‘Not welcome’ mat rolled out for Asian clams

UC DAVIS (US)—Scientists are hoping that an acre of rubber sheeting at the bottom of Lake Tahoe will control a dime-sized clam that is threatening the lake’s ecological balance, including its trademark clarity.

First observed in the lake in 2002, the population of the non-native Asian clam, Corbicula fluminea has reached thousands per square yard, mainly along the California-Nevada state line in the southeast corner of the lake.

The Asian clam is undesirable because it:

  • Displaces native clams, snails and other organisms living on the lake bottom, which are important members of the lake’s native food web.
  • Fosters the growth of bright green algae, which change the look of the water, and smell when they decompose.
  • Could help foster an invasion of quagga mussels, another aggressive non-native species, by creating desirable habitat for them.

The sheeting is expected to kill the clams by depriving them of oxygen and will remain in place all summer.

“The goal of this experiment is to determine whether it is feasible to control clams using impermeable bottom barriers,” explains Geoffrey Schladow, director of the Tahoe Environmental Research Center at University of California at Davis.

“We need to know how to efficiently deploy and remove large areas of rubber sheeting, and when it is all done, we must know whether the clams recolonize the treated areas.”

The ‘dissolved oxygen deprivation’ strategy was devised and tested on small patches of lake bottom last summer by Lake Tahoe experts at UC Davis and the University of Nevada, Reno.

That study and the results of this year’s acre-scale experiment will be used to help Tahoe Basin agencies develop a clam-management strategy.

The estimated $648,000 cost of the experimental treatment will be funded by the U.S. Fish and Wildlife Service, the Nevada Division of State Lands, and the Southern Nevada Public Land Management Act.

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