‘Starry Trek’ volunteers search 187 Minnesota Lakes, find starry stonewort in 1

Starry stonewort forms dense surface mats in lakes.

More than 225 trained volunteers searched 187 Minnesota lakes recently for the invasive algae starry stonewort during the University of Minnesota Extension’s annual “Starry Trek” event.

The Minnesota DNR has confirmed a volunteer report of starry stonewort in Wolf Lake in Hubbard County in north-central Minnesota.

During a follow-up survey in the lake, DNR invasive species specialists found a one-third-acre bed of starry stonewort at an undeveloped access off a township road.

Boat inspections have been expanded and treatment options are being considered, along with more follow-up surveys to watch for the invasive algae in other parts of the lake.

Starry stonewort has never been eradicated from any U.S. lake, but treatment can help reduce the risk of spread and provide nuisance relief for water-related recreational activities.

Dr. Ken Karol with the New York Botanical Garden provided scientific verification of the starry stonewort sample from Wolf Lake. Volunteers submitted samples from several other lakes during the search event that turned out to be chara (KAIR-uh), a native alga that looks similar to starry stonewort.

This year’s search results mirror the 2017 inaugural event. Last year, 200 volunteers searched 178 lakes and found starry stonewort in one. There are now 14 lakes in Minnesota where starry stonewort has been confirmed.

Since starry stonewort was first confirmed in Minnesota in 2015, most new populations have been reported in the month of August, when the telltale star-shaped bulbils are most abundant and visible. Now is the best time of year to look for it. Information on how to identify starry stonewort can be found on the DNR’s website. If people think they’ve found starry stonewort, they should report it to the DNR.

Starry stonewort is an alga that looks similar to other native plants and can form dense mats, which can interfere with 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.

Details about starry stonewort and other aquatic invasive species are available at mndnr.gov/ais.

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