Feds plan battle against aliens.

Creeping, crawling, tendril-snaking alien species have been invading the United States. Zebra mussels, transplants from Eurasia, thrive so well in the Great Lakes that they shut down power plants by clogging their water-intake valves. In New York and Chicago, Asian long-horned beetles topple shade trees. European leafy spurge is smothering western U.S. farm and grazing land, and Australian pines and Brazilian pepper trees are slurping up Florida's fresh water.

On Feb. 3, President Bill Clinton signed an executive order to coordinate the federal fight against such exotic invaders. The action establishes no new regulations or policies but creates an Invasive Species Council led by the secretaries of commerce, agriculture, and the interior. The council has 18 months to formulate a comprehensive plan.

It won't be easy to control invasive species or stem their influx. Introduced species with short reproductive cycles, voracious appetites, or no local enemies can quickly dominate an eco-system. The Nature Conservancy estimates that, next to habitat loss, invasive species pose the direst threat to native populations. Damage and losses due to these aliens add up to about $123 billion a year (SN: 2/6/99, p. 91).

Many alien species hitchhike in cargo and stow away in ships' ballast water. "Thousands of species are in motion every day in ballast water," says marine biologist James T. Carlton of Williams College's maritime program in Mystic, Conn. Currently, ships are asked to voluntarily exchange their ballast water far out to sea--a stop-gap measure, he says. Research into filtration, ultraviolet radiation, and thermal treatments may reveal a better method to "bake, remove, fry, or otherwise render ballast water as abiotic as possible," says Carlton.

International trade treaties, such as the North American Free Trade Agreement, increase the volume of shipments and so add to the risk of introducing pests. It's important that the Invasive Species Council address trade issues as it coordinates the dozens of federal agencies with a stake in the battle against exotic species, says biologist Daniel Simberloff of the University of Tennessee in Knoxville.

"We need an early-warning system to pick up species when they first become invasive," says biologist E.O. Wilson of Harvard University. invasive," says biologist E.O. Wilson of Harvard University.

Even brigades of biologists can't catch every alien invasion as it happens. "We want to alert fishermen, boaters, highway workers, people who have developed a familiarity with a community of organisms," says Bob Peoples of the U.S. Fish and Wildlife Service in Arlington, Va. "When something new shows up, we want them to talk to their state fish and game department."