, 28(1) 321-327.

The willingness and ability of wild adult northern pike Esox lucius, walleyes Sander vitreus, and white suckers Catostomus commersonii to ascend a 25- or 50-m experimental raceway against various water velocities (35-120 cm/s at 8 cm from the bottom) was measured. The probability that a fish of any given species would enter the raceway from its holding tank was significantly correlated with fork length, water temperature, and tank volume but was not correlated with water velocity. On average, 62.6% of northern pike, 45.0% of walleyes, and 44.2% of white suckers entered volitionally. For those fish that entered, the probability that at least one complete ascent would occur during the exposure period was not dependent on fish length, water temperature, raceway length, duration of the exposure period, time in captivity, or water velocity. On average, 74.4% of northern pike, 76.4% of walleyes, and 77.3% of white suckers that entered the raceway made at least one complete ascent. For northern pike and walleyes, the proportion of successful ascents at the highest water velocity tested (120 cm/s) was significantly lower than the proportions observed at the lower velocities. No significant differences were found among ascent proportions for white suckers. Fish in general may be more inclined to enter a culvert if the pool downstream of the entrance is relatively small. Culverts less than 50 m long should allow these species to pass as long as water velocities near the bottom do not exceed 100 cm/s. Fish passage models based on published data from forced performance trials predicted lower maximum allowable water speeds, which adds to a growing body of work that indicates the unsuitability of these tests for use in setting velocity criteria in culverts and fishways. © Copyright by the American Fisheries Society 2008.
Peake S.J. (2008). Gait transition speed as an alternate measure of maximum aerobic capacity in fishes. Journal of Fish Biology, 72(3) 645-655.

This study demonstrated that the transition from a steady to an unsteady locomotory gait (U<inf>STmax</inf>) in juvenile brook trout Salvelinus fontinalis can be measured easily using a new tilting raceway design and a simple experimental protocol. It was found that U<inf>STmax</inf> increased linearly with fork length (L<inf>F</inf>), and that this relationship was statistically identical in fish that swam volitionally in the raceway and those that were forced to perform, although slightly different data processing methods were needed in the latter to achieve this result. Furthermore, the relationship between L<inf>F</inf> and U<inf>STmax</inf> was statistically identical to that between L<inf>F</inf> and critical swimming speed (U<inf>crit</inf>), although L<inf>F</inf> in the former relationship explained 83% of the variance compared to 37% in the latter. This finding indicates that gait transition speed can be used to estimate maximum aerobic capacity, with less unexplainable variance than U<inf>crit</inf>. Gait transition speeds were also determined from U <inf>crit</inf> tests; however, this required measuring and incorporating ground speed into the analysis. U<inf>STmax</inf> as determined in the U <inf>crit</inf> tests was not significantly different from that measured in the raceway, suggesting that gait transition speed can be measured in raceways or swim tunnel respirometers. © 2008 The Author.
Peterson D.P., Fausch K.D., Watmough J., Cunjak R.A. (2008). When eradication is not an option: Modeling strategies for electrofishing suppression of nonnative brook trout to foster persistence of sympatric native cutthroat trout in small streams. North American Journal of Fisheries Management, 28(6) 1847-1867.

Subspecies of inland cutthroat trout Oncorhynchus clarkii occupy a fraction of their historic ranges, and displacement by nonnative brook trout Salvelinus fontinalis is among the greatest threats to existing populations in small, headwater streams. Electrofishing is often used to suppress brook trout and enhance cutthroat trout populations, but these efforts are labor intensive and costly. To help managers more effectively plan and implement brook trout control programs, we used survival estimates from a field experiment to construct matrix population models for both species and linked the models by making the vital rates of young cutthroat trout a function of brook trout density to represent the effect of invasion. We then explored the response of cutthroat trout populations (growth rate [λ] and probability of persistence for 50 years) to brook trout suppression across various levels of electrofishing frequency, sampling intensity, capture efficiency, and brook trout immigration rate. Cutthroat trout (λ = 1.10) and brook trout (λ = 1.20) both had moderate to high values of λ when biotic interactions were weak or absent, but the cutthroat trout λ declined markedly (λ = 0.61) when biotic interactions with brook trout were strong. Model results supported the hypothesis that rapid displacement of cutthroat trout is facilitated by the brook trout's inherent demographic advantage and biotic effects on young cutthroat trout. Where annual brook trout suppression was not possible, the temporal distribution of suppression events within a systematic control design strongly influenced the response of cutthroat trout. The absolute response and cost effectiveness of suppression efforts were influenced particularly by the brook trout immigration rate and also by removal efficiency. Multiple consecutive years of suppression (≥3 years) benefited cutthroat trout, but to be effective such suppression should not be interrupted for more than two consecutive years once initiated. Eradication would be ideal, but the maintenance control of brook trout and the management of cutthroat trout in sympatry with brook trout will probably remain among the viable management options for the foreseeable future. © Copyright by the American Fisheries Society 2008.
Riley S.C., Munkittrick K.R., Evans A.N., Krueger C.C. (2008). Understanding the ecology of disease in Great Lakes fish populations. Aquatic Ecosystem Health and Management, 11(3) 321-334.

Disease may be an important factor affecting wild fish population dynamics in the Great Lakes, but a lack of information on the ecology of fish disease currently precludes the prediction of risks to fish populations. Here we propose a conceptual framework for conducting ecologically-oriented fish health research that addresses the inter-relationships among fish health, fish populations, and ecosystem dysfunction in the Great Lakes. The conceptual framework describes potential ways in which disease processes and the population-level impacts of disease may relate to ecosystem function, and suggests that functional ecosystems are more likely to be resilient with respect to disease events than dysfunctional ecosystems. We suggest that ecosystem- or population-level research on the ecology of fish disease is necessary to understand the relationships between ecosystem function and fish health, and to improve prediction of population-level effects of diseases on wild fish populations in the Great Lakes. Examples of how the framework can be used to generate research questions are provided using three disease models of current interest in the Great Lakes: thiamine deficiency complex, botulism, and bacterial kidney disease. Copyright © 2008 AEHMS.
Sargent P.S., Methven D.A., Hooper R.G., Mckenzie C.H. (2008). A range extension of the Atlantic silverside, Menidia menidia, to coastal waters of Southwestern Newfoundland. Canadian Field Naturalist, 122(4) 338-344.

Previous literature documents Atlantic Silverside, Menidia menidia, as occurring from the southern Gulf of St. Lawrence to northeastern Florida. Beach seining in St. George's Bay, Newfoundland, revealed the presence of this species in coastal waters of southwestern Newfoundland. This is the first documented report of M. menidia in Newfoundland waters. This report extends the range of this species north of the Laurentian Channel, a significant biogeographic barrier to small coastal fishes. All M. menidia collected were young-of-the-year, less than 90 mm SL (Standard Length). These fish may be representative of a larger relict population originating from the Mid-Hypsithermal Interval (7000 years ago) that spawn in St. George's Bay and migrate offshore for winter. Alternatively, these M. menidia may be survivors of a more southern spawning population carried northward by ocean currents.
Sigourney D.B., Letcher B.H., Obedzinski M., Cunjak R.A. (2008). Size-independent growth in fishes: Patterns, models and metrics. Journal of Fish Biology, 72(10) 2435-2455.

A combination of a dynamic energy budget (DEB) model, field data on Atlantic salmon Salmo salar and brown trout Salmo trutta and laboratory data on Atlantic salmon was used to assess the underlying assumptions of three different metrics of growth including specific growth rate (G), standardized mass-specific growth rate (G<inf>S</inf>) and absolute growth rate in length (G<inf>L</inf>) in salmonids. Close agreement was found between predictions of the DEB model and the assumptions of linear growth in length and parabolic growth in mass. Field data comparing spring growth rates of age 1+ year and 2+ year Atlantic salmon demonstrated that in all years the larger age 2+ year fish exhibited a significantly lower G, but differences in growth in terms of G<inf>S</inf> and G<inf>L</inf> depended on the year examined. For brown trout, larger age 2+ year fish also consistently exhibited slower growth rates in terms of G but grew at similar rates as age 1+ year fish in terms of G<inf>S</inf> and G<inf>L</inf>. Laboratory results revealed that during the age 0+ year (autumn) the divergence in growth between future Atlantic salmon smolts and non-smolts was similar in terms of all three metrics with smolts displaying higher growth than non-smolts, however, both G<inf>S</inf> and G<inf>L</inf> indicated that smolts maintain relatively fast growth into the late autumn where G suggested that both smolts and non-smolts exhibit a sharp decrease in growth from October to November. During the spring, patterns of growth in length were significantly decoupled from patterns in growth in mass. Smolts maintained relatively fast growth though April in length but not in mass. These results suggest G<inf>S</inf> can be a useful alternative to G as a size-independent measure of growth rate in immature salmonids. In addition, during certain growth stanzas, G<inf>S</inf> may be highly correlated with G<inf>L</inf>. The decoupling of growth in mass from growth in length over ontogeny, however, may necessitate a combination of metrics to adequately describe variation in growth depending on ontogenetic stage particularly if life histories differ. © 2008 The Fisheries Society of the British Isles.
Sutherland A.B., Maki J., Vaughan V. (2008). Effects of suspended sediment on whole-body cortisol stress response of two southern appalachian minnows, Erimonax monachus and Cyprinella galactura. Copeia(1) 234-244.

Total immunoreactive corticosteroid (IRC) levels (adjusted for fish mass; ng/g) were measured in whole-body homogenates of 2- and 8-months old Whitetail Shiners (Cyprinella galactura) and 4-months old federally threatened Spotfin Chubs (Erimonax monachus) exposed for 48 hours to varying suspended sediment concentrations (SSC; 0, 25, 50, 100, and 500 mg/L). Hydrophobic fractions were extracted from individual frozen fish after sonication and centrifugation of tissues. Extracts were resuspended in a buffer compatible with a commercially available enzyme-linked immunosorbent assay (ELISA) kit. Serially diluted concentrations of cortisol and extracts collected from unstressed fish were used to standardize the assay. Two-months old C. galactura had the highest resting level of whole-body IRC at 0 mg/L SSC. They also elicited the greatest response (three- to four-fold increase) when exposed to SSCs greater than 25 mg/L. Resting whole-body IRC levels were lowest in 8-months old C. galactura. For these fish IRC levels at 25, 50, and 100 mg/L SSC were similar to controls. Four-months old E. monachus showed a non-linear response with a possible threshold effect between 50 and 100 mg/L. At SSC greater than 100 mg/L E. monachus demonstrated a three-fold increase in whole-body IRC levels over control fish. Exposure to SSC levels greater than 100 mg/L caused a significant increase in IRC levels above baseline in both species and in all three life stages. This investigation shows that whole-body levels of IRC in young minnows increase dramatically upon exposure to SSCs greater than 25 mg/L. These data suggest that even moderate levels of suspended sediment (i.e., 100 mg/L) can severely stress young-of-year E. monachus. The imperilment of E. monachus may in part be due to stress imposed on young fish by elevated suspended sediment. © 2008 by the American Society of Ichthyologists and Herpetologists.
van den Brink P.J., Sibley P.K., Ratte H.T., Baird D.J., Nabholz J.V., Sanderson H. (2008). Extrapolation of effects measures across levels of biological organization in ecological risk assessment. Extrapolation Practice for Ecotoxicological Effect Characterization of Chemicals 105-133.
van den Heuvel M.R., Landman M.J., Finley M.A., West D.W. (2008). Altered physiology of rainbow trout in response to modified energy intake combined with pulp and paper effluent exposure. Ecotoxicology and Environmental Safety, 69(2) 187-198.

Two experiments using rainbow trout (Oncorhynchus mykiss) were conducted to examine the combined effects of energy intake as manipulated by ration and pulp and paper mill effluent exposure over either one, or two consecutive reproductive cycles. This study demonstrated that the level of energy intake affected the full range of measured parameters from energy allocation to somatic growth and the gonadal development, steroid production and hematology. Increasing ration level expectedly increased growth, condition, liver and gonad size. Female trout in the higher ration treatments produced more follicles and had larger eggs, investing the same relative proportion of total energy into ovarian development. Sex steroid levels and hematological parameters were also positively influenced by increasing ration level in males and females. By far, the most dramatic impact of reduced ration on reproduction was to substantially reduce the frequency of sexually maturing fish. The effects of effluent exposure were not as marked as those linked to ration level and typically did not manifest unless fish were exposed through two consecutive reproductive cycles. The physiological effects of pulp and paper effluent exposure observed in these experiments were not consistent between the two experiments conducted herein, nor were they consistent with previously observed impacts in similar experiments with this effluent. Effluent exposure over one reproductive cycle did not impact physiological parameters in trout. However, when effluent exposure was maintained over two reproductive cycles, a new pattern of effluent response emerged including increased condition factor in both sexes, a decrease in the potential ability of the blood of females to transport oxygen, and increased sex steroids and reproductive investment in males. Effluent was also observed to cause reduced growth in male trout over two years. The effects of ration on gonad and liver size were far more obvious and consistent when a longer exposure was employed, thus, it appears to take more than one full year for energy intake changes to be reflected in those particular physiological endpoints. © 2007 Elsevier Inc. All rights reserved.
Aguilar C., González-Sansón G., Hernández I., MacLatchy D.L., Munkittrick K.R. (2007). Effects-based assessment in a tropical coastal system: Status of bicolor damselfish (Stegastes partitus) on the north shore of Cuba. Ecotoxicology and Environmental Safety, 67(3) 459-471.

The research was carried out to determine whether there are individual-level differences in the bicolor damselfish (Stegastes partitus) within the altered fish communities located on the north coast of Havana, Cuba. There was strong evidence of changes in some morphological and physiological characteristics associated with the impact of land-based pollution in the coastal zone. A combination of impaired recruitment due to habitat degradation with increased food supply due to eutrophication seems to be the best explanation for fishes being heavier and longer at polluted sites. The change in the proportion of color patterns and a very high number of atretic oocytes in the ovaries of fish caught near the mouth of the Almendares River strongly support the idea that not only is the pollution of river waters affecting the marine life in the coastal zone, but also that this pollution has greater effects than the pollution coming from the discharge of Havana Harbor. © 2006 Elsevier Inc. All rights reserved.
Alexander A.C., Culp J.M., Liber K., Cessna A.J. (2007). Effects of insecticide exposure on feeding inhibition in mayflies and oligochaetes. Environmental Toxicology and Chemistry, 26(8) 1726-1732.

The present study examined the effects of pulse exposures of the insecticide imidacloprid on the mayfly, Epeorus longimanus Eaton (Family Heptageniidae), and on an aquatic oligochaete, Lumbriculus variegatus Müller (Family Lumbriculidae). Pulse exposures of imidacloprid are particularly relevant for examination, because this insecticide is relatively soluble (510 mg/L) and is most likely to be at effect concentrations during runoff events. Experiments examined the recovery of organisms after a 24-h pulse exposure to imidacloprid over an environmentally realistic range of concentrations (0, 0.1, 0.5, 1, 5, and 10 μg/L). Effects on feeding were measured by quantifying the algal biomass consumed by mayflies or foodstuffs egested by oligochaetes. Imidacloprid was highly toxic, with low 24-h median lethal concentrations (LC50s) in early mayfly instars (24-h LC50, 2.1 ± 0.8 μg/L) and larger, later mayfly instars (24-h LC50, 2.1 ± 0.5 μg/L; 96-h LC50, 0.65 ± 0.15 μg/L.). Short (24-h) pulses of imidacloprid in excess of 1 μg/L caused feeding inhibition, whereas recovery (4 d) varied, depending on the number of days after contaminant exposure. In contrast to mayflies, oligochaetes were relatively insensitive to imidacloprid during the short (24-h) pulse; however, immobility of oligochaetes was observed during a 4-d, continuous-exposure experiment, with 96-h median effective concentrations of 6.2 ± 1.4 μg/L. Overall, imidacloprid reduced the survivorship, feeding, and egestion of mayflies and oligochaetes at concentrations greater than 0.5 but less than 10 μg/L. Inhibited feeding and egestion indicate physiological and behavioral responses to this insecticide. © 2007 SETAC.
Allen Curry R. (2007). Late glacial impacts on dispersal and colonization of Atlantic Canada and Maine by freshwater fishes. Quaternary Research, 67(2) 225-233.

Late glacial scenarios of ice retreat and biogeography databases constrain the dispersal routes of obligate freshwater fishes into Atlantic Canada and Maine. Evidence indicates glacial ice covered the present-day mainland and offshore islands at 18,000 14C yr before present. Possible refugia for extirpated freshwater fishes were the exposed outer edge of the Grand Banks (east), exposed Georges Bank (south-Atlantic Refugium), and the Mississippi Refugium in the west. It is improbable that the region was recolonized from the offshore refugia. Rather, fishes recolonized from the east via the upper St. Lawrence River valley into the upper Saint John River, Maine (Lake Madawaska) from 11,000 to 12,000 14C yr BP. The short period of entry resulted in the low diversity of obligate freshwater species in the region. Lake Madawaska was breached and dispersal continued into the remainder of the region after 8000 14C yr BP. By 6000 14C yr BP, access routes to the east along low-lying coastal zones were blocked by rising sea levels, which isolated Prince Edward Island, Cape Breton Island, and most probably Nova Scotia. Natural dispersal across the region appeared complete by this time. © 2006 University of Washington.
Baird D.J., Brown S.S., Lagadic L., Liess M., Maltby L., Moreira-Santos M., Schulz R., Scott G.I. (2007). In situ-based effects measures: determining the ecological relevance of measured responses. Integrated Environmental Assessment and Management, 3(2) 259-267.

The aim of this review is to examine how the choice of test species and study design employed in the use of in situ approaches in ecological risk assessment can maximize the ecological relevance of data. We provide a framework to define and assess ecological relevance that permits study designs to remain focused on the ecological question being addressed. This framework makes explicit the linkages between effects at lower levels of biological organization and higher-order ecological effects at the population, community, and ecosystem levels. The usefulness of this framework is illustrated by reference to specific examples from aquatic ecotoxicology. The use of models as both interpretive and predictive tools is discussed, with suggestions of appropriate methods for different protection goals.
Baird D.J., Burton G.A., Culp J.M., Maltby L. (2007). Summary and recommendations from a SETAC Pellston Workshop on in situ measures of ecological effects. Integrated Environmental Assessment and Management, 3(2) 275-278.

The objective of a SETAC Pellston Workshop held in Portland, Oregon, USA, in November 2004 was to evaluate the use of field-based biological effects and exposure techniques in the hazard and risk assessment of aquatic ecosystems, thereby improving the accuracy and relevance of the decision-making process. This objective was addressed by keynote presentations outlining the state of the science and providing case studies, followed by work-group discussions focusing on 4 main areas: 1) Improving stressor-effect diagnostic capability in the assessment process; 2) maximizing efficiency, quality assurance and quality control, and broad-scale applicability of in situ field bioassays and experimental approaches; 3) determining the ecological relevance and consequences of individual and food chain-based effect measures; and 4) incorporating results from field-based effect methods into a weight-of-evidence decision-making process. Major outcomes from group discussions are highlighted, and future priorities for research in this area are recommended.
Baird D.J., Van den Brink P.J. (2007). Using biological traits to predict species sensitivity to toxic substances. Ecotoxicology and Environmental Safety, 67(2) 296-301.

Species sensitivity distributions (SSD) assume that sensitivity to toxicants within target species is random. While the SSD approach has shown promise, it is limited by the fact that data are sparse for most compounds, and that these data are largely based on the lethal responses of a small group of testing lab species. Here we present an alternative approach, based on the hypothesis that organisms' sensitivity to stress is a function of their biology, and can be predicted from species traits such as morphology, life history, physiology and feeding ecology. Using data from the US EPA's AQUIRE database, we found that four species traits explained 71% of the variability in sensitivity to toxicants within a group of 12 species exposed to 15 chemicals. Our results indicate that this approach has promise, but effort is needed to compile species trait information to increase the power, precision and taxonomic representativeness of this approach. © 2006 Elsevier Inc. All rights reserved.
Barata C., Baird D.J., Nogueira A.J.A., Agra A.R., Soares A.M.V.M. (2007). Life-history responses of Daphnia magna Straus to binary mixtures of toxic substances: Pharmacological versus ecotoxicological modes of action. Aquatic Toxicology, 84(4) 439-449.

Two prevailing theoretical models: concentration addition (CA) and independent action (IA), predict mixture toxicity on the basis of known toxicities of the mixture components. To date, both models have been in most occasions evaluated using unicellular in vivo responses or biochemical in vitro responses. However, when considering more complex models such as the whole organism physiology or life-history traits, the dominant ecotoxicological mode of action, based on the exposure concentrations at which various toxicological effects become operative at the level of whole organism, should be considered. Offspring production in Daphnia magna is driven by the resources acquired from food, and the number of live offspring produced by an organism is the result of two independent factors: the number of eggs produced and the percentage of eggs that survive egg development. In this study joint toxicity effects on offspring production in D. magna were tested using binary mixtures of toxic contaminants known to specifically impair food acquisition (λ-cyhalothrin and cadmium) or to cause egg mortality during development (3,4 dichloroaniline). Tests were performed using a simplified 10-day reproduction assay initiated with gravid females. The results obtained indicate that irrespective of their primary pharmacological mode of action, the joint toxicity of cadmium and λ-cyhalothrin was predicted by the CA model, whereas the joint toxicity of cadmium and 3,4 dichloroaniline was predicted by the IA model. Thus, the results obtained indicate that for life-history traits such as reproduction responses, the dominant ecotoxicological rather than the pharmacological mode of action should be used for predicting joint mixture effects. © 2007 Elsevier B.V. All rights reserved.
Beckerman A.P., Wieski K., Baird D.J. (2007). Behavioural versus physiological mediation of life history under predation risk. Oecologia, 152(2) 335-343.

Predator-generated variation in prey energy intake remains the dominant explanation of adaptive response to predation risk in prey life history, morphology and physiology across a wide range of taxa. This "behavioural hypothesis" suggest that chemical or visual signals of predation risk reduce prey energy intake leading to a life history characterized by a small size and late age at maturity. However, size-selective predation can induce either smaller size-early age or large size-late age life history. The alternative "physiological hypothesis" suggests that size-selective cues decouple the relationship between energy and life history, acting instead directly on development. Here we use a series of experiments in a fish-daphnid predator-prey system to ask whether size-selective predator cues induce a physiological mediation of development, overshadowing behaviourally based changes in food intake. We found fish chemical cues reduce the net energy intake in Daphnia magna, suggesting a behaviourally mediated reduction in energy. Experimental manipulation of food levels show further that reductions in food lead to later but smaller size at maturity. However, in line with the physiological hypothesis, we show that D. magna matures earlier and at a smaller size when exposed to fish predation cues. Furthermore, our data shows that they do this by increasing their development rate (earlier maturity) for a given growth rate, resulting in a smaller size at maturity. Our data, from a classic size-selective predation system, indicate that predator-induced changes in this system are driven by physiological mediation of development rather than behavioural mediation of energy intake. © 2007 Springer-Verlag.
Breau C., Cunjak R.A., Bremset G. (2007). Age-specific aggregation of wild juvenile Atlantic salmon Salmo salar at cool water sources during high temperature events. Journal of Fish Biology, 71(4) 1179-1191.

This study quantified the use of cool water sources by wild 0+, 1+ and 2+ year Atlantic salmon Salmo salar during high water temperatures (i.e. >23°C) in summer 1995 and 2004. During these events, 0+ year Atlantic salmon did not aggregate or increase in abundance in cool water sites. Interestingly, 1+ and 2+ year Atlantic salmon numbers increased in cool water sites. In addition, these older juveniles formed numerous, discrete aggregations along the plume created by a tributary with aggregation locations being similar between years. Aged 2+ year fish aggregations were at the coolest sources whereas 1+ year aggregations were in locations cooler than the main river. Fish in aggregations on average used deeper sections (average depth: 380 mm) compared with the coolest available habitat in the thermal plume (average depth: 230 mm). Hence, during high temperature events, older juvenile Atlantic salmon moved to cooler water sites and then aggregated in deeper microhabitats. © 2007 The Authors.
Chara J., Baird D., Telfer T., Giraldo L. (2007). A comparative study of leaf breakdown of three native tree species in a slowly-flowing headwater stream in the Colombian Andes. International Review of Hydrobiology, 92(2) 183-198.

The dynamics of leaf breakdown in a headwater Colombian stream were evaluated for the native tree species Myrsine guianensis, Cupania latifolia and Nectandra lineatifolia using coarse and fine mesh litter bags. Ten bags of each species (five of each mesh size) were retrieved from the stream at 1, 8, 15, 30, 60 and 120 days, k values ranged from 0.0008 to 0.0058 day-1 and density of macroinvertebrates from 35 to 55 individuals per leaf bag, peaking at day 8. Myrsine guianensis degraded more rapidly than the other species for both coarse and fine mesh bags. This species and Nectandra lineatifolia presented differences in k values between coarse and fine mesh bags, suggesting that macroinvertebrates influenced the decay rate. Despite the low densities of macroinvertebrates found, shredders represented 12.7% of individuals and 50 to 68% of the invertebrate biomass in bags, indicating that this functional feeding group was an important component of fauna associated with litter breakdown in this first order tropical stream. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.
Chernoff E., Curry R.A. (2007). First summer growth predetermined in anadromous and resident brook charr. Journal of Fish Biology, 70(2) 334-346.

Early growth of wild, anadromous and non-anadromous (resident) brook charr Salvelinus fontinalis was compared under controlled laboratory conditions. Offspring were collected as they emerged from natural redds in the Miramichi River, New Brunswick, Canada. Anadromous offspring were initially longer and heavier than residents. Anadromous offspring had lower specific growth rates during their first 2 months post-emergence, but surpassed residents by the third month. Consequently, anadromous offspring remained larger at the end of 3 months and it is concluded that they had a predetermined, maternal and genetic advantage related to body size, rather than an environmentally determined advantage during their first summer of growth. Other studies hypothesize that juvenile development affects life-history strategy adopted as adults, which suggests anadromy in this population may be, at least in part, predetermined by maternal and genetic effects. © 2007 The Fisheries Society of the British Isles.
Culp J.M., Baird D.J. (2007). Establishing Cause-Effect Relationships in Multi-Stressor Environments. Methods in Stream Ecology 835-854.
Cunjak R.A., Curry R.A., Scruton D.A., Clarke K.D. (2007). Fish-forestry interactions in freshwaters of Atlantic Canada. Fishes and Forestry Worldwide Watershed Interactions and Management 439-462.
Curry R.A., Doherty C.A., Jardine T.D., Currie S.L. (2007). Using movements and diet analyses to assess effects of introduced muskellunge (Esox masquinongy) on Atlantic salmon (Salmo salar) in the Saint John River, New Brunswick. Environmental Biology of Fishes, 79(1-2) 49-60.

The muskellunge was introduced in the Saint John River system from stockings in a headwater lake in the 1970s. They have migrated down the system as far as the river's first dam, Mactaquac Hydroelectric Facility, at Fredericton and appear to have established several reproducing populations along the river. This exotic invader represents a potential threat to the severely depleted Atlantic salmon stocks in the river. We radio-tracked muskellunge over a 2-year period in the middle reaches. Home ranges extended to ∼100 km in both riverine and lacustrine areas, including 78% of individuals trans-located upstream of the dam making their way back through the dam successfully. Downstream of the dam, home ranges were <25 km. No spawning areas were detected. An isotope analyses of diet indicated that the large sub-adults and adults had established the greatest proportion of their biomass in a more 15N depleted environment typical of areas farther upstream. Isotope mixing models could not accurately determine the proportion of Atlantic salmon smolts that may have been consumed by muskellunge, but anadromous salmon had ≤7% probabilities of being in the diet. A bioenergetics model suggested ≤5% of the annual food intake by muskellunge occurs during the smolt out-migration period. For the Saint John River, the impacts of growing numbers of muskellunge are multi-faceted creating a complex management challenge. Muskellunge appear to minimally increase predation risk for Atlantic salmon smolts while their increasing numbers are creating a growing recreational fishery and potential threat to the native fish community and ecosystem. © 2007 Springer Science+Business Media, Inc.
Dietrich J.P., Cunjak R.A. (2007). Body and scale growth of wild Atlantic salmon smolts during seaward emigration. Environmental Biology of Fishes, 80(4) 495-501.

The relationship between scale and body growth for emigrating Atlantic salmon, Salmo salar, smolts was previously not understood and therefore was examined in this study using mark-recapture techniques. The size of smolts at time of recapture was significantly greater than when marked (P = 0.0002). The growth in length of smolts emigrating 5 km over an average of 20 days was 7.7 ± 6.1 mm per day. Instantaneous somatic growth (G <inf>body</inf>) ranged from 7.0 × 10-4 to 5.1 × 10-3 (mean = 2.7 × 10-3 ± 1.3 × 10-3). The mean number of plus growth circuli present per scale was significantly greater for smolts when recaptured compared to when marked (P = 0.0014). The instantaneous growth rate of scales (G <inf>scale</inf>) ranged from 1.4 × 10-3 to 11.5 × 10-3 (mean = 6.6 × 10-3 ± 4.3 × 10-3). The relationship between body size and scale radius showed positive allometry rather than isometry. The relationship of G <inf>scale</inf> with G <inf>body</inf> showed positive allometry indicating that scales grew at a slightly faster rate than the body during the emigratory period. © 2006 Springer Science+Business Media, Inc.
Edwards P.A., Cunjak R.A. (2007). Influence of water temperature and streambed stability on the abundance and distribution of slimy sculpin (Cottus cognatus). Environmental Biology of Fishes, 80(1) 9-22.

Sculpin are small-bodied fish that exhibit limited mobility. These fish may therefore be an ideal choice as sentinel species in environmental effects monitoring as they may be more reflective of ambient local conditions than are the large-bodied, more wide-ranging species historically used in monitoring programs. This study quantified the spatial and temporal density and distributional patterns of the slimy sculpin (Cottus cognatus) population in Catamaran Brook, New Brunswick, with the aim of gaining a better understanding of their response to natural environmental variability. We predicted that sculpin densities would follow a longitudinal temperature gradient from headwater to mouth and would be highly sensitive to fluctuations in stream flow and substrate disturbance. Electrofishing surveys conducted twice per year from 1991 to 1998 revealed significant differences in sculpin density between years, reaches, and habitats, but not between seasons. The highest sculpin densities were found in those reaches with the coolest summer water temperature. The Middle reach in Catamaran Brook annually supported the highest sculpin density, followed by the headwater or Upper reach and then by the two lowermost reaches: Gorge and Lower. Stochastic events also influenced population dynamics. A mid-winter ice break-up (1996) and its associated flood and ice scour caused the greatest disturbance of the sculpin population, resulting in a significant density decline and a shift in the population age structure. A bedload movement experiment conducted to further assess sculpins' response to substrate stability identified greater bed stability in the Upper and Middle reaches of the brook than in the Lower reach. The pattern of sculpin distribution observed in this study is consistent with the idea that distribution and abundance of sculpin are significantly influenced by stream temperature but also, in part, by stream bed stability. © 2006 Springer Science+Business Media B.V.
Goldschneider A.A., Haralampides K.A., MacQuarrie K.T.B. (2007). River sediment and flow characteristics near a bank filtration water supply: Implications for riverbed clogging. Journal of Hydrology, 344(1-2) 55-69.

Riverbed clogging is an important issue related to the sustainable exploitation of riverbank filtration well fields. In this research, several complementary field techniques are employed to assess the current state and possible evolution of riverbed clogging at a site in the Saint John River, New Brunswick. The study is conducted in regions of the riverbed that have previously been identified as allowing recharge to the semi-confined aquifer that has been used since 1955 to supply water to the City of Fredericton. Flow velocity measurements, video imaging, and suspended sediment and bed sediment analyses conducted during the low flow (summer) period indicate that part of the recharge area closest to the well field, about 20% of the total area, is affected by bed armoring with cobbles and boulders. Consistent with previous studies, with increasing distance from the riverbank the sediment size decreases and the armor layer disappears. Previous research indicates that turbulent impacting of fine particles into the voids between the cobbles and boulders of the armor layer may reduce infiltration by up to 95%; however, the suspended sediment load in the river is mainly composed of organic matter, and the measured concentrations of suspended sediment (up to 3 mg/L) are not considered high enough to create such large reductions in infiltration. Additionally, the mineral fraction of the suspended sediment would not be expected to settle under the calculated average shear velocity of 0.012 m/s. Other sources of particulate matter, such as the degradation of aquatic vegetation on the riverbed, may be more significant with respect to riverbed clogging; however, annual peak flows may also create bed shear stresses that serve to limit long-term clogging effects. © 2007 Elsevier B.V. All rights reserved.
Horrigan N., Dunlop J.E., Kefford B.J., Zavahir F. (2007). Acute toxicity largely reflects the salinity sensitivity of stream macroinvertebrates derived using field distributions. Marine and Freshwater Research, 58(2) 178-186.

Two types of salinity tolerance information are commonly used for assessing salinity risk to freshwater organisms. These are data from laboratory experiments, usually acute (≤96-h LC<inf>50</inf>) values, and field distributions. Both approaches have advantages and limitations, and their applicability to the formation of guidelines and assessment of risks is not clear. In the present study, the acute lethal tolerances (72-h LC<inf>50</inf>) and acute tolerance scores (ATS) of 37 macroinvertebrate families from Queensland, Australia, were compared with maximum field conductivities and previously derived salinity sensitivity scores (SSS). LC<inf>50</inf> values were significantly correlated with maximal field conductivities and SSS. To investigate this relationship further, the changes in community structure related to an increase in salinity were assessed. A salinity index (SI) (based on cumulative SSS) and acute salinity index (ASI) (based on cumulative ATS) were calculated using an independent data set from south-east Queensland (429 samples) and compared with each other and actual conductivity levels. Both indices were significantly correlated with each other and followed a similar trend when plotted against actual conductivity. These results support the notion that salinity sensitivity of macroinvertebrates derived from acute toxicity experiments reflects sensitivities derived using field distributions. Definition of this relationship will allow the two sources of salinity sensitivity to be combined in a weight-of-evidence approach, resulting in a more robust data set with which to estimate safe salinity concentrations. © CSIRO 2007.
Huusko A., Greenberg L., Stickler M., Linnansaari T., Nykänen M., Vehanen T., Koljonen S., Louhi P., Alfredsen K. (2007). Life in the ice lane: The winter ecology of stream salmonids. River Research and Applications, 23(5) 469-491.

Despite the common view that conditions in winter strongly influence survival and population size of fish, the ecology of salmonids has not been as extensively studied in winter as in other seasons. In this paper, we review the latest studies on salmonid winter survival, habitat use, movement and biotic interactions as they relate to the prevailing physical and habitat conditions in rivers and streams. The majority of research conducted on the winter ecology of salmonids has been carried out in small rivers and streams, where temperatures are above zero and where there is no ice. Investigations in large rivers, regulated and dredged rivers, and under conditions of different ice formations are almost totally lacking, presumably related to sampling difficulties with these systems. The studies-at-hand indicate that a multitude of physical and biological factors affect the survival, behavior, and habitat use of salmonids in winter. The general concept that winter functions as a critical period for the survival of young salmonids is not well supported by the literature. Instead, overwinter survival of juvenile fish appears to be context-dependent, related to specific habitat characteristics and ice regimes of streams. In general, over wintering salmonids prefer sheltered, low velocity microhabitats, are mainly nocturnal, and interact relatively little with conspecifics or interspecifics. Specific descriptions of microhabitat preferences of salmonids are difficult to make due to highly disparate results from the literature. We suggest that future research should be directed towards (1) being able to predict the dynamics of freezing and ice processes at different scales, especially at the local scale, (2) studying fish behavior, habitat use and preference under partial and full ice cover, (3) evaluating the impacts of man-induced environmental modifications (e. g. flow regulation, land-use activities) on the ecology of salmonids in winter, and (4) identifying methods to model and assess winter habitat conditions for salmonids. Copyright © 2007 John Wiley & Sons, Ltd.
Keeler R.A., Breton A.R., Peterson D.P., Cunjak R.A. (2007). Apparent survival and detection estimates for PIT-tagged slimy sculpin in five small New Brunswick Streams. Transactions of the American Fisheries Society, 136(1) 281-292.

The slimy sculpin Cottus cognatus is an abundant and widespread benthic fish that inhabits cold lakes and rivers in North America. The objective of this study was to estimate survival and detection probabilities for slimy sculpin in relation to several environmental and biological predictors. Passive integrated transponder (PIT) tags were implanted into 337 adult slimy sculpin in five tributaries of the Kennebecasis River, New Brunswick, Canada. A portable PIT tag antenna was used to search for marked individuals from June 2003 to July 2004. Cormack-Jolly-Seber open population models were used to test several predictions and to estimate apparent survival and detection probabilities. We found that survival was high (73-99%) among sampling events; the average period was about 4 weeks (range, <1-22 weeks). Survival was positively related to fish length and negatively related to maximum stream discharge. The mean detection probability of tagged sculpin was 0.80, but it varied among sampling events and with respect to the minimum electrical current of our antenna and the percentage of boulder substrate at the site. This study demonstrates that a portable PIT tag system can be used in conjunction with capture-mark-recapture models to acquire an understanding of the basic life history characteristics of slimy sculpin and possibly other small-bodied fish in freshwater systems. © Copyright by the American Fisheries Society 2007.
Keeler R.A., Cunjak R.A. (2007). Reproductive ecology of slimy sculpin in small New Brunswick streams. Transactions of the American Fisheries Society, 136(6) 1762-1768.

The male slimy sculpin Cottus cognatus guards a nest rock and provides parental care for the offspring of one or more females, which deposit all their eggs into the male's nest. The purpose of our research was to determine the timing of nest acquisition, spawning, and hatching and to describe biological (number of eggs) and physical characteristics of the nest. In total, we monitored 77 nests during the 2004 spawning period (April-June). Females' egg masses contained an average of 106 eggs. Males guarded an average of 239 eggs; most guarded two or three females' egg masses. Most males (60%) began guarding nests in early May, about a week before egg deposition, and left the nest by the end of June. Males tended to use cobble in shallow water as nests. These findings suggest that slimy sculpin may be sensitive to changes in natural flow conditions during their reproductive period. © Copyright by the American Fisheries Society 2007.
Kidd K.A., Blanchfield P.J., Mills K.H., Palace V.P., Evans R.E., Lazorchak J.M., Flick R.W. (2007). Collapse of a fish population after exposure to a synthetic estrogen. Proceedings of the National Academy of Sciences of the United States of America, 104(21) 8897-8901.

Municipal wastewaters are a complex mixture containing estrogens and estrogen mimics that are known to affect the reproductive health of wild fishes. Male fishes downstream of some wastewater outfalls produce vitellogenin (VTG) (a protein normally synthesized by females during oocyte maturation) and early-stage eggs in their testes, and this feminization has been attributed to the presence of estrogenic substances such as natural estrogens [estrone or 17β-estradiol (E2)], the synthetic estrogen used in birth-control pills [17α-ethynylestradiol (EE2)], or weaker estrogen mimics such as nonylphenol in the water. Despite widespread evidence that male fishes are being feminized, it is not known whether these low-level, chronic exposures adversely impact the sustainability of wild populations. We conducted a 7-year, whole-lake experiment at the Experimental Lakes Area (ELA) in northwestern Ontario, Canada, and showed that chronic exposure of fathead minnow (Pimephales promelas) to low concentrations (5-6 ng-L-1) of the potent 17α-ethynylestradiol led to feminization of males through the production of vitellogenin mRNA and protein, impacts on gonadal development as evidenced by intersex in males and altered oogenesis in females, and, ultimately, a near extinction of this species from the lake. Our observations demonstrate that the concentrations of estrogens and their mimics observed in freshwaters can impact the sustainability of wild fish populations.
Klassen C.N., Peake S.J. (2007). The use of black fly larvae as a food source for hatchery-reared lake sturgeon. North American Journal of Aquaculture, 69(3) 223-228.

Live and frozen black fly larvae (Diptera: Simuliidae) were incorporated into the diets of larval lake sturgeon Acipenser fulvescens in 2002 and 2005 for a 6-week period to determine whether fish would accept this invertebrate diet more readily than conventional bloodworm (Diptera: Chironomidae) diets. In 2002, daily feedings of live black fly larvae within an 8-h period resulted in a mean survival rate of 37%. Adjusting the diet regime in 2005 (i.e., initial diet of brine shrimp Artemia spp., two daily feedings within a 14-h period, and diet transition periods of 3, 5, and 7 d) resulted in overall mean survival rates greater than 80%. Survival of lake sturgeon transitioned to black fly larvae was significantly better than that of control groups transitioned to bloodworms over 3 d and statistically similar to that of bloodworm-fed groups transitioned over 5 and 7 d. Fewer feedings and lower daily rations of black fly larvae in comparison with bloodworms did not result in differences between the final mean mass of fish in 2005. We conclude that frozen black fly larvae can reduce the effort required to transition lake sturgeon from an initial diet of brine shrimp without compromising current survival and growth standards achieved with bloodworm diets. © Copyright by the American Fisheries Society 2007.
Kullman M.A., Podemski C.L., Kidd K.A. (2007). A sediment bioassay to assess the effects of aquaculture waste on growth, reproduction, and survival of Sphaerium simile (Say) (Bivalvia: Sphaeriidae). Aquaculture, 266(1-4) 144-152.

Increasing concerns regarding the environmental sustainability of freshwater cage aquaculture have encouraged new research on the potential impacts of this industry. A trout aquaculture facility was operated in Lake 375 at the Experimental Lakes Area (ELA) in northwestern Ontario, Canada, in 2003 and 2004. As part of this experiment, the spatial extent and magnitude of the potential impacts of aquaculture waste on the benthic community were assessed in 2004 through a novel sediment bioassay using the fingernail clam Sphaerium simile (Say) (Bivalvia: Sphaeriidae). Survival, growth, reproduction, and metal body burdens were evaluated for individual clams exposed for 6 weeks to sediment collected from directly below the fish cage, and from 1, 3, 5, 8, and 50 m away. The clams exposed to sediment from directly under the cage experienced 100% mortality, and this was attributed to the lower bulk density of the sediment (0.09 g cm- 3 dw) that was heavily influenced by the sedimentation of farm waste, as compared with sites further from the cage (0.11-0.12 g cm- 3 dw). In addition, copper and zinc concentrations were 5 and 7 times greater in the sediment from directly under the cage at mean concentrations of 109 and 1054 μg g- 1 dw, respectively, compared to all other sites at 14-22 and 116-152 μg g- 1 dw, respectively, and may have also contributed to the mortality of these clams. Clams in all other sediment treatments experienced no mortality and had low tissue concentrations of copper (3.9-5.4 μg g- 1 dw) and zinc (23.9-32.3 μg g- 1 dw), consistent with the low concentrations of copper and zinc observed in all of these sediments. Clams exposed to sediment from 1 m from the cage had significantly greater growth than clams exposed to sediments collected 3, 5, and 8 m from the cage. There were no significant differences in average embryo size, but the number of embryos per adult was significantly greater in the clams exposed to the 1 m sediment than those exposed to the 50 m sediment. No significant differences were detected in sediment nutritional quality as measured by C:N ratios and organic content, which were both similar between the 1, 3, 5, 8, and 50 m sites. Results from this study suggest that the effects of rainbow trout (Oncorhynchus mykiss Walbaum) aquaculture on fingernail clams would mainly occur directly under or within a close radius of the cage. This sediment bioassay was an effective method for testing the impacts of cage culture on the growth, reproduction and survival of benthic invertebrates such as the fingernail clam. © 2007 Elsevier B.V. All rights reserved.
Linnansaari T., Roussel J.M., Cunjak R.A., Halleraker J.H. (2007). Efficacy and accuracy of portable PIT-antennae when locating fish in ice-covered streams. Hydrobiologia, 582(1) 281-287.

Active tracking of passive integrated transponder (PIT)-tags using portable antennae is becoming an increasingly common technique in fish habitat studies in shallow rivers. We carried out "blind testing" to test the efficacy (% tags found) and accuracy (distance between predicted and true tag location) of a portable antenna system (Texas Instruments) in winter conditions using 23-mm PIT-tags. Up to 90 cm reading range was achieved and signals penetrated ice, rock, wood and water. In the "blind test" trials, a majority of the hidden tags (N = 12-30) were found indicating high tracking efficacy. PIT-tags that were oriented with their cylindrical axis parallel to the plane of the antenna coil inductor loop resulted in a bimodal detection field that had low detection range in the centre of the loop. The utilization of this bimodal detection field proved to be a very accurate method for identifying tag position (mean ± SE distance from predicted to true tag location 10.9 ± 1.4 cm) and thus well suited for microhabitat and activity studies in winter conditions. Aggregations of tags (multiple tags within 1 m2) and obstacles for the antenna maneuvering (e.g., boulders, logjams) reduced the pinpointing accuracy (mean ± SE 13.3 ± 1.8 cm), but the reduction in accuracy was statistically non-significant between the single and aggregated tags. © 2007 Springer Science+Business Media B.V.
Linnansaari T.P., Cunjak R.A. (2007). The performance and efficacy of a two-person operated portable PIT-antenna for monitoring spatial distribution of stream fish populations. River Research and Applications, 23(6) 559-564.

Passive Integrated Transponder (PIT) technology has enabled the tracking of individual fish by using data-logging stations and one-person operated portable tracking units. Whereas data-logging stations are fixed at a certain location, the portable units have traditionally been used in studies that require tracking operations at small spatial scales (< 1000 m2) due to the time investment necessary to fully scan the stream channel. We developed a two-person operated portable antenna that is stretched between the operators and the area in between is scanned for PIT-tags. The antenna was five metres wide but can be customized to fit stream-specific needs. The antenna can be used with existing Texas Instruments Series 2000 tracking units, and the detection distance ranged between 46 and 61 cm when using 23- or 32-mm PIT-tags, respectively (tag held parallel to the plane of the open coil inductor loop). To assess antenna performance in field trial, we compared the efficacy (% tags found) and time-efficiency (time used to track a study site) between one- and two-person antennae in three separate stream sites. The new antenna type proved to be very efficient (95.2-100%) for locating tags in all trials. However, the new antenna type might not perform adequately in areas with high structural complexity (e.g. logjams, overhanging vegetation) and a follow-up with one-person operated antenna is recommended in such complex habitats. The time consumption was always lower (10-53%) with the new antenna and significant time savings can be assumed especially in areas with a low density of PIT-tagged individuals. Further, we have successfully used the new antenna type to track juvenile Atlantic salmon both in winter conditions (ice-free) and warmer water (14°C) without causing fright responses. The new antenna type makes the use of PIT-technology feasible not only at the micro/mesohabitat scale but also at the segment/reach scale and can thus be used to monitor behavioural responses of fish at the population level in wadable streams. Copyright © 2007 John Wiley & Sons, Ltd.
Martell D.J., Kieffer J.D. (2007). Persistent effects of incubation temperature on muscle development in larval haddock (Melanogrammus aeglefinus L.). Journal of Experimental Biology, 210(7) 1170-1182.

Muscle development and growth were investigated in haddock larvae (Melanogrammus aeglefinus L.) incubated under controlled temperatures (4, 6, 8°C) and reared post-hatch through yolk-dependent and exogenous-feeding stages in a 6°C post-hatch environment. Changes in cell number and size in superficial and deep myotomes within the epaxial muscle were investigated for 28 days following hatch. Distinct and significant differences in muscle cellularity following separate developmental strategies were observed in superficial and deep myotomes. The number of superficial myofibres increased with time and, although not in a manner proportional to temperature during the first 21 days post hatch (d.p.h.), there was observed a trend during the final 7 days of greater mean cell size that was strongly associated with increased temperature. In addition, there was an apparent correspondence between increased temperature and increased size between 21 and 28 d.p.h. Among all temperature groups the superficial myotome not only demonstrated a consistent unimodal myofibre-size distribution but one that increased in range proportional to temperature. In the deep muscle, myotomes from higher incubation temperatures had a broader range of fibre sizes and greater numbers of myofibres. The onset of a proliferative event, characterized by a significant recruitment of new smaller myofibres and a bimodal distribution of cell sizes, was directly proportional to incubation temperature such that it occurred at 14 d.p.h. at 8°C but not until 28 d.p.h. at 4°C. The magnitude of that recruitment was also directly proportional to temperature. Following hatch, those embryos from the greatest temperature groups had the largest mean deep muscle size but, as a result of the proliferative event, had the smallest-sized cells 28 days later. The muscle developmental and growth strategy as indicated by sequential changes in cellularity and cell-size distributions between myotomes in response to temperature are also discussed in light of whole animal growth and development.
Mitchell S.C., Cunjak R.A. (2007). Relationship of upstream migrating adult Atlantic salmon (Salmo salar) and stream discharge within Catamaran Brook, New Brunswick. Canadian Journal of Fisheries and Aquatic Sciences, 64(3) 563-573.

Stream discharge has long been associated with abundance of returning adult spawning salmonids to streams and may also affect body size distribution of adult salmon as low flows interfere with returns of larger-bodied fish. We examined these relationships of abundance and body size within Catamaran Brook, a third-order tributary to the Miramichi River system of New Brunswick, Canada, to investigate the causes of a declining trend in annual returns of Atlantic salmon (Salmo salar) to this stream. Regression models of adult abundance, proportion of the run as grilse, and body size of returning adults as functions of maximum daily stream discharge during the period of upstream spawner migration were constructed. Adult abundance shows a logarithmic relationship with stream discharge and provides good predictive ability, while appearing to not be significantly related to adult abundance in the larger Miramichi system. The proportion as grilse in the run and female body size are also logarithmically related to stream discharge, with low flow years being very influential in the regressions. These relationships of Atlantic salmon population abundance and body size characteristics have implications with respect to stock integrity and production of the following generation. © 2007 NRC.
Mitchell S.C., Cunjak R.A. (2007). Stream flow, salmon and beaver dams: Roles in the structuring of stream fish communities within an anadromous salmon dominated stream. Journal of Animal Ecology, 76(6) 1062-1074.

1. The current paradigm of fish community distribution is one of a downstream increase in species richness by addition, but this concept is based on a small number of streams from the mid-west and southern United States, which are dominated by cyprinids. Further, the measure of species richness traditionally used, without including evenness, may not be providing an accurate reflection of the fish community. We hypothesize that in streams dominated by anadromous salmonids, fish community diversity will be affected by the presence of the anadromous species, and therefore be influenced by those factors affecting the salmonid population. 2. Catamaran Brook, New Brunswick, Canada, provides a long-term data set to evaluate fish community diversity upstream and downstream of an obstruction (North American beaver Castor canadensis dam complex), which affects distribution of Atlantic salmon Salmo salar. 3. The Shannon Weiner diversity index and community evenness were calculated for sample sites distributed throughout the brook and over 15 years. Fish community diversity was greatest upstream of the beaver dams and in the absence of Atlantic salmon. The salmon appear to depress the evenness of the community but do not affect species richness. The community upstream of the beaver dams changes due to replacement of slimy sculpin Cottus cognatus by salmon, rather than addition, when access is provided. 4. Within Catamaran Brook, location of beaver dams and autumn streamflow interact to govern adult Atlantic salmon spawner distribution, which then dictates juvenile production and effects on fish community. These communities in an anadromous Atlantic salmon dominated stream do not follow the species richness gradient pattern shown in cyprinid-dominated streams and an alternative model for stream fish community distribution in streams dominated by anadromous salmonids is presented. This alternative model suggests that community distribution may be a function of semipermeable obstructions, streamflow and the distribution of the anadromous species affecting resident stream fish species richness, evenness, biomass and production. © 2007 The Authors.
Monk W.A., Wood P.J., Hannah D.M., Wilson D.A. (2007). Selection of river flow indices for the assessment of hydroecological change. River Research and Applications, 23(1) 113-122.

A wide range of 'ecologically relevant' hydrological indices (variables) have been identified as potential drivers of riverine communities. Recently, concerns have been expressed regarding index redundancy (i.e. similar patterns of variance) across the host of hydrological descriptors on offer to researchers and water resource managers. Some guiding principles are required to aid selection of the most statistically defensible and meaningful river flow indices for hydroecological analysis. In this short communication, we investigate the utility of a principal components analysis (PCA)-based method that identifies 25 hydrological variables to characterize the major modes of statistical variation in 201 hydrological indices for 83 rivers across England and Wales. The emergent variables, and all 201 hydrological variables, are used to develop regression models [for the whole data set and three river flow regime shape (i.e. annual hydrograph form) classes] for an 11-year macroinvertebrate community dataset (i.e. LIFE scores). The same 'best' models are produced using the PCA-based method and all 201 hydrological variables for two of the three river flow regime groups. However, weaker models are yielded by the PCA-based method for the remaining (flashy) river flow regime class and the whole data set (all 83 rivers). Thus, it is important to exercise caution when employing data reduction/index redundancy approaches, as they may reject variables of ecological significance due to the assumption that the statistically dominant sources of hydrological variability are the principal drivers of, perhaps more subtle (sensitive), hydroecological associations. © Crown copyright 2006. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.
Munkittrick K.R. (2007). Environmental effects of effluents from pulp and paper mills. Fishes and Forestry Worldwide Watershed Interactions and Management 336-362.
Newbury R.W., Bates D.J. (2007). Dynamics of Flow. Methods in Stream Ecology 79-101.
Pavey B., Saint-Hilaire A., Courtenay S., Ouarda T., Bobée B. (2007). Exploratory study of suspended sediment concentrations downstream of harvested peat bogs. Environmental Monitoring and Assessment, 135(1-3) 369-382.

Peat bog harvesting is an important industry in many countries, including Canada. To harvest peat, bogs are drained and drainage water is evacuated towards neighboring rivers, estuaries or coastal waters. High suspended sediment concentrations (SSC) were found in the drainage water at one particular site during the 2001-2002 spring seasons in New Brunswick (Canada). The main objective of this study was to verify this observation at other sites, compare SSC levels leaving harvested peat bogs with those leaving an unharvested bog, and to determine if high SSC events happen only in Spring or all year round. Suspended sediment concentrations were monitored downstream of three harvested peat bogs and an unharvested reference bog located in New Brunswick during the ice free seasons of 2003-2004. On average, SSC at the harvested sites exceeded 25 mg/l, which is the recommended daily maximum concentration, 72% of the time, while the same concentration was exceeded 30% of the time at the unharvested sites. SSC were found to be significantly higher at harvested sites than at the reference sites for all seasons. The highest SSC medians were recorded in the Fall but SSC was elevated in all seasons. High SSC levels in receiving waters may be caused by field ditching activities and insufficient sediment controls. Findings suggest the NB Peat Harvesting 25 mg/l SSC guideline should be reviewed. © Springer Science+Business Media B.V. 2007.
Peters R.E.M., Courtenay S.C., Cagampan S., Hewitt M.L., MacLatchy D.L. (2007). Effects on reproductive potential and endocrine status in the mummichog (Fundulus heteroclitus) after exposure to 17α-ethynylestradiol in a short-term reproductive bioassay. Aquatic Toxicology, 85(2) 154-166.

A short-term reproductive bioassay with the mummichog (Fundulus heteroclitus) was developed to link changes in endocrine status to reproductive potential subsequent to endocrine disrupting substance (EDS) exposure. Sexually mature mummichog were separated by sex and exposed to the synthetic estrogen 17α-ethynylestradiol (EE<inf>2</inf>) at nominal concentrations of 0-100 ng/L for 21 days using a static daily renewal protocol. Half of the fish were sampled on Day 21. At 100 ng/L, male fish had induction of vitellogenin (VTG), increased gonadosomatic index (GSI), decreased testosterone production and decreased circulating 11-ketotestosterone (11-KT). Female fish had decreased circulating estradiol (E<inf>2</inf>) and testosterone (T) at 100 ng/L. There were some impacts at lower concentrations of EE<inf>2</inf> in both sexes, though the results were not consistent. On Day 21, the remaining male and female fish were combined at each treatment and exposed for an additional 7 days during which spawning and fertilization success were also assessed. Males exposed to 100 ng/L EE<inf>2</inf> exhibited VTG induction, increased GSI, and decreased T production on Day 28. Female fish had increased E<inf>2</inf> and T production at 1 and/or 10 ng/L and circulating E<inf>2</inf> levels remained depressed above 10 ng/L. Female fish exposed to 100 ng/L spawned fewer eggs; fertilization was also impaired. In a parallel exposure, measured EE<inf>2</inf> water concentrations were approximately 10-20% of nominal for the 100 ng/L EE<inf>2</inf> treatment over a 24-h static exposure; levels in the other treatments were below detectable levels. Fish exposed to nominal concentrations of EE<inf>2</inf> below environmentally relevant levels (i.e., <10 ng/L) showed minimal effects while both the endocrine system and reproductive potential were affected at 100 ng/L EE<inf>2</inf> (nominal). © 2007 Elsevier B.V. All rights reserved.
Sharpe R.L., MacLatchy D.L. (2007). Lipid dynamics in goldfish (Carassius auratus) during a period of gonadal recrudescence: Effects of β-sitosterol and 17β-estradiol exposure. Comparative Biochemistry and Physiology C Toxicology and Pharmacology, 145(4) 507-517.

The potential for contaminants to alter lipid or cholesterol dynamics in fish is rarely investigated and may include critical physiological endpoints that are impacted by exposure to endocrine-active substances. The current study investigated plasma and tissue lipid dynamics over a period of recrudescence in goldfish, while also examining the potential for β-sitosterol (β-sit), a phytosterol and 17β-estradiol (E<inf>2</inf>), an endogenous estrogen, to alter lipid homeostasis. Goldfish were exposed to 0 μg/g (no chemical; control), 200 μg/g β-sit (72.3% sitosterol mixture) or 10 μg/g 17β-estradiol (E<inf>2</inf>) via Silastic® implants for a period of five months. Plasma lipids peaked in control fish coincident with maximum liver size, while gonadal cholesterol concentration was highest concomitant with maximum gonad size. Plasma lipid concentrations were highly affected by E<inf>2</inf> but not β-sit exposure; E<inf>2</inf> elevated total cholesterol (p < 0.001) and triglyceride (TG; p < 0.001) and decreased high-density lipoprotein (HDL) concentration (p < 0.001) in male fish. Tissue cholesterol concentrations were minimally affected by β-sit exposure, while hepatic cholesterol concentrations were increased in E<inf>2</inf> exposed females (p = 0.041), indicating elevated liver lipogenesis in response to E<inf>2</inf>, but not β-sit, exposure. The present study demonstrates differential effects by β-sit and E<inf>2</inf> on plasma lipoprotein profile and TG concentration and indicates estrogen-specific effects on hepatic lipid metabolism during gonadal development. © 2007 Elsevier Inc. All rights reserved.
Sharpe R.L., Woodhouse A., Moon T.W., Trudeau V.L., MacLatchy D.L. (2007). β-Sitosterol and 17β-estradiol alter gonadal steroidogenic acute regulatory protein (StAR) expression in goldfish, Carassius auratus. General and Comparative Endocrinology, 151(1) 34-41.

Fish exposed to the phytosterol β-sitosterol (β-sit) have decreased circulating hormone and cholesterol concentrations, and decreased gonadal intra-mitochondrial cholesterol pools. The current study examined the potential for β-sit to alter abundance of the key cholesterol transport protein, steroidogenic acute regulatory (StAR) protein, which delivers cholesterol to the first and rate-limiting steroidogenic enzyme P450 side chain cleavage (P450<inf>scc</inf>) inside the mitochondria. Plasma testosterone (T) and lipids (cholesterol, lipoproteins and triglycerides) were also measured. Goldfish were exposed to 200 μg/g β-sit (97% pure or as a 72.6% pure phytosterol mixture) and 10 μg/g 17β-estradiol (E<inf>2</inf>; estrogenic control) by intra-peritoneal Silastic® implants for 21-days or for five-months. Plasma T was significantly decreased in male fish exposed to the phytosterol mixture following the long-term exposure (p < 0.001). There were no differences in total cholesterol concentrations among treatments in the short- or long-term exposure, but male fish in the long-term exposure had significantly lower HDL as compared to control fish (p < 0.025) with a corresponding increase in LDL. StAR transcript levels were unchanged following the short-term exposure, but were reduced after five months in male β-sit fish (p = 0.05) and E<inf>2</inf>-treated female fish (p = 0.05). This reduction in StAR transcript abundance in conjunction with decreased plasma T and altered plasma lipoprotein fractions demonstrates a non-estrogenic effect of β-sit. This is the first study to show that β-sit has the capacity to alter gonadal StAR transcript abundance, offering a mechanism by which β-sit disrupts reproductive endocrine endpoints. © 2006 Elsevier Inc. All rights reserved.
Shaughnessy K.S., Belknap A.M., Hewitt L.M., Dubé M.G., MacLatchy D.L. (2007). Effects of kraft pulp mill condensates on plasma testosterone levels in mummichog (Fundulus heteroclitus). Ecotoxicology and Environmental Safety, 67(1) 140-148.

Past studies at a bleached kraft pulp mill located in Saint John, NB, Canada have shown that chemical recovery condensates significantly depress circulating and gonadal steroids in mummichog (Fundulus heteroclitus), an endemic fish species. In the present study, compounds were extracted from the condensates, and a toxicity identification evaluation (TIE) was conducted to characterize the hormonally active substances (HASs) in the condensates. Extracts were fractionated by high performance liquid chromatography (HPLC) and mummichog were exposed to the fractions in a 7-day bioassay. Plasma testosterone was measured for each sex following exposure. Responses in fish exposed to the whole extract at 1% v/v were not as pronounced as had been observed previously (female plasma testosterone was reduced by 16% in the current study compared to 75% previously). Dose-response experiments showed an exposure concentration of 4% v/v was required to elicit significant plasma steroid reductions. Despite these responses, individual condensate fractions actually increased steroid levels in mummichog, which suggests that multiple HASs may need to act synergistically or additively to elicit effects, and if separated, the compounds may have different hormonal activity. The HASs in question caused a reduction in male gonad size at 4% v/v, and have sex-dependent mechanisms of action (males were more responsive to exposure than females). © 2006 Elsevier Inc. All rights reserved.
Suski C.D., Kieffer J.D., Killen S.S., Tufts B.L. (2007). Sub-lethal ammonia toxicity in largemouth bass. Comparative Biochemistry and Physiology A Molecular and Integrative Physiology, 146(3) 381-389.

Guidelines for ammonia toxicity in fish are often determined using static exposure tests with immature fish over a 96-h period. These results may not be relevant to aquaculture, hauling or angling tournament scenarios where mature fish can be exposed to ammonia for shorter durations, often following additional stressors such as handling. The current study sought to quantify (1) the impact of ambient ammonia on the ability of largemouth bass to recover from exercise, (2) the behavioural response of largemouth bass to elevated ambient ammonia and (3) the concentration of ammonia that can accumulate in a live-release vessel at an angling tournament. After approximately 3 h, total ammonia (T<inf>amm</inf>) concentrations in a live-release vessel at an angling tournament were almost 200 μM. Exposure of fish to 1000 μM T<inf>amm</inf> (a value approximately 80% below the criteria maximum concentration for largemouth bass) caused significant reductions in ventilation rates, and increases in erratic swimming and irregular ventilation. Exposure to 100 μM T<inf>amm</inf> impaired the ability of largemouth bass to recover from exercise relative to fish recovering in fresh water. Therefore, sub-lethal ambient ammonia concentrations cause physiological disturbances that can impair the recovery of largemouth bass from exercise. © 2006 Elsevier Inc. All rights reserved.
Thériault M.H., Courtenay S.C., Munkittrick K.R., Chiasson A.G. (2007). The effect of seafood processing plant effluent on sentinel fish species in coastal waters of the Southern Gulf of St. Lawrence, New Brunswick. Water Quality Research Journal of Canada, 42(3) 172-183.

This study evaluated effects of effluents discharged by seafood processing plants on populations of fish living in shallow estuarine waters of the southern Gulf of St. Lawrence. To monitor potential nutrient and/or toxicity impacts on fish populations living and possibly feeding in the effluent, we measured indices of survival (age), growth (weight-at-age), reproduction (gonad weight), and energy storage (liver weight, condition factor) on mummichog (Fundulus heteroclitus) and Atlantic silverside (Menidia menidia) in spring, summer, and fall. Fish exposed to effluents in three bays were compared to fish from a local reference site within the same bay and from regional reference sites in bays without seafood plants. Mummichog caught near seafood processing plants showed a number of differences from reference fish consistent with a localized nutrient enrichment effect including elevated growth (3 of 3 plants), liver size (2 of 3), and condition factor (1 of 3) in at least one of the months sampled. Female silverside caught near one of the three fish plants showed an elevated condition factor in spring, but otherwise silverside did not differ significantly from all four reference sites. In a number of cases, fish exposed to effluent differed from reference fish sampled from bays without fish plants but not from the local reference site, implying that the entire bay was affected either by the seafood processing plant or by some other factors. No harmful impacts such as reduced growth or survival were found in our study, possibly because the processing plants studied were relatively small and the amounts of waste discharged could be flushed by tides and currents and/or assimilated by the fish and other biota in the receiving environments. Copyright © 2007, CAWQ.
Vallis L., MacLatchy D.L., Munkittrick K.R. (2007). Assessment of the potential of the rock gunnel (Pholis gunnellus) along the Atlantic coast of Canada as a species for monitoring the reproductive impacts of contaminant exposures. Environmental Monitoring and Assessment, 128(1-3) 183-194.

Evaluating the impacts of point source discharges on fish species in estuarine environments can be challenging because of a paucity of resident species. We evaluated the biology of rock gunnel (Pholis gunnellus) at three relatively uncontaminated sites in the Bay of Fundy, along the Atlantic coast of Canada. Rock gunnel are seasonally resident (April to November) in tide pools, but little was known about their life history in Atlantic Canada or their potential for use for monitoring environmental quality. Fish were collected between April and November, and ranged from 2.46 g-15.2 g in weight and 97 mm-170 mm in length, with a maximum age of 7 years. Both males and females were similar in size, and both reached sexual maturity at a size of 5.5 g. Organ weights and condition indices of fish were stable from spring when they returned from offshore (April to May) until late summer (August to September), but fall fish (October to November) had slightly larger gonads, livers and condition indices. Rock gunnel may be a useful indicator to provide insight into local impacts of point sources over a short time period. However, they do not provide adequate information on reproductive development and performance since they are not exposed to onshore contaminants during the periods of gonadal development that have most commonly found to be sensitive to anthropogenic stressors. © Springer Science+Business Media B.V. 2006.
Vallières G., Munkittrick K.R., MacLatchy D.L. (2007). Assessing fish community structure in relation to water quality in a small estuarine stream receiving oil refinery effluent. Water Quality Research Journal of Canada, 42(2) 72-81.

A large oil refinery discharges its effluent into Little River, a small estuarine stream entering Saint John Harbour, New Brunswick, Canada. An effects-based approach was used to assess the potential responses of fish and fish habitat to the effluent from the oil refinery. The study included a fish community survey and a water quality survey. Lower abundance, species richness, and biodiversity, as well as increased frequency of empty minnow traps, were found downstream of the effluent discharge. Water quality surveys demonstrated that the receiving environment is subjected to extended periods of low dissolved oxygen levels downstream of the effluent discharge. The anoxic periods correlated with the discharge of ballast water through the waste treatment system. Copyright © 2007, CAWQ.
Wroblewski J.S., Kryger-Hann L.K., Methven D.A., Haedrich R.L. (2007). The fish fauna of Gilbert Bay, Labrador: A marine protected area in the Canadian subarctic coastal zone. Journal of the Marine Biological Association of the United Kingdom, 87(2) 575-587.

The Marine Protected Area in Gilbert Bay, Labrador is the first established in the subarctic coastal zone of eastern Canada. A standardized survey of the fish fauna of Gilbert Bay was initiated during the ice-free season of 2004 to provide baseline information on the fish present in water less than 15 m deep. Beach seines and gill-nets sampled three management zones within the bay which are afforded different levels of protection from human activity. The 25 species in 15 families recorded belong to five ecological guilds: (1) estuarine and marine fish resident in the bay; (2) anadromous species transiting the bay; (3) marine species which migrate into the bay to spawn; (4) offshore-spawning marine fish for which the bay is a nursery area; and (5) marine species which occasionally migrate into the bay to feed. Gilbert Bay lies in a transition zone between Arctic and cold-temperate biogeographical provinces, and its fish fauna is dissimilar from a cold-temperate fish assemblage described for Trinity Bay in eastern Newfoundland.
Allen Curry R., Van De Sande J., Whoriskey F.G. (2006). Temporal and spatial habitats of anadromous brook charr in the Laval River and its estuary. Environmental Biology of Fishes, 76(2-4) 361-370.

Anadromy in brook charr occurs across the species' range, but few studies have examined contiguous seasonal movements and habitat utilization of freshwater and estuarine environments. We used acoustic telemetry to track movements of anadromous brook charr for 1 year in the Laval River, Quebec. Fish entered the marine environment in May and June, inhabited shallow (<1.7 m), near-shore areas (<500 m from shore), and rarely ventured beyond the headlands of the bay. They were found where salinities were 1-34 ppt and temperatures 5-18°C. There was a strong tidal periodicity to observed movements with fish running up into bays as they became inundated at high tide and then returning to deep river channels in the bays at low tide. Between late July and early September, the charr returned to freshwater and spawned in the middle and upper sections of the river in October and November. Winter habitats were dispersed over 22 km of the river including two lakes. These detailed observations are an important contribution to our understanding of the evolutionary significance of anadromy in this species. The salinity and temperature co-tolerance provides insights into the species' post-glacial dispersal, present-day distribution, and potential habitat maps for conservation, restoration, and enhancement programmes. © Springer Science+Business Media B.V. 2006.
Al T.A., Leybourne M.I., Maprani A.C., MacQuarrie K.T., Dalziel J.A., Fox D., Yeats P.A. (2006). Effects of acid-sulfate weathering and cyanide-containing gold tailings on the transport and fate of mercury and other metals in Gossan Creek: Murray Brook mine, New Brunswick, Canada. Applied Geochemistry, 21(11) 1969-1985.

Gossan Creek, a headwater stream in the SE Upsalquitch River watershed in New Brunswick, Canada, contains elevated concentrations of total Hg (Hg<inf>T</inf> up to 60 μg/L). Aqueous geochemical investigations of the shallow groundwater at the headwaters of the creek confirm that the source of Hg is a contaminated groundwater plume (neutral pH with Hg and Cl concentrations up to 150 μg/L and 20 mg/L, respectively), originating from the Murray Brook mine tailings, that discharges at the headwaters of the creek. The discharge area of the contaminant plume was partially delineated based on elevated pH and Cl concentrations in the groundwater. The local groundwater outside of the plume contains much lower concentrations of Hg and Cl (<0.1 μg/L and 3.8 mg/L, respectively) and displays the chemical characteristics of an acid-sulfate weathering system, with low pH (4.1-5.5) and elevated concentrations of Cu, Zn, Pb and SO<inf>4</inf> (up to 5400 μg Cu/L, 8700 μg Zn/L, 70 μg Pb/L and 330 mg SO<inf>4</inf>/L), derived from oxidation of sulfide minerals in the Murray Brook volcanogenic massive sulfide deposit and surrounding bedrock. The Hg<inf>T</inf> mass loads measured at various hydrologic control points along the stream system indicate that 95-99% of the dissolved Hg<inf>T</inf> is attenuated in the first 3-4 km from the source. Analyses of creek bed sediments for Au, Ag, Cu, Zn, Pb and Hg indicate that these metals have partitioned strongly to the sediments. Mineralogical investigations of the contaminated sediments using analytical scanning electron microscopy (SEM), transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM), reveal discrete particles (<1-2 μm) of metacinnabar (HgS), mixed Au-Ag-Hg amalgam, Cu sulfide and Ag sulfide. © 2006 Elsevier Ltd. All rights reserved.
Bandelj E., van den Heuvel M.R., Leusch F.D.L., Shannon N., Taylor S., McCarthy L.H. (2006). Determination of the androgenic potency of whole effluents using mosquitofish and trout bioassays. Aquatic Toxicology, 80(3) 237-248.

This study combined bioassay-derived and direct chemical analysis of steroidal compounds in pulp and paper and municipal sewage effluent in order to determine the cause of masculinization of female mosquitofish. The bioassays used in this study consisted of androgen and estrogen receptor binding, and aromatase inhibition using tissues from rainbow trout. This study observed no masculinization of female mosquitofish from a pulp and paper mill effluent that was previously observed to cause this effect. Mosquitofish sampled from the receiving environment of the same mill verified that masculinization was not occurring in the wild. The municipal sewage effluent also had no masculinizing effect. In vitro bioassays indicated significant sources of both androgens and estrogens in the effluents tested with sewage effluent having both the highest estradiol (41 ng/L) and testosterone (182 ng/L) equivalent concentration. These results could not be attributed to any particular compounds measured in the effluents. Two compounds implicated in the masculinization of mosquitofish by pulp and paper effluent, androstenedione and androstadienedione required relatively large (10-100 μg/L) waterborne concentrations to elicit a masculinizing effect and neither of these compounds are likely to occur at levels this high in the natural environment. The potent aromatase inhibitor, 4-hydroxyandrostenedione also did not cause masculinization at 100 μg/L indicating that masculinization did not occur through this mechanism. The mammalian anti-androgen, cyproterone acetate was only partially effective in mosquitofish and reduced the severity of masculinization in the presence of methyl testosterone. While neither effluent masculinized mosquitofish, there was a significant reduction of in vitro ovarian steroid production with the most severe effects observed with the sewage effluent. Overall, this study found the disappearance of a masculinizing effect that had been previously observed; concluded that based on 21 days aqueous exposures androstenedione and androstadienedione are not likely candidates for mosquitofish masculinization, and showed that masculinization and in vitro steroid production are unrelated biological endpoints. © 2006 Elsevier B.V. All rights reserved.
Barata C., Baird D.J., Nogueira A.J.A., Soares A.M.V.M., Riva M.C. (2006). Toxicity of binary mixtures of metals and pyrethroid insecticides to Daphnia magna Straus. Implications for multi-substance risks assessment. Aquatic Toxicology, 78(1) 1-14.

Two different concepts, termed concentration addition (CA) and independent action (IA), describe general relationships between the effects of single substances and their corresponding mixtures allowing calculation of an expected mixture toxicity on the basis of known toxicities of the mixture components. Both concepts are limited to cases in which all substances in a mixture influence the same experimental endpoint, and are usually tested against a "fixed ratio design" where the mixture ratio is kept constant throughout the studies and the overall concentration of the mixture is systematically varied. With this design, interaction among toxic components across different mixture ratios and endpoints (i.e. lethal versus sublethal) is not assessed. In this study lethal and sublethal (feeding) responses of Daphnia magna individuals to single and binary combinations of similarly and dissimilarly acting chemicals including the metals (cadmium, copper) and the pyrethroid insecticides (λ-cyhalothrin and deltamethrin) were assayed using a composite experimental design to test for interactions among toxic components across mixture effect levels, mixture ratios, lethal and sublethal toxic effects. To account for inter-experiment response variability, in each binary mixture toxicity assay the toxicity of the individual mixture constituents was also assessed. Model adequacy was then evaluated comparing the slopes and elevations of predicted versus observed mixture toxicity curves with those estimated for the individual components. Model predictive abilities changed across endpoints. The IA concept was able to predict accurately mixture toxicities of dissimilarly acting chemicals for lethal responses, whereas the CA concept did so in three out of four pairings for feeding response, irrespective of the chemical mode of action. Interaction effects across mixture effect levels, evidenced by crossing slopes, were only observed for the binary mixture Cd and Cu for lethal effects. The analysis of regression residuals showed that interaction effects across mixture ratios were restricted to feeding responses in binary mixtures that included Cu. These results indicate that the ability of the CA and IA concept to predict mixture toxicity effects varies from lethal to sublethal endpoints irrespective of their primary mode of action. This suggests that when considering complex responses, the pharmacological notion of mode of action should be extended to encompass an ecotoxicological mode of action, based on the concentration at which various toxicological effects become operative in the biological system under consideration. © 2006 Elsevier B.V. All rights reserved.
Belknap A.M., Solomon K.R., MacLatchy D.L., Dubé M.G., Hewitt L.M. (2006). Identification of compounds associated with testosterone depressions in fish exposed to bleached kraft pulp and paper mill chemical recovery condensates. Environmental Toxicology and Chemistry, 25(9) 2322-2333.

In previous experiments, bleached kraft chemical recovery condensates generated during softwood pulp production have been identified as a primary source of substances causing testosterone depressions in mummichog (Fundulus heteroclitus). Recent toxicity identification evaluations have encountered inconsistencies in the potential of condensates and fractions to reduce steroid concentrations between three repeated exposures. To assess the sources of these inconsistencies, temporal assessments of condensate extractives and analytical methodologies were evaluated. Condensates were collected during a six-month period, extracted by solid-phase extraction (SPE), and analyzed by gas chromatography-mass spectrometry and gas chromatography-flame photometric detection. All unique extractives were cataloged by mass spectra, peak area, and gas chromatographic retention time, and nine were confirmed and quantified against authentic standards. Confirmed components included phenolic guaiacyl-based lignin degradation products, sulfur (S<inf>8</inf>), three diterpenoids, and a dimethoxy stilbene. Concentrations of confirmed condensate extractives were consistent in all samples collected. Spiking experiments of confirmed extractives revealed substantial losses following high-pressure liquid chromatographic fractionation and three different methods of fraction preparation. In an effort to propose chemical classes associated with biological activity, all unique condensate extractives in previously established bioactive and inactive fractions were classified based on their potential to depress testosterone in mummichog. Of 39 unique components in bioactive SPE extracts of condensates, six were associated with hormonal activity. Mass spectral interpretation indicated hydroxylated diterpenoids, sesquiterpenoids, and a lignin-derived stilbene as classes of chemicals associated with steroid depressions. © 2006 SETAC.
Betancourt-Lozano M., Baird D.J., Sangha R.S., González-Farias F. (2006). Induction of morphological deformities and moulting alterations in Litopenaeus vannamei (Boone) juveniles exposed to the triazole-derivative fungicide tilt. Archives of Environmental Contamination and Toxicology, 51(1) 69-78.

A tropical marine bioassay was developed with juveniles of Pacific white shrimp, Litopenaeus vannamei, in order to test the acute and sublethal toxicity of Tilt, which is the commercial formulation of the fungicide propiconazole. A 10-d acute toxicity and a 32-d sublethal test were performed. A median lethal concentration (LC50) was determined for different exposure times, resulting in a 24-h LC50 of 1167 (1101-1386) μg/L (concentration based on active ingredient propiconazole), and reaching a threshold LC50 (72-h) at 1043 (1018-1068) μg/L. The sublethal exposure test was performed with propiconazole concentrations ranging from 367 to 825 μg/L. Animals in most treatments showed a significant increase in intermoult duration compared to those in the control treatment, although this did not seem to be concentration-dependent. However, the shrimps exposed to the sublethal concentrations of this fungicide showed morphological deformities, with a significant positive relationship between concentration and deformities of the rostrum, paraeopods, and uropods. Altogether, the results presented indicate the potential effects of Tilt on shrimp, particularly under long-term exposures, although these were found to occur at concentrations exceeding those reported in natural environments. © 2006 Springer Science+Business Media, Inc.
Butler K.E., Nadeau J.C., MacQuarrie K.T.B., Dawe M.R., Hunter J.A., Parrott R. (2006). Hydrostratigraphy and recharge in a river valley aquifer as inferred from seismic, electromagnetic, and thermal methods. 19th Symposium on the Application of Geophysics to Engineering and Environmental Problems Sageep 2006 Geophysical Applications for Environmental and Engineering Hazzards Advances and Constraints, 2 976-989.

Near-surface riverine, land, and borehole geophysical surveys have been used to refine the hydrostratigraphic model of a glaciofluvial river valley aquifer at Fredericton, New Brunswick, Canada. Waterborne electromagnetic apparent conductivity profiling has revealed where the aquifer penetrates through an overlying clay/silt aquitard and is in direct hydraulic communication with the Saint John River. High-resolution acoustic sub-bottom profiles have imaged the clay/silt aquitard's structure and stratigraphy, including its termination against the esker-like sand and gravel ridge that makes up the main part of the aquifer. A land-based CMP seismic reflection survey has penetrated through the aquifer system to confirm major variations in the thickness of the underlying impermeable glacial till layer that overlies fractured bedrock at 50 - 60 m depth. Finally, integration of geological boreholes logs with the geophysical information has yielded a contour map showing the structure and paleogeography of the aquifer sand body and major variations in the thickness of its clay/silt cap. This map shows that the aquifer ridge exhibits both topographic and lateral irregularities and crosses beneath the Saint John River near two well fields on opposite sides of the downtown area. The hydrostatigraphic model has been used on a local scale to help design and constrain hydrogeological and hydrogeochemical studies of aquifer recharge and riverbank filtration. Hydraulic head data and temperature time series, collected at discrete points beneath the riverbed, have been used to confirm recharge and determine spatial and temporal patterns in infiltration velocities. The geophysical results are also relevant, on a larger scale to aquifer protection and future well field development.
Chará J.D., Baird D.J., Telfer T.C., Rubio E.A. (2006). Feeding ecology and habitat preferences of the catfish genus Trichomycterus in low-order streams of the Colombian Andes. Journal of Fish Biology, 68(4) 1026-1040.

Six lower order streams in the south-west of Colombia were sampled on a monthly basis in order to determine the status of Trichomycterus species in relation to their food supply (macroinvertebrates), and physico-chemical habitat. Fishes were sampled by electrofishing and samples taken for dietary analysis. Macroinvertebrates were collected using a Surber sampler. Trichomycterus spp. populations were present in all streams in habitats ranging from soft to hard substrata and from relatively stagnant waters to fast flowing streams. The average density of the fishes ranged from 0.06 to 1.14 individuals m-2 with peaks in population corresponding to recruitment of individuals of <1 g. Trichomycterus spp. were found to be benthic carnivores with a diet mostly of aquatic insects. The index of relative importance for the dietary items was 35.0, 10.5, 1.9 and 7.8% for Chironomidae, Trichoptera, Ephemeroptera and Oligochaeta respectively. Combined with physical habitat data, ordinations of fishes and macroinvertebrate data suggested that differences in abundance among sites were driven by stream size and flow regime, indicating dominance of the physical habitat, although a high correlation between Trichomycterus spp. and Chironomidae abundances (r = 0.81, P = 0.049) was also recorded. © 2006 The Fisheries Society of the British Isles.
Courtemanche D.A., Whoriskey F.G., Bujold V., Curry R.A. (2006). Assessing anadromy of brook char (Salvelinus fontinalis) using scale microchemistry. Canadian Journal of Fisheries and Aquatic Sciences, 63(5) 995-1006.

Brook char (Salvelinus fontinalis) exist in both freshwater and anadromous forms, often in sympatry, the ecology of the latter being poorly understood. As strontium (Sr) can substitute to calcium (Ca) and as its concentration in seawater is higher than in freshwater, scale circulii laid down during seawater exposure should be enriched in Sr, allowing precise identification of residence patterns in freshwater and seawater. We attempted to document movements of anadromous brook char using wavelength-dispersive X-ray electron microscopy on individual circulii of sagittally sectioned scales. Body scales of brook char experimentally transferred between freshwater and seawater had elevated Sr/Ca ratios in regions laid down during exposure to seawater. Wild anadromous brook char body scales had consistently higher Sr/Ca ratios than river-resident form. However, in both experimental and wild brook char, Sr/Ca ratios in the scale circulii from freshwater periods showed elevated Sr/Ca ratios after seawater exposure, suggesting whole-scale Sr enrichment associated with exposure to seawater. Although whole-scale elemental composition revealed whether a fish has ever resided in a marine environment, analysis of Sr patterns at the level of individual circulii did not allow resolution of fine-scale patterns of these movements in brook char. © 2006 NRC Canada.
Dietrich J.P., Cunjak R.A. (2006). Evaluation of the impacts of Carlin tags, fin clips, and Panjet tattoos on juvenile Atlantic salmon. North American Journal of Fisheries Management, 26(1) 163-169.

The potential impacts of marking techniques on juvenile Atlantic salmon Salmo salar were assessed in a hatchery and in the wild. Hatchery-reared parr ranging from 12.0 to 20.8 cm were marked with Carlin tags and fin-clipped. Anal, pelvic, or caudal fin clips were used to investigate the rate of fin regeneration. No mortality or tag loss occurred, and there was no significant change in condition factor between marked and unmarked treatments or among fish of different mark groups. Carlin tag wounds began to heal within 28 d. However, this was followed by a period where the majority of wounds became irritated, thus slowing the healing process; thereafter, the majority of individuals showed an accelerated healing that continued until the end of the hatchery experiment (146 d). Caudal fins showed the first signs of regeneration, and pelvic fins showed the greatest amount of regeneration by the end of the experiment (146 d). Anal fins showed significantly less fin regeneration than pelvic or caudal fin clips and so were used as a secondary mark in the field to investigate differences in survival and mark retention between Panjet tattoos and Carlin tags. Panjet-tattooed and Carlin-tagged smolts held for 24 h posthandling showed no difference in survival (97% overall), and mark retention was 100%. Recapture success was equivalent between tagged and tattooed individuals, and none of the recaptured smolts showed evidence of tag loss. The results of this study provide evidence of the efficacy in using anal fin clips, tattoos, and Carlin tags as marking techniques in fisheries research. © Copyright by the American Fisheries Society 2006.
Dubé M.G., MacLatchy D.L., Hruska K.A., Glozier N.E. (2006). Assessing the responses of creek chub (Semotilus atromaculatus) and pearl dace (Semotilus margarita) to metal mine effluents using in situ artificial streams in Sudbury, Ontario, Canada. Environmental Toxicology and Chemistry, 25(1) 18-28.

Mining of the world's second-largest nickel deposits in the area of Sudbury, Ontario, Canada, has caused acidification and metal saturation of some catchments. We conducted artificial stream studies in the years 2001 and 2002 to assess the effects of treated metal mine effluents (MMEs) from three different mining operations discharging to Junction Creek, Sudbury, on two fish species, creek chub (Semotilus atromaculatus) and pearl dace (Semotilus margarita). Treatments tested for 35 to 41 d included reference water, Garson MME (30%), Nolin MME (20%), and Copper Cliff MME (45%). In 2001, effects on chub included reduced survival and depressed testosterone levels (fivefold reduction) after exposure to all MMEs. In 2002, chub and dace survival were reduced to less than 60% in the Copper Cliff and Garson treatments. Tn addition, the total body weights of male and female dace were reduced after exposure to the Garson and Copper Cliff treatments. In 2001 and 2002, responses were most common to the 45% Copper Cliff and 30% Garson effluents, with consistent increases in nickel, rubidium, strontium, iron, lithium, thallium, and selenium observed across treatment waters and body tissues. More work is required to link observed effects to field effects and to identify multitrophic level responses of the ecosystem to the MMEs. The artificial stream studies provided a mechanism to identify changes in the endpoints of relevant fish species exposed to present-day metal mine discharges independent of historical depositions of metals in the Sudbury area. © 2006 SETAC.
Galloway B.J., Munkittrick K.R. (2006). Influence of seasonal changes in relative liver size, condition, relative gonad size and variability in ovarian development in multiple spawning fish species used in environmental monitoring programmes. Journal of Fish Biology, 69(6) 1788-1806.

Basic biological information was collected to assist in understanding the biology of selected small-bodied fishes for use in environmental monitoring programmes. Gonado-somatic index (I<inf>G</inf>) and hepato-somatic index (I<inf>H</inf>) profiles of female blacknose dace Rhinichthys atratulus, mummichog Fundulus heteroclitus and golden shiner Notemigonus crysoleucas were similar, decreasing gradually during the spawning season. I<inf>G</inf> and I<inf>H</inf> profiles of female northern redbelly dace Phoxinus eos peaked twice suggesting oocyte recruitment was continuous throughout the spawning season. Regressions of ovary mass to adjusted body mass (M<inf>A</inf>) were more variable in dace relative to the other fish species. For female blacknose dace, variability in the relationship between ovary mass and M<inf>A</inf> was minimized by selecting either 2 year-old fish and fish that weighed 2-4 g. © 2006 The Fisheries Society of the British Isles.
Haralampides K., Rodriguez A. (2006). Erosional properties of the sediments in the Petitcodiac River estuary at Moncton, New Brunswick. Canadian Journal of Civil Engineering, 33(9) 1209-1216.

The Petitcodiac River estuary was modified after the construction of a causeway in 1968 at Moncton, New Brunswick. To address some of the sediment-related issues associated with recent proposed changes to the causeway, it is essential to characterize the sediment properties. Several samples were obtained in 2003 and 2004 at eight sites from the upper 5 km of the existing estuary to determine sediment properties including particle size, bulk density, in situ water content, and organic content. These properties were determined from cores extracted from the field and reconstituted cores prepared in the laboratory. Facilities to evaluate the erosion rates of relatively undisturbed sediment cores from the field were constructed; four box cores were tested in a 10 m flume to determine erosion rates with depth. In most cases, erosion rates increased with an increase in the applied boundary shear stress and were strongly dependent on sediment properties and the depositional history of the bed. © 2006 NRC Canada.
Jardine T.D., Curry R.A. (2006). Unique perspectives on the influence of size and age on consumer δ15N from a rainbow smelt complex. Journal of Fish Biology, 69(1) 215-223.

Analysis of covariance indicated size had a greater influence than age on δ15N in three rainbow smelt Osmerus mordax morphotypes of Lake Utopia, New Brunswick, Canada. The distinction in size between the three forms allowed a unique analysis and separation of size and age effects, which is not commonly possible because of the strong correlation between size and age. These results provide support for the continued use of δ15N as a trophic level indicator in food web studies. While a slight increase in δ15N with age (P ≤ 0.05) in intermediate-sized smelt raises questions about a potential accumulation of 15N with age, the effect of size was far stronger in governing δ15N values. The possible confounding influence of age when interpreting trophodynamics of short-lived consumers appears to be small. © 2006 The Authors.
Jardine T.D., Kidd K.A., Fisk A.T. (2006). Applications, considerations, and sources of uncertainty when using stable isotope analysis in ecotoxicology. Environmental Science and Technology, 40(24) 7501-7511.

Stable isotope analysis (SIA) has become a powerful tool for ecotoxicologists to study dietary exposure and biomagnification of contaminants in wild animal populations. The use of SIA in ecotoxicology continues to expand and, while much more is known about the mechanisms driving patterns of isotopic ratios in consumers, there remain several considerations or sources of uncertainty that can influence interpretation of data from field studies. We outline current uses of SIA in ecotoxicology, including estimating the importance of dietary sources of carbon and their application in biomagnification studies, and we present six main considerations or sources of uncertainty associated with the approach: (1) unequal diet-tissue stable isotope fractionation among species, (2) variable diet-tissue stable isotope fractionation within a given species, (3) different stable isotope ratios in different tissues of the animal, (4) fluctuating baseline stable isotope ratios across systems, (5) the presence of true omnivores, and (6) movement of animals and nutrients between food webs. Since these considerations or sources of uncertainty are difficult to assess in field studies, we advocate that researchers consider the following in designing ecotoxicological research and interpreting results: assess and utilize variation in stable isotope diet-tissue fractionation among animal groups available in the literature; determine stable isotope ratios in multiple tissues to provide a temporal assessment of feeding; adequately characterize baseline isotope ratios; utilize stomach contents when possible; and assess and integrate life history of study animals in a system. © 2006 American Chemical Society.
Jones F.C., Baird D., Bowman M., Cameron G., Craig B., Cutler B., Diamond J., Dmytrow N., Nicol M., Parker J., Pascoe T., Vaughan H., Whitelaw G. (2006). Performance of Ontario's Benthos Biomonitoring Network: Impacts on participants' social capital, environmental action, and problem-solving ability. Environments, 34(1) 37-53.

The Ontario Benthos Biomonitoring Network (OBBN) is a collaborative initiative that monitors bottom-dwelling aquatic invertebrates to assess ecological condition. The Network is led by Ontario's Ministry of Environment and Environment Canada's Ecological Monitoring and Assessment Network Coordinating Office, and is part of the Canadian Aquatic Biomonitoring Network. This paper evaluates OBBN performance, emphasizing impacts on participants' social capital, environmental action, and problem-solving ability. A questionnaire was used to characterize participants' reasons for joining, their experience and degree of involvement, their satisfaction with the Network, and their socio-economic status and demography. Three hypotheses were tested: (1) that participants' social capital has increased as a result of Network involvement; (2) that OBBN involvement has catalyzed an increase in participants' civic environmental action, or the effectiveness of that action; and (3) that Network members' problem-solving abilities have improved as a result of their participation. Evidence supports all three hypotheses, and participants' subjective assessments suggest that the Network is performing well. New participants join the Ontario Benthos Biomonitoring Network for a variety of water-management-related and social reasons. Most participants categorize the government-participant relationship in the OBBN as a voluntary partnership or collaboration, with an acceptable distribution of funding burden among partners. Participants are generally satisfied with the OBBN, and most believe it to be credible, relevant, legitimate, and inclusive.
Kelly M.H., Hagar W.G., Jardine T.D., Cunjak R.A. (2006). Nonlethal sampling of sunfish and slimy sculpin for stable isotope analysis: How scale and fin tissue compare with muscle tissue. North American Journal of Fisheries Management, 26(4) 921-925.

We found that the sampling of tissues that do not result in the death of the fish, such as scale and fin tissue, may be substituted for muscle tissue in stable isotope analysis (SIA) of fishes. Comparisons were made between the values of δ13C and δ15N found in muscle tissue with the corresponding scale tissue of three sunfish species (bluegill Lepomis macrochirus, pumpkinseed L. gibbosus, and redbreast sunfish L. auritus) and with caudal fin tissue of slimy sculpin Cottus cognatus. The fish showed strong linear correlation in δ13C values between their nonlethally sampled scale or fin tissue and their muscle tissue (combined sunfish: r = 0.97; slimy sculpin: r = 0.84). Sunfish δ13C values were higher in scale tissue than in muscle tissue and required a correction factor for converting the scale values to the muscle values (regression equation: y = 1.1673x + 1.0531). Slimy sculpin δ13C fin and muscle values were similar and did not require a correction factor. The correlation of δ15N values between the tissues was also strong in both sunfish (r = 0.94) and slimy sculpin (r = 0.90). A correction factor was needed to convert δ15N values from scale to muscle in the three sunfish species (y = 0.8504x + 2.6698) and from fin to muscle in slimy sculpin (y = 1.2658x - 3.3234). Results of this study and other literature support the use of nonlethally sampled tissues for SIA of fish. These methods may be used for investigations of rare and endangered species and also allow for analysis of archived fish scales. © Copyright by the American Fisheries Society 2006.
Lopes I., Baird D.J., Ribeiro R. (2006). Genetic adaptation to metal stress by natural populations of Daphnia longispina. Ecotoxicology and Environmental Safety, 63(2) 275-285.

Loss of genetic diversity in natural populations as a result of chemical contamination has been reported in some studies. Here, four field populations of Daphnia longispina, two from sites historically impacted by acid mine drainage (AMD) and two from reference sites, were used to address four objectives: (1) identify differences in sensitivity between the stressed and reference populations; (2) distinguish between the components responsible for those differences (environmental influence vs genetic determination); (3) determine if genetically determined responses of reference and stressed populations converge from lethal to sublethal levels of contamination; and (4) evaluate losses of variability in genetically determined resistance by the stressed populations. Lethal and sublethal assays were carried out by exposing nonacclimated and acclimated neonates to AMD-contaminated waters and to copper dissolved in an artificial medium. Results indicate that both nonacclimated and acclimated individuals from the stressed populations are significantly less sensitive to AMD-contaminated waters than those from the reference populations, at both lethal and sublethal levels. The hypothesis of a convergence from lethal to sublethal responses was confirmed. © 2005 Elsevier Inc. All rights reserved.
Morand C., Haralampides K.A. (2006). Numerical modelling of tidal barrier modification alternatives: Petitcodiac river case study. Canadian Water Resources Journal, 31(2) 123-132.

The purpose of this study was to simulate the hydraulic behaviour of the Petitcodiac Estuary in order to later predict the sediment transport associated with the potential modification of the causeway near Moncton, NB. Six scenarios, each corresponding to the incremental increase of opening the five sluice gates, as well as the complete removal of the causeway, were simulated under various conditions. A three-dimensional (3D) finite element shelf circulation model, QUODDY, was selected to simulate the hydrodynamics. Velocity profiles near the sediment/water interface generated by the calibrated model were used to qualitatively predict the shear stresses that initiate sediment transport. The velocities and shear stresses downstream of the causeway increased as more gates were opened. Preliminary estimates of the depositional and erosional characteristics of the cohesive sediments constituting the channel bed were obtained through laboratory studies. These estimates, in combination with the shear stress predictions from the numerical modelling, were used to map predicted areas of erosion and deposition immediately following the modification of the Petitcodiac River causeway. © 2006, Taylor & Francis Group, LLC.
Ouellette C., Courtenay S.C., St.-Hilaire A., Boghen A.D. (2006). Impact of peat moss released by a commercial harvesting operation into an estuarine environment on the sand shrimp Crangon septemspinosa. Journal of Applied Ichthyology, 22(1) 15-24.

Current methods used in harvesting peat in eastern Canada have raised concerns regarding potential impacts of escaped peat particles on aquatic ecosystems. A study was carried out in Mill Creek, an estuarine tributary of the Richibucto River in New Brunswick, where peat originating from a commercial operation has accumulated over several years. The sand shrimp Crangon septemspinosa Say (1818) was selected to determine potential environmental stress related to presence of peat in the sediment because of its close association with the substrate. Despite the introduction of sedimentation ponds at the harvesting site in 1994, peat particles continued to enter and accumulate in Mill Creek between 1997 and 1999. Increases in peat depth ranged from 6 to 31 cm and the volume of surficial (0-15 cm) sediments containing peat increased from 35% in 1997 to 44% in 1998 and 76% in 1999. Beach seine surveys carried out during July to September of 1996-1998 indicated that fewer sand shrimp occurred over substrates having higher (>66%) peat concentration than over sand or mud with lower (<33%) peat concentration. Length of sand shrimp did not vary consistently with peat concentration but sand shrimp caught over substrates containing medium (34-65%) peat concentration displayed lower condition [wet weight at total length (TL)] than conspecifics from substrates of both higher and lower peat concentration in all surveys. In a separate survey, peat was found in the stomachs of sand shrimp caught over substrates composed of high but not low peat concentration. We conclude that present mitigation measures at this site have been ineffective in preventing escape of peat moss into the estuarine environment and that the resulting peat deposition has reduced habitat quality for estuarine macrofauna as reflected in a reduction of the number and condition of sand shrimp. © 2006 Blackwell Verlag, Berlin.
Palace V.P., Wautier K.G., Evans R.E., Blanchfield P.J., Mills K.H., Chalanchuk S.M., Godard D., McMaster M.E., Tetreault G.R., Peters L.E., Vandenbyllaardt L., Kidd K.A. (2006). Biochemical and histopathological effects in pearl dace (Margariscus margarita) chronically exposed to a synthetic estrogen in a whole lake experiment. Environmental Toxicology and Chemistry, 25(4) 1114-1125.

Potential effects of exposure to the synthetic estrogen 17α-ethynylestradiol (EE2) were examined in several species of fish from a lake experimentally treated with environmentally relevant concentrations of the contaminant. Ethynylestradiol was added to Lake 260, a small Precambrian shield lake at the Experimental Lakes Area in northwestern Ontario, Canada, from May to October of 2001, 2002, and 2003. Mean concentrations of EE2 in epilimnetic waters ranged between 4.5 and 8.1 ng/L during the three years, with overall means of 6.1 (±2.8), 5.0 (±1.8), and 4.8 (±1.0) ng/L for the three years, respectively. Male and female pearl dace (Marguriscus margarita) captured after EE2 additions began contained up to 4,000-fold higher concentrations of the egg yolk precursor vitellogenin than fish captured from the same lake before the EE2 additions or when compared to fish from reference lakes. Edema in the ovaries, inhibited development of testicular tissue, intersex, and histopathological kidney lesions were all evident in fish exposed to EE2. Some indications that EE2 exposure affected in vitro steroidogenic capacity of the ovaries and the testes existed, although results were not always consistent between years. Pearl dace abundance was similar in the lake treated with EE2 and the reference lake. A trend exists toward a reduced overall population of pearl dace from the treated and reference lakes, as do indications that young-of-the-year size classes are less abundant in the EE2-treated lake. Biochemical and histopathological impacts observed in fish exposed to EE2 in this study have not yet been linked to clear population level impacts in pearl dace. Monitoring of these populations is ongoing. © 2006 SETAC.
Peake S.J., Farrell A.P. (2006). Fatigue is a behavioural response in respirometer-confined smallmouth bass. Journal of Fish Biology, 68(6) 1742-1755.

Fatigue in respirometer-confined smallmouth bass Micropterus dolomieu was confirmed as being largely a behavioural response, and not brought about by depletion of anaerobic fuel stores. While data collected from these fish did not preclude the possibility that the behavioural response was triggered when some physiological threshold was exceeded, locomotory gait transition patterns in confined fish exposed to increasing water velocities support an alternate hypothesis. This is that fatigue is a behavioural decision made at (or near) the gait transition swimming speed, in an effort to avoid activity that, by virtue of the limited space in a typical respirometer, is energetically inefficient and biomechanically difficult. © 2006 The Fisheries Society of the British Isles.
Ramachandran S.D., Sweezey M.J., Hodson P.V., Boudreau M., Courtenay S.C., Lee K., King T., Dixon J.A. (2006). Influence of salinity and fish species on PAH uptake from dispersed crude oil. Marine Pollution Bulletin, 52(10) 1182-1189.

The use of chemical oil dispersants to minimize spill impacts causes a transient increase in hydrocarbon concentrations in water, which increases the risk to aquatic species if toxic components become more bioavailable. The risk of effects depends on the extent to which dispersants enhance the exposure to toxic components, such as polycyclic aromatic hydrocarbons (PAH). Increased salinities can reduce the solubility of PAH and the efficiency of oil dispersants. This study measured changes in the induction of CYP1A enzymes of fish to demonstrate the effect of salinity on PAH availability. Freshwater rainbow trout and euryhaline mummichog were exposed to water accommodated fractions (WAF), and chemically-enhanced water accommodated fractions (CEWAF) at 0‰, 15‰, and 30‰ salinity. For both species, PAH exposure decreased as salinity increased whereas dispersant effectiveness decreased only at the highest salinity. Hence, risks to fish of PAH from dispersed oil will be greatest in coastal waters where salinities are low. © 2006 Elsevier Ltd. All rights reserved.
Roy N.K., Courtenay S.C., Chambers R.C., Wirgin I.I. (2006). Characterization of the aryl hydrocarbon receptor repressor and a comparison of its expression in atlantic Tomcod from resistant and sensitive populations. Environmental Toxicology and Chemistry, 25(2) 560-571.

Atlantic tomcod from the Hudson River. USA, are resistant to cytochrome P4501A1 (CYP1A1) mRNA induction and early life stage toxicities induced by coplanar polychlorinated biphenyls (PCBs) or tetrachlorodibenzo-p-dioxins but not polycyclic aromatic hydrocarbons. We sought to determine if basal expression or inducibility of aryl hydrocarbon receptor repressor (AHRR) mRNA is higher in tomcod from the resistant Hudson River population than in those from sensitive populations. Tomcod AHRR cDNA was characterized and its expression quantified in different tissues and life stages of tomcod from the Hudson River, Miramichi River, Canada (sensitive), and among environmentally exposed tomcod from these two sources and the St. Lawrence River, Canada. Phylogenetic analysis revealed that tomcod AHRR falls within the clade of other vertebrate aryl hydrocarbon receptors (AHRs) but is most closely related to the four previously identified AHRR genes. Induction of AHRR mRNA was observed in all tissues of PCB77-treated juvenile tomcod of Miramichi River descent, and expression differed among tissues and was significantly related to levels of CYP1A1 mRNA expression. Aryl hydrocarbon receptor repressor mRNA was similarly inducible in F2 embryos of Miramichi and Hudson River descent by benzo[a]pyrene but less by PCB77 in Hudson River offspring. A significant, positive correlation was observed between CYP1A1 mRNA and AHRR mRNA concentrations in environmentally exposed tomcod from the three rivers. We conclude that differences in basal expression or inducibility of AHRR mRNA are not the mechanistic basis of resistance but that levels of AHRR often mirror those of CYP1A1, suggesting that a common AHR pathway-related mechanism may modulate expression of both genes. © 2006 SETAC.
Sharpe R.L., Drolet M., MacLatchy D.L. (2006). Investigation of de novo cholesterol synthetic capacity in the gonads of goldfish (Carassius auratus) exposed to the phytosterol beta-sitosterol. Reproductive Biology and Endocrinology, 4.

Total and intra-mitochondrial gonadal cholesterol concentrations are decreased in fish exposed to the phytoestrogen beta-sitosterol (beta-sit). The present study examined the potential for beta-sit to disrupt de novo cholesterol synthesis in the gonads of goldfish exposed to 200 microgram/g beta-sit and 10 microgram/g 17beta-estradiol (E2; estrogenic control) by intra-peritoneal Silastic® implants for 21 days. The de novo cholesterol synthetic capacity was estimated by incubating gonadal tissue with 14C-acetate for a period of 18 hours, followed by chloroform/methanol lipid extraction and thin layer chromatography (TLC) lipid separation. Lipid classes were confirmed using infrared spectroscopy. Plasma testosterone (T) and total cholesterol concentration were measured and gonadosomatic index (GSI) was calculated. Plasma T was significantly reduced in male beta-sit-treated fish compared to control and E2-treated fish (p < 0.001). 14C-Acetate incorporation into cholesterol and cholesterol esters was not significantly different among treatment groups for male and female fish, however, 14C-enrichment was higher than expected in both triglycerides (TG) and free fatty acids (FFA). FFA incorporation was significantly higher in male control fish than either beta-sit or E2 treatments (p = 0.005). Plasma cholesterol concentration was significantly increased in the male beta-sit treatment group compared to controls (p = 0.027). These results indicate gonadal de novo cholesterol biosynthetic capacity is not disrupted by betasit or E2 treatment in early recrudescing male or female goldfish, while plasma cholesterol and steroid concentrations are sensitive to beta-sit exposure. © 2006 Sharpe et al; licensee BioMed Central Ltd.
Shaw S.A., Al T.A., MacQuarrie K.T.B. (2006). Mercury mobility in unsaturated gold mine tailings, Murray Brook mine, New Brunswick, Canada. Applied Geochemistry, 21(11) 1986-1998.

Elevated concentrations of Hg are present (averaging 36 μg/g), mainly as cinnabar, in the Murray Brook Au deposit, located in northern New Brunswick, Canada. After the mined ore was subjected to CN leaching, the tailings were deposited in an unsaturated pile, and 10 a after mine closure an estimated 4.7 × 103 kg of CN and 1.1 × 104 kg of Hg remain in the pile. Elevated Hg concentrations have been measured in the groundwater (up to 11,500 μg/L) and surface water (up to 32 μg/L) down-gradient of the tailings. To investigate the controls on Hg mobility and leaching persistence, laboratory experiments were conducted using unsaturated columns filled with tailings. Within the first 0.2 pore volumes (PV) eluted, the concentrations of Hg and CN increased to peak concentrations of 12,900 μg Hg/L and 16 mg CN/L, respectively. In the subsequent 0.9 PV, concentrations decreased to approximately 1300 μg Hg/L and 2.8 mg CN/L. Thermodynamic calculations demonstrate that >99.8% of the mobilized Hg in the tailings pore water is in the form of Hg-CN complexes, indicating that Hg mobility to the surrounding aquatic environment is directly dependent on the rate of CN leaching. One-dimensional transport simulations suggest that leached CN can be partitioned into conservative (24%) and non-conservative (76%) fractions. Extrapolation of simulation results to the field scale suggests that CN, and by extension Hg, will continue to elute from the tailings for at least an additional 130 a. © 2006 Elsevier Ltd. All rights reserved.
Sigourney D.B., Letcher B.H., Cunjak R.A. (2006). Influence of beaver activity on summer growth and condition of age-2 Atlantic salmon parr. Transactions of the American Fisheries Society, 135(4) 1068-1075.

The activity of beavers Castor canadensis in freshwater environments can have considerable localized impacts on the physical and biological components of riparian ecosystems. By changing the habitat of a stream, beaver dams can cause spatial variation in growth opportunity that may have direct consequences for the growth of resident fish. In a small stream in eastern Canada, we studied the effects of an ephemeral beaver pond on the growth and maturity of age-2 Atlantic salmon Salmo salar parr tagged with passive integrated transponder tags. Water temperature remained relatively uniform throughout the study site. We found very little movement of recaptured fish in the study site. Fish that were recaptured in the beaver pond displayed faster summer growth rates in both length and mass than fish that were recaptured immediately above or below the pond. We also found that parr in the pond maintained relatively high condition factors, whereas fish above and below the pond appeared to decrease in condition factor throughout the summer. In addition to growth, the maturation rates of age-2 males were higher above the dam than below. This study demonstrates the effect a beaver dam can have on individual growth rates. By influencing growth during sensitive periods, the beaver pond may also influence individual life history pathways. This information could be an important component in ecosystem models that predict the effect of beaver population dynamics on the growth of individual salmonids at the landscape scale. © Copyright by the American Fisheries Society 2006.
Skinner M.A., Courtenay S.C., Parker W.R., Curry R.A. (2006). Evaluation of techniques for the marking of mummichogs with emphasis on visible implant elastomer. North American Journal of Fisheries Management, 26(4) 1003-1010.

We conducted two experiments to determine the most appropriate method for use in a mark-recapture study of movements of the mummichog Fundulus heteroclitus in the southern Gulf of St. Lawrence. In the first experiment, 315 mummichogs were marked with fin clips, fingerling tags, acrylic paint, or visible implant elastomer (VIE) and were held for 144 d. Percent tag retention (98.5%) and survival (100%) were highest for the VIE group, and no negative effect was observed on length growth. This led to a more detailed experiment (167 d) to assess potential negative effects of VIE on the growth and survival of 144 mummichogs marked on various body locations; we also assessed mark retention and readability in this experiment. No negative effects on growth were detected; mean daily length increases ranged from 0.04 to 0.12 mm, and specific growth rates for all groups ranged from 0.129% to 0.470%. Mean survival of all groups was 90.8% (range = 66.7-100%) and was higher in marked groups than controls. All marks were retained and visible without the aid of a light-emitting diode light at the end of the experiment, thus demonstrating that VIE is a suitable method for the marking of mummichogs. © Copyright by the American Fisheries Society 2006.
St-Hilaire A., Courtenay S.C., Diaz-Delgado C., Pavey B., Ouarda T.B.M.J., Boghen A., Bobée B. (2006). Suspended Sediment Concentrations Downstream of a Harvested Peat Bog: Analysis and Preliminary Modelling of Exceedances Using Logistic Regression. Canadian Water Resources Journal, 31(3) 139-156.

Acting as natural filters, peatlands are important wetland ecosystems in many northern countries, including Canada. To harvest peat, the vegetation must be removed and the harvested area ditched to drain and dry the peat. Drainage ditches are often designed to route water to settling ponds prior to releasing runoff into nearby water bodies. The present study investigated one key water quality variable, suspended sediment concentration (SSC), downstream of settling ponds in an actively harvested peatland. Time series of SSC for two spring seasons (2001-2002) were recorded at two sites using optical back scatterometers (OBS) calibrated in situ. SSC values exceeded the New Brunswick provincial guideline of 25 mg/L between 53.6 and 86.0% of the time. Even when the threshold was raised to relatively high values such as 500 mg/L, the percentage of exceedance remained relatively high (between 11 and 60%). A statistical model of SSC exceedance, based on logistic regression, was tested to investigate which hydrological forcings may explain high SSC values. Various independent variables were used in conjunction with an autoregressive component and were compared using different goodness of fit criteria. For a threshold of 500 mg/L, the best fit among all the logistic regression models tested included lag 1 and 2 autoregressive terms, as well as five-day cumulative precipitation, air temperature and three-day lagged discharge. The model was able to correctly predict 82% of exceedances. © 2006, Taylor & Francis Group, LLC.
Yuan Z., Courtenay S., Chambers R.C., Wirgin I. (2006). Evidence of spatially extensive resistance to PCBs in an anadromous fish of the Hudson River. Environmental Health Perspectives, 114(1) 77-84.

Populations of organisms that are chronically exposed to high levels of chemical contaminants may not suffer the same sublethal or lethal effects as naive populations, a phenomenon called resistance. Atlantic tomcod (Microgadus tomcod) from the Hudson River, New York, are exposed to high concentrations of polycyclic aromatic hydrocarbons (PAHs) and bioaccumulate polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs). They have developed resistance to PCBs and PCDDs but not to PAHs. Resistance is largely heritable and manifests at early-life-stage toxic end points and in inducibility of cytochrome P4501A (CYP1A) mRNA expression. Because CYP1A induction is activated by the aryl hydrocarbon receptor (AHR) pathway, as are most toxic responses to these compounds, we sought to determine the geographic extent of resistance to CYP1A mRNA induction by PCBs in the Hudson River tomcod population. Samples of young-of-the-year tomcod were collected from seven locales in the Hudson River, extending from the Battery at river mile 1 (RM 1) to RM 90, and from the Miramichi River, New Brunswick, Canada. Laboratory-reared offspring of tomcod adults from Newark Bay, in the western portion of the Hudson River estuary, were also used in this study. Fish were partially depurated in clean water and intraperitoneally injected with 10 ppm coplanar PCB-77, 10 ppm benzo[a]pyrene (BaP), or corn oil vehicle, and levels of CYP1A mRNA were determined. CYP1A was significantly inducible by treatment with BaP in tomcod from the Miramichi River, from laboratory-spawned offspring of Newark Bay origin, and from all Hudson River sites spanning 90 miles of river. In contrast, only tomcod from the Miramichi River displayed significantly induced CYP1A mRNA expression when treated with PCB-77. Our results suggest that the population of tomcod from throughout the Hudson River estuary has developed resistance to CYP1A inducibility and probably other toxicities mediated by the AHR pathway. Tomcod from the Hudson River may represent the most geographically expansive population of vertebrates with resistance to chemical pollutants that has been characterized.
Yuan Z., Courtenay S., Wirgin I. (2006). Comparison of hepatic and extra hepatic induction of cytochrome P4501A by graded doses of aryl hydrocarbon receptor agonists in Atlantic tomcod from two populations. Aquatic Toxicology, 76(3-4) 306-320.

Atlantic tomcod Microgadus tomcod from the Hudson River, New York, are exposed to high levels of polycyclic aromatic hydrocarbons (PAHs) and bioaccumulate mixtures of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and polychlorinatedfurans (PCDD/Fs). Previous studies demonstrated that hepatic cytochrome P4501A (CYP1A) mRNA was not inducible in tomcod from the Hudson River treated with single doses of PCB77 or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), but was inducible with PAHs. In this study, we sought to determine if CYP1A mRNA was inducible with higher doses of these and other halogenated aromatic hydrocarbons (HAHs) in Hudson River tomcod and if decreased sensitivity to gene inducibility occurs across all tissues. Tomcod from the Hudson River and the cleaner Miramichi River, New Brunswick, were treated individually with graded doses of TCDD and coplanar PCBs (PCB77, PCB81, PCB126, PCB169) and profiles of hepatic CYP1A mRNA expression were compared between the two populations. CYP1A mRNA inducibility was also compared in multiple tissues of tomcod from the two rivers that were treated with PCB77. Additionally, hepatic CYP1A mRNA was characterized in Miramichi River tomcod treated with pairs of PCB congeners that included aryl hydrocarbon receptor (AHR) agonists and antagonists. Hepatic CYP1A mRNA was significantly inducible by all agonists in tomcod from the Miramichi River and TCDD and two of four PCBs in tomcod from the Hudson River. CYP1A mRNA was also significantly inducible in four of five tissues of tomcod from the Miramichi River but only in liver of Hudson River tomcod. In summary, CYP1A mRNA inducibility was approximately two orders of magnitude less sensitive in tomcod from the Hudson River than in those from the Miramichi River. But when achieved, maximum levels of CYP1A expression were similar in tomcod from the two populations. Co-administration of PCB126 and PCB77 did not produce significantly greater CYP1A mRNA induction than administration of PCB126 alone and co-administration of mono-ortho-substituted PCB105 significantly decreased CYP1A mRNA inducibility by PCB77. These results indicate that CYP1A mRNA expression is significantly inducible by HAHs in tomcod from the Hudson River and suggest that all components of the AHR pathway are present and functional, but that the pathway is less sensitive to activation than in tomcod from the Miramichi River. Our results also indicate that CYP1A mRNA levels in environmentally exposed fish may not reflect additive tissue burdens of PCB congeners. © 2005 Elsevier B.V. All rights reserved.
Boudreau M., Courtenay S.C., MacLatchy D.L., Bérubé C.H., Hewitt L.M., Van Der Kraak G.J. (2005). Morphological abnormalities during early-life development of the estuarine mummichog, Fundulus heteroclitus, as an indicator of androgenic and anti-androgenic endocrine disruption. Aquatic Toxicology, 71(4) 357-369.

We tested the hypothesis that gross morphological abnormalities are a sensitive indicator of exposure to waterborne androgenic and anti-androgenic compounds during embryonic, larval and juvenile stages of development in the common estuarine killifish, the mummichog (Fundulus heteroclitus; Pisces: Cyprinodontidae). Static exposures with daily renewal were carried out with 10-100,000 ng/L of the androgen agonist, 17α-methyltestosterone (MT), or the androgen antagonist, cyproterone acetate (CA), for 60 days post-fertilization (PF) in duplicate exposures. Measured concentrations were 78.4-155.8% of nominal concentrations for MT and 13.5-168.1% for CA. No dose-related or consistent effects of MT or CA were observed before hatch. In 60 days PF juveniles, incidence of skeletal abnormalities (scoliosis, lordosis, head, facial and fin), soft tissue abnormality (anal swelling) and hemorrhaging were significantly increased by MT but only at high concentrations (≥1000 ng/L). The 10,000 and 100,000 ng/L concentrations of MT produced a wider range of abnormalities than 1000 ng/L. Over 90% of fish exposed to 10,000 or 100,000 ng/L were abnormal with an average of over 3.5 abnormalities per fish. CA did not increase the incidence of any type of abnormality. Survival of juveniles to the end of the exposure was reduced by MT at concentrations of 1000 ng/L and greater in the first experiment and at concentrations of 10,000 ng/L and greater in the second experiment. Juvenile length was reduced by high concentrations of MT (≥10,000 ng/L) in the first experiment and by most concentrations in the second experiment. We conclude that morphological abnormalities in early-life stages of mummichogs are not a sensitive indicator of exposure to androgenic or anti-androgenic waterborne EDSs at environmentally relevant concentrations. Crown Copyright © 2004 Published by Elsevier B.V. All rights reserved.
Chen D.J.Z., MacQuarrie K.T.B. (2005). Correlation of δ15N and δ18O in NO 3- during denitrification in groundwater. Journal of Environmental Engineering and Science, 4(3) 221-226.

Stable isotopes of nitrogen and oxygen are important tools for investigating the occurrence of denitrification in groundwater. Previous investigators have noted a linear relationship between δ15N and δ18O field data collected from shallow groundwater systems, but the reason for such a linear correlation is not clear. In this study, we represent denitrification reactions using parallel, first-order kinetics, and reaction rate constants that depend on the nitrogen or oxygen isotope present in nitrate. The derived mathematical relationship between δ15N and δ18O indicates that nitrogen and oxygen isotopes should fractionate at a constant ratio. Using the laboratory reaction rate constants obtained by Olleros (1983), our equations give a theoretical fractionation ratio value of b = 0.51. A review of published field studies in which denitrification in groundwater has been confirmed, and δ15N and δ18O data has been collected, shows that the mean fractionation ratio value is 0.55 (standard deviation = 0.08, n = 6). The field values therefore agree well with the predicted fractionation ratio value of b = 0.51. It is concluded that a linear relationship between δ15N and δ18O values, with a slope (b) close to 0.51, provides additional, unambiguous evidence that denitrification is responsible for nitrate concentration decline and enrichment in nitrogen isotope values in shallow groundwater. © 2005 NRC Canada.
Courtemanche D.A., Whoriskey F.G., Bujold V., Curry R.A. (2005). A nonlethal approach using strontium in scales to distinguish periods of marine and freshwater residency of anadromous species. Canadian Journal of Fisheries and Aquatic Sciences, 62(11) 2443-2449.

Spatiotemporal migration patterns of brook trout (Salvelinus fontinalis) and various other anadromous fish are poorly understood in many rivers of North America. A new, nonlethal approach to investigate these movements using analysis of scale microchemistry was developed that is relatively simple, cost effective, and potentially more accurate than other monitoring techniques. As fish grow, their scales incorporate in the calcified matrix different concentrations of trace elements present in ambient waters. Seawater Sr concentrations are 10-100 times higher compared with fresh water; thus, a higher Sr/Ca ratio in circulii corresponding to periods of life in seawater would be predicted. We used a wavelength-dispersive X-ray electron microprobe to assess Sr/Ca ratios along sagittal cross sections of scales, spanning the life history of a fish. We demonstrate that existing wavelength-dispersive X-ray electron microprobe studies using Sr analysis may suffer inaccuracies related to scale surface topography, and using the alternative embedding and cutting technique increases significantly the precision of Sr/Ca readings. © 2005 NRC.
Cucherousset J., Roussel J.M., Keeler R., Cunjak R.A., Stump R. (2005). The use of two new portable 12-mm PIT tag detectors to track small fish in shallow streams. North American Journal of Fisheries Management, 25(1) 270-274.

This paper describes two prototypes of portable detectors based on radio frequency identification modules and antennas commercially available in Europe and North America for reading small (2.1-mm X 11.5-mm) passive integrated transponder tags. Maximum tag detection distances ranged from 17 to 36 cm, depending on the system and orientation of the tag to the antenna. The efficiency of the detectors was field-tested with both wild juvenile brown trout Salmo trutta and adult slimy sculpin Cottus cognatus that had been marked by injection of a tag into the peritoneal cavity. By probing the water with the antenna, we were able to detect, on average, 69% of age-1 trout (fork length, 148 ± 26 mm [mean ± SD]), 82% of age-0 trout (fork length, 72 ± 8 mm), and 82% of adult sculpin (total length, 74 ± 9 mm). We did not conduct a formal study to compare the performances of the two prototypes or to determine how habitat characteristics may alter their efficiency. © Copyright by the American Fisheries Society 2005.
Culp J.M., Glozier N.E., Cash K.J., Baird D.J. (2005). Insight into Pollution Effects in Complex Riverine Habitats: A Role for Food Web Experiments. Dynamic Food Webs 354-368.

This chapter summarizes examples of how food web experiments can improve the understanding of pollution effects from pulp mill and metal mining effluents in complex river environments and how an understanding of the food web aids interpretation of ecological responses to stressor gradients. Assessing pollution impacts in rivers is particularly challenging, because flowing water environments receive multiple, interacting effluent discharges from cities and industries, as well as nonpoint source inputs. Field biomonitoring in rivers is further hindered by uncertainties in estimating exposure to pollutants. River ecologists are faced with the dilemma that large-scale experiments, which incorporate contaminant or nutrient stressors, are not feasible on ethical and practical grounds because they may cause severe acute and chronic effects on riverine communities. In complex environments in situ food experiments can elucidate dose-response relationships between components of the model food web and single or multiple stressors better than standard field observations. The results of ecotoxicological experiments in model food webs can provide a wealth of information on possible species interactions within a community, including knowledge of functional redundancy of species and various indirect effects. © 2006 Elsevier Inc. All rights reserved.
Cunjak R.A., Roussel J.M., Gray M.A., Dietrich J.P., Cartwright D.F., Munkittrick K.R., Jardine T.D. (2005). Using stable isotope analysis with telemetry or mark-recapture data to identify fish movement and foraging. Oecologia, 144(4) 636-646.

Information about animal movements has often been inferred from stable isotope analysis (SIA), but is dependent on animals assimilating site-specific isotopic signatures via diet. This potential weakness in ecological interpretation can be overcome by using other investigative tools that provide precise information about individual movement patterns. In this paper, we demonstrate the value of combining SIA with telemetry or mark-recapture data from trapping, electrofishing and remote detection of individuals to study the movement and feeding ecology of fishes in different habitats. In a fjord lake system in Newfoundland, Canada, juvenile Atlantic salmon delayed downstream migration (smolts) or actively moved into a large lake (parr) where they foraged for periods reflecting different life history strategies. In the Miramichi River (New Brunswick, Canada), SIA provided evidence of distinct foraging habitats (tributary versus large river). By tracking fish implanted with passive integrated transponder (PIT) tags, we distinguished between movements related to foraging versus seeking cool water refugia during high temperature events. Finally, site fidelity and limited mobility of slimy sculpin, a small benthic fish, was established where δ13C in muscle tissue showed a progressive enrichment downstream and where a median displacement of <10 m was estimated for sculpin tagged with PIT tags. Technological improvements have permitted non-destructive tissue sampling of wild fishes for SIA, and the tagging and remote detection of animals smaller than was previously possible. These advancements and the combination of investigative tools promise new insights into animal ecology. © Springer-Verlag 2005.
Curry R.A. (2005). Assessing the reproductive contributions of sympatric anadromous and freshwater-resident brook trout. Journal of Fish Biology, 66(3) 741-757.

The δ13C, δ15N and δ34S isotope values of newly emerged, brook trout Salvelinus fontinalis alevins (free-swimming individuals beginning exogenous feeding) were examined to determine if progeny of anadromous female spawners could be detected and their contributions to reproduction assessed in river systems with mixed migration strategies. Separation of anadromous and freshwater resident and immigrant sources of progeny could be detected primarily using δ13C values before alevins reached a size of 28 mm fork length and c. 20 days after exogenous feeding began. Among 10 populations, the contributions of anadromous females ranged from 0 to 42% of newly emerged alevins. Correlations between anadromous contributions and estimates of total brook trout density and alevin production were unexpectedly negative. © 2005 The Fisheries Society of the British Isles.
Curry R.A., Currie S.L., Arndt S.K., Bielak A.T. (2005). Winter survival of age-0 smallmouth bass, Micropterus dolomieu, in north eastern lakes. Environmental Biology of Fishes, 72(2) 111-122.

We examined the winter survival of age-0 smallmouth bass,Micropterus dolomieu, in lakes at their northern limit of distribution in New Brunswick, Canada. Pre- and post-winter collections over a 3 year period suggested the smallest individuals, <50 mm total length, died during winter under ice. Experiments with wild, age-0 smallmouth bass held in lakes demonstrated a size-dependent survival where smaller individuals had greater survival with an increasing temperature of exposure, but the largest individuals had reduced survival at warmer temperatures. Survivors lost 22-54% of pre-winter energy reserves measured as ash-free dry weight, which was similar to wild individuals captured in spring. Body size at the onset of winter affects survival, but it also appears that temperature interacting with a suite of environmental and biological factors affect changes in energy use and therefore survival of age-0 smallmouth bass under ice in winter. © Springer 2005.
Curry R.A., Munkittrick K.R. (2005). Fish assemblage structure in relation to multiple stressors along the Saint John River, New Brunswick, Canada. American Fisheries Society Symposium, 2005(45) 505-521.

The Saint John River is located on the mainland of eastern North America, forming in northern Maine-southeastern Quebec, and flows east and south through New Brunswick. Fish collections were conducted at sites located from 135 to 625 km above the mouth in 2000 and 2001. Methods development trials demonstrated that the highest success was achieved with a standardized netting protocol consisting of a combination of dusk seining, nighttime electrofishing, and short-term gill net sets. A total of 36 species of fish were collected, with the greatest diversity occurring at the farthest downstream site. Upstream migration of anadromous species is restricted by the absence or poor performance of fish passage facilities at the five hydroelectric dams along the river system. The downstream migration of introduced muskellunge Esox masquinongy and upstream range expansions of introduced smallmouth bass Microptenis dolomieu and rainbow trout Oncorhynchus mykiss were observed. Fish species and abundances varied along the river, but the cumulative effects of human activities were not easily identified within the fish assemblage. There may have been a critical threshold within the fish assemblage defined by an accumulation of 20 anthropogenic developments. Cyprinid species declined in abundance and yellow perch Perca flavescens and brown bullhead Ameiurus nebulosus increased in abundance downstream of this apparent threshold. © 2005 by the American Fisheries Society.
Doherty C.A., Galloway B., Curry R.A., Munkittrick K.R. (2005). Performance of white sucker populations along the Saint John River Main Stem, New Brunswick, Canada: An example of effects-based cumulative effects assessment. Water Quality Research Journal of Canada, 40(3) 361-373.

White sucker (Catostomus commersoni) are widely distributed in North America and are often used in environmental monitoring. Whole organism characteristics of three white sucker populations determined to be resident (outside of spawning) within small sections of the Saint John River, New Brunswick, were studied in 2001 and 2002. Significant differences in performance characteristics were present among sites. The differences can be interpreted as either improved sucker performance at Florenceville (upstream site), or decreased performance at Woodstock. Without further investigation it is difficult to identify whether the apparent improved performance is a response to nutrient enrichment, or increased mortality associated with the recent prevalence of lesions. Confounding factors are also present. Daily water level fluctuations resulting from an upstream dam discharge way change habitat availability and/or diversity, thereby altering the fish community. Liver sizes in Saint John River white sucker are considerably larger than in fish collected in Ontario, but are not relative to nearby New Brunswick river populations. This has implications for the importance of reference site selection and understanding the natural variability within a species (intra-specific variation) on multiple spatial scales. Copyright © 2005, CAWQ.
Dubé M.G., MacLatchy D.L., Kieffer J.D., Glozier N.E., Culp J.M., Cash K.J. (2005). Effects of metal mining effluent on Atlantic salmon (Salmo salar) and slimy sculpin (Cottus cognatus): Using artificial streams to assess existing effects and predict future consequences. Science of the Total Environment, 343(1-3) 135-154.

In the summer of 2000, the effects of metal mine discharge on fish growth and exercise performance were assessed at a Zn-Pb-Cu mine in New Brunswick, Canada. Juvenile Atlantic salmon (Salmo salar) were exposed to 0%, 20%, and 80% treated metal mine effluent in a mobile, fish-only artificial stream system. Fish were fed commercial salmon pellets throughout the study. Young-of-the-year slimy sculpins (Cottus cognatus) were exposed to the same treatments in a multitrophic level, modular artificial stream system or mesocosm, in which the fish were dependent on seeded algae and invertebrates for nutrition. Treatment concentrations were chosen to represent existing discharge dilutions (80%) and a scenario of reduced effluent discharge (20%) as predicted upon mine closure (scheduled for 2008). Al, Ba, B, Fe, Mn, Sr, Tl, Ti, and Zn increased in a concentration-dependent fashion across the three treatments. Salmon body burdens of Ba, Cd, Li, Cu, Mn, Se, Sr, and Zn were increased in the 80% treatment, while Tl increased across all treatment levels. Mortalities and depressions in growth in both fish species paralleled treatment concentrations (80%>20%>0%). Salmon liver weight was significantly greater in fish exposed to 20% and 80% effluent in a concentration-dependent fashion. Exercise performance in fish, as assessed by the ability to recover from forced exercise, showed little effect of treatment. The contamination of the receiving environment by mine discharges has led to loss of fish, making it impossible to study the system in situ. However, the use of the artificial stream systems enabled us to assess effects of present conditions on fish, as well as the potential impacts of mine reclamation. The 20% discharge predicted following mine reclamation is potentially favourable for the reinstitution of native fishes into the system. Crown Copyright © 2004 Published by Elsevier B.V. All rights reserved.
Gallant M.J., Haralampides K.A. (2005). An ecohydraulics approach to increasing production of juvenile wild Atlantic salmon (Salmo salar). Proceedings Annual Conference Canadian Society for Civil Engineering, 2005 F-106-9.

The wild Atlantic salmon is considered an endangered species worldwide (Bardonnet and Bagliniere 2000). In New Brunswick, the Department of Fisheries and Oceans reported a marked decline in abundance in the Restigouche River in 1999 (DFO 2000). This study was initiated to devise a long term riverine wild Atlantic salmon population increase by enhancing juvenile Atlantic salmon habitat using boulder clusters in the Little Main Restigouche River in New Brunswick. Current literature shows boulder clusters have increased local abundance of juvenile Atlantic salmon in the short term. However, a lack of information exists on long-term cluster stability and long-term fish responses. Enduring boulder cluster designs will be devised based on juvenile Atlantic salmon habitat preferences, field surveys, water level monitoring, micro-habitat hydraulics, and laboratory tests of different size, alignment, and placement of boulders under varying flow and ice regimes. As this study is ongoing, only preliminary results will be presented.
Gormley K., Guignion D., Teather K. (2005). Distribution and abundance of slimy sculpin (Cottus cognatus) on Prince Edward Island, Canada. American Midland Naturalist, 153(1) 192-194.

Slimy sculpin (Cottus cognatus) are found throughout much of North America; however, their presence has never been recorded on Prince Edward Island (PEI), Canada. After slimy sculpin were discovered in one river in western PEI (Big Pierre Jacques River), all of the rivers on PEI were sampled to determine their distribution. Sculpin were discovered in one additional watershed, the Brae River, which is separated from the Big Pierre Jacques by one watershed. In both rivers, all age classes of sculpin were present, indicating a healthy population. As there are no historical records of slimy sculpin in the province, it is not known whether these fish were introduced to the area, or whether they were historically present but were extirpated from other rivers across the province.
Gormley K.L., Teather K.L., Guignion D.L. (2005). Changes in salmonid communities associated with pesticide runoff events. Ecotoxicology, 14(7) 671-678.

Two agricultural runoff events involving the pesticide azinphos-methyl occurred in July 2002 on the Wilmot River, Prince Edward Island, Canada, resulting in the death of thousands of fish. The fish communities from three sites on this river had been sampled in 2001, permitting comparisons of brook trout (Salvelinus fontinalis) and rainbow trout (Oncorhynchus mykiss) populations before and after the events. Samples taken immediately after the runoff events suggested that brook trout suffered higher mortality than rainbow trout. Young-of-the-year fish were more affected than older age classes for both species. Sampling in 2003, a year after the pesticide runoff events, revealed salmonid communities that were still skewed towards rainbow trout, and a decrease in the 1+ age class density (2002's young of the year) at affected sites. These results suggest a differential effect of the pesticide azinphos-methyl on salmonid species and age classes under natural conditions, and a subsequent change in population and community structure. The possibility of these pesticide runoff events selecting for rainbow trout, an exotic species, is a consideration in management of agriculturally impacted rivers. © 2005 Springer Science+Business Media, Inc.
Gray M.A., Curry R.A., Munkittrick K.R. (2005). Impacts of nonpoint inputs from potato farming on populations of slimy sculpin (Cottus cognatus). Environmental Toxicology and Chemistry, 24(9) 2291-2298.

The potential influence of agricultural activity, particularly potato cultivation, on slimy sculpin populations (Cottus cognatus) was examined at 19 rivers of New Brunswick, Canada. Comparisons with forested streams resulted in differences in fish density, size, and reproductive performance. Young-of-the-year (YOY) sculpin were present only at two of 11 agricultural sites, though they were present at all nine forested sites. Sediment deposition was greatest at agricultural sites, with increased fine sediments deposited. Larger, coarse sands were deposited at two sites with active forest operations. Temperature had a stronger correlation than sedimentation with sculpin size and density in the agricultural region. Agricultural catchments were warmer than in forested catchments (median = 16.0 and 13.3°C, respectively). Body size of slimy sculpin was correlated positively and YOY densities correlated negatively with temperature, and sites with temperatures ≥25°C were devoid of YOY sculpin. Our data indicate there is a significant effect of temperature on slimy sculpin populations in rivers of potato farming areas, highlighting the importance of examining indirect factors when investigating possible impacts of nonpoint source agricultural inputs. Indirect factors such as sediment deposition and temperature need to be considered in order to discriminate accurately the chronic impacts of agricultural chemicals on fish populations. © 2005 SETAC.
Gray M.A., Munkittrick K.R. (2005). An effects-based assessment of slimy sculpin (Cottus cognatus) populations in agricultural regions of northwestern New Brunswick. Water Quality Research Journal of Canada, 40(1) 16-27.

Recently in Atlantic Canada, there has been increased concern associated with potato farming due to an increase in the frequency and magnitude of fish kills downstream of agricultural cultivation activities following major storm events. Over a period of three years (1999-2001), we monitored the population structure and physiological performance of slimy sculpin (Cottus cognatus) within the Little River, located in an intensive potato cultivation region of northwestern New Brunswick. The slimy sculpin, a small-bodied benthic fish, was considered suitable for monitoring due to its natural abundance throughout the system, limited mobility, lack of commercial fishing pressures, and easily measured life history characteristics. Rather than focus on particular agricultural stressors, an effects-based assessment of the fish in the system was conducted to determine whether there were observable and persistent responses of sculpin in the agricultural region. We found that the local population structure at agricultural sites consisted of fewer young-of-the-year sculpin in 2 of 3 fall collections. In comparison with forested reaches, adult sculpin were larger but with smaller gonads, and females had smaller livers, gonads, and fewer and smaller eggs. These biological responses were reduced in the fall of the third year following drier conditions than the previous two years. The effects-based approach successfully demonstrated biological impacts on sculpin both temporally and spatially and therefore the species' potential for studying non-point source impacts in environmental monitoring. Copyright © 2005, CAWQ.
Gray M.A., Peake S.J., Farrell A.P., Bruch R. (2005). Acute didecyl dimethyl ammonium chloride toxicity to larval lake sturgeon, Acipenser fulvescens rafinesque, walleye Sander vitreus mitchill, and northern pike, Esox lucius linnaeus. Bulletin of Environmental Contamination and Toxicology, 75(5) 890-896.
Hanson S.D., Curry R.A. (2005). Effects of size structure on trophic interactions between age-0 smallmouth bass and juvenile anadromous alewives. Transactions of the American Fisheries Society, 134(2) 356-368.

Age-0 alewives Alosa pseudoharengus may compete for food with age-0 smallmouth bass Micropterus dolomieu, possibly resulting in declines to some smallmouth bass fisheries in the northeastern United States and Atlantic Canada. Such competition could dramatically influence the recruitment of smallmouth bass in this region because they are at their northern limit of distribution and age-0 smallmouth bass must accumulate sufficient lipid reserves to survive the overwinter period. We examined the temporal patterns of diet and isotopes of carbon and nitrogen for age-0 alewives and smallmouth bass in a natural lake and a reservoir where alewife escapement is managed. Multiple alewife spawnings occurred in the lake, and small-bodied alewives were abundant throughout the summer. There was minimal diet overlap, age-0 alewives became a significant component of the age-0 smallmouth bass diet, and age-0 bass grew larger in this system. In the reservoir, escapement of alewife spawners was truncated, and a single-size age-0 cohort was observed. Alewives were similar in size to age-0 smallmouth bass, and by late summer their diets showed some overlap and δ13C and δ15N levels were similar. Both predation and the potential for competition existed for these species, and their interactions depended on body size relationships. This is an important consideration in alewife management strategies where coexisting fisheries for smallmouth bass are desired. © Copyright by the American Fisheries Society 2005.
Hewitt L.M., Dubé M.G., Ribey S.C., Culp J.M., Lowell R., Hedley K., Kilgour B., Portt C., MacLatchy D.L., Munkittrick K.R. (2005). Investigation of cause in pulp and paper environmental effects monitoring. Water Quality Research Journal of Canada, 40(3) 261-274.

Environmental Effects Monitoring (EEM) Programs in Canada have been developed for the pulp and paper and metal mining industries. The EEM Program conducts cyclical evaluations of receiving environments to determine whether effects exist when facilities comply with existing regulations. Investigation of cause (IOC) is a specific stage in the EEM Program that is used after environmental effects in fish and/or benthos have been detected, confirmed and their extent and magnitude have been documented. This paper presents an overview of the processes associated with this phase of monitoring. The objective of an IOC is to obtain suf ficient information so that the source of the effect can be identified and removed, or its effects reduced to an acceptable level. The initial direction of an IOC is dependent upon the type of response patterns observed for fish and/or benthos during EEM cycles and extent/magnitude studies. The framework presented in this paper is based on an amalgamation of research projects conducted at Canadian pulp mills over the last decade and selected studies are summarized as examples. It also represents an integration of several research philosophies and scientific disciplines. The framework is based on national response patterns from the second cycle of pulp and paper EEM studies. IOCs are directed into either an eutrophication-based investigation or a contaminant-based investigation (including metabolic disruption in fish). The framework is constructed with a progression of investigative levels designed to provide more information on the causative factors. Each of these phases also represents a decision point for stakeholders to determine if sufficient information has been attained about the causal factor(s) and whether the IOC should be concluded. It is expected that the framework will evolve with a growing knowledge base of causal factors, as facilities enter into this phase of the EEM Program. Copyright © 2005, CAWQ.
Imre I., Grant J.W.A., Cunjak R.A. (2005). Density-dependent growth of young-of-the-year Atlantic salmon Salmo salar in Catamaran Brook, New Brunswick. Journal of Animal Ecology, 74(3) 508-516.

1. While density-dependent mortality and emigration have been widely reported in stream salmonid populations, density-dependent growth is less frequently detected. A recent study suggests that density-dependent growth in stream salmonids occurs at low densities, whereas density-dependent mortality and emigration occur at high densities. 2. To test the hypothesis that density-dependent growth occurs primarily at low rather than at high densities, we examined the relationship between average fork length and population density of young-of-the-year (YOY) Atlantic salmon at the end of the growing season using a 10-year data set collected on Catamaran Brook, New Brunswick. We tested whether (1) average body size decreases with increasing density; (2) the effect of density on average body size is greatest at low densities; (3) growth rate will decrease most rapidly at low effective densities [∑(fork length) 2]; (4) density-dependent growth is weaker over space than over time; and (5) the strength of density-dependent growth increases with the size of the habitat unit (i.e. spatial scale) when compared within years, but not between years. 3. There was a strong negative relationship between the average body size and population density of YOY Atlantic salmon in the autumn, which was best described by a negative power curve. Similarly, a negative power curve provided the best fit to the relationship between average body size and effective density. Most of the variation in average body size was explained by YOY density, with year, location and the density of 1 + and 2+ salmon accounting for a minor proportion of the variation. 4. The strength of density-dependent growth did not differ significantly between comparisons over space vs. time. Consistent with the last prediction, the strength of density-dependent growth increased with increasing spatial scale in the within-year, but not in the between-year comparisons. 5. The effect of density on growth was strongest at low population densities, too low to expect interference competition. Stream salmonid populations may be regulated by two mechanisms: density-dependent growth via exploitative competition at low densities, perhaps mediated by predator-induced reductions in drift rate, and density-dependent mortality and emigration via interference competition at high densities. © 2005 British Ecological Society.
Jardine T.D., Al T.A., MacQuarrie K.T.B., Ritchie C.D., Arp P.A., Maprani A., Cunjak R.A. (2005). Water striders (family Gerridae): Mercury sentinels in small freshwater ecosystems. Environmental Pollution, 134(1) 165-171.

To circumvent some of the previous limitations associated with contaminant-monitoring programs, we tested the suitability of the water strider (Hemiptera: Gerridae) as a mercury sentinel by comparing total mercury concentrations in water striders and brook trout (Salvelinus fontinalis) from a variety of stream sites in New Brunswick, Canada. There was a strong association between the two variables across sites (r 2 = 0.81, P < 0.001) in systems where both atmospheric deposition and a point source (an abandoned gold mine) were likely contributing to ambient mercury levels. In a small stream draining the gold mine tailings pile, water striders had mercury concentrations an order of magnitude higher than those from reference locations. Temporal variation at three southern New Brunswick stream sites was non-significant. These results suggest that water strider mercury levels accurately quantify food chain entry of the element. The use of sentinel species holds great potential for expanding contaminant-monitoring programs. Water striders accurately reflect the entry of mercury in food chains of small freshwater systems. © 2004 Elsevier Ltd. All rights reserved.
Jardine T.D., Cartwright D.F., Dietrich J.P., Cunjak R.A. (2005). Resource use by salmonids in riverine, lacustrine and marine environments: Evidence from stable isotope analysis. Environmental Biology of Fishes, 73(3) 309-319.

We measured stable isotope ratios (δ13C and δ15N) of invertebrates, Atlantic salmon, Salmo salar, and brook trout, Salvelinus fontinalis, in three distinct freshwater environments (headwater tributary, ultra-oligotrophic lake, and main-stem river) in the Western Brook system, Newfoundland, Canada. Large differences in the stable carbon signatures of invertebrates allowed the identification of organic matter assimilation from each environment by resident parr and migrating smolts. Brook trout captured in the headwater tributary in June had a carbon signature characteristic of the tributary, while those collected in August had enriched 13C (maximum = -15.6‰) and 15N (maximum = 12.8‰) values. These enriched carbon and nitrogen signatures were indicative of foraging at sea. There was a low correlation between δ13C and δ15N (r 2 = 0.198) for individual fish that was likely due to the confounding influence of trout feeding in the lake and the lower main-stem of the river, where δ13C of food sources was high but δ15N was low. Smolts emigrating from Western Brook Pond where they had been foraging (based on lacustrine carbon signatures) were significantly larger than those emigrating from a nursery brook and the main river in the same basin, despite having the same median age. These results suggest better growth opportunities in the lake environment. Trout fork length was positively correlated with δ13C and δ15N, demonstrating that larger individuals had been feeding outside the brook. These results support previous studies that found increased growth potential for salmonids in lacustrine and marine environments, and further, indicate possible adaptive advantages for salmonid movement away from natal brooks. © Springer 2005.
Jardine T.D., Cunjak R.A. (2005). Analytical error in stable isotope ecology. Oecologia, 144(4) 528-533.

The increasing popularity of stable isotope analysis (SIA) as an ecological research tool and the ease of automated analysis have created a knowledge gap between ecologists using SIA and the operators of isotope ratio mass spectrometry (IRMS) equipment. This has led to deterioration in the understanding of IRMS methodology and its proper dissemination in the ecological literature. Of 330 ecological research papers surveyed, 63 (19%) failed to report any form of analytical error associated with IRMS. Of the 267 papers that reported analytical error, there was considerable variation both in the terminology and approach used to quantify and describe error. Internal laboratory standards were often used to determine the analytical error associated with IRMS, so chosen because they are homogenous and have isotopic signatures that do not vary over time. We argue that true ecological samples collected in the field are complex bulk mixtures and often fail to adhere to these two criteria. Hence the analytical error associated with samples is potentially greater than that of standards. A set of standard data run over time with a precision typically reported in the ecological literature (1 standard deviation: 1SD=0.26‰) was simulated to determine the likelihood of spurious treatment effects depending on timing of analysis. There was a 90% likelihood of detecting a significant difference in the stable nitrogen ratio of a single sample (homogenized bovine liver) run in two time periods when n>30. Minor protocol adjustments, including the submission of blind replicates by researchers, random assignment of sample repeats within a run by analytical labs, and reporting 1SD of a single sample analyzed both within and between runs, will only serve to strengthen the interpretation of true ecological processes by both researchers and reviewers. © Springer-Verlag 2005.
Jardine T.D., Curry R.A., Heard K.S., Cunjak R.A. (2005). High fidelity: Isotopic relationship between stream invertebrates and their gut contents. Journal of the North American Benthological Society, 24(2) 290-299.

Benthic macroinvertebrate families were sampled along 3 rivers in New Brunswick, Canada. Stable isotopes of C and N were compared between body tissue and gut contents of individuals. δ13C and δ15N of body tissue and gut contents were strongly correlated (r = 0.94 and 0.93, respectively) over a wide range of δ values. In nonpredators, only minor fractionation of δ13C and δ15N was observed. In predators, diet-tissue fractionation of 13C was minor, but 15N fractionation that may have been related to diet quality (N content) was observed. The influence of diet quality on N-isotope fractionation was inconsistent in direction and strength among families. Our results suggest that subjecting primary consumers to gut clearance prior to processing for stable-isotope analysis is unnecessary, but the guts of predators should be removed before processing. © 2005 by The North American Benthological Society.
Jardine T.D., MacLatchy D.L., Fairchild W.L., Chaput G., Brown S.B. (2005). Development of a short-term in situ caging methodology to assess long-term effects of industrial and municipal discharges on salmon smolts. Ecotoxicology and Environmental Safety, 62(3) 331-340.

Trial experiments to develop an in situ method for determining effects of short-term exposure to contaminants on salmon during the sensitive smolt stage were carried out. Wild Atlantic salmon (Salmo salar) smolts were caged at various estuarine locations in northeast New Brunswick, Canada at different levels of anthropogenic impact in 2000 and 2001. Survival, growth (weight and K), and feeding (δ13C and δ15N) parameters were measured following summer grow-out at a hatchery. A summary of distributions of the four parameters indicated that smolts caged at locations receiving lower levels of industrial and municipal discharges feed and grow better than those caged at sites receiving higher levels. The findings, however, were not repeatable between the 2 years studied. The observed inconsistency between years may be a consequence of the relatively low concentrations of alkylphenolic contaminants (putative causative agents) and overall steroidogenic potency in river water at the time of caging. Differences in temperature and salinity from 2000 to 2001 may have further confounded comparisons across treatments and between years. In future studies, caging in closer proximity to industrial and municipal discharges or in systems with higher concentrations of waterborne contaminants or impoundments would help further the assessment and applicability of this methodology and allow a more robust comparison of smolt feeding and growth among reference and exposure sites. © 2005 Elsevier Inc. All rights reserved.
Lopes I., Baird D.J., Ribeiro R. (2005). Genetically determined resistance to lethal levels of copper by Daphnia longispina: Association with sublethal response and multiple/coresistance. Environmental Toxicology and Chemistry, 24(6) 1414-1419.

The development of resistance to toxicants has been reported for a wide range of organisms. Two questions were addressed in the present study: Are genetically determined resistance responses at lethal levels (min to h) of copper associated with responses at extreme lethal (h to d) and sublethal levels and does genetically determined resistance to lethal levels of copper confer resistance to lethal levels of other chemicals? Twelve cloned lineages of Daphnia longispina, differing in their resistance to copper, were exposed to sublethal concentrations of copper and to lethal concentrations of copper, zinc, cadmium, hydrogen ions, and a pyrethroid insecticide (deltamethrin). Three kinds of toxicity assays were carried out: Survival time (death occurs in min to h; only for metals and hydrogen ions), cumulative mortality (death occurs in h to d; for all tested chemicals), and feeding depression assays (only for copper). A correlation between different levels of toxicity was observed only for extreme and moderate lethal responses to copper, and no correlation was found between lethal and sublethal levels of copper. Multiple resistance to lethal levels of toxicants was observed only for the pair copper/zinc. © 2005 SETAC.
Lopes I., Baird D.J., Ribeiro R. (2005). Resistance to metal contamination by historically-stressed populations of Ceriodaphnia pulchella: Environmental influence versus genetic determination. Chemosphere, 61(8) 1189-1197.

Field populations of daphnids historically-stressed by metal contamination may show increased resistance to those contaminants. This study was undertaken aiming to confirm/infirm three main hypotheses: (1) field populations living in historically-impacted environments are more tolerant to metal stress than populations from reference sites; (2) resistance differences are genetically-determined, i.e., differences persist after controlling for environmental and maternal effects, by acclimating cloned lineages to similar conditions; and (3) resistance to stress in field populations living in historically-impacted environments is due to the disappearance of sensitive individuals rather than the appearance of highly resistant ones, i.e., the shift in the central tendency of resistance is linked to a decrease in the range of population resistance and not to an increased upper limit of the population resistance. Three populations of the cladoceran Ceriodaphnia pulchella Sars in Southern Portugal were sampled; one of which has been historically-stressed by acid mine drainage (AMD) from an abandoned cupric-pyrite mine and two from reference sites within the same watershed. To assess if resistance differences were genetically-determined, the three populations were acclimated for at least five generations under the same controlled conditions. Assays with AMD contaminated water samples were performed with both non-acclimated and acclimated individuals from all studied populations. Reproduction results in sub-lethal assays revealed significant differences between the reference and stressed populations. Significant differences in resistance to lethal levels of toxicity were observed for both non-acclimated and acclimated populations, individuals from population I being more resistant than those from reference populations. The existence of genetically-determined sensitivity differences was attested by the presence of significant differences in resistance to lethal levels of toxicity in acclimated individuals from reference and stressed populations. Results from cumulative mortality assays revealed that sensitive individuals were most probably present in the original population, but no conclusion could be draw about the presence of extreme resistant individuals in the historically-stressed population. Finally, it was shown that responses among populations converged from high to low levels of contamination. © 2005 Elsevier Ltd. All rights reserved.
Peake S.J., Farrell A.P. (2005). Postexercise physiology and repeat performance behaviour of free-swimming smallmouth bass in an experimental raceway. Physiological and Biochemical Zoology, 78(5) 801-807.

We studied postexercise physiology and behaviour of small-mouth bass (Micropterus dolomieu) that voluntarily ascended experimental raceways of varying length (20-50 m) against water velocities ranging from 8 to 120 cm/s. Our first objective was to link mean swimming speed to metabolism using patterns in postexercise muscle glycogen, muscle lactate, and plasma lactate. Our second objective was to examine several behavioural indices (attempt rate, success rate, and recovery time between an ascent and a subsequent attempt) and determine whether patterns in these data reflected those from the physiological measurements. Postexercise muscle glycogen and plasma lactate data suggest that smallmouth bass powered swimming speeds up to 70-80 cm/s using energy from aerobic processes. However, lactate did not begin to accumulate in the white muscle until speeds in excess of 120-130 cm/s were reached. The behavioural parameters measured did not indicate the presence of a physiological threshold at 70-80 cm/s; however, patterns in all factors changed appreciably when fish maintained speeds in excess of 120-130 cm/s. Therefore, it is clear that behaviour and physiology are tightly linked in this species and that maximum aerobic swimming capacity may not limit performance (or re-performance) during short-duration swims. © 2005 by The University of Chicago. All rights reserved.
Riddell D.J., Culp J.M., Baird D.J. (2005). Sublethal effects of cadmium on prey choice and capture efficiency in juvenile brook trout (Salvelinus fontinalis). Environmental Toxicology and Chemistry, 24(7) 1751-1758.

Prey choice in juvenile brook trout (Salvelinus fontinalis) was investigated under sublethal Cd stress in the presence of alternative prey types. Following 30-d exposures to either 0, 0.5, or 5.0 μg/L Cd, individual fish held in artificial stream channels were presented with both motile (Baetis tricaudatus) and nonmotile (Chironomus tentans) prey items and their foraging behavior and capture success was observed. The Cd-exposed trout were found to express a significant preference for C. tentans larvae as alternative prey to B. tricaudatus nymphs. Nevertheless, these preliminary findings indicate that, irrespective of prey choice, the capture efficiency of Cd-stressed trout declined by 20 to 55% with increasing Cd concentration when compared with control fish, and the activity of individual trout increased by 25% over controls, although these responses were not statistically significant. Cadmium significantly affected fish condition factors: The condition factor of control fish increased by 34% over the 30-d period, and Cd-exposed fish declined in condition by 12 to 18%. It is hypothesized that such a switch by fish to feeding on benthic prey under natural exposure conditions and their proximity to contaminated sediment may further exacerbate the sublethal effects of Cd on these individuals by intensifying or prolonging Cd exposure through a combination of trophic transfer and altered foraging behavior. © 2005 SETAC.
Scharler U.M., Hulot F.D., Baird D.J., Cross W.F., Culp J.M., Layman C.A., Raffaelli D., Vos M., Winemiller K.O. (2005). Central Issues for Aquatic Food Webs: From Chemical Cues to Whole System Responses. Dynamic Food Webs 451-462.

Aquatic ecosystems worldwide provide important resources for human populations. Estuarine and marine habitats provide many essential ecosystem services, including climate regulation, yet currently these systems are impacted over large areas through over-exploitation and degradation. Moreover, aquatic ecosystems represent an integrative picture of environmental impacts and management practices operating in the terrestrial hinterland. Scientists have as yet not been able to develop predictive whole ecosystem simulation models, and no single method of food web analysis has been subjected to extensive validation of its predictive capabilities. This chapter describes factors that act at the level of individuals and populations, but whose influence on the food web dynamics and ecosystem functioning is as yet poorly understood. It is suggested that the neglect of these factors, among others to be discovered and explored, contributes to the uncertainty of predictive ecosystem simulation models. The use of larger-scale network approaches and the need for quantitative descriptors of food webs is emphasized, and concluded with challenges in application of food web theory to management issues in aquatic systems. © 2006 Elsevier Inc. All rights reserved.
Skinner M.A., Courtenay S.C., Parker W.R., Curry R.A. (2005). Site fidelity of mummichogs (Fundulus heteroclitus) in an Atlantic Canadian Estuary. Water Quality Research Journal of Canada, 40(3) 288-298.

The site fidelity of mummichogs (Fundulus heteroclitus) within the upper Miramichi River estuary, New Brunswick, Canada, was investigated to assess the value of using this fish as a sentinel species for monitoring effects of point source anthropogenic effluents such as pulp and paper mill effluent. During the ice-free season (May to November) of 2002, 4123 adult mummichogs (>30 mm TL) were captured, by beach seine and minnow trap, biweekly from four sites within the estudary. Fish were marked intramuscularly using Visible Implant Elastomer (Northwest Marine Technologies, Inc., Shaw Island, Wash., U.S.). Recaptures were made at the marking sites and elsewhere during this period and again during the ice-free season of April to November 2003. A total of 639 (15.5% of those marked) mummichogs were recaptured with 617 (96.6%) found within 200 m of the point of initial release. Twenty-nine of the 617 were recaptured 2 or 3 times at sites of original marking. The remaining 22 recaptured fish moved distances ranging from 600 to 3600 m up- and downstream of initial marking sites. Eighty-two percent of recaptures were made within 12 weeks of the start of marking with the remainder recovered up to 72 weeks later. These findings are consistent with the results from studies of mummichog movement in smaller water bodies and other parts of the species' range. With regard to mobility, these results add to the growing body of literature supporting the usefulness of mummichogs as a sentinel species in environmental monitoring programs for point-source impacts in Atlantic Canadian estuaries. Copyright © 2005, CAWQ.
Sorrentino C., Roy N.K., Courtenay S.C., Wirgin I. (2005). Co-exposure to metals modulates CYP1A mRNA inducibility in Atlantic tomcod Microgadus tomcod from two populations. Aquatic Toxicology, 75(3) 238-252.

Populations from urbanized and industrialized sites are often exposed to mixtures of chemical contaminants including aromatic hydrocarbons (AHs) and heavy metals. The effects of mixtures of these contaminants on these populations are largely unknown. The Hudson River Estuary is highly contaminated with a variety of AHs including, PCBs and PAHs, and metals, and its population of Atlantic tomcod Microgadus tomcod bioaccumulates those which are persistent. The Hudson River's tomcod population exhibits resistance to persistent AHs as exemplified by significantly decreased inducibility of hepatic cytochrome P4501A (CYP1A) mRNA. We used hepatic CYP1A mRNA inducibility in tomcod from the Hudson River and a sensitive population to investigate the effects of acute co-exposure to metals on aryl hydrocarbon receptor (AHR)-mediated gene expression. Adult tomcod from the Hudson River and the cleaner Miramichi River were i.p. injected with one dose of benzo[a]pyrene (B[a]P) or coplanar PCB77 and graded doses of four metals, As, Cd, Cr, and Ni, and levels of hepatic CYP1A mRNA and protein were assayed. We observed no effects of metals treatment on basal levels of hepatic CYP1A mRNA expression, but all four metals significantly reduced CYP1A mRNA inducibility in tomcod from one or both populations. The magnitude of the inhibition of CYP1A mRNA inducibility differed among the metals and fish from the two populations. Also, the profile of the metals modulation of induced CYP1A mRNA showed differences that depended on the time after treatment of sacrifice. Our results demonstrate that co-exposure to several metals can impact inducible, but not basal levels of CYP1A expression and perhaps other toxicities mediated by the AHR. © 2005 Elsevier B.V. All rights reserved.
Aguilar C., González-Sansón G., Munkittrick K.R., MacLatchy D.L. (2004). Fish assemblages on fringe coral reefs of the northern coast of Cuba near Havana Harbor. Ecotoxicology and Environmental Safety, 58(1) 126-138.

It is difficult to separate effects on fish community assemblages due to anthropogenic stressors from natural factors. We examined small-bodied-fish communities along the northern coast of Cuba near Havana Harbor during the dry (February/March of 2000) and wet (June 2000) seasons. Over 35,000 individual fish were visually counted at 15 sites along the coast in three areas located 0-2.4, 2.4-6.1, and 6.1-10.3km from the entrance to Havana Harbor. Fish communities in four substrate biotopes did not vary significantly between wet and dry seasons, but did vary with water depth. Proximity to Havana Harbor was the second most important factor affecting fish assemblages, and sites closest to the harbor had reduced populations of the bluehead wrasse (Thalassoma bifasciatum) and an increased abundance of slippery dick (Halichoeres bivittatus). More studies are required at the population and individual levels to link stressors (e.g., contaminants, siltation) directly to observed effects. © 2003 Elsevier Inc. All rights reserved.
Arsenault J.T.M., Fairchild W.L., MacLatchy D.L., Burridge L., Haya K., Brown S.B. (2004). Effects of water-borne 4-nonylphenol and 17β-estradiol exposures during parr-smolt transformation on growth and plasma IGF-I of Atlantic salmon (Salmo salar L.). Aquatic Toxicology, 66(3) 255-265.

4-Nonylphenol (4-NP) is an endocrine disrupting substance (EDS) capable of mimicking the action of 17β-estradiol (E<inf>2</inf>). It has been hypothesized that 4-NP in a pesticide formulation is linked to historical declines in Canadian Atlantic salmon (Salmo salar L.) populations, with effects being related to exposure during parr-smolt transformation (PST). To test this hypothesis, Atlantic salmon smolts were exposed to pulse-doses of water-borne 4-NP (20ug/l), sustained doses of water-borne E<inf>2</inf> (100ng/l) (positive control), or ethanol vehicle (negative control) in mid-May during the final stages of PST. Individually tagged smolts were then sampled at three times (June, July and October) to monitor subsequent growth in sea water and plasma insulin-like growth factor I (IGF-I) concentrations. Smolt weights and plasma IGF-I concentrations were both affected by E<inf>2</inf> and 4-NP. The effects of E<inf>2</inf> and 4-NP on mean smolt weights were most prominent in July and October {E<inf>2</inf> (*98.1±2.8, *242.3±10.6g), 4-NP (*102.1±3.1, 255.7±9.5g), controls (112.5±2.8, 282.3±8.8g)} (P<0.05), while their effects on mean plasma IGF-I concentrations were most prominent in June and October {E<inf>2</inf> (15.0±1.9, 28.4±1.8ng/ml), 4-NP (*14.8±1.9, *21.6±1.7ng/ml), controls (20.0±1.1, 31.1±2.0ng/ml)} (P<0.05). Additionally, results suggest that the mechanisms of action of E<inf>2</inf> and 4-NP involve disruption in the GH/IGF-I axis, and that they may be different from each other. The effects of E<inf>2</inf> and 4-NP on growth and plasma IGF-I concentrations observed in this study are ecologically significant because they evoke concerns for successful growth and survival of wild salmon smolts exposed to low levels of estrogenic substances that may occur from current discharges into rivers supporting sea-run salmon stocks. Crown Copyright © 2003 Published by Elsevier B.V. All rights reserved.
Boudreau M., Courtenay S.C., MacLatchy D.L., Bérubé C.H., Parrott J.L., Van Der Kraak G.J. (2004). Utility of morphological abnormalities during early-life development of the estuarine mummichog, Fundulus heteroclitus, as an indicator of estrogenic and antiestrogenic endocrine disruption. Environmental Toxicology and Chemistry, 23(2) 415-425.

To evaluate the use of morphological abnormalities for standard testing of endocrine-disrupting substances (EDS), we tested the hypothesis that developmental abnormalities are a sensitive indicator of exposure to waterborne estrogenic and antiestrogenic EDS during embryonic, larval, and juvenile stages in the common estuarine killifish, the mummichog (Pisces: Cyprinodontidae). Static exposures with daily renewal were carried out with 10 to 10,000 ng/L of the estrogen agonist 17α-ethynylestradiol (EE<inf>2</inf>) or antagonist ZM189,154 (ZM) for the first 25 or 60 d of life. Incidence of skeletal abnormalities (scoliosis, lordosis, head, craniofacial, jaw, fin) and soft tissue abnormality (anal swelling) were significantly increased by EE <inf>2</inf> but only at high concentrations (1,000 or 10,000 ng/L). Sixty-day exposure produced more severe abnormalities than 25-d exposure and in a higher proportion of fish. Within the longer exposure, 10,000 ng/L EE<inf>2</inf> produced more abnormal fish than 1,000 ng/L (100% vs 51.6%) and more abnormalities per abnormal fish (5.73 vs 1.47). Fish reared to 12 months in clean water after exposure for 60 d to 10,000 ng/L EE<inf>2</inf> survived at a lower rate than controls, retained abnormalities with the exception of anal swelling and, like fish exposed to other concentrations of EE<inf>2</inf> and ZM, showed increased weight at length at 6 and 12 months. Sixty-day exposure to ZM increased the incidence of scoliosis (1,000 ng/L) but decreased the overall incidences of abnormal fish and lordosis (10 and 10,000 ng/L). No impacts of EE<inf>2</inf> or ZM were observed before hatch, and clearing and staining of larvae demonstrated that expression of vertebral abnormalities coincided temporally with ossification. We conclude that morphological abnormalities in mummichogs are not a sensitive indicator of exposure to estrogenic or antiestrogenic waterborne EDSs at environmentally relevant concentrations.
Brasfield S.M., Bradham K., Wells J.B., Talent L.G., Lanno R.P., Janz D.M. (2004). Development of a terrestrial vertebrate model for assessing bioavailability of cadmium in the fence lizard (Sceloporus undulatus) and in ovo effects on hatchling size and thyroid function. Chemosphere, 54(11) 1643-1651.

In the terrestrial environment, standardized protocols are available for measuring the exposure and effects of contaminants to invertebrates, but none currently exist for vertebrates. In an effort to address this, we proposed that developing lizard embryos may be used as a terrestrial vertebrate model. Lizard eggs may be particularly susceptible to soil contamination and in ovo exposure may affect hatchling size, mortality, as well as thyroid function. Toxicant-induced perturbations of thyroid function resulting from in ovo chemical exposure may result in toxicity during the critical perinatal period in reptiles. Fertilized Eastern fence lizard (Sceloporus undulatus) eggs were placed in cadmium (Cd)-spiked expanded perlite (0, 1.48, 14.8, 148, 1480, 14800 μg Cd/g, nominal concentrations), artificially incubated at 28°C, and examined daily for mortality. Whole lizard hatchlings as well as failed hatches were homogenized in ethanol and the homogenate was divided for Cd body residue analysis and thyroid hormone (triiodothyronine (T<inf>3</inf>) and thyroxine (T<inf>4</inf>)) analyses. Acute mortality was observed in the two highest doses (1480 and 14800 μg Cd/g). Cadmium body residues showed a higher internal concentration with increasing exposure concentration indicating uptake of Cd. There was a decrease in T<inf>3</inf>:T<inf>4</inf> ratio at the highest surviving dose (148 μg Cd/g), however, there were no differences observed in hatchling size measured as weight and snout-vent length, or in whole body thyroid hormone levels. In summary, this study has shown Cd amended to a solid phase representing soil (perlite) can traverse the thin, parchment-like shell membrane of the fence lizard egg and bioaccumulate in lizard embryos. We believe this study is a good first step in investigating and evaluating this species for use as a model. © 2003 Elsevier Ltd. All rights reserved.
Charles K., Roussel J.M., Cunjak R.A. (2004). Estimating the contribution of sympatric anadromous and freshwater resident brown trout to juvenile production. Marine and Freshwater Research, 55(2) 185-191.

Carbon and nitrogen stable isotope analysis was used to study the reproductive contributions of anadromous and freshwater resident female brown trout (Salmo trutta L.) in La Roche Brook (Normandy, France), where both forms live in sympatry. Sixty-nine emerging fry were sampled by electrofishing in three different locations in the lower, middle and upper reaches of the stream, in March-April 2002. A collection of samples with known origin (brown trout eggs and fin tissues and benthic invertebrates) allowed classification of each emerging fry as the progeny of freshwater resident (δ13C = -26.0‰ ± 0.8 s.d.; δ15N = 12.5‰ ± 1.4 s.d.) or anadromous (δ13C = -18.8‰ ± 0.6 s.d., δ15N = 14.8‰ ± 0.9 s.d.) female brown trout. It was then possible to estimate the relative contribution (33%) of anadromous females to the population of fry that emerged from redds in 2002 and to evaluate the extent to which freshwater and anadromous spawning grounds overlapped in the stream.
Curry R.A., Currie S.L., Bernatchez L., Saint-Laurent R. (2004). The rainbow smelt, Osmerus mordax, complex of Lake Utopia: Threatened or misunderstood? Environmental Biology of Fishes, 69(1-4) 153-166.

We report on the spawning ecology, genetic characteristics, and predation threats to spawning groups of rainbow smelt, Osmerus mordax, in Lake Utopia, New Brunswick where a dwarf morpho-type has been listed as a threatened species. Two spawning groups in three inlet streams had been previously identified; we observed three groups using four inlet streams. The earliest group was the largest in body size (12-29 cm fork length (FL)), lowest in numbers (∼1 000), and completed spawning approximately two weeks before the second group. The early spawners were previously identified as the normal morpho-type, but we now classify these as a giant morphotype. The second group spawned in three different streams. They were intermediate in body size (10-15 cm FL) and numbers (∼10 000). The dwarf group began spawning as the intermediate group completed spawning and within the same three streams. The dwarfs were numerous (∼1 000 000), small in size (<12 cm), and with higher gill raker counts. Microsatellite analyses suggested that gene flow among groups occurred, but genetic divergence was high and genetic separation among populations of the same group among streams and within a stream occurred. Stable isotopes and stomach contents indicated the dwarf group were likely consumed by a variety of fishes, but they were not the sole food resource of any predator including a population of landlocked salmon. These are some of the complexities of smelt ecology, but there are clearly life history tactics that we do not yet understand.
Curry R.A., MacNeill W.S. (2004). Population-level responses to sediment during early life in brook trout. Journal of the North American Benthological Society, 23(1) 140-150.

The spawning sites, incubation success, and density of young-of-the-year (YOY) brook trout (Salvelinus fontinalis) were examined in stream populations experiencing varying levels of sediment stress. Our objective was to determine effects on embryos and YOY and examine cumulative effects on the populations. Early development was unaffected (88% survival). Mortality occurred at late, encapsulated embryo stages likely as a function of oxygen deprivation within redds. Survival to emergence from the substrate was significantly reduced (∼50%) in redds in which fine sediments accumulated. Groundwater reduced sediment accumulation in redds and enhanced survival. Sediment may have affected dispersal of YOY trout. All populations appeared successful in term of total density (average = 72/100 m2). Our findings emphasize the importance of targeting multiple life-history stages and understanding local adaptations when searching for true population-level effects in any stressed ecosystem.
Gray M.A., Cunjak R.A., Munkittrick K.R. (2004). Site fidelity of slimy sculpin (Cottus cognatus): Insights from stable carbon and nitrogen analysis. Canadian Journal of Fisheries and Aquatic Sciences, 61(9) 1717-1722.

Concerns regarding sentinel species for assessing environmental impacts include residency, abundance, and suitability for measuring responses, if effects are to be attributable to local conditions. Stable isotope analysis was used as a tool to investigate site fidelity of slimy sculpin (Cottus cognatus) to establish residency and exposure for the sculpin. We predicted that sculpin collected from sites adjacent to agricultural activity would show higher δ15N values than those collected from sites in forested areas because of isotopic enrichment by fertilizers in the former. The predominant use of chemical fertilizer applications in the region, however, resulted in no specific enrichment of 15N in sculpin collected in the agricultural region. However, there was an incremental enrichment in the fish muscle tissue of approximately 5‰ in δ13C values in a downstream direction, irrespective of surrounding land use. As a result, the dual-isotope comparison was successful at demonstrating site-specific isotopic signatures across sites for 30 km of the river system. The site-specific signatures suggest that slimy sculpin are not moving considerable distances among sites and are incorporating their isotopic signatures over a narrow spatial scale. The results support the use of the slimy sculpin as a sentinel species for investigating site-specific environmental impacts.
Heard S.B., Buchanan C.K. (2004). Grazer-collector facilitation hypothesis supported by laboratory but not field experiments. Canadian Journal of Fisheries and Aquatic Sciences, 61(6) 887-897.

Grazing invertebrates in streams feed by harvesting algal cells from surfaces, and in doing so release fine particulate organic matter (FPOM). The "grazer-collector facilitation hypothesis" holds that FPOM production by grazers facilitates growth and (or) survival of FPOM-collecting invertebrates. We tested for grazer-collector facilitation in laboratory and field experiments. In recirculating flumes in the laboratory, we tested for facilitation of the collector Hydropsyche slossonae by the grazers Physa gyrina, Glossosoma intermedium, and Baetis tricaudatus. All three grazers increased FPOM levels in flume water, but only Physa facilitated Hydropsyche growth. In the field, we manipulated Physa and Glossosoma densities to test for facilitation (at a local scale) of natural collector assemblages in an eastern Iowa stream. We did not detect facilitation of any collector by either grazer in the field, despite high power to detect such interactions. We suspect that grazer-collector facilitation was not observed in the field because (unlike in our laboratory flumes) field FPOM levels are often high and extremely variable in time and space and because organic particles can arise from sources other than grazer activity (= grazer-independent processing). Therefore, at local scales, collectors may not be significantly limited by the supply of grazer-derived FPOM.
Irving E.C., Liber K., Culp J.M. (2004). Lethal and sublethal effects of low dissolved oxygen condition on two aquatic invertebrates, Chironomus tentans and Hyalella azteca. Environmental Toxicology and Chemistry, 23(6) 1561-1566.

Low dissolved oxygen (DO) conditions occur frequently during sediment toxicity testing, with potentially adverse effects on test organisms. The present study addressed the current lack of good information regarding low DO thresholds for toxicity tests using two common test species, juvenile Hyalella azteca and Chironomus tentans larvae. Results indicated that H. azteca was less tolerant of hypoxia than C. tentans. The 10-d highest- and no-observed-effect concentrations (HOEC and NOEC, respectively) for H. azteca were 1.2 ± 0. 1 and 2.9 ± 0.1 mg/L DO, respectively. The 10-d NOEC for C. tentans was 1.2 ± 0.1 mg/L DO, the lowest test concentration. Mortality was the predominant response of H. azteca to low DO exposure, with changes in growth and positioning behavior only evident at lethal DO concentrations. Although exposure to 1.2 ± 0.1 mg/L DO for 10 d did not affect C. tentans survival or growth, significant behavioral changes were evident at 2.0 ± 0.1 mg/L DO or less. Overall, the present results indicate that the North American guidelines for low DO thresholds during 10-d toxicity tests seem reasonable for juvenile H. azteca. However, the Environment Canada Guideline (3.4 mg/L DO at 23°C) may be considered to be conservative for 10-d toxicity testing with C. tentans if only short-term effects on survival and growth are considered.
Jardine T.D., MacLatchy D.L., Fairchild W.L., Cunjak R.A., Brown S.B. (2004). Rapid carbon turnover during growth of Atlantic salmon (Salmo salar) smolts in sea water, and evidence for reduced food consumption by growth-stunts. Hydrobiologia, 527(1) 63-75.

Wild Atlantic salmon smolts were captured during spring out-migration in the Northwest Miramichi River, New Brunswick, Canada, and placed on an isotopically distinct hatchery diet to determine the relative contributions of growth and metabolic turnover to isotopic change. As expected for an ectothermic species, growth explained a large amount of isotopic variation in changing stable carbon ratios of muscle tissue (average r 2 = 0.46 ) for the 3 years of study. Turnover rates of muscle carbon in all 3 years in growing fish (0.24-0.66 month -1) were higher than previously reported values for other ectothermic species, but there was little evidence for isotopic change in non-growers (average r 2 = 0.041, p > 0.1). It is unlikely that non-growers had consumed any of the hatchery diet over a 2-month period, thus preventing them from acquiring the new carbon isotopic signature. This period of food deprivation resulted in nitrogen-15 enrichment in liver relative to muscle (p = 0.003). It is advised that future isotope studies of metabolic turnover rates in ectotherms be conducted on slow-growing animals over a long time period. This would serve to avoid the obscuring effects of growth on isotopic change, and provide stronger comparisons to endothermic tissue turnover rates.
Lopes I., Baird D.J., Ribeiro R. (2004). Avoidance of copper contamination by field populations of Daphnia longispina. Environmental Toxicology and Chemistry, 23(7) 1702-1708.

Almost all terrestrial and aquatic assays that are accepted as standardized, or that have been proposed, involve the exposure of confined organisms to toxicants. If avoidance (sensu evasion, displacement) of contaminants occurs in real situations, then bioassays involving forced exposure severely underestimate pernicious effects of contamination. Two main objectives were achieved in this study: To verify the occurrence of avoidance of copper by cladocerans; to determine the association between avoidance and other toxicity endpoints (lethality and feeding depression), and therefore, to ascertain if fully acclimated individuals from a reference field population exhibited a genetically determined avoidance markedly different from those belonging to a historically metal-stressed population. Twelve cloned lineages of the cladoceran Daphnia longispina, collected from two field populations, were selected according to their lethal sensitivity to copper and acclimated to controlled conditions for more than 30 generations. A 1.1-m test chamber with five compartments was built, allowing the establishment of a dissolved toxicant gradient and the free movement of individuals. In the absence of any toxicant, juveniles from each cloned lineage distributed themselves randomly along the test chamber and furthermore, no significant differences were observed between the two replicates, attesting the repeatability of this novel assay. All lineages showed significant avoidance to copper when exposed to a gradient from 3 to 87 μg/L. The most sensitive lineages to lethal levels of copper began avoiding this metal earlier than resistant ones. An intense association was observed between other endpoints and avoidance; furthermore, avoidance was determined to be much more sensitive than lethality. Therefore, avoidance assays should be recommended as a complementary tool in ecological risk assessments and effluent biomonitoring because such assays can provide cost-effective and ecologically relevant information.
Peterson D.P., Fausch K.D., White G.C. (2004). Population ecology of an invasion: Effects of brook trout on native cutthroat trout. Ecological Applications, 14(3) 754-772.

Invasion by nonnative brook trout (Salvelinus fontinalis) often results in replacement of cutthroat trout (Oncorhynchus clarki) in the inland western United States, but the underlying mechanisms are not well understood. We conducted a four-year removal experiment to test for population-level mechanisms (i.e., changes in recruitment, survival, emigration, and immigration) promoting invasion success of brook trout and causing decline of native Colorado River cutthroat trout (O. c. pleuriticus). We chose 700-1200 m segments of four small mountain streams where brook trout had recently invaded cutthroat trout populations, two each at mid elevation (2500-2700 m) and high elevation (3150-3250 m), and annually removed brook trout from two streams (treatments), but not the other two (controls). We used depletion electrofishing, two-way fish weirs, and mark-recapture methods to estimate abundance, movement, and survival of trout. At mid elevation, age-0 and age-1 cutthroat trout survived at 13 times and two times higher rates on average, respectively, where brook trout were removed. At high-elevation sites, recruitment of cutthroat trout failed despite brook trout removals, apparently because of cold water temperatures. In contrast, age-2 and older cutthroat trout survived at similar rates, whether brook trout were removed or not and regardless of elevation. Summer movement by cutthroat trout was unaffected by removal of brook trout. We conclude that brook trout depress cutthroat trout populations at mid elevation through age-specific biotic interactions that reduce juvenile cutthroat trout survival, whereas populations restricted to high-elevation sites by invasion continue to decline because an abiotic factor (low temperature) causes recruitment failure. In comparison, brook trout survived at the same or higher rates than same-aged cutthroat trout. High immigration by brook trout recolonized depleted segments, and may help sustain invasions in sink habitats where environmental conditions limit recruitment. In streams similar to those we studied, eradication of brook trout is likely necessary to eliminate the threat to native cutthroat trout, but selective removal regimes that capture a high percentage of the brook trout population for least three consecutive years, repeated periodically, may permit cutthroat trout populations to persist with brook trout. To identify underlying mechanisms responsible for successful invasion by mobile, age-structured vertebrates such as stream fishes, experiments conducted at realistic spatial and temporal scales and including multiple age classes will be required.
Rogers S.M., Curry R.A. (2004). Genetic population structure of brook trout inhabiting a large river watershed. Transactions of the American Fisheries Society, 133(5) 1138-1149.

The genetic population structure of brook trout Salvelinus fontinalis inhabiting the Miramichi River, New Brunswick, a large (14,000-km2) river system composed of three main stems, was assessed using six microsatellite DNA loci. Samples from 12 sites incorporating four temporal replicates were analyzed. An individual-based assignment method without a priori knowl-edge of geographic origin suggested the presence of five candidate source populations within the 12 sites. Drainage structuring based on the 12 sampling sites did not explain the observed patterns of genetic population structure (analysis of molecular variance: 0.74% of variance explained; not significant). Conversely, the five candidate source populations estimated under the assignment approach significantly explained the genetic population structure observed (3.47% of variance explained; P < 0.001), the level of population fragmentation within sampling sites increasing significantly with proximity to the mouth of the watershed (P = 0.011). These results suggested elevated levels of brook trout dispersal within a large river watershed where geographic distance among sampling sites did not have a significant impact on the genetic population structure. Brook trout populations inhabiting a large river watershed may therefore be more influenced by ecological variables affecting the observed patterns of divergence, such as alternative life history strategies (e.g., anadromy) and habitat selection.
Roussel J.M., Cunjak R.A., Newbury R., Caissie D., Haro A. (2004). Movements and habitat use by PIT-tagged Atlantic salmon parr in early winter: The influence of anchor ice. Freshwater Biology, 49(8) 1026-1035.

1. Movements and habitat use by Atlantic salmon parr in Catamaran Brook, New Brunswick, were studied using Passive Integrated Transponder technology. The fish were tagged in the summer of 1999, and a portable reading system was used to collect data on individual positions within a riffle-pool sequence in the early winter of 1999. Two major freezing events occurred on November 11-12 (Ice 1) and November 18-19 (Ice 2) that generated significant accumulations of anchor ice in the riffle. 2. Individually tagged parr (fork length 8.4-12.6 cm, n = 15) were tracked from 8 to 24 November 1999. Over this period, emigration (40%) was higher from the pool than from the riffle. Of the nine parr that were consistently located, seven parr moved <5 m up- or downstream, and two parr moved more than 10 m (maximum 23 m). Parr moved significantly more by night than by day, and diel habitat shifts were more pronounced in the pool with some of the fish moving closer to the bank at night. 3. During Ice 2, there was relatively little movement by most of the parr in the riffle beneath anchor ice up to 10 cm in thickness. Water temperature was 0.16°C above the freezing point beneath anchor ice, suggesting the existence of suitable habitats where salmon parr can avoid supercooling conditions and where they can have access to low velocity shelters. To our knowledge, these are the first data on habitat use by Atlantic salmon parr under anchor ice.
Sharpe R.L., MacLatchy D.L., Courtenay S.C., Van Der Kraak G.J. (2004). Effects of a model androgen (methyl testosterone) and a model anti-androgen (cyproterone acetate) on reproductive endocrine endpoints in a short-term adult mummichog (Fundulus heteroclitus) bioassay. Aquatic Toxicology, 67(3) 203-215.

A short-term gonadal recrudescence bioassay using the mummichog (Fundulus heteroclitus) was employed to examine the consequences of environmentally relevant and pharmacological exposures (1-1000ng/l) of the androgen, 17α-methyl testosterone (MT), and the anti-androgen, cyproterone acetate (CA), on reproductive endocrine endpoints. Recrudescing male (GSI=approx. 2%) and female (GSI=approx. 10%) fish were exposed to graded concentrations of MT and CA for 7 or 14 days. In the first experiment (7-day exposure), MT concentrations of 250 or 1000ng/l decreased circulating testosterone (T) and estradiol (E<inf>2</inf>) in female fish, and 11-ketotestosterone (11-KT) in male fish. Plasma T, 11-KT and E<inf>2</inf> were decreased following CA exposure (250 and 1000ng/l). Gonadal steroid biosynthetic capacity was also inhibited in both sexes after exposure to MT or CA, as evidenced by decreased in vitro production of T and E<inf>2</inf>. In experiment 2 (14-day exposure), exposures to lower MT and CA concentrations (1, 10 and 100ng/l) resulted in decreased plasma T, with females showing greater sensitivity than males. Both 11-KT and E<inf>2</inf> were significantly reduced beginning at 10ng/l MT. In vitro gonadal T production was impaired at 100ng/l MT in both males and females while 1ng/l CA caused a significant decrease in female fish. In experiment 2, in vitro E<inf>2</inf> production was decreased in females at all concentrations of MT and CA, while only 100ng/l reduced 11-KT synthesis in males. Plasma vitellogenin (Vtg) was reduced in females exposed to 1000ng/l (experiment 1) and 100ng/l (experiment 2) MT, while CA did not alter plasma Vtg at any concentration. This bioassay has the potential to be used to assess the possible consequences in estuarine fish of exposure to environmental anti/androgens. © 2004 Elsevier B.V. All rights reserved.
Wakefield A.M., Cunjak R.A., Kieffer J.D. (2004). Metabolic recovery in Atlantic salmon fry and parr following forced activity. Journal of Fish Biology, 65(4) 920-932.

Atlantic salmon Salmo salar fry and parr were subjected to 5 min of forced activity and the subsequent changes in oxygen consumption and ammonia excretion rates were evaluated over a 24 h period. In a second experiment, individual Atlantic salmon fry and parr were freeze-clamped in liquid nitrogen, before, immediately following a 5 min activity period, or after periods of recovery up to 2h. Samples were analysed for whole body phosphocreatine (PCr), ATP and lactate. Five minutes of forced activity resulted in significant increases in both oxygen consumption and ammonia excretion rates. Changes in the oxygen consumption rates were greater in the parr compared with the fry. In contrast, the post-exercise ammonia excretion rates were nearly twice as high for the fry compared with the parr. Exercise also caused a marked decrease in PCr levels (c. 47 and 65% in fry and parr, respectively), no change in ATP levels and a significant increase in lactate levels in Atlantic salmon fry and parr. Recovery of PCr occurred quickly (between 15 and 30 min) in fry and parr. Although the post-activity levels of lactate were lower in fry (c. 3 μmol g-1) compared with parr (c. 14 μmol g-1), lactate levels returned to control levels within 60 min in fry, but it took >2h for this metabolite to recover in parr. Compared with parr, these findings show that Atlantic salmon fry possess a reduced anaerobic capacity, and these results are consistent with the theoretical and experimental evidence that smaller fish support burst swimming through aerobic processes. © 2004 The Fisheries Society of the British Isles.
Culp J.M., Cash K.J., Glozier N.E., Brua R.B. (2003). Effects of pulp mill effluent on benthic assemblages in mesocosms along the Saint John River, Canada. Environmental Toxicology and Chemistry, 22(12) 2916-2925.

We used mesocosms to examine the impact of different concentrations of pulp mill effluent (PME) on structural and functional endpoints of a benthic assemblage in the Saint John River (NB, Canada) during 1999 and 2000. Previous studies on this effluent's effects produced conflicting results, with field surveys suggesting a pattern of mild nutrient enrichment, while laboratory toxicity tests linked effluent exposure to moderate contaminant effects. Experimental treatments included three concentrations of sulfite pulp mill effluent (0, 5, 10% v/v PME). Endpoints for the assessment included algal biomass and taxonomic composition, benthic invertebrate abundance and composition, and insect emergence. Low concentrations of PME increased periphyton biomass and caused changes in community structure within the diatom-dominated community. Pulp mill effluent addition had little effect on several structural endpoints measured for benthic invertebrates, including abundance and taxonomic richness, but significantly changed community composition. For both periphyton and benthic invertebrates, community composition endpoints were more sensitive indicators of PME exposure. Insect emergence was a highly relevant functional endpoint. When benthic and emerged insects were combined, total abundance increased with PME addition. Results from two trophic levels, which provided multiple lines of evidence, indicated that the main impact of these PME concentrations is nutrient enrichment rather than effluent toxicity. Our findings also suggest that benthic invertebrate and periphyton assemblages, algal biomass production, and insect emergence are sensitive response measures. Future studies may confirm this observation. The consideration of both functional and structural endpoints at different trophic levels can greatly improve our understanding the effects of discharges to rivers. Such an understanding could not have been obtained using standard assessment techniques and illustrates the value of mesocosms and the benthic community assemblage approach in environmental assessment.
Curry R.A., Brady C., Morgan G.E. (2003). Effects of recreational fishing on the population dynamics of lake-dwelling brook trout. North American Journal of Fisheries Management, 23(1) 35-47.

Data collected over 7 consecutive years were used to examine the population dynamics of the exploited brook trout Salvelinus fontinalis of Meach Lake in central Ontario. Numbers of age-1 and older trout averaged 975 among years. The largest trout were 490 mm long and weighed 1,807 g. Few trout lived beyond age 4. Annual mortality rates varied among age-classes and between sexes; average total instantaneous mortality was 0.95 and average total and fishing mortalities were 78% and 44%, respectively. Exploitation was greatest for age-2 and age-3 brook trout of both sexes. Catchability was uncorrelated with abundance. There was evidence of density-dependent growth at age-2 or age-3 but no indication of density-dependent mortality. A “hockey stick” model appeared to best describe the stock–recruitment relationship. Abundance of potential competitors was not correlated with brook trout size, although abundance of white suckers Catostomus commersoni was correlated with numbers of age-2 male brook trout. We conclude that total mortality rates are naturally very high and existing levels of harvests in this lake may not be increasing total mortality. To ensure the sustainability of brook trout fisheries, lake-dwelling populations should be managed to maintain total mortality rates below those observed in this study. © 2003 Taylor and Francis Group, LLC.
Dubé M.G. (2003). Cumulative effect assessment in Canada: A regional framework for aquatic ecosystems. Environmental Impact Assessment Review, 23(6) 723-745.

Sustainable development of the aquatic environment depends upon routine and defensible cumulative effects assessment (CEA). CEA is the process of predicting the consequences of development relative to an assessment of existing environmental quality. Theoretically, it provides an on-going mechanism to evaluate if levels of development exceed the environment's assimilative capacity; i.e., its ability to sustain itself. In practice, the link between CEA and sustainable development has not been realized because CEA concepts and methods have developed along two dichotomous tracks. One track views CEA as an extension of the environmental assessment (EA) process for project developments. Under this track, stressor-based (S-B) methods have been developed where the emphasis is on local, project-related stressors, their link with aquatic indicators, and the potential for environmental effects through stressor-indicator interactions. S-B methods focus on the proposed development and prediction of project-related effects. They lack a mechanism to quantify existing aquatic quality especially at scales broader than an isolated development. This limitation results in the prediction of potential effects relative to a poorly defined baseline state. The other track views CEA as a broader, regional assessment tool where effects-based (E-B) methods specialize in quantification of existing aquatic effects over broad spatial scales. However, the predictive capabilities of E-B methods are limited because they are retrospective, i.e., the stressor causing the effect is identified after the effect has been measured. When used in isolation, S-B and E-B methods do not address CEA in the context necessary for sustainable development. However, if the strengths of these approaches were integrated into a holistic framework for CEA, an operational mechanism would exist to better monitor and assess sustainable development of our aquatic resources. This paper reviews the existing conceptual basis of CEA in Canada including existing methodologies, limitations and strengths. A conceptual framework for integrating project-based and regional-based CEA is presented. Crown Copyright © 2003 Published by Elsevier Inc. All rights reserved.
Gilman C.I., Leusch F.D.L., Breckenridge W.C., MacLatchy D.L. (2003). Effects of a phytosterol mixture on male fish plasma lipoprotein fractions and testis P450scc activity. General and Comparative Endocrinology, 130(2) 172-184.

Plant sterols (phytosterols) have been identified as one potential source of reproductive effects in fish living downstream of pulp mills. β-Sitosterol, the predominant plant sterol in pulp mill effluent, has previously been shown to decrease plasma sex steroid and cholesterol levels and in vitro gonadal steroid production in fish. In this study, male brook trout (Salvelinus fontinalis) and goldfish (Carassius auratus) were exposed to a phytosterol mixture (72% β-sitosterol) via Silastic intraperitoneal implants to help elucidate the mechanisms of action of phytosterols on steroid depression. As cholesterol is exogenously supplied for gonadal steroidogenesis, changes in plasma cholesterol fractions were examined. In male brook trout, low-density lipoprotein cholesterol and triglyceride levels decreased significantly, 43 and 50%, respectively, in phytosterol-treated fish. It is improbable, however, that these decreases are linked to depressed gonadal steroidogenesis in fish. The activity of P450scc, which converts cholesterol to pregnenolone (the first step in the steroidogenic pathway), was not affected in testis mitochondria isolated from brook trout or goldfish. Further investigation of the mechanisms of action of phytosterols is required. © 2003 Elsevier Science (USA). All rights reserved.
Leusch F.D.L., MacLatchy D.L. (2003). In vivo implants of β-sitosterol cause reductions of reactive cholesterol pools in mitochondria isolated from gonads of male goldfish (Carassius auratus). General and Comparative Endocrinology, 134(3) 255-263.

β-Sitosterol, a phytosterol found in high concentrations in pulp mill effluents, has been proposed as one of the causative agents for steroid depressions observed in fish exposed to pulp mill effluents. Previous studies have suggested a cholesterol-mediated mechanism; however, it is unknown how β-sitosterol depresses gonadal steroidogenesis. In this study, adult male goldfish (Carassius auratus) were exposed for 24-31 days to β-sitosterol (55% of a phytosterol mixture or 96% pure; 150μg/g; Silastic implant) after which gonadal mitochondria were isolated. Pregnenolone production, an indicator of the size of the pool of reactive cholesterol, was then measured in the isolated mitochondria. Sterol exposure did not affect P450 side-chain cleavage enzyme (converts cholesterol to pregnenolone) activity but did decrease the size of the mitochondrial pool of reactive cholesterol, suggesting β-sitosterol is impeding cholesterol transfer across the mitochondrial membrane. This finding is supported by the observation that 25- hydroxycholesterol, which passes through mitochondrial membranes without need for a membrane transporter, restores β-sitosterol-induced reductions in pregnenolone production. © 2003 Elsevier Inc. All rights reserved.
MacLatchy D.L., Courtenay S.C., Rice C.D., Van Der Kraak G.J. (2003). Development of a short-term reproductive endocrine bioassay using steroid hormone and vitellogenin end points in the estuarine mummichog (Fundulus heteroclitus). Environmental Toxicology and Chemistry, 22(5) 996-1008.

We have developed a short-term gonadal recrudescence test with the estuarine mummichog (Fundulus heteroclitus) and determined endocrine end points sensitive to a strong estrogen agonist (ethynylestradiol; EE<inf>2</inf>) and an antiestrogen (ZM 189,154; ZM) at concentrations of 0 to 1,000 ng/L in three separate experiments. A protocol was developed to ensure a year-round supply of recrudescing fish. A protocol for determining steroid production (testosterone and 11-ketotestosterone [11-KT] in incubated testes tissue and testosterone and 17-estradiol [E<inf>2</inf>] in incubated prematurational follicles) was optimized. Recrudescing fish (males, gonadosomatic index = 2%; females = 10%) were exposed to graded doses of EE<inf>2</inf> or ZM for 7 to 15 d using a static daily-renewal protocol. At high EE<inf>2</inf> (>250 ng/L), the effect on males was depression of androgen steroidogenesis and plasma steroid levels. In females, high EE<inf>2</inf> depressed gonadal production and circulating E<inf>2</inf> levels; however, EE<inf>2</inf> concentrations <100 ng/L caused increased gonadal production and plasma E<inf>2</inf>. Low ZM (<lOO ng/L) had little effect on male and female fish, while higher concentrations (>250 ng/L) increased E<inf>2</inf> and 11-KT production while decreasing plasma 11-KT and E<inf>2</inf> (1,000 ng/L only). Male and female plasma vitellogenin responded in a concentration-dependent fashion to EE<inf>2</inf> with no effect by ZM. The low observable effect concentrations for the endocrine parameters were 1 ng/L for EE<inf>2</inf> and 250 ng/L for ZM. The bioassay and results encompassing the environmentally relevant exposure range (1-100 ng/L) will be useful for assessing effects of endocrine-active contaminants in estuarine environments.
Peterson D.P., Fausch K.D. (2003). Testing population-level mechanisms of invasion by a mobile vertebrate: A simple conceptual framework for salmonids in streams. Biological Invasions, 5(3) 239-259.

Invasion biology suffers from a lack of the ability to predict the outcome of particular invasions because of reliance on verbal models and lack of rigorous experimental data at the appropriate scale. More progress is likely to be made by considering invasions as population-level phenomena and initially focusing on specific taxa or particular categories of invasions. To this end, we propose a simple conceptual framework to motivate studies of invasion by salmonids (salmon, trout, grayling, and whitefish) in streams that emphasizes population-level mechanisms affecting native species and promoting spread by the invader. Specifically, the only direct mechanisms by which the abundance of the native species can decline are through biotic interactions which cause decreased reproductive rates or survival at specific life stages, net emigration, debilitating or fatal diseases introduced by the invader, or a combination of these factors. Conversely, abundance of the invader must increase by local reproduction, high survival, net immigration, or a combination of these factors. Review of existing salmonid invasion literature suggests that future studies could be improved by using manipulative field experiments at a spatial and temporal scale appropriate to address population-level processes, characterizing how movement affects the establishment and spread of an invader, and including abiotic context in experimental designs. Using the example of brook trout (Salvelinus fontinalis) invasion into streams containing native Colorado River cutthroat trout (Oncorhynchus clarki pleuriticus) in the central Rocky Mountains (USA), we demonstrate how the framework can be used to design a manipulative field experiment to test for population-level mechanisms causing ecological effects and promoting invasion success. Experiments of this type will give invasion ecologists a useful example of how a taxon-specific invasion framework can improve the ability to predict ecological effects, and provide fishery biologists with the quantitative foundation necessary to better manage stream salmonid invasions.
Peterson D.P., Fausch K.D. (2003). Upstream movement by nonnative brook trout (Salvelinus fontinalis) promotes invasion of native cutthroat trout (Oncorhynchus clarki) habitat. Canadian Journal of Fisheries and Aquatic Sciences, 60(12) 1502-1516.

To understand how immigration and emigration influence the processes by which invading nonnative brook trout (Salvelinus fontinalis) displace native cutthroat trout (Oncorhynchus clarki), we studied trout movement in long segments of three mountain streams in Colorado during 1999-2001. Over 3500 trout were captured and marked at weirs and during electrofishing, both within and downstream of stream segments. Nearly 80% of brook trout captured at weirs were moving upstream, whereas almost 65% of cutthroat trout were moving downstream. Brook trout movements peaked in early summer and again in fall. Brook trout immigration rates from downstream source populations were high, and in one stream, invaders repopulated a segment where they were removed within 8 months. Immigrant brook trout were typically mature adults in similar body condition to the general population. Brook trout immigrated from a range of distances, with local movement within 250 m more frequently detected, but fish also moved from many distances up to 2 km away within a summer. Brook trout encroachment and invasion was characterized by a wave of local movement exerting biotic pressure on the downstream limit of the cutthroat trout population and jump dispersers moving upstream beyond the invasion front promoting rapid population spread.
Curry R.A., Scruton D.A., Clarke K.D. (2002). The thermal regimes of brook trout incubation habitats and evidence of changes during forestry operations. Canadian Journal of Forest Research, 32(7) 1200-1207.

The thermal regimes in streambed substrates used by brook trout, Salvelinus fontinalis Mitchell, for incubation of embryos were examined in reference and treatment (0- and 20-m riparian buffer strips) streams in a clear-cut harvested, northern temperate forest of western Newfoundland. In these streams, incubation habitats (redds) were primarily composed of downwelling surface waters with variable but minor mixing of upwelling groundwater. The resulting incubation temperatures were cold (<1°C) and surface water temperatures were accurate predictors of redd temperatures. Both treatment streams displayed evidence of warming in the fall and spring of the 2 years beginning the year of initial harvesting. The increase was most pronounced in the stream without a riparian buffer strip. Clear-cut harvesting with and without a riparian buffer strip altered the thermal regime of surface water and the hyporheic zone in this northern temperate forest where, in addition to salmonid incubation, many biological processes take place. The potential for impacts on stream ecosystems is estimated to be high for the managed forests of this region. Future studies should strive to enhance our understanding of the hydrological connections between forests and streams on this landscape to determine the full effects of timber harvesting on the hydrology and biology of a watershed and its streams.
Curry R.A., Sparks D., Van De Sande J. (2002). Spatial and temporal movements of a riverine brook trout population. Transactions of the American Fisheries Society, 131(3) 551-560.

The year-round movements of brook trout Salvelinus fontinalis were monitored in a large river (125 km) and brackish-water estuary by using radio and acoustic tags and a fish counting fence over a 3-year period. Trout moved upstream 65-100 km during the spring after ice loss over a protracted 4-month period (April-July). Summer movements were minimal, and habitats were deep pools and runs with cover in the same reaches each year. Trout moved short distances <10 km) to spawning areas in the fall (September). Downstream movements were observed for both postspawned and immature trout. By the time of the river freeze-up (January), major movements had ceased and trout wintered in the lower to middle reaches of the main river, with only one trout leaving the river. That fish remained in habitats with salinity less than 5‰ during winter and returned to the river by May. By improving the scale of observation, we identified an apparent mix of tactics related to the use of marine and freshwater environments within this population. Such behavior may have important implications for the ecological and evolutionary significance of mobility and anadromy within the species and the Salmoninae. © 2002 Taylor & Francis Group, LLC.
Hewitt L.M., Smyth S.A.M., Dubé M.G., Gilman C.I., MacLatchy D.L. (2002). Isolation of compounds from bleached kraft mill recovery condensates associated with reduced levels of testosterone in mummichog (Fundulus heteroclitus). Environmental Toxicology and Chemistry, 21(7) 1359-1367.

Previous studies have identified chemical recovery condensates as a primary source of hormonally active substances within a Canadian bleached kraft pulp mill. Although reverse osmosis treatment of condensates raises the exposure threshold that alters circulating levels of testosterone in mummichog (Fundulus heteroclitus), the responsible chemicals have not been characterized. In this study, a solid-phase extraction (SPE) method was developed to isolate chemical recovery condensate extractives for evaluation of hormonal activity. Condensates generated during softwood and hardwood pulp production were investigated for their relative potential to affect both circulating and gonadal production of sex steroids in mummichog. Mummichog were exposed to whole condensates, extracts from suspended particulates (< 1 μm), two fractions from SPE, and residual condensates after SPE. The distribution of bioactivity among condensate fractions was similar for both wood furnishes. In both sexes, significant depressions in circulating testosterone and in in vitro gonadal testosterone production were associated with exposure to whole condensates, particulate extracts, one SPE fraction, and residual material after SPE. An optimized SPE method subsequently demonstrated complete recovery of polar, bioavailable chemicals that reduced testosterone levels in both sexes. Characterizations of active fractions by gas chromatography-mass spectrometry (GC-MS) showed the presence of extractives with molecular masses ≥240 amu possessing functionalities consistent with lignin degradation products. This study provides the first isolation of chemicals derived from pulp production associated with impaired reproductive performance in fish.