By Angelique Dahlberg, MAISRC Graduate Fellow
Zebra mussels are one of the most problematic invasive species in Minnesota, causing significant ecological and
economic impacts in waterbodies where they establish. Currently, the main strategy for controlling zebra mussels is preventing their initial introduction. MAISRC is currently exploring what to do once zebra mussels are established. One promising method for control is application of copper-based pesticides (specifically, copper sulfate).
This past July, our zebra mussel control research team - a collaboration of researchers from the U.S. Geological Survey (USGS) and the University of Minnesota - brought a mobile laboratory to the northeast shore of Pelican Lake. There, they spent just under three weeks running experiments with very low concentrations of copper to see how effective those concentrations were at controlling zebra mussel veligers (the larval life stage). Because copper toxicity changes with copper bioavailability, which is dependent on water chemistry, the team used the specific water chemistry of Pelican Lake to select the concentrations used. These experiments provide insight into copper dosages that could one day be used to control zebra mussels and tell us if measuring water chemistry can allow us to select low concentrations that are individually appropriate for each unique lake.
In addition to testing the concentrations on zebra mussel veligers, the team tested those same concentrations on snails, four native fish species, one native mussel species, and Daphnia (water flea - a zooplankton species) to see how other species would respond to this type of treatment. The team will spend the winter going through their findings and use that information to inform the next steps in this research.
Next summer, the team will return to Lake Minnetonka to explore how the water chemistry there affects the concentrations of copper needed for a successful treatment. In 2019, the team was very effective at controlling zebra mussels - and saw mortality in both the veligers and adults, suggesting an even lower concentration could be used. Next year, the team will identify and test that idea in a new part of the lake.
After a very productive summer of research, we wanted to include a huge “thank you” from our research team to the Pelican Lake community. It was great to meet some of you at the annual meeting and at the mobile lab – thank you for all of your interest and the great questions! Additionally, a special thank you goes out to Susan Koering, President of the Pelican Lakes Association. Susan generously offered to host the mobile laboratory on her own property on Pelican Lake this summer. Our research could not have happened without you--thank you!