Zebra Mussels Threat to Western Waters?

-- Kansas Conference Will Assess Risk

What's round, black and tan striped, less than an inch long and can cost water use facilities over $200,000 annually? The zebra mussel.

The seriousness of potential zebra mussel infestation is so great, in fact, that a consortium of state and federal agencies will hold a three-day conference November 18-20, 1997, in Kansas City, Missouri to weigh the risks zebra mussels might pose to water supplies and biological communities in the West.

"We hope this conference will help focus public attention and help prevent a very serious problem," according to Linda Drees, a conference coordinator and aquatic nuisance specialist with the U.S. Fish and Wildlife Service, one of the six sponsoring agencies. "We don't have zebra mussels in this region, yet," Drees noted, "but almost all the biological requirements for them would be easily met in most of the major river systems and impoundments."

The zebra mussel is a small shellfish native to the Baltic Sea drainage in northern Europe. It is believed that they were first inadvertently introduced into North America through the release of ballast waters from cargo vessels. Ships often take on ballast water in their home ports and later discharge it to help maintain buoyancy and load balance. The zebra mussel was first discovered in Lake St. Clair in 1988. Since that initial discovery, the mussel has spread virtually throughout the Great Lakes Region, inflicting tens of millions of dollars in damages to municipal and industrial water intake systems.

The mollusc feeds by filtering near-microscopic food organisms, called plankton, from the water. They try to locate in favorable current areas that will bring the maximum amount of food past; hence, structures that create or enhance current such as water intakes, piers and bridge pilings are extensively colonized. Concentrations of up to 700,000 per square meter have been observed in the Great Lakes.

Biologists are still evaluating the impacts of zebra mussel invasions in the Great Lakes and adjacent drainage, but the preliminary reports are cause for concern. Field studies have indicated that zebra mussels can cover and displace native freshwater clams and mussels, many species of which are already threatened or endangered and facing grave threats from environmental contaminants. It is also believed that some popular species of gamefish such as bass and walleye may be negatively impacted either by zebra mussel infestation of their spawning sites, or by filtering out many of the small plankton that the fry of these fish require for their early growth.

"We want people to know the threat is real and fortunately, there are some positive steps that can help reduce the chance for infestation," said Drees. Boaters, for example, should be extra sure to thoroughly drain their live wells and carefully check the hull and motor housing on their boats before departing a lake or river -- especially if they've been boating anywhere in the upper Mississippi River or Great Lakes area."

The three-day conference is sponsored by the U.S. Bureau of Reclamation; U.S. Army Corps of Engineers; Kansas City, Missouri Water Services Department; Sea Grant/CSREES-USDA; the Zebra Mussel Training Initiative; and the Service. The conference will be held at the Wyndham Garden Hotel in Kansas City, Missouri, and will feature sessions on zebra mussel biology and risk manage-ment, monitoring, impacts and control methods. Registration fee prior to November 18, 1997 is $50.00; after that date $60.00. Additional conference information is available from Linda Drees, U.S. Fish and Wildlife Service (913-539-3474 ext. 20), or Tracie Green, U.S. Bureau of Reclamation (303-236-6007, ext. 228).

-FWS-

Release #:R97-102

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