A study began in Lake Minnetonka this week on a potential new method to effectively manage zebra mussel populations.
During three separate weeks between now and mid-August, low levels of a federally approved copper-based product, EarthTec QZ, are being applied in six enclosures near the shoreline of Lake Minnetonka’s Robinson’s Bay in Deephaven. Following each application, researchers will evaluate the impact of different concentrations of the product on the survival of zebra mussel larvae, called veligers.
Researchers from the Minnehaha Creek Watershed District (MCWD) and the Minnesota Aquatic Invasive Species Research Center (MAISRC) at the University of Minnesota are partnering on the project. Their goal is to decrease the overall zebra mussel population by targeting the invasive species at its earliest stage.
“As we explore feasible, cost-effective ways to manage the zebra mussel population in Lake Minnetonka and elsewhere, we are interested in seeing if this can be a viable tool,” said MCWD Aquatic Invasive Species Program Manager Eric Fieldseth. “We are grateful for the partnership with MAISRC to better understand how to control this invasive species.”
The product is species-specific and poses no health risks to people or other aquatic life, according to the watershed district. Recreational access to Robinson’s Bay will not be impacted during the study.
The study is the first known field test of its kind in the country. It is funded by a $24,000 grant from Hennepin County, a state appropriation for AIS prevention and management programs.
The first round of trials began this week, the second round is planned for the week of Aug. 1 and the third and final round is set for the week of Aug. 15.
Zebra mussels on Lake Minnetonka
Zebra mussels have long-term water quality and recreational impacts. They alter the food chain that fish and other aquatic life depend on, they attach to docks, boats and other hard surfaces, and their sharp shells litter beaches and lake bottoms.
Since zebra mussels were discovered in Lake Minnetonka six years ago, they have spread throughout the lake. Some of the largest concentrations are in the study area in Robinson’s Bay. Because zebra mussel adults live only three to five years, they rely on veliger production to maintain their populations. Reducing veliger survival could ultimately reduce the overall population of adult zebra mussels and may be an approach to management, particularly on newly infested lakes.
“Lake Minnetonka is a valuable laboratory for testing new potential zebra mussel control methods,” said Dr. Michael McCartney, MAISRC research assistant professor. “This study’s findings will help inform future efforts to manage these populations, slow their spread, and lessen their impact on our lakes.”
The applications on Robinson’s Bay coincide with another Lake Minnetonka MAISRC-partner project focused on veligers this summer. Last May, the center announced its partnership with the Minnesota Department of Natural Resources, Brunswick Freshwater Boat Group and Tonka Bay Marina to launch research aimed at reducing the spread of invasive zebra mussels by recreational boaters.
That project is examining “residual water,” or water left after a boat’s operator has attempted to fully drain it, which can contain veligers and thus act as a carrier of aquatic invasive species (AIS). Sample collection is taking place this summer and next on weekends, June through August, on Lake Minnetonka and Gull Lake in Cass County.