Outdoors

Divers to assess Asian clam invasion in Pend Oreille

In this July 9, 2010, photo UC Davis research scientist Marion Wittmann holds a handful of Asian clams removed from the bottom of Lake Tahoe in California. Scuba-diving scientists unrolled long rubber mats across the bottom of that lake's coves in an attempt to quell the clam invasion. (AP/The Sacramento Bee, Randy Pench)
In this July 9, 2010, photo UC Davis research scientist Marion Wittmann holds a handful of Asian clams removed from the bottom of Lake Tahoe in California. Scuba-diving scientists unrolled long rubber mats across the bottom of that lake's coves in an attempt to quell the clam invasion. (AP/The Sacramento Bee, Randy Pench)

Divers will descend Monday into Lake Pend Oreille to take a closer look at a recently discovered invasion of Asian clams.

The aggressive, non-native species spreads quickly in lakes, rivers and canals, overtaking native invertebrates, altering habitats and spoiling recreation.

The Asian clam was found along 150 feet of shoreline in the Ellisport Bay area of Hope, Idaho, during a recent drawdown on Lake Pend Oreille. No other areas of the sprawling lake have shown signs of the clam.

The Bonner County Sheriff’s Office dive team, Boundary County dive team and Idaho Department of Agriculture are teaming up to determine the distribution area of the Asian clam. A joint dive in Ellisport Bay is scheduled for 10:30 a.m. Monday, according to Bonner County Sheriff’s Deputy Phil Stella, the county’s dive team coordinator.

The Asian clam, Corbicula fluminea, has spread rapidly throughout North America since first detected in the Western U.S. in 1938.

They can grow as large as a silver dollar, but those found in Lake Pend Oreille are about the size of a nickel, Stella said.

The clams were found in 2002 in Lake Tahoe, the Sierra Nevada lake that straddles the California-Nevada border, after they were likely inadvertently brought in by boaters.

In 2010, scuba-diving scientists unrolled long rubber mats across the bottom of Lake Tahoe coves in an attempt to quell the clam invasion, fearing the species could cloud the world-renowned cobalt waters.

The half-acre mats are designed to smother the clams, which can reach populations of 5,000 per square yard.

Geoffrey Schladow, director of the Tahoe Environmental Research Center run by the University of California, Davis, said the clams promote so much algae growth that they can turn some coves from blue to green.

“They suck in the water and they filter out the algae. Their excretions are highly concentrated packages of nutrients,” he said.


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Rich Landers

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