Invasive zebra mussels found in lower Susquehanna River

ANNAPOLIS, Md. — The Maryland Department of Natural Resources (DNR) recently confirmed the presence of zebra mussels in the lower Susquehanna River. The latest zebra mussels found in Maryland were recovered from a boat docked in Harford County. Biologists are calling for vigilance and assistance from boaters and anglers to prevent spread of harmful zebra mussels.

"Maryland's freshwater reservoirs have a lot to lose if zebra mussels get in," said Dr. Ron Klauda, a biologist with the Maryland Department of Natural Resources. "By taking a few simple precautionary steps now, boater and anglers can help prevent the devastating economic impact and ecological havoc caused by this invasive species."

The zebra mussel, a small freshwater mollusk from the Caspian Sea, has already infested much of the Great Lakes region, causing economic and ecological damage. Free-swimming zebra mussel larvae will stick to any hard surface and once attached will begin to grow. As the mussels grow, they physically clog water systems, coat boat bottoms and any structures in water. Zebra mussels have encrusted boats, ruined power plant intakes and changed the way municipal water systems must operate.

Ecologically, zebra mussels are killing native mussels, including endangered species. Their presence been connected with widespread ecological impacts from increasing toxic microorganisms to declining duck populations.

Since inadvertent introduction into the Great Lakes in the mid-1980s, the zebra mussel has spread rapidly into freshwater habitats from Louisiana to New Hampshire. While the species' free-swimming larvae move rapidly with natural currents, the main mechanism for its transport up rivers and to inland lakes is hitchhiking with people.

"Recreational boaters can unknowingly carry zebra mussels around in their bilge, minnow buckets or aquatic vegetation on their trailer." explained Klauda. "In Minnesota and a number of other states, fishermen and boaters have been very effective in halting the spread of this serious pest by a little preventative maintenance. We hope that Maryland boaters will help us by washing down hulls, cleaning bilges, removing aquatic vegetation from props and trailers, and limiting movement from place to place, particularly from the Susquehanna River to other waterbodies."

Boaters and anglers who use the Susquehanna, the only water body in Maryland where zebra mussels have been found, should be particularly careful to avoid spreading these invasive species to other state waters.

The DNR has teamed up with the Chesapeake Bay Trust to post signs at all Maryland boat ramps to inform boaters about the problem and how they can avoid being carriers. For the past few years, owners of recreational craft of trailer-able size received brochures from the DNR by mail informing them how to prevent zebra mussels' spread.

"The rate of spread of this species is nothing short of astounding," said Klauda. "We've been watching for it and trying to prevent its arrival, but here it is. Time will tell if this species will become established in the Susquehanna, but its record elsewhere is pretty grim."

The stakes are high for uninfected areas. The U.S. Army Corps of Engineers calculated economic losses between 1993 and 1999 at over $5 billion, even without accounting for ecological damage.

For more information, visit the Maryland Department of Natural Resources's Web site, www.dnr.state.md.us.