6/05/2017  |   09:00 - 09:15   |  305B

MESOCOSM EXPERIMENTS: REDUCTIONIST DISTRACTIONS OR MEANINGFUL COMPLEMENTS TO LABORATORY AND FIELD-BASED ASSESSMENTS OF CONTAMINANT EFFECTS? Although small-scale experiments (e.g., microcosms and mesocosms) have been employed for several decades to assess effects of contaminants and other stressors on aquatic communities, these approaches have been harshly criticized in the literature. Despite these criticisms, we feel that small-scale experiments represent an important “middle ground” between laboratory toxicity tests and field assessments of contaminant effects. Because mesocosm experiments typically measure responses at larger spatiotemporal scales and across levels of biological organization, results provide greater ecological realism compared to laboratory toxicity tests. The major challenge using field-derived data is to separate effects of the specific stressor of interest from other potentially confounding factors. Mesocosm experiments provide an ecologically realistic alternative to laboratory toxicity tests while controlling for the confounding variables associated with field-based approaches. In addition to providing mechanistic insight into stressor-response relationships across different levels of biological organization, mesocosm experiments can be coupled with field assessments to address important policy issues. In this presentation we will review results of several large scale studies in which mesocosm experiments were integrated with field-based approaches to validate laboratory-derived estimates of contaminant effects.

William Clements (Primary Presenter/Author), Colorado State University, william.clements@colostate.edu;


Christopher Kotalik ( Co-Presenter/Co-Author), United States Geological Survey, ckotalik@usgs.gov;


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6/05/2017  |   09:15 - 09:30   |  305B

Nutrients, neonics and predators: lessons learned after a decade of mesocosm experiments. The ecological effects of neonicotinoid insecticides, or ‘neonics’, on field-collected, aquatic insect community structure and function were evaluated in a series of experiments that began in 2003. These experiments occurred in flow-through, outdoor mesocosms and investigated i) the effects of neonics in pulse/press study designs, ii) the potential for nutrient additions to attenuate pesticide effects, iii) the effect of neonics on food webs (e.g., predator-prey interactions), and iv) how neonic toxicity is affected by the presence of other pesticides. Mesocosms are particularly useful for interdisciplinary research and enable the teasing apart of confounding factors such as the interaction between nutrients and mixtures of contaminants to reveal underlying patterns of aquatic communities. Moreover, this mesocosm research has highlighted the limitations of our understanding of pesticide effects on stream invertebrates (e.g., effects of low concentrations of neonics on body size) by unveiling both the complexity and simplicity of relationships between organisms and the environment. How best to deploy these systems to incorporate the spatial and temporal variation of real streams and some common design issues (e.g., open vs. closed systems, pseudoreplication) will be discussed.

Alexa Alexander (Primary Presenter/Author), Environment and Climate Change Canada, alexa.alexander-trusiak@canada.ca;


Joseph M. Culp ( Co-Presenter/Co-Author), Environment and Climate Change Canada and Canadian Rivers Institute, Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada, N2L 3C5, joseph.culp@canada.ca;


Donald Baird ( Co-Presenter/Co-Author), Environment and Climate Change Canada @ Canadian Rivers Institute, Department of Biology, University of New Brunswick, Fredericton, NB, Canada, djbaird@unb.ca;


Allan Cessna ( Co-Presenter/Co-Author), Agriculture Agri-Foods Canada, allan.cessna@agr.gc.ca ;


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6/05/2017  |   09:30 - 09:45   |  305B

Ecological Realism of U.S. EPA Experimental Stream Facility Studies The USEPA’s Experimental Stream Facility (ESF) conducts meso-scale ecotoxicology studies that account for both structural and functional responses of whole stream communities to contaminants or other stressors. The 16 mesocosms of ESF are indoors and consist of a tiled run section (0.152 m W x 4.268 m L x 0.105 m D) that widens to a gravel riffle section (0.305 m W x 4.268 m L x 0.19 m D). They are intermediate size among studies reporting stream mesocosm results. Their set-up is unique for their size, with a high degree of engineering controls for continuous flow-through dose-response designs, yet fixed, chronic exposures to contaminants under conditions that quantifiably mimic real stream riffle/run habitat with consistent upstream renewal. With fifty standard operating procedures serving ESF studies, the background and boundary condition information is collected to determine the realism critical to the field relevance of the results. Parallel ex situ and in situ single species exposure formats including fish survival and fecundity metrics are also included. With this framework studies at ESF provide scientifically defensible evaluation of proposed aquatic life criteria.

Christopher Nietch (Primary Presenter/Author), U.S. Environmental Protection Agency, nietch.christopher@epa.gov;


Donald Brown ( Co-Presenter/Co-Author), U.S. EPA, Office of Research and Development, brown.donald@epa.gov;


Jim Lazorchak ( Co-Presenter/Co-Author), United States Environmental Protection Agency, Office of Research and Development, Center for Environmental Measurement and Modeling, Cincinnati, OH 45268, lazorchak.jim@epa.gov;


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6/05/2017  |   09:45 - 10:00   |  305B

COMMUNITY RESPONSES TO DIRECT AND INDIRECT EFFECTS OF METALS STRESSORS USING STREAM MESOCOSMS The ecological effects of trace metals on streams and rivers are well documented through laboratory, field, and mesocosm approaches. While most water quality criteria (WQC) are developed using traditional laboratory toxicity tests, mesocosm experiments offer a valuable middle ground between laboratory methods and field surveys. We evaluated the direct and indirect effects of metals by exposing benthic communities to Cu and Zn mixtures and Fe oxide for 14 d. Measured responses included the timing and abundance of emerging adult taxa, algal colonization, community metabolism, and community composition. Results of both mesocosm experiments show differences in larval and adult responses within the same taxonomic groups, particularly among midges (Chironomidae) and mayflies (Ephemeroptera); however, algal colonization and community metabolism displayed the greatest sensitivity to exposure. In general, significant responses were observed at concentrations below the WQC for Fe, whereas observed effects for Cu and Zn occurred at or above their reported toxic concentrations. This research demonstrates the usefulness of mesocosms experiments for assessing effects of different environmental stressors, while highlighting the need to comprehensively assess contaminant effects with ecologically meaningful endpoints.

Christopher Kotalik (Primary Presenter/Author), United States Geological Survey, ckotalik@usgs.gov;


William Clements ( Co-Presenter/Co-Author), Colorado State University, William.Clements@colostate.edu ;


Pete Cadmus ( Co-Presenter/Co-Author), Colorado Parks and Wildlife, pete.cadmus@state.co.us;


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6/05/2017  |   10:00 - 10:15   |  305B

Thames River Experimental Stream Sciences Centre: Opportunities for Collaborative Research Understanding the effects of physical, chemical and biological stressors on ecological function is inherently problematic using field surveys because of confounding factors. Artificial streams can help resolve this problem by allowing controlled testing of multiple stressors and interactive ecological effects. The Thames River Experimental Stream Sciences (TRESS) Centre is a unique, artificial stream facility in southern Ontario, Canada constructed in collaboration with academic, government and community partners. A fundamental aim of TRESS research is to test novel questions essential to river management. Such questions include improved scientific understanding of stressor effects on stream ecological function to inform environmental policy needs. This presentation aims to increase awareness of TRESS and encourage partnerships with researchers seeking opportunities to conduct controlled, scalable studies on stream function. Several examples of recent TRESS research include describing phosphorus thresholds for endpoints of ecological function as well as comparative response to pulse and press exposure to phosphorus. Comparisons of results from artificial stream experiments with local field studies will also be described.

Adam G. Yates (Primary Presenter/Author), Western University & Canadian Rivers Institute, adam.yates@uwo.ca;


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6/05/2017  |   10:15 - 10:30   |  305B

MESOCOSM METALS EXPOSURES TO NATURAL AQUATIC MACROINVERTEBRATE COMMUNITIES AS A MEASURE OF RESTORATION EFFECTIVENESS Aquatic insect communities in the upper Arkansas River have been monitored for over 25 years to assess responses before and after restoration of a US EPA ‘Superfund Site’ near Leadville, CO. By many traditional monitoring metrics (e.g. total abundance and species richness) it would appear that communities downstream of the main metals source (California Gulch) have recovered. However, the composition of aquatic insect communities differs between sites upstream and downstream of California Gulch. We hypothesized that different community structure would result in differing responses to metals exposure, and thus, would provide additional evidence that the communities are not yet fully recovered. To test this, we conducted mesocosm experiments using communities from a reference site upstream and a contaminated site downstream of California Gulch that were replicated over time (2009 and 2016). Our results indicate that downstream communities remain tolerant to metals, suggesting that these communities may not be fully recovered. We suggest that mesocosm experiments of natural communities will bolster current restoration monitoring, and may provide novel insight into ecological and evolutionary processes not possible through conventional biomonitoring methods alone.

Brian Wolff (Primary Presenter/Author), Colorado State University, wolffba@gmail.com;


William Clements ( Co-Presenter/Co-Author), Colorado State University, William.Clements@colostate.edu ;


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