Zebra mussels are armed with root-like threads of protein, called "byssal threads," that allow them to firmly attach themselves to hard surfaces such as rocks, native mussels, docks, or boats/NPS

A search is underway at Voyageurs National Park in Minnesota for the presence of zebra mussels, an invasive species that can wreck havoc with ecosystems.

The search, through August 5, will involve divers searching areas of Black Bay on Rainy Lake just outside of park boundaries where the Minnesota Department of Natural Resources detected zebra mussel veligers (larval stage of zebra mussels) in 2021. The divers will also search in other park waters.

Through this effort, Voyageurs National Park will gain information on the status of the zebra mussel infestation of Rainy Lake and will search for infestations in other park waters. This information will be used to optimize efforts to prevent further spread of zebra mussels. 

Zebra mussels can substantially harm aquatic ecosystems by reducing the health and populations of native fish and native mussels, according to park staff. For example, in Minnesota lakes infested by zebra mussels and spiny water fleas, the average size of first-year walleyes is 25 percent smaller than in uninfested lakes. This size decrease is concerning because there is evidence that smaller first-year walleyes have higher mortality rates than larger first-year walleyes.

Back in 2013 a small number of invasive quagga mussels were found in Lake Powell at Glen Canyon National Recreation Area in Utah. At the time, 14 of the mussels were removed from the lake. At the time, Park Service officials thought they could control the mussels. Come forward to 2022, and the lake is infested with quagga mussels and there's no current hope of removing them.

Though native to the Caspian, Black, and Azov seas in eastern Europe, the mussels are thought to have hitchhiked to North American in the ballast water of ocean-going ships. Arriving in the Great Lakes around 1986, the shellfish have continually expanded their habitat in the United States, first moving through the Great Lakes and Mississippi River Basin states before heading in all compass directions by catching rides on boats and trailers.

According to the United States Geological Survey, "quaggas are prodigious water filterers, removing substantial amounts of phytoplankton and suspended particulate from the water... By removing the phytoplankton, quaggas in turn decrease the food source for zooplankton, therefore altering the food web."