MUSSEL GROWTH AND ENERGY STORAGE IN RIVERS WITH DIFFERING LEVELS OF AGRICULTURAL IMPACT
Numerous studies indicate that freshwater mussel abundance and richness is often reduced in rivers impacted by agriculture. We found similar results in four river systems in Minnesota across an agricultural land-use gradient. Three of these rivers are part of the Minnesota River watershed that has heavy agricultural land use, and one, serving as a low-agricultural land-use reference site, is located in the St. Croix River watershed. We also found that in watersheds with more agriculture, mussels tended to be larger than in watersheds with less agriculture. For two species (Lampsilis cardium and Lasmigona complanata) we measured glycogen content (an energy storage compound) and found that glycogen content increased with increased levels of agriculture. We also estimated mussel growth rates in two species (Lampsilis cardium and Amblema plicata) using the length of external growth rings. Again, mussels from watershed with higher levels of agriculture exhibited greater growth rates. These results suggest that while agricultural impacts may negatively impact mussel abundance and richness, individual mussels may receive more nutrition resulting in higher growth, potentially from nutrient enrichment in agricultural river systems.
Dan Hornbach (Primary Presenter/Author), Macalester College, firstname.lastname@example.org;
Mark Hove (Co-Presenter/Co-Author), University of Minnesota, email@example.com;
Kelly MacGregor (Co-Presenter/Co-Author), Macalester College, firstname.lastname@example.org;
Jessica Kozarek (Co-Presenter/Co-Author), St. Anthony Falls Laboratory, University of Minnesota, email@example.com;
Patricia Ries (Co-Presenter/Co-Author), U.S. Geological Survey, Upper Midwest Environmental Sciences Center, firstname.lastname@example.org ;
Teresa Newton (Co-Presenter/Co-Author), U.S. Geological Survey, Upper Midwest Environmental Sciences Center, email@example.com;