Well, chalk up another invasive species in Minnesota's most popular walleye lake.
The Minnesota Department of Natural Resources issued a release this week saying its staff discovered spiny waterfleas in Lake Mille Lacs last week. Zebra mussels, another invasive species, already is in the lake and officials have been trying to educate boaters and anglers about that problem.
Now they have another that could impact the lake. It's the first time spiny waterfleas have been found in Minnesota outside of Lake Superior and U.S.-Canadian border waters, including Lake of the Woods, Rainy Lake and Namakan Lake. Definitely not good news.
Here's what the DNR news release says:
Spiny waterflea impacts to lake ecosystems are largely unknown. The waterfleas compete with small fish for food called zooplankton. While larger fish eat them, tiny fish may not be able to consume this invader. In certain types of lakes, they can change the species and numbers of zooplankton, which may harm those lake ecosystems.
However the waterfleas can collect in masses, sticking to fishing lines, downrigger cables and anchor lines. The masses can resemble gelatin or cotton batting with tiny black spots, which are the creatures' eyes or eggs. Individual animals are difficult to distinguish without magnification because they are only 1/4 to 5/8 inch long.
The spiny waterfleas in Lake Mille Lacs were first observed collecting on fishing lines in the water. The find was later confirmed from water samples collected by the DNR.
"Spiny waterfleas can spread when boats, fishing or bait harvesting gear become contaminated with egg-laden females or when water from the infested lakes and rivers is transported," said Rich Rezanka, DNR invasive species specialist. "Although the waterfleas may die between fishing trips, they might be carrying resting eggs that can begin a new infestation."
Spiny waterfleas are zooplankton - microscopic crustacean animals like the Daphnia in lakes. They have a long tail spine with up to three pairs of barbs sticking out of it. As a predator, they eat other zooplankton, and they often can become abundant in late summer and fall.
