Current Research in the Stream and Wetland Ecology Laboratory

Our research interests broadly encompass the ecology of streams, rivers, and wetlands on a changing planet, and emphasize: (i) interactions among aquatic ecosystems, such as ecological subsidies and the exchange of biological and chemical substances between ecosystems,(ii) the ecology of benthic organisms, particularly periphyton and macroinvertebrates, as they interact with other food web components, (iii) responses of stream and wetland structure and function to environmental stressors, including land-use change and and chemical toxicants, (iv) impacts of non-native organisms on freshwater ecosystems such as Pacific salmon in the Great Lakes and invasive plants in Alaska. Current areas of investigation in our laboratory include the ecology of deltaic ponds in Alaska subject to global change, the restoration of degraded aquatic ecosystems in the Great Lakes region, the influence of nutrient subsidies on stream ecosystem structure and function, and the impacts of emerging contaminants on aquatic ecosystems. Several externally funded research projects ongoing in the laboratory are presented below.

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1) Ecology of Alaska Freshwater Ecosystems: Coastal Wetlands and Salmon Streams (Funded by National Fish and Wildlife Foundation and USDA Forest Service). Our group has been studying deltaic wetlands and salmon streams in southeast Alaska for the past 20 years. Current research is centered in the Copper River delta of the Chugach National Forest in southcentral Alaska. We study the vast array of freshwater ecosystems on the delta as they respond to global drivers of environmental change including invasive species and climate warming. Incredible vertebrate and invertebrate diversity dominate these ecosystems, which may serve as sentinels for global environmental change. We study the trophic structure and ecosystem processes of ponds on the delta to predict future impacts of these drivers on critical populations such as rearing salmon, which ultimately impact human populations.  Past work has been completed in the Tongass National Forest of southeast Alaska where we found that salmon migrations into nutrient-poor streams contribute essential nutrients to streams during and after the salmon run as carcasses decompose. We demonstrated that all levels of stream food webs (periphyton, macroinvertebrates, and fish) respond to this enrichment, and even riparian systems benefit from salmon runs via scavenging by terrestrial vertebrates and enrichment of riparian soils and plants with salmon nutrients.

2) Impacts of Emerging Contaminants in the Great Lakes Watershed (Funded by National Sea Grant and the U.S. Geological Survey). The Great Lakes have a long legacy of environmental contamination by industrial chemicals related to coastline development and urbanization. While many such organic contaminants are now banned (e.g., DDT, PCBs), they continue to persist in the lakes and translocate to food webs.  Heavy metals (e.g., Hg) continue to be released into the lakes from industrial accidents and atmospheric deposition. In addition, “emerging” contaminants such as microplastics threaten the ecological integrity of the lakes. We have active projects on emerging and legacy chemicals that emphasize their fate and transport through the Great Lakes food web. Our current emphasis is on fluorinated compounds called PFAS, which we are finding in Great Lakes food webs and ultimately in sportfish that humans consume. These chemicals also have the potential to be bioaccumulated and biotransported by migratory fishes such as introduced salmon into streams and rivers where these fish spawn, thereby contaminating native organisms. Mitigation strategies for these contaminants requires ecological understanding of their fate and transport through linked aquatic ecosystems.

3) Implementing a Great Lakes Coastal Wetland Monitoring Program (Funded by the USEPA Great Lakes Restoration Initiative). Coastal wetlands are critical components of the Great Lakes ecosystem, yet they have been severely degraded and dramatically reduced in extent. To aid restoration and conservation of these unique habitats, we and our collaborators are establishing and implementing the first ever basin-wide coastal wetland monitoring program. Site selection, data collection/storage, and analysis will follow protocols developed by the Great Lakes Coastal Wetlands Consortium and the Great Lakes Environmental Indicators Project. Fish, invertebrate, bird, amphibian, and plant communities along with chemical/physical variables will be assessed. During this 5-year project, we anticipate assessing the majority of all coastal wetland complexes greater than 4 ha in size. A strategically-selected subset will be monitored repeatedly to identify time trends. Together, these efforts will initiate a robust and sustainable long-term monitoring system that will produce scientifically-defensible information on the status and trends of coastal wetland condition across the Great Lakes basin.

4) Environmental DNA Applied to Aquatic Ecosystems (Funded by Department of Defense SERDP Program).  Detection of environmental DNA (eDNA) in freshwater systems is a pioneering technique developed at Notre Dame to monitor rare or endangered species and combat invasive species. Our objective is to further develop eDNA as a conservation tool for freshwater ecosystems by moving from basic research to field application. Aquatic species are difficult to detect with traditional methods; alternatively, traces of eDNA from an organism can remain in suspension and be collected in a water sample, revealing the presence of a target organism. While eDNA documents presence/absence of aquatic species, knowledge of population distributions and abundances is critical for it to be an effective tool. Although eDNA can travel long distances in fluvial systems (i.e., streams and rivers), current data come from idealized experiments in standing water, leaving significant knowledge gaps in interpretation of eDNA in streams and rivers. Our research will advance the science and knowledge necessary to (i) provide improved confidence in species presence or absence determinations, (ii) more accurately pinpoint the physical location of target species, and (iii) provide more precise links between eDNA concentration and species abundance in flowing aquatic systems.

5) GLOBES Graduate Certificate Program in Environment and Society. (Originally funded by the National Science Foundation). Students in our laboratory typically engage in the GLOBES graduate certificate program housed in the Reilly Center for Science and Technology. This training program emphasizes the linkages between human society and environmental change, and solutions that will benefit both sectors. GLOBES advocates an interdisciplinary approach to human and environmental health research by coalescing the complementary skills of environmental biologists, social scientists, public policy experts, lawyers, and religious and community leaders to seek innovative and interdisciplinary solutions to a wide range of interrelated problems in environmental and human health. Teams of GLOBES student scholars, faculty, and staff from throughout the Colleges of Science, Engineering, Arts and Letters, and Law School work together to find solutions to complex issues that threaten the well-being of humanity and the planet. Through GLOBES, students gain hands-on experience using a range of analytical tools from genomic to ecological to economic to policy analysis; they train with scientists and other professionals both on campus and in Washington, D.C., to hone teaching, communication, and leadership skills. More information on GLOBES is available here and you can apply for admission upon matriculation into our graduate program