Many freshwater mussel populations in Minnesota have dramatically declined or disappeared due to widespread habitat destruction, pollution, land-use change, introduction of exotic species, and/or over-harvesting. For example, in the Minnesota River, where mussel diversity was once equal to that of the St. Croix, nearly half of the mussel fauna has been lost and in the past 50 years. In addition, about 20 species have been lost from the Upper Mississippi River basin during the same time period. The loss of freshwater mussels has consequences for both water quality and habitat. Mussels filter phytoplankton and other suspended material from the water column. The physical presence of both living mussels and their spent shells stabilizes sediment, creating habitat for other benthic life including fish, amphibians, insect larvae, and algae. Large aggregations of mussels can improve water clarity and enhance bed stability, decreasing sediment re-suspension during high flows and reducing downstream transport of target contaminants such as excess nutrients, suspended solids, and bacteria. Because of the multitude of factors responsible for mussel population decline, there is a need to understand the interactions among mussels, riverbed habitat and water quality.
As part of a three-year grant titled "Conserving Minnesota’s native mussel legacy: Quantifying habitat interactions", our summer 2016 research, led by Dr. Jessica Kozarek at the University of Minnesota’s St. Anthony Falls Laboratory (SAFL), will focus on experiments that look at the physical response of mussels to changing fluvial conditions, including suspended sediment concentrations, flow velocity, and turbulence. The work will involve using our experimental Outdoor StreamLab facility and a flume at SAFL to catalogue mussel response to varying environmental conditions. Mussel response will be measured by using gape sensors, tracking mussel movement, and taking soft tissue samples to assess overall health.
Results from this study will analyze the significance of various environmental conditions on native freshwater mussel health and vitality, and help develop strategies to conserve and restore native freshwater mussel habitat throughout Minnesota.
Environment and Natural Resources Trust Fund through the Legislative-Citizen Commission on Minnesota Resources (LCCMR)
Jessica Kozarek, SAFL Research Associate and Project Manager, St. Anthony Falls Laboratory, University of Minnesota
Miki Hondzo, Professor, Civil, Environmental, and Geo-Engineering, University of Minnesota and St. Anthony Falls Laboratory
Mark Hove, Research Fellow, Department of Fisheries, WIldlife, and Conservation Biology, University of Minnesota
Daniel Hornbach, Professor, Department of Biology, Macalester College
Kelly Macgregor, Professor, Department of Geology, Macalester College
Pat Nunnally, River Life, Institute for Advanced Study, University of Minnesota
The overall project began in early 2015 with a field campaign to survey and re-sample sites previously sampled by the MN DNR across a gradient of water quality and habitat conditions in the Minnesota River Basin. This research will continue through September 2017.