Invasive mussels have been highly successful invaders throughout the Michigan waters of Lakes Erie, Huron, and Michigan, causing significant biological and ecological changes over the past 30 years. Two mussel species – zebra (Dreissena polymorpha) and quagga (D. bugensis) – have affected lake waters by increasing water clarity, which fuels growth of aquatic plants, and causing dense growth in lake bottoms and on infrastructure of municipal and industrial water intakes.
In addition, mature adult mussels can release up to 1 million larvae, known as veligers, that also pose potential risk to Great Lakes aquatic communities. Specifically, veligers may replace the biomass of small aquatic invertebrates that represent important prey and nutritional resources for juvenile fish species such as yellow perch and walleye.
In a recently completed Michigan Sea Grant-funded project, researchers provided data on the nutritional quality of dreissenid veligers as a potential food source for Great Lakes invertebrate and fish predators and improved understanding of their limited contributions to energy transfer. To accomplish this task, the research team measured the fatty acid and energy contents of veligers collected from Lake Huron’s Saginaw Bay. They also measured consumption of veligers by invertebrate predators to understand how they may contribute to energy and nutrient transfer in Great Lakes food webs.
Led by Gordon Paterson, Assistant Professor in the Department of Biological Sciences at Michigan Technological University, the team found fatty acid and energy density of veligers to be of lower nutritional quality relative to similarly sized and larger natural aquatic invertebrate species from Saginaw Bay. The research showed that veligers contain approximately 20% less food energy relative to crustacean zooplankton, including similarly sized invertebrates that veligers have replaced in Great Lakes food webs. In addition, veligers had lower proportions of essential fatty acids, or omega-3 compounds, such as α-linolenic and eicosapentaenoic that are required for the normal growth and development of higher level predator species such as fishes.
According to the team, this project is among the first to generate energy density and fatty acid composition information for veligers in the Great Lakes in addition to measuring veliger production within the plankton community of a Great Lakes food web. For resource managers, this information can help inform ecosystem-based and fisheries modelling approaches used by Michigan’s resource managers and stakeholders to help support planning and forecasting, decision-making strategies, and resource-management approaches.
