Zebra Mussel Distribution
Source: U.S. Geological Survey Noindigenous Aquatic Species Program
Map Description:
Zebra mussels (Dreissena polymorpha), a nonnative mollusk, were first discovered in North America in 1988. The first account of an established population came from Canadian waters of Lake St. Clair, a small water body connecting Lake Huron and Lake Erie. By 1990, zebra mussels have been found in all the Great Lakes. The following year, zebra mussels escaped the Great Lakes basin and found their way into the Illinois and Hudson rivers. The Illinois River was the key to their introduction into the Mississippi River drainage, which covers over 1.2 million square miles. By 1992, the following rivers had established populations of zebra mussels: Arkansas, Cumberland, Hudson, Illinois, Mississippi, Ohio, and Tennessee. By 1994, the following states had reported records of zebra mussels within their borders or in water bodies adjacent to their borders: Alabama, Arkansas, Illinois, Indiana, Iowa, Kentucky, Louisiana, Michigan, Minnesota, Mississippi, Missouri, New York, Ohio, Oklahoma, Pennsylvania, Tennessee, Vermont, West Virginia, and Wisconsin.

It is highly likely that the presence of zebra mussels in the Great Lakes was a result of ballast water introduction. Its rapid dispersal throughout the Great Lakes and major river systems was due to its ability to attach to boats navigating these lakes and rivers. Its rapid range expansion into connected waterways was probably due to barge traffic where it is theorized that attached mussels were scraped or fell off during routine navigation. Zebra mussels are notorious for their biofouling capabilities by colonizing water supply pipes of hydroelectric and nuclear power plants, public water supply plants, and industrial facilities. They colonize pipes constricting flow, therefore reducing the intake in heat exchangers, condensers, fire fighting equipment, and air conditioning and cooling systems.

Most of the biological impacts of zebra mussels in North America are not yet known. However, information from Europe tells us that zebra mussels have the potential to severely impact unionids (native mussels) by interfering with their feeding, growth, locomotion, respiration, and reproduction. Researchers are observing some of these effects as they study interactions between zebra mussels and native unionids in the Great Lakes. According to early studies, zebra mussels are having a minimal effect on fish populations in the Great Lakes. It may be too soon to determine some of the effects, which may take more time to develop.

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This map only provides general locations.

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