Environmental Protection and Fish and Boat Commission officials have confirmed the discovery of a zebra mussel at the Conowingo Hydroelectric Dam in Maryland; the first time the Driessena polymorpha has been found in the lower Susquehanna River.

The mussel, about a half inch in size, was found inside a water intake at the hydroelectric plant while monitoring juvenile shad migration on the river. It had not yet attached itself to the intake structure.

The nine-mile lake behind the Conowingo Dam stretches into Pennsylvania for five miles. No other zebra mussels have been found in the lake at this time.

"Controlling zebra mussels has cost more than $1 billion since they were first discovered in the Great Lakes in 1988," said DEP acting Secretary John Hanger. "It will require constant vigilance by fishermen, boaters and others who use our waterways to keep these invasive creatures out of the Susquehanna River and its tributaries."

Zebra mussels pose serious threats because of their potential to plug industrial and public water supply intakes that draw from infested waters. Zebra mussels also disrupt aquatic food chains by filtering out the microscopic plankton upon which fish and other aquatic organisms rely. One zebra mussel can filter more than a quart of water each day.

Further, the mussels have created new pathways for diseases like Type E (Avian) Botulism in the Great Lakes, causing further damage to the Great Lakes' ecosystem.

"The introduction of invasive species like zebra mussels can have a substantial and lasting impact on the balance of aquatic life in a waterway," said Doug Austen, Fish and Boat Commission's executive director. "The best thing anglers and boaters can do is to disinfect boats, trailers, boots and gear before entering a new body of water."

Adult zebra mussels can be found in other Pennsylvania waters, including Lake Erie, the Ohio River and lower portions of the Allegheny and Monongahela rivers. The mussels have also been reported in Edinboro and Sandy Lakes in northwestern Pennsylvania, as well as upper French Creek in Crawford County and Cowanesque Lake in Tioga County. The mussels have also been introduced into diving quarries throughout the commonwealth.

The zebra mussel is native to the Black and Caspian seas region of Eastern Europe. They were introduced to North American waters when ocean-going ships released infested ballast water into the Great Lakes.

The Pennsylvania Zebra Mussel Monitoring Network, which is sponsored by the Department of Environmental Protection, Pennsylvania Sea Grant and the National Oceanic and Atmospheric Administration's Coastal Zone Management Program, works to help slow the spread of invasive mussels in the Commonwealth's rivers, streams and lakes.

For more information on zebra mussels, visit the Pennsylvania Sea Grant invasive species website.

NewsClip: Invasive Mussel Found At Dam In Susquehanna River

11/29/2008