Pennsylvania's Zebra and Quagga Mussel Monitoring Network
Supported in part by the Pennsylvania Sea Grant program
Dedicated to protecting Pennsylvania's aquatic habitats
HomeNews & EventsMonitoringDistribution MapsResourcesContact Us The Pennsylvania Zebra and Quagga Mussel Monitoring Network is dedicated to protecting Pennsylvania's aquatic habitats from the threat of two harmful aquatic invasive species (AIS), zebra and quagga mussels.


Searching for Zebra Mussels under DockIn the Great Lakes region alone, Ohio Sea Grant estimates that water users spend more than $30 million each year for treatments to control zebra mussels. These mussels clog water intake pipes and disrupt aquatic communities by filtering food that native species rely upon. After storm events, beaches are littered with sharp shells that can injure beach goers walking barefoot.

Zebra mussels probably came to the Great Lakes in the ballast tanks of ships. They were first discovered in Lake St. Clair in 1988, and then found in Lake Erie in the late 1980's. In 1991, quagga mussels were found in Lake Erie. Since then, invasive mussels have spread and become established in several inland lakes and rivers in Pennsylvania. See the complete timeline for zebra mussels and quagga mussels in Pennsylvania at the USGS web site.

Current map of ZM/QM distribution in PA (click to see larger image)

How do zebra mussels and quagga mussels spread to new locations?
In Pennsylvania, it is illegal to possess or transport zebra and quagga mussels. However, in most cases, people spread invasive mussels without knowing it. Both mussels can survive out of water for up to five days, making it easy for them to be carried from lake to lake on recreational boating equipment, fishing gear, and diving equipment. Adult mussels canSearching for Zebra Mussels attach to boat hulls, trailers, motors, vegetation and equipment left in the water using sticky fibers called byssal threads. In their youngest form the microscopic larvae, called veligers, can move to new locations naturally by floating along in a water body for up to 4 weeks.

Why is monitoring important?
In Pennsylvania, only a few of the 12,000 lakes and 84,000 miles of streams are infested with invasive mussels. Monitoring is needed to detect new AIS introductions before they become established and to alert people who use those lakes, rivers and streams to take proper precautions to prevent the spread of invasive mussels. We need people who care about protecting Pennsylvania's waterways to join the monitoring efforts - find out how you can get involved!


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Pennsylvania Department of Environmental Protection
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Normandeau Associates, Inc.
U.S. Army Corps of Engineers
Erie County Department of Health
Exelon Corporation

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Last Updated: November 5, 2012 - Sara Grise
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