Starry Stonewort Confirmed in Three More Minnesota Lakes

The invasive algae species Starry stonewort has be confirmed in Lake Winnibigoshish, Moose Lake and Rice Lake by the Minnesota Department of Natural Resources.

A resort owner on Moose Lake reported seeing a “dense growth” in a section of the lake for several years, according to the DNR. Rice Lake is connected to Lake Koronis and Mud Lake, two affected waters that were first confirmed in August 2015. Officials will determine the extent of the infestation near the southwest public access to determine if any treatment methods would be effective. 

The spread and depth of the algae in Lake Winnibigoshish also suggests that it has been growing there for years. Current treatment options are limited due to its magnitude, with efforts focused on preventing the spread to other areas such as Mississippi River. The DNR is investigating to see if it may have spread into the river and downstream bodies of water.

“Since it was first confirmed in Minnesota, people are becoming more aware of how to identify starry stonewort and are bringing it to our attention,” said Heidi Wolf, DNR invasive species unit supervisor, in a statement. “It is important for people to contact the DNR if they suspect they’ve found starry stonewort or any other aquatic invasive species.”

Four lakes, including Moose Lake, in Beltrami County have confirmed the presence of the species. According to the press release, the DNR has been investigating reports of the algae that were false.

“The telltale star-shaped bulbils for which it is named typically don’t appear until late in the season,” said DNR invasive species specialist Tim Plude in a statement. “If people see it in June or July, they’ll see what looks like heavy weed growth, and the bulbils aren’t easily visible until later in the year. They typically emerge in August and into the fall, which is why these new cases are being found now and why it’s a good time for everyone to look for it.”

Treatment of isolated infestations on Turtle Lake and Upper Red Lake began last week. Treatment options for Cass Lake are currently in discussion. 

Starry stonewort are grass-like macro algae appearing in dense mats, which can choke out native plants and impede use of the water. It is typically spread by transportation of plant fragments from infested areas to another body of water.