The sediment fossil record as an early warning system in the Great Lakes

Session: Building an Early Warning System for the Great Lakes

Elizabeth Alexson, Natural Resources Research Institute, University of Minnesota Duluth, [email protected]
Euan Reavie, University of Minnesota Duluth, [email protected]
Lisa Estepp, Natural Resources Research Institute, University of Minnesota Duluth, [email protected]
Gerald Sgro, John Carroll University, [email protected]
Andrew Bramburger, Natural Resources Research Institute, University of Minnesota Duluth, [email protected]
Meijun Cai, Natural Resources Research Institute, University of Minnesota Duluth, [email protected]
Robert Pillsbury, University of Wisconsin-Oshkosh, Biology Dept., [email protected]
Victoria Chraïbi, Tarleton State University, [email protected]

Abstract

Multiple stressors need management options in the Laurentian Great Lakes and paleolimnology provides tools to track changing conditions and predict future impairments. We can provide early data reflecting aquatic impacts before they are realized in higher trophic levels, thereby predicting future conditions. Here are two examples of how paleolimnology is being used to inform management decisions for the Great Lakes. (1) The RAP for the St. Louis River requires removal of beneficial use impairments associated with nutrients. Sediment cores were analyzed for physical, chemical and biological remains and long-term changes in fossil algae provided evidence that some areas have improved since nutrient abatement. However, nearshore areas show increasing nutrients and algal abundance, likely due to stressors that are not fully understood (climate change, sediment nutrients). Recommendations for delisting and future studies are forthcoming. (2) A diatom-based paleolimnological study has revealed the first biological effects of climate change on the base of the food webs in all five Great Lakes: an increasing relative abundance of Cyclotella sensu lato. Atmospheric warming is the strongest correlate with these changes, and recommendations are made regarding the eventual impacts on food webs throughout the Great Lakes system.