Scientists aim to prevent spread of zebra mussels from reservoir

May 08, 2002|By Heather Dewar | Heather Dewar,SUN STAFF

Zebra mussels, one of the most notorious aquatic pests in the nation, have been discovered in a small New York reservoir that feeds into the Susquehanna River, and top scientists are meeting today to outline a plan to prevent them from spreading in the Chesapeake Bay watershed.

The tiny mollusks, which are native to Europe and have no natural enemies here, have spread rapidly since they were brought to the Great Lakes in a ship's ballast water in the early 1980s. They grow so quickly that they can clog intake pipes at power plants, factories and municipal water plants, forcing them to shut down.

A breeding population of zebra mussels has appeared in a reservoir in Madison County, N.Y., near the headwaters of the Susquehanna, said biologist Thomas Horvath of the State University of New York at Oneonta. The invasive creatures have apparently been in Eaton Brooke Reservoir since 1999, Horvath said.

A creek connects the reservoir to a tributary of the Susquehanna, Horvath told a conference of Chesapeake Bay scientists in Baltimore yesterday.

"That gives zebra mussels now the potential to colonize the entire freshwater system of the Susquehanna River," Horvath told the gathering.

One Maryland expert said the zebra mussels are more than 400 miles from the Chesapeake, and probably cannot tolerate the saltier waters of the open bay.

"It is certainly something we should be concerned about, because we don't want to risk the efforts we've made in restoring the Chesapeake Bay," said Frank Dawson of the Maryland Department of Natural Resources. "We're still at a stage where we can control it.

"Unfortunately, our ability to control it may not be as great as we would like," said Dawson, who heads a scientific committee advising the bay restoration program.

The scientists at the two-day Baltimore conference are brainstorming ways to control half a dozen different kinds of non-native plants and animals that have invaded the region and are crowding out native wildlife.

Dawson said the advisory committee learned about the infestation in the upstate New York reservoir last year, and will work with Madison County officials during the summer on a control plan.

"We need to take action right now to confine them to that one reservoir," Horvath said.

The mussel infestations sometimes become so thick that they radically change conditions in rivers and lakes. In the Hudson River, dense beds of mussels filter so much algae that the water is becoming clearer, Horvath said.

However, a dense zebra mussel population in the Susquehanna might harm efforts to restore shad runs and might allow more nutrients to reach the bay, Horvath said. Nutrient pollution is considered the bay's biggest problem, causing a cascade of harmful effects on living things.

In Australia, wildlife managers have used chemicals that kill mollusks to get rid of zebra mussels in small bodies of water, Horvath said. The larvae can also be killed by draining the areas where they live, but it takes several days of drying to kill the adults, he said.

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