BEMIDJI — Starry stonewort. Zebra mussels. Eurasian watermilfoil. Spiny waterfleas. These are just some of the invasive flora and fauna that, once settled in a Minnesota lake, are seemingly impossible to eradicate.
Some of these aquatic invasive species, native to Europe and Asia, were introduced unintentionally through contaminated cargo ship ballast water discharged into the Great Lakes, with infestation beginning to spread along the St. Lawrence River in the 1970s.
Others, like curly-leaf pondweed, were byproducts of the intentional introduction of common carp as a game fish to Midwest waters in the 1880s. Curly-leaf pondweed — native to Eurasia, Africa and Australia — was first noted in Minnesota in 1910.
Turtle Lake, known locally as Big Turtle, is about 10 miles north of Bemidji. It has been a go-to lake for local anglers for decades, with a good population of walleye, northern pike and smallmouth bass.
It’s also infested with starry stonewort, a fast-growing plantlike algae. Since 2017, counties across Minnesota have participated in the University of Minnesota Extension’s “Starry Trek” event, set for Aug. 10. Community members can become citizen scientists for the day to check area lakes for starry stonewort and other aquatic invasive species.
Beltrami County Aquatic Invasive Species Coordinator Alec Wilcox explained how this starry stonewort intereferes with the lake.
"The reason it's an issue here is because it can grow and outcompete native species. It clogs up the access and makes it hard to get boats in and out," Wilcox said.
Late summer is typically the time when starry stonewort’s tell-tale white bulbils appear among the dense foliage, distinguishing it from native stonewort. Left unchecked, it can create large dense mats in area lakes.
“It's a problem for recreational purposes. Fishing, boating, kayaking, that kind of thing. We're trying to do our best to control it and stop the spread to other places,” Wilcox said.
There are only a couple of known ways to mitigate starry stonewort once it’s been introduced to a lake. Since it’s algae, it can spread faster than regular vegetation, making early detection key to avoid costly mitigation efforts.
"We just did hand removal of starry stonewort on two lakes within the county, Turtle River Lake and Pimushe Lake,” Wilcox said.
“We have a certified diver come up and they get down to the surface. They hand pull [starry stonewort] and make sure it doesn't fragment and break up and spread to other places.”
Wilcox said it’s most likely that invasive species spread by people via the highways, not birds via the flyways.
"I know there's a lot of conversation about whether waterfowl and wildlife spread aquatic invasive species, and there have been some studies done ... that show that it's not likely that it happens that way," Wilcox said.
“If we look at a map of how these AIS are spreading, it definitely follows highways and roadways and systems. So there is a pretty easy indicator to look at that shows that [AIS follow] these roadways.”
Wilcox demonstrated a boat cleaning station, a new device at Big Turtle funded through state-allocated aquatic invasive species prevention dollars. The solar-powered machine helps boaters clean plant debris and other contaminants to prevent the spread of starry stonewort and other invasive species.
In the Brainerd lakes area, starry stonewort was recently confirmed in Middle Cullen Lake. Jessica Shea in the Crow Wing County Land Services department said the county is adding more boat inspectors at nearby public accesses and staying in communication with the area lake association.
"It's kind of up to the lake association what they'd like to do. We're here to help as much as we can,” Shea said.
“Right now, we're just setting funds aside, so we have a pot that we're growing for these infestations because, if it gets large, it is very costly to treat. ... But when speaking with the DNR, this is a very small infestation, at least at that time.”
Lake Koronis in Stearns County was the first confirmed starry stonewort infested lake in Minnesota in 2015. As of June 2024, 30 Minnesota water bodies are infested with starry stonewort.
Tony Coffey is the president of the Whitefish Area Property Owners Association, one of the largest such groups in the state representing those who live on the Whitefish Chain in northern Crow Wing County. He expressed his concern about the impact of starry stonewort.
"We live on a small bay on the Whitefish Chain, and if we had starry stonewort somewhere in our bay, it would be devastating for us,” Coffey said.
“Not only with the cost of having to try to mitigate it, if we could, but then also the cost to the recreational activities and other aquatic life within the lake, so you know it's a very dangerous kind of thing.”
Coffey added cross-boat traffic between popular fishing lakes in Northern Minnesota put lake associations in the Brainerd Lakes area on alert for starry stonewort.
"We're seeing it spread more. It was recently found, not only in Middle Cullen but also in [Lake] Pokegama, then also it was found several years ago at Leech [Lake],” Coffey said.
“There's a lot of cross-boat traffic between all of these lakes and so it puts a lot of the lakes in Crow Wing County in the bullseye of the infestation.”
Minnesota law requires boaters to clean all visible aquatic plants and prohibited invasive species from watercraft and trailers before leaving any access or watershed; drain water-related equipment before leaving a water access or shoreline property; and dispose of unwanted bait in the trash.
Funding for this environmental story was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR).
