It may have a pretty name and sound more like a fun character from Harry Potter, but a new form of aquatic invasive species is being called ugly and a possible detriment to water recreation.

Starry stonewort, a grass-like form of algae not native to North America, was first confirmed on Lake Koronis near Paynesville in Stearns County in August of last year.

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Since that time, it has now been confirmed, according to the Department of Natural Resources, in four other Minnesota lakes - Rice in Stearns County, Winnibigoshish in both Itasca and Cass counties and Turtle and Moose in Beltrami County.

Dave Rush and Justin Swart from Douglas County Land and Resource Management said it was also recently found in two other Minnesota lakes - Upper Red in Beltrami County and Cass in Cass County.

Swart, an environmental planning technician, said that starry stonewort reproduces from the white star-shaped nodule, or bulbil, that are only a couple of millimeters in size. The bulbil is what gives the invasive species its name.

According to the DNR website, starry stonewort is similar in appearance to native grass-like algae such as other stoneworts and musk-grass. It is a green macro-algae with whorls of long, narrow branchlets in groups of four to six coming off of the main shoots.

"Think thick matted vegetation that is hard to recreate through," said Rush, who is the director of Land and Resource Management. "As it spreads, it completely fills the space or environment it is in. It is a solid mass of vegetation that grows out 25 to 30 feet. There is no room for fish or anything else."

Both Rush and Swart said they don't know exactly what the long-term effects of starry stonewort could be on a body of water as there is not a lot of research on it yet, but they questioned what could happen to the fish population.

"What we do know right now is that it is very disruptive to everyone's enjoyment of the lake," Rush said. "How can you enjoy it if you can't even get your boat in the water?"


Rush said that starry stonewort most often pops up around lake accesses and then will spread out from there.

Starry stonewort is transferred from one body of water to another by the unintentional transfer of the bulbils. The fragments are most likely attached to trailered boats, personal watercraft, docks, boat lifts, anchors and any other water-related equipment that is not properly cleaned.

The motto of clean, drain and dry should now also include flush, said Rush. Not only completely emptying out such areas as livewells, he said, but also flushing out every little crevice is going to be helpful and extremely important to keep from spreading the starry stonewort.

Swart and Rush said to either do the flushing process at home or use one of the DNR's mobile courtesy decontamination sites that are set up during the regular boating season. In Douglas County, there are typically five units available. There is a map on the DNR's website that shows where the locations are each day.


According to the Minnesota Aquatic Invasive Species Research Center, current efforts include assessing risk of further spread of the starry stonewort in Minnesota by using data on where it has already invaded not only in Minnesota, but the rest of the United States, to identify waterbody characteristics and environmental conditions associated with invasion risk. In addition, identifying lakes in Minnesota where the stonewort may be more likely to survive and persist if introduced.

Tests also are being done on how long the starry stonewort can remain viable out of water to assess risk of overland spread. Laboratory experiments are being conducted on different algaecides.

Swart mentioned that a copper herbicide treatment in an isolated area has been used on it, which has helped to eliminate about 90 percent of the biomass. Other efforts include trying to hand harvest it, Rush said.

"But trying to hand harvest this stuff is an uphill battle," he said. "It may not be very successful."

Swart and Rush feel that the public needs to be vigilant and aware of not only starry stonewort, but all aquatic invasive species.

"We are not trying to scare people," said Rush. "We just want the community to know what's out there."