Zebra Mussels Are Spreading Rapidly, USGS Reports

Biologists have tracked the zebra mussel since 1988 when it wasfirst detected in Lake St. Clair, a small lake in the Great Lakes chain.  Anew 1997 distribution map shows zebra mussels have spread to 19 states inless than 10 years.  The USGS reports new locations in Lake Champlain onthe New York-Vermont border and along the Ohio and Monongahela Rivers.

Older populations in the Great Lakes and the Mississippi River continue tospread.  And, biologists believe the population in the Tennessee River hasyet to reach its peak.

Native to Eastern Europe and Asia, zebra mussels have few naturalenemies in the U.S. and their rapid reproduction has caused widespreadeconomic and environmental damage. 

Concentrating at underwater sites wherewater flows rapidly, zebra mussels have clogged intake pipes of communitywater systems and power stations and have fouled the engine cooling systemsof recreational boats, the USGS scientists said.  In May, it was reportedthat a paper company had to remove 400 cubic yards of zebra mussels fromits intake in Lake Michigan at a cost of $1.4 million.

The USGS tracks and maps the spread of zebra mussels at its FloridaCaribbean Science Center in Gainesville.  Updated information is madeavailable to federal, state and local officials, universities and privateindustries.

  "The zebra mussel invasion is of grave concern. Our scientistsplay an important role in helping develop a blueprint for those chargedwith fighting its spread," said USGS Chief Biologist Denny Fenn.

"The maps developed at Gainesville help focus our research programsby identifying vulnerable sites and conditions,"  Fenn said.  Other USGSbiological research centers are developing and testing a wide range ofstrategies to control the spread of the zebra mussel or minimize itsimpact, he said.

"Zebra mussels are extraordinarily persistent," said Fenn. "Theyare small, can attach themselves to a variety of surfaces and can surviveseveral days out of water.  In fact, live zebra mussels have been reportedin California and Virginia where they were found attached to boats beingtrailered from the Great Lakes."

Scientists fear that recreational boaters may unknowingly spreadthe zebra mussel from infested rivers and lakes to previously unaffectedwaterways.  "That's why we are being so vigilant in our mapping andmonitoring efforts," said Fenn.

It is believed that zebra mussels entered the Great Lakes in theballast water of commercial ships from abroad.  As the ballast tanks wereflushed, the mussels were inadvertently introduced to an environment wherethey could thrive without natural enemies to control their numbers. Theirrapid distribution throughout the Great Lakes and major U.S. river systemsis attributed to their ability to attach to boats and barges using thesewaterways.

Zebra mussels were named for the striped pattern of their shells.On average, zebra mussels are less than an inch long, yet each filtersabout a quart of water per day to feed on algae.  Zebra mussels attachthemselves to hard or rocky surfaces, and will even attach to vegetation.

Layers of zebra mussels several inches thick coat large areas of substratein Lakes Erie and Ontario, USGS biologists reported, elevating concernsabout the survival of remaining native mussels.

The invaders attach themselves to the native mussel species,interfering with their feeding, growth, movement, reproduction andrespiration.  This is of particular concern since North America has thegreatest variety of native mussel species in the world, many of which areendangered, said Chief Biologist Fenn.

The zebra mussels' impact on the economy is felt at hydroelectricand nuclear power plants, industrial facilities, and public water supplieswhere colonies can be dense enough to cut off water flow and affectcondensers, firefighting equipment, air conditioning, and cooling systems.

The U.S. Army Corps of Engineers reported new sightings of zebramussels this year on the Ohio River at Dashields Lock and Dam west ofPittsburgh and at Lock 3 on the Monongahela River near Elizabeth, PA.  

  In states adjacent to the Great Lakes, zebra mussels continued to expand theirrange into many small lakes.  Zebra mussels were reported from 90 lakes inthe eight states bordering the Great Lakes, up from 79 a year ago.Biologists are extremely concerned about a dramatic increase inrange and reproduction of zebra mussels in Lake Champlain.

   Zebra mussels can be found throughout the lake, even in the northeastern arm where theyhad not been previously reported, USGS scientists said.Information on zebra mussel distribution is used by the U.S.

Department of the Interior, National Oceanographic and AtmosphericAdministration (NOAA), the U.S. Army Corps of Engineers, Tennessee ValleyAuthority, state agencies, universities, and numerous U.S. and Canadianprivate industries.

According to Amy Benson, the USGS zebra mussel database manager,"Distribution information is available to anyone who can access theInternet."  To see the zebra mussel maps and to track their spread from1988 to 1997, visit the USGS web site athttp://nas.nfrcg.gov/zebra.mussel/

Other USGS research centers conducting zebra mussel researchinclude the Environmental Management Technical Center (Onalaska, Wisc.),the Upper Mississippi Science Center (LaCrosse, Wisc.), and the Great LakesScience Center (Ann Arbor, Mich.).

As the Nation's largest natural resources science and civilianmapping agency, the USGS works in cooperation with nearly 2,000organizations across the country to provide the reliable, impartialinformation needed by resource managers and planners. This information isgathered by USGS scientists in every state to minimize the loss of life andproperty from natural disasters; to maintain water, biological, energy andmineral resources; to enhance and protect the quality of life; and tocontribute to sound economic and physical developme