Facts About Starry Stonewort
Starry Stonewort (SSW, Nitellopsis obtusa) is an aquatic macroalgae, invasive to the Great Lakes region from Eurasia, that closely resembles a vascular plant. It invades lakes, ponds, and slow-moving water bodies where it attaches to the sediment using rhizoids, and grows to 2 meters. (Kipp et al., 2017). The rhizoids resemble thin fishing line with star shaped reproductive structures called bulbils attached. These are usually buried in the sediment. The first occurrence of SSW was documented in 1974 in the St. Lawrence River between New York State and Ontario, Canada. Ballast water is the prime suspect for entry and subsequent spread throughout the Great Lakes basin (GLB). Left unchecked, it is thought that the SSW can cause harm to natural environmental systems and inhibit the use of waterways, which can potentially result in economic impacts.
Photo credit: Paul Skawinski
Average size of a Starry Stonewort
Photo credit: Scott Brown
Underwater view of Nitellopsis obtusa
In this video learn to identify Starry Stonewort (Nitellopsis obtusa) and distinguish it from several look-alike species.
A production of the Wisconsin Lakes Partnership.
Where did it come from?
Starry Stonewort is native to parts of Europe and western Asia. The first occurrence of SSW was documented in 1978 in the St. Lawrence River between New York (NY) and Ontario, Canada. Ballast water is the prime suspect for entry and subsequent spread throughout the Great Lakes basin (GLB).
Why is it a problem?
Like many invasive species Nitellopsis obtusa spreads very quickly especially in disturbed areas. It can regenerate from very small fragments and can be spread between water bodies on vehicles and boat trailers.
Rake toss sample showing nearly 100% SSW, Keuka Lake Outlet, Penn Yan, NY
Left unchecked SSW grows into great “meadows” or pillows that cause harm to natural environmental systems and make fishing, swimming or boating nearly impossible. This in turn can potentially result in economic impacts to areas near infested
A bed of Starry Stonewort, Keuka Lake Outlet, Penn Yan, NY