Zebra mussels are a fingernail-sized mollusk native to the Black, Caspian, and Azov Seas of Eastern Europe. Their name comes from the dark, zigzagged stripes on each shell. By the late 18th and early 19th centuries, the construction of extensive canal systems enabled the spread of zebra mussels to almost all major drainages of Europe.
The first report of zebra mussels in the United States was in 1988 when mussels were found in Lake St. Clair, located between Lake Huron and Lake Erie. These mussels were transported from Europe in the ballast tanks of large shipping vessels. By 1990, zebra mussels had spread into all five Great Lakes. Over the next two years, they spread to the Illinois, Hudson, Arkansas, Cumberland, Hudson, Mississippi, Ohio, and Tennessee rivers.
Zebra mussels can easily spread from one body of water to another through human-related activities. Their microscopic larvae can spread invisibly through common recreational activities like fishing, boating, and scuba diving. Adult zebra mussels can also spread by “hitchhiking” on other organisms such as crayfish or by attaching to boat hulls trailered from one body of water to another.
Today, zebra mussels are established in more than 600 lakes and reservoirs in at least 33 states. The Columbia River Basin is one of the few major U.S. watersheds that remains uninfested by zebra mussels presenting tremendous opportunities to prevent significant damage if action is taken immediately.
On March 1, 2021, U.S. Geological Survey (USGS) scientists were alerted that zebra mussels were found attached and inside moss balls sold as aquarium plants across the country. If you have moss balls in your aquarium you have an important role to play in protecting our ecosystem. Destroy! Don’t Dump! to keep our waterways safe.
Zebra mussels are one of the most devastating invasive species in North America. When they become established in an environment, they alter food webs and change water chemistry, harming native fish plants and other aquatic life. They clog pipelines used for water filtration, render beaches unusable, and damage boats. These filter feeders outcompete other native species in infested rivers and lakes. The waste they produce accumulates and degrades the environment, using up oxygen, making the water acidic, and producing toxic byproducts.
Threats to Native Mussels
Zebra mussels can reduce native mussel populations by attaching to them - hindering their movement, feeding, and respiration. Researchers are observing some of these effects as they study interactions between zebra mussels and native mussels in the Great Lakes. Unfortunately, research shows zebra mussels prefer to attach to the shells of live mussels rather than to dead ones or to stones. Some native mussels have been found thousands of zebra mussels attached to them.
Adult zebra mussels are incredibly effective filter feeders. They remove so much microscopic plant and animal biomass from the water that they disrupt the entire base of the food web, causing a disruption of the ecological balance of a body of water.
Preventing the spread of zebra mussels and other aquatic invasive species starts with you. A cooperative effort by all of us is necessary to protect our aquatic resources and recreational opportunities.
Detailed information on the ecological risks of zebra mussels can be found in our Ecological Risk Screening Summary (ERSS).
Reporting is essential to detect new invasions and respond quickly to keep species from becoming established and spreading. If you think you have found a new invasive organism, contact your state fish and wildlife agency to see if they are aware of the species.
Report zebra mussels, as well as any new or unusual species, sightings to the USGS Nonindigenous Aquatic Species database.