Quagga mussels threaten western U.S. waters, researcher reports

Tag : oxygen pipe
The threat was outlined by Chuck O'Neill, a senior extensionassociate with Cornell and New York Sea Grant, in testimony beforethe U.S. House of Representatives Committee on Natural ResourcesSubcommittee on Water and Power, June 24. He discussed the economicand infrastructure impacts of both zebra (Dreissena polymopha) andquagga mussels (Dreissena bugensis).

First discovered in Lake St. Clair (between Canada and the UnitedStates) in 1988, zebra mussels spread to the Great Lakes in 1989and were found throughout the East and as far west as theMississippi by the early 2000s.

Quagga mussels showed up in the Great Lakes in the early 1990s andfollowed a similar path. In the East, quagga mussels are colonizingdeeper water and are out-competing zebra mussels, O'Neill told theHouse committee. Last year, quaggas were discovered for the firsttime in the West in Nevada's Lake Mead and have since been founddown the Colorado River in Lake Mojave, Lake Havasu and in variouslocations in California.

"[The spread west] is not a surprise," said O'Neill. "It'ssomething that's been expected to happen."

Both quagga and zebra mussels originated in Eurasia in the Caspian,Ural and Baltic seas and spread to the United States in ballastwater from freighters.

Zebra mussels filter food as small as 15 microns (the size of amold spore); quagga mussels can feed on even smaller bacteria andout-compete their relatives. In both species, mature femalesproduce up to one million eggs at a time that turn intofree-swimming larvae called veligers. Two to five weeks afterhatching, veligers become too heavy to float and search for hardsurfaces to attach themselves. Water-intake pipes and similarstructures offer ideal habitat for their colonization because thecontinuous flow of water provides steady food and oxygen andcarries away waste; the structures protect the veligers againstpredation, silt and waves.