Invasive spiny water flea spreading throughout the Boundary Waters

The invasive spiny water flea, a tiny crustacean with a spiky tail that disrupts the food web in lakes and rivers, is continuing its spread across the Boundary Waters Canoe Area.

State Department of Natural Resources officials confirmed Thursday that the flea has spread to Basswood Lake north of Ely, a lake popular with anglers and one of the few lakes in the BWCA accessible by motor boat.

The discovery was confirmed in zooplankton samples taken by the University of St. Thomas and DNR researchers.

• Map: Aquatic invasive species across the state

The lake will be added to the list of infested waters, along with Crooked, Iron and Bottle lakes downstream. The Basswood and Bottle Rivers will also be designated as infested waters because of the likelihood the flea will spread there.

Spiny water fleas were confirmed in Lac La Croix, a large lake downstream of Basswood, in 2008.

"The DNR is coordinating with Canadian officials at the Ontario Ministry of Natural Resources to alert boaters and other recreationists about the risk of spreading the invasive species," DNR aquatic biologist Rich Rezanka said.

Spiny water fleas likely came to the United States from Europe and Asia in the ballast water of cargo ships. They were first found in Lake Superior in 1987.

They're a concern because they compete with small fish as they forage on microscopic animal plankton. Yet because of its long tail spike, the water flea is not a food source for those fish. They can also clog fishing lines and other water equipment.