Destructive clams invade Adirondack lake

September 04, 2010|Associated Press

BOLTON LANDING, N.Y. — A thumbnail-sized clam blamed for clouding the azure bays of Lake Tahoe high in the Sierra Nevada has turned up in a mountain-ringed Adirondack lake renowned for its spring-fed waters.

The invasive Asian clam, Corbicula fluminea, is known as the “golden clam’’ in the aquarium trade and the “good luck clam’’ in its native Southeast Asia. But in Lake George, scientists call it an unwelcome invader that could cause ecological and economic harm.

An intensive search launched after a few clams were found at a beach last month turned up no additional infestations, suggesting the invasion was discovered before it had a chance to spread across the 32-mile-long lake, a popular vacation spot.

“The next step is to determine their age and concentration by taking sediment core samples,’’ said Sandra Nierzwicki-Bauer, director of Rensselaer Polytechnic Institute’s Darrin Fresh Water Institute. “Then we’ll decide what to do about them.’’

Since scattered numbers of Asian clams were discovered in Lake Tahoe in 2002, the population there has exploded, a consequence of the mollusk’s ability to self-fertilize and release up to 2,000 juveniles per day. Their waste has helped trigger algae blooms that turned the cobalt-blue water bright green.

Asian clams can also clog water intake pipes and other structures, and their sharp shells can befoul swimming beaches. The fast-growing clams, which mature in months, also compete for food with slow-growing native freshwater mussels, which can live 60 years.

As part of a $1.4 million clam-eradication effort at Lake Tahoe, scuba-diving scientists unrolled long plastic mats on the bottom of coves this summer to smother clam populations, which can reach concentrations of 5,000 per square yard.

“A lot of comparisons are made between Lake Tahoe and Lake George,’’ Nierzwicki-Bauer said. “Both are known for gorgeous scenery, excellent water quality, and high biodiversity. Both are very important economically as well as ecologically.’’