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Invasion of the mollusks; Quagga and zebra mussels pose a threat to California

Posted by: Aqua Blog Maven on June 4, 2008 at 5:56 am

Quagga mussels cover a boat\'s propeller; photo by Fresno BeeFrom the Fresno Bee:

Central California lakes and waterways are being threatened by tiny mollusk invaders that pose as hitchhikers. Because quagga and zebra mussels are spread primarily through human-related activities, the Department of Fish and Game is asking for cooperation from boaters to prevent these destructive species from gaining a foothold in the San Joaquin Valley.

Many other areas of the state have been on high alert since last fall, when quagga mussels were discovered in numerous places along the Colorado River drainage, including Lake Mead, Lake Havasu and several San Diego-area reservoirs. Closer to home, zebra mussels were found inhabiting San Justo Reservoir outside Hollister in January. Although these close cousins, which belong to the same family of shellfish, have yet to turn up in the Valley, their history suggests it’s only a matter of time.

“Right now there’s not really anything keeping people from coming up here and spreading these mussels,” said Mark Watson, the quagga/zebra mussel biologist for DFG Region 4, which is headquartered in Fresno. “People need to be educated.”

Once established, fast-reproducing quagga and zebra mussels can destroy a lake’s ecology by overwhelming vital elements of the food chain. They also can clog waterway infrastructure and damage boats.

Quagga and zebra mussels are typically about the size of a fingernail but can grow up to 2 inches in diameter. After attaching to hard surfaces, including metal, glass, plastic and wood, they feed themselves by consuming microscopic plants and animals from the water. Each adult mussel can filter up to one liter of water per day.

“They filter out all the food, and the native fish don’t have anything left to eat,” Watson said. “It basically changes the whole ecosystem.”

Read more from the Fresno Bee by clicking here.

June 4, 2008 · Filed Under Invasive Species

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