NY scientists launch assault on invasive clams

By Mary Esch

Associated Press

Published: Tuesday, April 26 2011 4:46 p.m. MDT

Workers launch a boat with materials to cover the floor of Lake George in Lake George, N.Y., on Tuesday, April 26, 2011. Scientists and a corps of volunteers are launching an all-out assault on the tiny, invasive Asian clam that has clouded the azure bays of Lake Tahoe, in hopes of preventing it from befouling the crystal-clear waters of this beloved Adirondack lake.

Mike Groll, Associated Press

LAKE GEORGE, N.Y. — Scientists have launched an all-out assault on a tiny invasive clam that has clouded the cobalt blue bays of Lake Tahoe and now threatens to befoul the crystal-clear waters of a beloved Adirondack lake.

This week, divers began laying 900 50-foot-long plastic mats on the sandy bottom of Lake George to smother the hundreds of thousands of Asian clams discovered last August in a six-acre area of the lake, a popular tourist destination and upscale second-home location 55 miles north of Albany.

In a two-acre test last fall, all of the invasive clams were killed in 45 days by the mats, said Sandra Nierzwicki-Bauer, director of the Rensselaer Polytechnic Institute's Darrin Fresh Water Institute on Lake George. Scientists say the outbreak likely started when someone dumped a few dozen clams from a bait bucket or aquarium three years ago.

Peter Bauer, executive director of the Fund for Lake George, said Asian clams have spread to bodies of water across the country and all efforts to control them have been unsuccessful. In Lake Tahoe in the Sierra Nevada, more than a million dollars has been spent on efforts to curb the clams, but the mollusks have become so widespread that they're impossible to eradicate.

"Lake George is in a unique position in that we detected the clams early and we believe that this is the only site they are in," Bauer said. Lake George also has strong oversight from non-profit groups, scientific organizations, regulatory agencies and state and local governments, who quickly mobilized a $400,000 eradication effort, he said.

"We hope we have a chance to do here what, so far, has not been successful in other places," Bauer said. "Lake Tahoe is a cautionary tale for us."

Bauer noted that scientists in Lake Tahoe were unable to mount an immediate eradication effort because of regulatory, financial and other reasons. Today, Asian clams have spread to over 220 acres there, he said.

The invasive clams were first documented in the U.S. on the West Coast in 1938 and have spread to more than 40 states. In New York, they have been found in Owasco and Cayuga lakes and the Susquehanna River.

The Asian clam, Corbicula fluminea, is known as the "golden clam" in the aquarium trade and the "good luck clam" in its native southeast Asia. The golden, thumbnail-size clams multiply rapidly because of their ability to self-fertilize and release up to 2,000 juveniles a day during breeding seasons in May and August.

The mollusk's excretions feed algal blooms and the sharp shells from dead clams wash up on beaches in large numbers. Their detrimental effect on the ecology is of major concern in Lake George, where heavy development pressure already threatens water quality.

Lake George has launched successful campaigns against other notorious invasive species, including Eurasian watermilfoil, which has been held at bay by benthic barriers like those being used to smother the clams, and zebra mussels, which were wiped out by volunteer divers who hand-picked 25,000 of them from rocks.

"We hope to achieve the same success with Asian clams," Nierzwicki-Bauer said.

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