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Current Research in the Stream Ecology Laboratory
My research interests are centered in aquatic ecology, especially stream and river ecology, 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 communities and ecosystem processes to environmental stressors, including land-use change and chemical toxicants, (iv) impacts of non-native organisms on freshwater ecosystems such as Pacific salmon in the Great Lakes. Current areas of investigation in my laboratory include the ecology of deltaic ponds in Alaska, the restoration of degraded aquatic ecosystems, the influence of nutrient subsidies on stream ecosystem structure and function, and the ecology of natural and human-induced disturbance on aquatic ecosystems. Several funded research projects that are ongoing in my laboratory, along with my Notre Dame collaborators, are presented below:
1) Ecology of Alaska Freshwater Ecosystems: Salmon Streams, Rivers, and Deltas. (Funded by USDA Forest Service; collaborative with Drs. J. Tank and D. Chaloner at UND and others). We have been studying salmon streams in southeast Alaska for the past 10 years. Salmon migrations into nutrient-poor streams of the Pacific Northwest are thought to contribute essential nutrients to streams after salmon die and carcasses decompose in the stream. All levels of stream food webs (periphyton, macroinvertebrates, and fish) may respond to this enrichment. We further hypothesize that riparian systems benefit from salmon runs via scavenging by terrestrial vertebrates and possible enrichment of riparian soils and plants with salmon nutrients. This project strives to determine if stream and riparian structure and function are linked to enrichment by marine-derive nutrients released by anadromous salmon. The project is centered in the marvelous Tongass National Forest of southeast Alaska and Chugach National Forest in southcentral Alaska, where natural runs of salmon are still near historical levels. In southeast Alaska, we mostly study the small salmon streams that dominate this island archipelago. In southcentral Alaska, we study the enormous delta of the Copper River, where freshwater ponds and tidal sloughs dominate the landscape. Incredible vertebrate and invertebrate diversity dominate this ecosystem, which may serve as a sentinel for global environmental change such as in climate.
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2) Role of Large Woody Debris in Maintaining Stream Ecosystem Function in Managed U.S. Forests. (Funded by National Fish and Wildlife Foundation and National Park Service; collaborative with Drs. J. Tank and A. Moerke). The USDA Forest Service manages forests for multiple uses, including timber, water, wildlife/fisheries, and recreation. In the upper Midwestern U.S. (and in many other parts of the country), the legacy of past forest harvest has left streams and rivers nearly devoid of natural quantities of large woody debris (LWD). Previous research has shown that LWD is an important component of stream ecosystems; it promotes channel stability, retains organic matter, increases substrate diversity, and provides habitat for invertebrates and fish. Some forests are now being managed for recovery of LWD both on the forest floor and in streams. While it is generally recognized that LWD plays an important structural role in streams, the functional role of LWD in forested streams is virtually unknown. There remains a paucity of information on how wood alters stream ecosystem processes such as stream productivity and metabolism, nutrient cycling, and material (energy) flow through food webs. For example, although LWD may be a local “magnet” for fish, it remains unknown whether stream productivity has been enhanced at the stream reach scale. Our study takes the unique perspective of investigating LWD in low-gradient streams where effects have not been previously studied, and integrating large wood into on-the-ground restoration strategies.
3) Implementing a Great Lakes Coastal Wetland Monitoring Program (Funding is pending from the U.S. EPA, 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) Impacts of Introduced Pacific salmon on Ecological Communities of Great Lakes Tributaries (Funded by Great Lakes Fishery Trust; collaborative with Drs. D. Chaloner and A. Moerke). Biological introductions, especially of species that influence nutrient levels, food web dynamics, or disturbance regimes, often raise conservation concerns because they may change the evolutionary pressures on indigenous communities and can ultimately alter natural ecosystem processes. Nowhere is this more apparent than in the Great Lakes basin, which contains approximately 91 non-native fish species and where native lake communities are highly impacted, including the decline of many native vertebrate and invertebrate species. However, the impact of non-native species on flowing waters in the Great Lakes basin has received considerably less attention. This research project will determine how introduced Pacific salmon affect food web composition, energy flow, and contaminant biotransport in tributary streams to the Great Lakes. Impacts will be assessed by measuring the response of algae, macroinvertebrates, and stream-resident fish to salmon spawners, including incorporation of salmon-derived nutrients and pollutants transported by salmon. The results of this project will help Great Lakes states preserve native stream communities that might otherwise be altered by introduced salmon.
5) IGERT: Global Linkages of Biology, Environment, and Society (GLOBES). (Funded by NSF). This new graduate training grant was recently funded by the National Science Foundation and will support up to 20 Ph.D. students at its completion. GLOBES will bring together the complementary skills of biologists, environmental and 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. The problems plaguing the environment are multifaceted in origin: from global issues such as climate change and infectious diseases, to "backyard" problems like invasive plants and animals. Because these problems have interrelated causes and feedbacks that are both biological and social in nature, resolving them demands biological, cultural, economic, legal, and ethical considerations. The University of Notre Dame's GLOBES program takes an interdisciplinary approach to human and environmental health studies. Teams of GLOBES student scholars, faculty, and researchers from throughout the University’s Colleges of Science, 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 will engage in field studies in North America, Africa and China; gain hands-on experience using a range of analytical tools from genomic to economic to policy analysis; and train with scientists and other professionals both on campus and in Washington, D.C., to hone teaching, communication, and leadership skills. More information on this IGERT is available at http://globes.nd.edu/ and I urge to indicate on your formal application an interest in this program so that you will be considered for admission to the IGERT.