Zebra mussels have become a household name because of the significant environmental and economic damage they have caused across the Great Lakes region. Now, recent scientific findings show that another aquatic invasive species may have entered southern Lake Michigan.
On July 8, water samples collected from the Calumet Harbor by researchers from The Nature Conservancy, University of Notre Dame, and Central Michigan University tested positive for Eurasian ruffe DNA. The fact that these samples were found at the mouth of the Chicago Area Waterway System means that if ruffe are present, they not only pose enormous risks to the southern Great Lakes, but to the Mississippi River basin as well.
The Waterway System consists of more than 100 miles of canals and waterways, including the Chicago River and the Calumet River. The system moves storm water and sewage away from Chicago’s water supply and creates an artificial connection between the Mississippi River and Lake Michigan. This artificial connection is a high-risk area for the movement of aquatic invasive species in both directions. Zebra mussels and round goby easily moved through the Waterway System to invade the Mississippi basin, and more are on the way. Another 29 aquatic invasive species in the Great Lakes could swim or float through the Waterway System and enter the Mississippi basin — one of which is Eurasian ruffe.
Eurasian ruffe were introduced into Lake Superior from ships’ ballast water in the mid-80s, and have slowly spread into northern Lake Michigan and Lake Huron. If ruffe establish in the southern lakes, they may compete with native species like walleye and perch. Additionally, this fish potentially poses a grave threat to the Mississippi River basin, as its tributaries have nearly twice the number of native fish as the Great Lakes and are considered the world center of freshwater mussel diversity.
The introduction of Eurasian ruffe to the Mississippi basin could spell disaster not only for native fish and wildlife populations, but to local economies as well. A 2012 report by Anderson Economic Group revealed that it costs hundreds of millions of dollars to control aquatic invasive species annually in the Great Lakes alone. Currently there are 10 aquatic invasive species (including Asian carp) in the Mississippi River that could use the Waterway System to invade the Great Lakes. Industries like sport and commercial fishing, water treatment, power generation and tourism are all threatened by aquatic invasive species.
There are preventative measures in place, but we need to do more. The electric barriers currently used to keep Asian Carp from entering Lake Michigan only work one way; they won’t stop Lake Michigan species from moving into the Mississippi River. Furthermore, these barriers will not prevent the passage of invertebrates or aquatic plants that can be just as harmful as invasive fish.
While we need additional testing to confirm the presence of Eurasian ruffe in southern Lake Michigan, we cannot afford to wait to take action. This is a shared problem that requires a shared solution.
About the author: Helen Taylor is state director for The Nature Conservancy in Michigan and a Great Lakes Commissioner. She has spent more than 25 years working on Great Lakes protection and conservation. She serves on the recently formed Michigan Department of Environmental Quality’s Water Use Advisory Council.
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