Story and Photo by Scott Brown, ML&SA Executive Director
Starry stonewort (Scientific Name: Nitellopsis obtusa), a member of the Characeae family, and considered a beneficial, though increasingly rare “connoisseur of clean water” within its native range of northern Europe and Asia, was first observed as an invasive species within the North American waters of the St. Lawrence Seaway in 1978, and was later detected in the St. Clair-Detroit River system by the summer of 1983. Discovered in Michigan inland lakes in February of 2006, successful colonization of over one hundred twenty five of the state’s inland lakes had been confirmed by the Michigan Department of Environmental Quality by the spring of 2012. Due to the repeatedly observed ability of invasive starry stonewort to degrade ecologically sensitive areas of shallow water habitat within colonized inland lakes, federal and state government agencies, including the United States Aquatic Nuisance Species Task Force and the Michigan Department of Environmental Quality, have classified starry stonewort as a highly invasive aquatic species. Michigan limnologists Pullman and Crawford (2010) have suggested that rapidly proliferating starry stonewort “may be one of greatest challenges ever faced by management professionals and lake user groups in Michigan.”
Starry stonewort frequently produces dense monotypic meadows that have been commonly observed in Michigan inland lakes extending from near shore areas in depths of less than one meter to the outer most edges of the littoral zone in depths of up to nine meters, completely engulfing the most sensitive and productive of areas within colonized inland lakes. Aquatic meadows of invasive starry stonewort form dense benthic barriers of up to two meters thick that effectively prevent the growth of an important array of native submerged aquatic plants that rely upon access to bottom sediments for vertical stability and for the uptake of nutrients. In colonized inland lakes, it is not uncommon to observe littoral areas that once supported diverse plant communities now entirely dominated by vast starry stonewort meadows and completely devoid of native submerged aquatic plants. Dense monotypic aquatic meadows possess the ability to significantly alter and/or destroy submerged native macrophyte communities. Native submerged macrophytes play a vital role in inland lake ecosystems by reinforcing and exerting influence on several vital physical, biological and chemical mechanisms that contribute to sediment stability, water transparency, moderate biological productivity levels and the promotion and sustainability of plant and animal biodiversity. Severe degradation and/or loss of native submerged macrophyte communities represent a significant threat to the immense ecological, recreational and economic value of Michigan’s inland lakes.
The evidence that starry stonewort has now successfully colonized several hundred Michigan inland lakes continues to mount. It is extremely important that lakefront property owners, recreational boaters, the fishing community and inland lake users in general learn to identify starry stonewort. Early detection and management of the rapidly growing species is critical to sparing your inland lake or favorite fishing spot from the ecological ravages of this unprecedented biological invasion.
To learn more about invasive starry stonewort and its impact on Michigan’s inland lakes, please plan on attending the 2014 Michigan Inland Lakes Convention which will be held on May 1st, 2nd and 3rd at the Boyne Mountain Resort in Boyne Falls, Michigan. To find out more about the first ever lakes convention, visit http://michiganlakes.msue.msu.edu/convention .