Natural invaders pose big threat

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Along with domestic terrorists, the nation has a whole new set of invaders to worry about.

Beware the serrated swimming crab, the dreaded African clawed frog and those lacy-crust bryozoans. And for heaven's sake, watch out for Wright's nut-rush and roundleaf toothcup.

They are among scores of feisty, adaptive creatures and plants that have become such nuisances that the Department of the Interior has created a new alert system to track them from sea to shining sea.

The official "Nonindigenous Aquatic Species Alert System" is up and running, tracing the known whereabouts of snakehead fish -- also known as the infamous "Frankenfish" -- in Maryland, Virginia and Wisconsin; plus spiny water fleas in New York, alligators in Pennsylvania and opossum shrimp in Montana.

Operated by the U.S. Geological Survey (USGS), the system uses computer databases and a population of devoted observers who spy on dozens of alien species that arrive, thrive and essentially take over.

"Early detection and response are critical in reducing the damage caused when nonindigenous species become invasive," said Pam Fuller, a USGS biologist who developed the one-of-a-kind system that links professional wildlife managers, scientists, hobbyists and even concerned fishermen by e-mail.

"Waterways, lakes and ocean are particularly vulnerable because underwater surveillance is certainly more difficult than monitoring land," she said.

But survey they do, charting exotic species often innocently introduced by well-meaning or simply clueless humans who cannot imagine potential harm in, say, releasing the contents of their fishbowl into a backyard stream.

But a few little critters can multiply into a burgeoning population that decimates the food supply and bullies native species -- with expensive results. Collectively, invasive aquatic species cause $100 billion in damages to local ecosystems, game fish populations, dams, docks, power and water-purification plants, and other industrial sites, according to the U.S. Fish and Wildlife Service (FWS)

Cities on the shores of the Great Lakes, for example, spend $30 million yearly to control zebra mussels alone, which arrived in the region two decades ago in the ballast water of foreign ships, expelled unceremoniously in American waters. The area also is troubled by the aggressive rusty crawfish, an Ohio native that hitchhiked in, officials think, fishermen's bait buckets.

The Great Lakes region tracks 137 other invasive species, the Chesapeake Bay watershed must contend with more than 120, and the Hudson River, 154. Nationwide, 4,500 nuisance flora and fauna flourish -- from Chinese mitten crabs to purple loosestrife. About 15 percent of these life forms are known to cause "serious damage," according to the FWS.

Such matters vexed federal officials enough to put aside departmental differences and, in 1999, form the National Invasive Species Council, which now includes members from a dozen agencies.

To combat waterborne troublemakers, FWS recently organized the Aquatic Nuisance Species Task Force in conjunction with the National Oceanic and Atmospheric Administration to coordinate governmental efforts.

The group already has inaugurated "Stop Aquatic Hitchhikers," a public-awareness program for those who don't realize that alien species may lurk in the mud on their boots, equipment -- or even on their pets.

Most of the species "tag along with people who are some of our best conservation partners," noted FWS Director Steve Williams. "They are the people who are out there for recreation -- fishing, boating, diving, hunting."

Meanwhile, the Nonindigenous Aquatic Species Alert System is going full tilt with reports of errant snakeheads and rogue Cuban tree frogs.

The alert system can be found online at nas.er.usgs.gov.