Starry stonewort (Nitellopsis obtusa) is a microalgae from Eurasia that was likely introduced to the US accidentally in ballast water. Starry stonewort first appeared in the US in 1978 in the St. Lawrence River between New York and Ontario, and has since spread throughout the Great Lakes basin into Michigan, Indiana, Wisconsin and Minnesota. Starry stonewort has been identified along the shoreline of the Saginaw Bay in Tuscola, Bay, Huron and Arenac counties.
When left unchecked, starry stonewort grows in large underwater mats that harm natural ecosystems, and make fishing, swimming or boating nearly impossible. Starry stonewort can reproduce sexually or asexually from fragmentation, making them difficult to control. The stonewort takes its name from the white, star-shaped bulbils at the branch nodes. The bulbils set the starry stonewort apart from similar native species, making the invasive plant easy to identify.
Like many other aquatic invasive species, starry stonewort spreads through waterways on boats and aquatic gear. Plants can regrow from very small fragments, so preventing the spread of fragments is crucial. You can prevent the spread of starry stonewort by washing off boating and recreational gear when leaving any freshwater body.
When left unchecked, starry stonewort grows in large underwater mats that harm natural ecosystems, and make fishing, swimming or boating nearly impossible. Starry stonewort can reproduce sexually or asexually from fragmentation, making them difficult to control. The stonewort takes its name from the white, star-shaped bulbils at the branch nodes. The bulbils set the starry stonewort apart from similar native species, making the invasive plant easy to identify.
Like many other aquatic invasive species, starry stonewort spreads through waterways on boats and aquatic gear. Plants can regrow from very small fragments, so preventing the spread of fragments is crucial. You can prevent the spread of starry stonewort by washing off boating and recreational gear when leaving any freshwater body.
Starry stonewort form large pillowy masses that prevent fish movement and damage natural ecosystem functions.
Photo: Barbara Tokarska-Guzik, University of Silesia, Bugwood.org
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Identification:
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Habitat:
Invades lakes, ponds, reservoirs, and slow moving rivers. Will inhabit freshwater habitats from 3 to 95 feet in depth. |
Starry stonewort spreads through waterway through fragmentation. Even very small fragments are enough to regrow a whole plant.
Photo: Scott Brown, Michigan Lake and Stream Association
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White bulbils at the branch nodes give the starry stonewort its distinctive characteristic.
Photo: Paul Skawinski
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Additional Resources
Starry Stonewort Collaborative
Starry Stonewort Status and Strategy
Starry Stonewort Boater's Beware Card
Michigan Invasive Species Website
MISIN Species Training Module
Starry Stonewort Collaborative
Starry Stonewort Status and Strategy
Starry Stonewort Boater's Beware Card
Michigan Invasive Species Website
MISIN Species Training Module
Banner Credit: Michael Shephard USDA Forest Service