Aquatic Food Webs

Effects of nearshore nutrient cycling on Lake Michigan’s benthic invasive species

Kevin Pangle, Central Michigan University

Nutrient cycling in Lake Michigan has shifted in recent years, with an increased proportion of incoming nutrients being claimed by benthic, or bottom-dwelling, organisms living near shore. In places where the benthic near-shore habitat is dominated by invasive species, this diversion of energy may have wide-ranging impacts on Lake Michigan’s food web. The project team surveyed populations of bottom-dwelling invasive species in nearshore habitats and set up artificial habitats to test how well these invasive species performed under different nutrient conditions. Finally, they sampled and analyzed various Lake Michigan invertebrates, algae, plankton, and fish to determine how nutrients are cycling through nearshore and offshore habitats.

Journal article (PDF)

Understanding changes in fish populations in Saginaw Bay

Sara Adlerstein, University of Michigan
Edward Rutherford, University of Michigan

Full title: Impact of Exotic Species and Nutrient Decline on Fish Community Structure and Food Web Linkages in Saginaw Bay, Lake Huron

Walleye and yellow perch are two key sport fish in Saginaw Bay. Over the past decade, less available nutrients, competition with invasive species, and changes in the way the fisheries are managed has led to dramatic changes within the fisheries. Investigators used state-of-the-art statistical modeling techniques to quantify the impacts of these changes on fish community structure and distribution, particularly on walleye and yellow perch populations. Methods included an analysis of existing fisheries data and the creation of an ecosystem view of Saginaw Bay.

Project: R/ME-3

The impact of the Diporeia decline on the competitive interactions and distributions of slimy and deepwater sculpins in Lake Michigan

David Jude, University of Michigan

Project: R/ME-4

Complex interactions between zebra mussels and phytoplankton: Variation in grazing effects across the trophic gradient

Orlando Sarnelle, Michigan State University

Project: M/PD-16

Nutrient enrichment and food web changes in Lakes Michigan and Superior

Peggy Ostrom and Nathaniel Ostrom, Michigan State University

Full title: Evaluation of the Trophic State of Lakes Michigan and Superior

Researchers applied a new approach for evaluating the water quality of Lakes Michigan and Superior and developed a detailed database of water quality changes in the two lakes. They used oxygen isotopes to compare the rate of photosynthesis by algae to the rate of respiration by aquatic organisms, providing an indicator of the level of nutrients and algae in the waters. With funding from the U.S. Environmental Protection Agency Great Lakes National Program Office, the research has been extended to Lake Erie. The work is part of the Lake Erie Trophic Status project to understand the ecosystem’s response to recent, dramatic changes in food web structure and composition. The combined data sets from Lake Erie, Lake Superior, and Lake Michigan’s Grand Traverse Bay offer a unique perspective on the factors controlling the development of algal blooms and hypoxia. This information should allow us to better predict how climate change and biological invasions will affect algae growth and aquatic food webs of the Great Lakes.

Project: R/ES-18