Zebra mussels in lake michigan1/10/2024 ![]() The WDNR, however, invests a tremendous amount of its funding into fighting the mussels and other invasive species. Of the state’s 15,000 lakes, he said 95 percent remain free of non-natives. WDNR Aquatic Invasive Species coordinator Bob Wakeman told the Wisconsin Radio Network that Wisconsin’s lakes are actually still in relatively good shape. Since the zebra mussels consume tremendous amounts of water, they also absorb pollutants and thus pass it up the food chain when they’re eaten. We also wrote a few months ago how research shows that the zebra mussels can introduce toxins, such as PCBs, into the food chain under certain circumstances. The WDNR notes the biggest issue is they can make the water so clear that sunlight is able to reach deeper in the water and feed massive growths of weeds, which profoundly alter the aquatic ecosystem. ![]() This leads to some negative consequences, though. Thus, they act as natural water filters and are able to make the water clearer and cleaner. They intake an enormous amount of water, roughly one liter per day, along with any suspended sediments or toxic substances within the water. Zebra mussels can be a mixed blessing and a curse. By 1993, they had infiltrated the Bay of Green Bay and from there began infesting a number of surrounding water ecosystems, including every major water body in Northeast Wisconsin and several smaller lakes. Zebra mussels first entered the Great Lakes region through Lake Michigan at the beginning of the 1990s. The WDNR last week added ten new lakes to its list of water bodies riddled with the mussels. Reprinted with permission from the Science Museum of Minnesota.Invasive zebra mussels have now infested 130 Wisconsin lakes and rivers, announced the Wisconsin Department of Natural Resources. Zebra and quagga mussels sped up that process, rapidly shifting how nutrients and energy are cycled and distributed in the lake, leading to dramatic changes in seasonality and abundance of those important and favored diatom food sources for Diporeia. Point source phosphorus control measures started in the late 1970s and 80s had already begun to limit algae growth in Lake Michigan. However, the research team also showed that the change in food resources had started before the mussel invasion. It confirmed that Diporeia had a highly selective diet Diporeia wanted to eat only the choicest diatom morsels that sank to the bottom of the lake. During the mussel invasion, Diporeia was forced to shift its diet to smaller and much less nutritious diatom species, resulting in its eventual demise as young Diporeia were unable to survive to adulthood.Ī comparison of those diets with the sediment record revealed additional telling evidence. The answer was clear based on Edlund’s diet analysis: Pre-invasion Diporeia fed almost exclusively on three types of microscopic diatom algae known for their high lipid content and abundance in spring and early summer. The team used a novel combination of diet analysis of historical Diporeia collections made in the 1980s through 2000s paired with analysis of sediment cores over the same time period to test how food resources and diets changed during the zebra and quagga mussel invasion. Diporeia are nearly gone now, and their loss led to the collapse of the Great Lakes food web.Ī recent paper in the Journal of Great Lakes Research by SEAS alumnus Mark Edlund (MS '92, PhD '98) of the Science Museum of Minnesota and colleagues David Jude and Tom Nalepa of the University of Michigan provides new clues as to why this happened. Diporeia was a keystone species, serving as the critical link between the microscopic algae they ate and the renowned Great Lakes fisheries they fed. In the depths of Lake Michigan, a small shrimp-like animal, the half-inch-long Diporeia, used to be the most abundant animal living in the bottom of the lake-averaging more than 7,000 animals per square meter. Those highly visible impacts divert our attention from other changes in the Great Lakes that are more evident in offshore waters. ![]() Beaches are now covered with shells, algae, and dead birds and fish wash up on the shoreline from botulism outbreaks. ![]() The introduction of zebra mussels and the closely related quagga mussel to the Great Lakes changed everything. ![]()
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