5/25/2016  |   15:30 - 15:45   |  309-310

IMPACTS OF AN INTRODUCED TREE ON FOOD WEB FUNCTIONALITY Reciprocal insect and organic matter transfer between aquatic and terrestrial ecosystems contributes to the productivity of riparian systems. Yet, the ecological integrity of riparian corridors has often been compromised by human activities. These ecosystems are particularly prone to species invasions, which can lead to novel ecosystems with unique species assemblages and altered ecosystem functions. In the Piceance basin of northwest Colorado, an introduced tree, Robinia neomexicana, has become established in riparian areas of the Clear Creek watershed. The primary goal of this project is to quantify riparian food web response to the introduction of R. neomexicana in the Piceance Basin. I collected benthic and terrestrial insects and quantified the flow of insects emerging from and falling into the stream channel. To better understand the physical and biological differences occurring between sites, I also conducted vegetation surveys and measured stream characteristics. Preliminary results show decreased abundances of terrestrial insects and insects falling into streams at sites with R. neomexicana. I also found evidence of disturbance, such as greater abundance of bare ground and other non-native plants at R. neomexicana sites.

Hannah Riedl (Primary Presenter/Author), Colorado State University, hanriedl@gmail.com;


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


Liba Pejchar ( Co-Presenter/Co-Author), Colorado State University, liba.pejchar@colostate.edu ;


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5/25/2016  |   15:45 - 16:00   |  309-310

HOW STRESSORS SHAPE SUBSIDIES: LESSONS FROM METAL-IMPACTED STREAMS Ecological subsidies link food webs in disparate ecosystems. As a result, stressors assumed to impact only local production can affect consumers and basis of production in connected food webs. Our work in metal-impacted mountain streams and adjacent riparian food webs revealed that aqueous metals can almost eliminate adult insect emergence and food subsidies to terrestrial consumers, that emergence is reduced more strongly than larval densities over a metals gradient, and that fish in streams with elevated metals (and fewer aquatic insects) consume proportionately more terrestrial insect prey. These results, combined with findings for other stressors (e.g., climate, Larsen et al. 2015; predators, Wesner 2016), suggest two general principles governing the impacts of stressors on cross-ecosystem linkages, 1) that ecological subsidies (linkages between food webs) may be more sensitive to stressors than within-food web dynamics, especially when animals with complex life histories comprise the subsidy, and 2) that reductions in local resource availability due to environmental stressors can increase reliance of consumers on alternative subsidies. Both principles have strong implications for managing linked food web systems in a changing world.

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


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.

Richard Wanty ( Co-Presenter/Co-Author), U.S. Geological Survey, rwanty@usgs.gov;


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


Justin Pomeranz ( Co-Presenter/Co-Author), Colorado Mesa University, jfpomeranz@gmail.com;
o Justin is an assistant professor of environmental science at Colorado Mesa University. He is a community ecologist with a special affinity for streams and benthic macroinvertebrates. Justin’s research is focused on understanding the variation in community biomass distributions from both natural and anthropogenic causes. He enjoys working with large datasets across scales and playing the banjo. Justin received a BS and MS from Colorado State University and a PhD from the University of Canterbury in New Zealand.

Andrew S. Todd ( Co-Presenter/Co-Author), U. S. Geological Survey, Crustal Geophysics and Geochemistry Science Center, Denver, CO 80225, atodd@usgs.gov;


Laura Heiker ( Co-Presenter/Co-Author), University of Northern Colorado, lmheiker@gmail.com ;


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5/25/2016  |   16:00 - 16:15   |  309-310

ASSOCIATIONS BETWEEN STREAM METAL CONTAMINATION AND BAT ACTIVITY IN THE EASTERN COLORADO ROCKIES Metal contamination in freshwater ecosystems is a widespread consequence of mining, but effects on nearby riparian predators, such as bats, that depend on aquatic-terrestrial subsidies are poorly understood. We hypothesized that more contaminated stream reaches (>3,000 m) in the Colorado Mineral Belt would have lower proximate bat activity due to reduced densities of adult aquatic emergent insect prey. From July to October 2014, we sampled fourteen sites for bat activity (defined as number of minutes with bat sonar passes per night), stream heavy metal concentrations, and aquatic emergent insect densities. Bat activity was low relative to studies at lower-elevation foothill sites. There was no relationship between total bat activity and aqueous metal concentration, despite a negative correlation between metal concentration and aquatic emergent insect biomass. However, streams with lower metal concentrations had more bat prey capture attempts (as measured by recorded feeding buzzes) than streams with higher metal concentrations. These data suggest that although bats are passing over streams of all contamination levels at a similar rate, they are encountering prey more often over cleaner streams.

Laura Heiker (Primary Presenter/Author), University of Northern Colorado, lmheiker@gmail.com ;


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


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


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


Rick Adams ( Co-Presenter/Co-Author), University of Northern Colorado, battings@yahoo.com;


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5/25/2016  |   16:15 - 16:30   |  309-310

EFFECTS OF SELENIUM AND PESTICIDES ON AQUATIC-TERRESTRIAL RESOURCE SUBSIDIES IN THE PRAIRIE POTHOLES Metamorphosis of aquatic insects is a primary link between aquatic and terrestrial systems, but it’s a process that can be disrupted by the presence of chemical stressors in freshwater systems. Pesticides and fertilizers are important categories of chemical stressors relevant to the Prairie Pothole wetlands of the Great Plains. These stressors can lead to bioaccumulation and transfer of toxins to terrestrial systems, declines in aquatic-terrestrial subsidies, or changes to the structure of adult aquatic insect communities. To understand the full impact of agricultural activities surrounding these wetlands, we take an approach that examines larval and emerging insects, water quality and physical characteristics of wetlands in the field. Our field sites experience chemical stress created by agricultural tile drainage, surface runoff, or were non-impacted controls. Through these parameters we found that June emergence in tile drain sites was 80% lower than those influenced by surface runoff, and 70% lower than control sites. Our results indicate shifts in the availability of aquatic-terrestrial resource subsidies in this system associated with agricultural runoff and more strongly impacted by tile drainage than by surface runoff.

Brianna Henry (Primary Presenter/Author), University of South Dakota, b.henry@eagle.clarion.edu;


Jake Kerby ( Co-Presenter/Co-Author), University of South Dakota, Jacob.kerby@usd.edu;


Jeff Wesner ( Co-Presenter/Co-Author), University of South Dakota, Jeff.Wesner@usd.edu;


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5/25/2016  |   16:30 - 16:45   |  309-310

RESOURCE SUBSIDIES FROM ADFLUVIAL FISH INCREASE STREAM PRODUCTIVITY The importance of potamodromous fish migrations and the subsidies they provide to stream ecosystems has received little attention. We determine the importance of excretion, eggs, milt, and carcasses as nutrient and energy sources from a large population of migrating suckers into a small oligotrophic river system. In total there was an estimated 5,635 kg of eggs, 2,025 kg of milt, and 1 kg of carcasses from suckers. Relative to other fishes, suckers provided 92% of the annual egg biomass and 95% of the milt and 84% and 78% of the annual subsidies of N and P. Epilithon biomass was nine times more abundant, benthic densities were two times higher, and fish biomass was eight times greater compared to non-subsidize sections. Stable isotopes revealed that subsidies were incorporated into multiple trophic levels in the stream food web and increased ecosystem productivity.We estimated that sucker eggs comprised 25-58% of the diet of stream fishes during the growing season. Suckers provided a large subsidy, greater than all other fishes, without mass mortality and significantly enhanced the productivity of the recipient river system.

Nicholas Jones (Primary Presenter/Author), Ontario ministry of Natural Resources - Trent University, nicholas.jones@ontario.ca;


Robert Mackereth ( Co-Presenter/Co-Author), Ontario Ministry of Natural Resources - Lakehead University, rob.mackereth@ontario.ca;


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5/25/2016  |   16:45 - 17:00   |  309-310

INFLUENCE OF PACIFIC SALMON SPAWNERS ON STREAM ECOSYSTEMS: WHY CONTEXT MATTERS Pacific salmon (Oncorhynchus spp.) provide a useful model for understanding the role of environmental context (i.e., chemical, physical, and biological characteristics) in the effects of ecosystem resource subsidies on lotic ecosystems. First, salmon transfer large amounts of organic material, accumulated while maturing in oceans or lakes, into lotic ecosystems where they spawn and die. Second, salmon have been intentionally introduced to numerous locations where the environmental context differs from where salmon spawners are native. For over ten years, we have studied mechanisms by which salmon influence stream ecosystems in Alaska and the Great Lakes, between which there is an especially strong contrast in environmental context. Evidence from research undertaken suggests salmon increase dissolved nutrients, disturb substrate, alter stream metabolism, and biotransport contaminants. However, the direction and extent can depend upon salmon spawner run dynamics (e.g., density, duration), local attributes (e.g., sediment size, background contaminant levels), and watershed conditions (e.g., land use, nutrient status). New insight into how environmental context modulates salmon resource subsidies will help predict and manage the consequences of environmental change for stream ecosystems that support migratory fishes.

Dominic Chaloner (Primary Presenter/Author), University of Notre Dame, dchalone@nd.edu;


Brandon Gerig ( Co-Presenter/Co-Author), Northern Michigan University, bgerig@nmu.edu;


David J. Janetski ( Co-Presenter/Co-Author), Indiana University of Pennsylvania, janetski@iup.edu;


Peter S. Levi ( Co-Presenter/Co-Author), Drake University, peter.levi@drake.edu;


Ashley Moerke ( Co-Presenter/Co-Author), Center for Freshwater Research and Education, Lake Superior State University, amoerke@lssu.edu;


Richard Rediske ( Co-Presenter/Co-Author), Grand Valley State University - Annis Water Resources Institute, redisker@gvsu.edu;


Janine Rüegg ( Co-Presenter/Co-Author), University of Lausanne, janine.ruegg@unil.ch;


Jennifer L. Tank ( Co-Presenter/Co-Author), University of Notre Dame, tank.1@nd.edu;


Scott Tiegs ( Co-Presenter/Co-Author), Oakland University, tiegs@oakland.edu;


Gary Lamberti ( Co-Presenter/Co-Author), University of Notre Dame, lamberti.1@nd.edu;


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