5/22/2016  |   13:30 - 13:45   |  313

ECOSYSTEM TOXICOLOGY? RECOGNIZING CONTAMINANTS AS AGENTS OF GLOBAL CHANGE AFFECTING ECOSYSTEM PROCESSES To fully understand the ecosystem dynamics of a world in which the mass and diversity of contaminants is increasing exponentially, research that investigates the influence of a variety of compounds on ecosystem structure and function is necessary. Due to their global spread, contaminants are present in nearly every ecosystem on earth, but the effects of these contaminants on such important ecosystem processes like primary production, nutrient cycling, secondary production, and decomposition rates are not well understood. We will review the current literature that investigates the influence of contaminants on ecosystem processes. In so doing, we will suggest areas of future research to advance our understanding of the influence of contaminants on how ecosystems function. We argue that contaminants are global drivers of ecological change and that research that seeks to understand the influence of contaminants on ecosystem function is needed to both fully predict the effects of contaminants on the environment and to understand what drives ecosystem function in the Anthropocene.

Emily Bernhardt (Primary Presenter/Author), Duke University, ebernhar@duke.edu;


Emma Rosi ( Co-Presenter/Co-Author), Cary Institute of Ecosystem Studies, rosie@caryinstitute.org;


David Walters ( Co-Presenter/Co-Author), United States Geological Survey, waltersd@usgs.gov;
Dr. David Walters is a Supervisory Research Ecologist at the Columbia Environmental Research Center. David has been a research ecologist with the USGS since 2008. Prior to that, he was an ecologist for the U.S. EPA, National Exposure Research Laboratory for 6 years. He is a freshwater ecologist with broad training in stream ecology, human impacts on aquatic ecosystems, and ecotoxicology. His current research topics include food webs and contaminant flux, aquatic-riparian linkages, stream fish ecology, land use and climate change, and invasive species.

Presentation:
This presentation has not yet been uploaded.

5/22/2016  |   13:45 - 14:00   |  313

CONTAMINANT AND ENERGY FLUXES THROUGH FOOD WEBS AS AN INTERSECTION BETWEEN ECOSYSTEM SCIENCE AND ECOTOXICOLOGY Ecology and ecotoxicology share common goals – tracing and quantifying material flux in the environment. Bridging these disciplines is challenging because they use different methodologies, terminologies, and objectives. Ecologists strive to identify pathways of carbon flow and how these flows affect properties like animal diversity. Ecotoxicologists measure flow pathways to better characterize wildlife exposures. Here, we illustrate how the concept of ecological fluxes (animal/material fluxes within and between food webs) can bridge ecosystem and exposure science and provide a better understanding of contaminant and resource movements. Integrating these disciplines would allow us to better address such questions as: How do carbon fluxes in food webs affect contaminant fluxes and consumer exposure; under what conditions are moving resources important drivers of contaminant flux; and under what conditions do contaminants alter the quality and quantity of resource subsidies? These questions are particularly relevant in aquatic food webs and linked aquatic-terrestrial systems because aquatic systems are major repositories for contaminants, and aquatic systems are sources of abundant, high-quality resources to terrestrial food webs.

David Walters (Primary Presenter/Author), United States Geological Survey, waltersd@usgs.gov;
Dr. David Walters is a Supervisory Research Ecologist at the Columbia Environmental Research Center. David has been a research ecologist with the USGS since 2008. Prior to that, he was an ecologist for the U.S. EPA, National Exposure Research Laboratory for 6 years. He is a freshwater ecologist with broad training in stream ecology, human impacts on aquatic ecosystems, and ecotoxicology. His current research topics include food webs and contaminant flux, aquatic-riparian linkages, stream fish ecology, land use and climate change, and invasive species.

Johanna Kraus ( Co-Presenter/Co-Author), United States Geological Survey, jkraus@usgs.gov;


Travis Schmidt ( Co-Presenter/Co-Author), USGS WY-MT Water Science Center, tschmidt@usgs.gov;


Emma Rosi ( Co-Presenter/Co-Author), Cary Institute of Ecosystem Studies, rosie@caryinstitute.org;


Presentation:
This presentation has not yet been uploaded.

5/22/2016  |   14:00 - 14:15   |  313

CONTAMINANTS AS AGENTS OF ECOLOGICAL CHANGE IN FRESHWATER AND RIPARIAN ECOSYSTEMS We utilize mesocosm studies to investigate the structural and functional effects of contaminants on aquatic insect communities to better understand the total effect of contaminants on ecosystems. Aquatic insect larval density declined at concentrations of metals and pesticides thought to be safe for aquatic life. Simultaneously, adult aquatic insect emergence was stimulated at low concentrations of contaminants and limited or eliminated at higher concentrations (loss of subsidy). Together these effects leave a remnant aquatic community that functions in a vastly different way from controls. Specifically, pesticide-related grazer mortality released biofilms from top-down pressure causing a net increase in biofilms (trophic cascade). Simultaneously collector/gatherer mayflies were released from interspecific competition causing their densities to increase (3x) at moderate pesticide concentrations. Thus aqueous contaminants are agents of change to both aquatic and riparian ecosystems.

Travis Schmidt (Primary Presenter/Author), USGS WY-MT Water Science Center, tschmidt@usgs.gov;


Holly Rogers ( Co-Presenter/Co-Author), U.S. EPA, hrogers290@gmail.com;


David Walters ( Co-Presenter/Co-Author), United States Geological Survey, waltersd@usgs.gov;
Dr. David Walters is a Supervisory Research Ecologist at the Columbia Environmental Research Center. David has been a research ecologist with the USGS since 2008. Prior to that, he was an ecologist for the U.S. EPA, National Exposure Research Laboratory for 6 years. He is a freshwater ecologist with broad training in stream ecology, human impacts on aquatic ecosystems, and ecotoxicology. His current research topics include food webs and contaminant flux, aquatic-riparian linkages, stream fish ecology, land use and climate change, and invasive species.

Johanna Kraus ( Co-Presenter/Co-Author), United States Geological Survey, jkraus@usgs.gov;


Presentation:
This presentation has not yet been uploaded.

5/22/2016  |   14:15 - 14:30   |  313

EFFECT OF POND PERMANENCE ON AQUATIC INSECT-MEDIATED FLUX OF METHYLMERCURY TO TERRESTRIAL ECOSYSTEMS Humans have built millions of small ponds in the Great Plains of the United States, and these ponds have become contaminated with atmospherically-deposited mercury (Hg). In aquatic ecosystems, less toxic forms of Hg deposited from the atmosphere are converted to highly toxic methylmercury (MeHg) and this MeHg can contaminate terrestrial food chains when MeHg-contaminated insects emerge as adults. Permanent and temporary ponds have been hypothesized to have different insect-mediated MeHg flux but this has not been tested. We conducted an experiment at the Eagle Mountain Fish Hatchery (Texas) in five permanent ponds that were stocked with fish and five fishless temporary ponds that were dried and refilled prior to the start of the experiment. Despite low MeHg flux from temporary ponds immediately after refilling, the cumulative MeHg flux was greater in the temporary ponds than in permanent ponds within one month of the start of the experiment. This study suggests that insect succession in the summer is rapid enough that MeHg flux is greater in fishless temporary ponds than permanent ponds where fish suppress insect emergence.

Matthew Chumchal (Primary Presenter/Author), Texas Christian University, m.m.chumchal@tcu.edu;


Ray Drenner ( Co-Presenter/Co-Author), Texas Christian University, r.drenner@tcu.edu;


Frank Greenhill ( Co-Presenter/Co-Author), Texas Christian University, f.greenhill@tcu.edu;


James Kennedy ( Co-Presenter/Co-Author), University of North Texas, kennedy@unt.edu;


Ashlyn Courville ( Co-Presenter/Co-Author), Texas Christian University, A.COURVILLE@tcu.edu;


Charlie Gober ( Co-Presenter/Co-Author), Texas Christian University, C.A.GOBER@tcu.edu;


Luke Lossau ( Co-Presenter/Co-Author), Texas Christian University, LUKE.LOSSAU@tcu.edu;


Presentation:
This presentation has not yet been uploaded.

5/22/2016  |   14:30 - 14:45   |  313

EFFECTS OF FISH ON ODONATE-MEDIATED METHYL MERCURY FLUX FROM EXPERIMENTAL PONDS Methyl mercury (MeHg) is an environmental toxin that can be transferred to terrestrial predators by emergent aquatic insects like odonates. We examined the effects of fish presence on odonate-mediated MeHg flux (emergent odonate biomass x MeHg concentration) in experimental ponds. Emergent odonates were collected weekly from ponds with fish (Lepomis sp.) (n = 5) and without fish (n = 5) over an eight-month period (January – August, 2015). The presence of fish significantly decreased MeHg flux by suppressing emergence of damselfies (Coenagrionidae) and dragonflies (Aeshnidae and Libellulidae). Emergence of Coenagrionidae, Aeshnidae and Libellulidae peaked in April, May and June, respectively, and overlapped with reproduction of red-winged black birds (Agelaius phoeniceus), an odonate predator, which nested at the study site.

Edward Williams (Primary Presenter/Author), Texas Christian University, edward.williams@tcu.edu;


Matthew Chumchal ( Co-Presenter/Co-Author), Texas Christian University, m.m.chumchal@tcu.edu;


Ray Drenner ( Co-Presenter/Co-Author), Texas Christian University, r.drenner@tcu.edu;


James Kennedy ( Co-Presenter/Co-Author), University of North Texas, kennedy@unt.edu;


Presentation:
This presentation has not yet been uploaded.

5/22/2016  |   14:45 - 15:00   |  313

CONTEXT-DEPENDENT RESPONSES OF AQUATIC COMMUNITIES TO CONTAMINANTS AND OTHER ANTHROPOGENIC STRESSORS Regional variation in community composition that may result from environmental, historical, biogeographical, and/or climatic factors represents a significant challenge for ecological risk assessment. Physicochemical characteristics (e.g. pH, hardness, DOC) are routinely included in the establishment of water quality criteria due to well understood mechanisms between water quality and toxicity. However, we know little about variation in sensitivity among communities, and this variation is often considered an impediment to predict ecological responses. We suggest that variation among communities and environmental gradients (context dependency) represents an opportunity to identify ecological factors that influence contaminant fate and effects. Specifically, we hypothesize that many of the factors which structure communities in aquatic ecosystems (e.g. food-webs, disturbance, productivity, exposure history) also determine their responses to contaminants. To test this hypothesis, we implemented several mesocosm experiments to quantify responses of communities from variable environmental conditions to various contaminates and other anthropogenic stressors. The ability to predict the effects of contaminants in aquatic ecosystems could be significantly improved by recognizing that responses to stressors are often context dependent, and by developing a mechanistic understanding of context dependency.

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


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


Presentation:
This presentation has not yet been uploaded.