The Zebra mussel
(Dreissena polymorpha)
is a mollusk native to the Caspian and Black Seas. The striped mussels have spread to the United Kingdom, Western Europe, Canada and the USA. In the United States, zebra mussels are reported in the Great Lakes, 15 states, and many major river systems in the Eastern U.S.
Zebra mussels are tolerant of a wide range of water quality conditions, which is one reason for their successful establishment in fragile inland ecosystems. Zebra mussels can live out of water for several days, are prolific reproducers, and are remarkable water filterers. Zebra mussels are able to filter much of the phytoplankton (and small zooplankton) in the 15-40 micrometer size range, making zebra mussels a fierce competitor in an ecosystem. Zebra mussels will eventually outcompete native populations of filter feeders in infested lakes and rivers.
Unionid populations (native North American bivalves) are particularly at risk from zebra mussel invasions. One of the greatest problems with zebra mussels is an effect known as biofouling, which is the build-up of zebra mussels on any surface, including Unionid shells, boat hulls, and water intake pipes. In addition, Studies have shown that zebra mussels can accumulate organic pollutants in their tissues in concentrations 300,000 times greater than in the environment. When other animals eat zebra mussels, the result is elevated contaminant concentrations in upper levels of the food chain (waterfowl and fish). Bioaccumulation of contaminants can lead to reproductive problems in the consuming animals and increased risk of human exposure to the contaminants through the consumption of affected waterfowl and fish.
