Invasive Species Starry Stonewort Discovered In Stearns County

Following an extensive search, the Department of Natural Resources has found the first new confirmed infestation of starry stonewort in a Minnesota lake in 2017.

With the help of 200 trained volunteers, in early August, the agency conducted an organized search of 178 lakes in 20 counties across the state. A light, isolated growth near the public access on Grand Lake in Stearns County was discovered during the search, according to a press release.

“Although we were hoping to find no new populations, we are glad this one was discovered early, thanks to the people who participated in the coordinated search known as ‘Starry Trek,’ said Heidi Wolf, DNR invasive species unit supervisor, in a statement. “We’re also encouraged that there hasn’t been a greater number of lakes found to have starry stonewort during this major search.”

Two other Stearns County lakes were previously confirmed to have starry stonewort: Rice Lake in 2016 and Lake Koronis in 2015. Koronis was the first lake in the state where the invasive species was confirmed, but an additional eight sites have since been added the list of infested waters.

Starry stonewort is an alga that can form dense mats, which can interfere with the use of a lake and compete with native plants. It is most likely spread when fragments have not been properly cleaned from trailered boats, personal watercraft, docks, boat lifts, anchors or other water-related equipment.

“All but one of Minnesota’s nine cases of starry stonewort have been reported in August, when the telltale star-shaped bulbils are most abundant and visible,” Wolf said. “Now is the time for people to look.”

This new confirmation is a reminder to boaters and anglers to follow Minnesota laws to prevent the spread of aquatic invasive species:

• Clean aquatic plants and animals from watercraft.
• Drain all water by removing drain plugs and keep drain plugs out while transporting watercraft.
• Dispose of unwanted bait in the trash.

Treatment options for the growth in Grand Lake are being considered. To date, starry stonewort has not been eradicated from any lake in the United States.

Details about starry stonewort and other aquatic invasive species are available at mndnr.gov/ais. More information about citizen science at the Minnesota Aquatic Invasive Species Research Center and the AIS detector program is available at aisdetectors.org.