Zebra mussels, an aquatic invasive species with destructive ecological impacts, have been detected in Rainy Lake.
Stretching across the Minnesotan and Canadian border, Rainy Lake is known for its spectacular recreation and angling opportunities. Rainy Lake serves as a major gateway to Voyageurs National Park, with approximately one-third of the lake falling within the park’s borders. The Minnesota DNR announced on Wednesday zebra mussel larvae were confirmed in Rainy Lake, just outside of the Voyageurs National Park’s boundary. The mussel larvae (referred to as “veligers”) were identified in four out of the five samples taken on the lake in July, 2021.
In July, 2020, the Minnesota DNR followed-up on a report of a single adult zebra mussel in Rainy Lake. None of the microscopic zebra mussel larvae were detected at that time. The emergence of larvae in the July, 2021 sampling suggests a reproducing zebra mussel population is active within the lake’s waters.
The DNR has been in communication with the National Park Service (NPS), Canadian government, and the Bois Forte Band of Chippewa. Since 1981, the NPS has been collecting water samples from Rainy Lake as a part of the co-operative Large Lake Water Quality Monitoring Program. Recent samples have not shown zebra mussel larvae in Voyageurs National Park’s boundaries. However, this larger monitoring effort will be crucial in understanding the spread and severity of zebra mussels throughout the interconnected lakes.
The National Park Service and Voyageurs Conservancy will continue to provide updates on what this invasion means for the park's aquatic ecosystems. Join our Voyageurs E-news list to receive up-to-date information.
Zebra Mussel, Dreissena polymorpha
What are zebra mussels and why are they a problem?
Zebra mussels are an invasive aquatic species from Eastern Europe and Western Russia that have spread throughout the past 200 years. Zebra mussels were detected in Duluth in 1989. Approximately 3% of Minnesota lakes are infested with zebra mussels, but this number continues to rise. Zebra mussels filter food particles out of lakes, which reduces available food for native fish and other animals. Additionally, these mussels attach to boats, clog pipes, cut swimmer’s feet, and increase blue-green algae (cyanobacteria).
Anyone who suspects a new infestation of an aquatic invasive plant or animal should note the exact location, take a photo or keep the specimen, and contact a Minnesota DNR aquatic invasive species specialist. More information is available at mndnr.gov/ais.
View over Rainy Lake, Jeff Kantor
