BEMIDJI -- Starry stonewort, an aquatic invasive species of macroalgae, has been confirmed in another Beltrami County lake, as well as in lakes in Cass, Itasca and Stearns counties.
According to the Minnesota Department of Natural Resources, a resort owner on Moose Lake in Beltrami County said he noticed a dense growth in the same area of the lake for several years. DNR invasive species specialists said the extent of the spread and depth of starry stonewort in Lake Winnibigoshish in Itasca and Cass counties indicate it has also been there for several years. Rice Lake is connected to Lake Koronis and Mud Lake, where starry stonewort was first confirmed in Minnesota in August 2015.
Starry stonewort is a grass-like algae that can produce dense mats, which are able to interfere with the use of the lake. The algae is also able to choke out native plants. It has been found in Big Turtle Lake, Upper Red Lake, Cass Lake and Moose Lake, as well as Lake Winnibigoshish.
"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 press release. "It is important for people to contact the DNR if they suspect they've found starry stonewort or any other aquatic invasive species."
On Aug. 10, the DNR confirmed starry stonewort was found in Big Turtle Lake north of Bemidji, and work started earlier this week to "vacuum" up the vegetation near the access.
Lake Winnibigoshish is a popular 88 square-mile lake that is fed by and also flows into the Mississippi River. The DNR is investigating whether starry stonewort has spread into the river and other downstream lakes, the release said.
DNR invasive species specialists have confirmed starry stonewort extensively along the western and northwestern shores of Lake Winnibigoshish, including a public access. Because the infestation is widespread, current treatment options are limited, with efforts focusing on preventing spread within the lake and to other lakes.
Moose Lake is the fourth Beltrami County lake in which starry stonewort has been confirmed. Dense mats of starry stonewort are present across a wide range of the lake. Infestation is extensive, limiting current treatment options and putting the focus on preventing spread within the lake and to other lakes, the DNR said.
DNR invasive species specialists also have confirmed starry stonewort around the southwest public access of Rice Lake. A more extensive search is being conducted to determine the extent of the infestation and potential for treatment.
The new findings and details are consistent with some of the challenges in identifying starry stonewort. The DNR said it has also recently investigated reports of starry stonewort that have turned out to be false.
"The telltale star-shaped bulbils for which it is named typically don't appear until late in the season," DNR invasive species specialist Tim Plude said in the release. "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."
DNR staff are collaborating with partners on an extensive, coordinated expansion of the search for starry stonewort. Meanwhile, aggressive treatment of isolated infestations on Big Turtle Lake and Upper Red Lake are underway, and treatment options are being discussed for Cass Lake, also in Beltrami County.
Starry stonewort are grass-like macro algae that may produce dense mats, which could interfere with use of the lake. The invasive algae also may choke out native plants. It is typically spread by lake users who transport fragments of the plant from an infested body of water.
These new infestations remind boaters and anglers to follow Minnesota laws to prevent the spread of aquatic invasive species:
-- Clean aquatic plants and animals from watercraft, along with mud and debris, which may carry starry stonewort bulbils.
-- Drain all water by removing drain plugs and keep drain plugs out while transporting watercraft.
-- Dispose of unwanted bait in the trash.
More information about aquatic invasive species and how to report them is available at www.mndnr.gov/ais.