The Department of Natural Resources confirmed the presence of Starry stonewort, an invasive macroalga, in three other lakes of Minnesota, including Lake Winnibigoshish in Itasca and Cass counties, Moose Lake in Beltrami County and Rice Lake in Stearns County.

According to the DNR, they noticed thanks to a resort owner in Moose Lake in Beltrami County who told them about a dense growth in the same area of the lake for several years, which was confirmed later by the Department of Natural resources given the depth and spread of the starry stonewort in Lake Winnibigoshish.

Starry stonewort is an invasive aquatic alga. Their star-shaped bulbils, which give them their name, don’t appear until late summer.  Photo credit: Monika Lawrence / MPR News
Starry stonewort is an invasive aquatic alga. Their star-shaped bulbils, which give them their name, don’t appear until late summer. Photo credit: Monika Lawrence / MPR News

“It is important for people to contact the DNR if they suspect they’ve found starry stonewort or any other aquatic invasive species,” said Heidi Wolf, DNR invasive species unit supervisor, in a press release. “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,” she added.

Invasive algae

Starry stonewort is an invasive aquatic alga. Their star-shaped bulbils, which give them their name, don’t appear until late summer. It typically emerges in August and in early fall, which is why these cases are being found in Lake Winnibigoshish, Moose, and Rice.

“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” stated DNR invasive species specialist Tim Plude. Starry stonewort is grass-like macro algae which produce dense vegetation, interfering the use of the lake; as well, it also can kill native plants.

But it is not the first time the starry stonewort appears in Minnesota it was confirmed in August 2015 in Lake Koronis and Mud Lake, which is connected to Rice Lake. It is usually spread by people who transport fragments of the algae from one body of water to the other.

What’s next for the Department of Natural Resources in Minnesota?

On August 10, the Department confirmed starry stonewort in Big Turtle Lake north of Bemidji. It has also been Upper Red Lake, Cass Lake, and Moose Lake, before being confirmed in Lake Winnibigoshish.

Lake Winnibigoshish is famous 88 square-mile Lake in Itasca and Cass counties. It flows into the Mississippi River. Right now, they are trying to find ways to prevent the spread of the macro algae to other downstream lakes, rivers and within the lake.

The infestation of starry stonewort is extensive along the western and northwestern shores of Lake Winnibigoshish. This extended spread limits the treatment options for the DNR. As well, they have conducted other studies of starry stonewort in lakes that turned out to be false. Currently, the DNR researchers are working and deepen research to find a way to treat the starry stonewort invasion for Cass Lake, also in Beltrami County.

They call on the boaters and anglers in Minnesota to collaborate to prevent the infection and further spread of algae and other aquatic invasive species by draining all water removing drain plugs, disposing unwanted bait in the trash, and other regulations under the Minnesota laws.

Source: D-L Online