The invasive aquatic plant Starry Stonewort was recently discovered in Little Cedar Lake in Washington County and Geneva Lake in Walworth County.
Starry stonewort was discovered in Little Cedar Lake by a Washington County staff person conducting an aquatic plant survey. The discovery in Geneva Lake was made by a lake management consultant conducting some aquatic plant control work. Experts at the DNR and the New York Botanical Gardens confirmed the discoveries.
Though the specific impacts of starry stonewort are largely unknown, anecdotal evidence suggests that the macro-algae can grow in thick mats at high densities, potentially impacting recreational and aesthetic uses. The DNR is working with partners around the country to determine effects of starry stonewort.
Little is known about these specific populations at this time. The DNR and local partners will assess the populations soon to determine potential management options for both lakes.
“A thoughtful and coordinated approach to managing these new populations will ultimately be most successful in limiting their impacts,” said Amy Kretlow, the DNR aquatic invasive species specialist for southeast Wisconsin. “The DNR and UW-Extension staff will work together with local partners on Geneva Lake and Little Cedar Lake to develop a response plan.”
At this time, there are no known effective eradication measures for starry stonewort. Chemical treatment has been attempted but did not effectively reduce the reproductive bulbils that are in the sediment. Mechanical treatments such as hand-removal and diver-assisted suction harvesting (DASH) have seen short-term success followed by regrowth.
Wisconsin and other neighboring states are continuing to research control options that can kill or remove the plant while reducing harm to native plant communities. Removing vegetation and mud from your watercraft, trailer, anchor, and other equipment is effective at preventing the spread of all invasive species. As a reminder, boaters can prevent the spread of invasive species through these
Stop Aquatic Hitchhikers Like Starry Stonewort:
- INSPECT your boat, trailer, and equipment including anchors.
- REMOVE any attached aquatic plants or animals (before launching, after loading, and before transporting on a public highway)
- DRAIN all water from boats, motors and all equipment
- NEVER MOVE live fish away from a waterbody
Starry stonewort remains a prohibited species in a limited number of Wisconsin’s lakes and the opportunity to prevent its spread still exists. DNR rapid response grants are available to communities that are dealing with new invasions and the Clean Boats Clean Waters watercraft inspection program keeps boats free of invasive species as they travel between lakes.