A Plant for a Plant
The nutria is killing the place Geise loves. He aims to return the favor. “To me,” complains Geise, now the Blackwater’s fire warden, “nutria are no different than somebody taking a bulldozer to the marsh.” Ecologists estimate that more than 6,000 alien plant and animal species like the nutria have invaded the United States, with dozens more arriving each year. A few arrived with the first Europeans 500 years ago, but the increase in global trade and tourism in the jet age has turned the trickle of previous centuries into a torrent. They cross oceans and continents in the shoes and luggage of tourists, in shipping ballast, in packing materials, even in bald tires heading to recapping plants. Most are stowaways; some are brought in deliberately.

Since 1995, the Moapa dace minnow, right, population has been decimated by the marauding blue tilapia, left, a fish native to the Nile River and introduced illegally four years earlier into the Muddy River in Nevada. (Moapa Valley National Wildlife Refuge)

Changing Whole Ecosystems
Aliens are redrawing the global landscape in ways no one imagined. They crowd out native plants and animals, spread disease, damage crops and threaten drinking water supplies. At Yellowstone Lake, alien sport fish introduced by fishermen munch on endangered cutthroat trout. In large parts of San Francisco Bay, aliens account for nine out of 10 species.      Exotic species are a parasite on the U.S. economy, sapping an estimated $138 billion annually according to a Cornell University study. That’s nearly twice the annual state budget of New York, or a third more than Bill Gates’ personal fortune. Aliens have contributed to the decline of 42 percent of the country’s endangered and threatened native species, according to the U.S. Fish and Wildlife Service. Nor is it a one-way street. The North American gray squirrel is wiping out native red squirrels in Europe. An Atlantic jellyfish contributed to the collapse of Black Sea fisheries already weakened by pollution.      Ecologists warn that, collectively, this “biological pollution” poses nearly as great an environmental threat as habitat losses generated by more familiar enemies of nature including development, clear-cut logging, overgrazing and oil spills.

The Battle Rages On
“We have inaugurated a new era of ecological chaos,” said Chris Bright of the Worldwatch Institute in Washington. “When an exotic establishes a new beachhead, it can spread to new areas and adapt. This is happening all the time, virtually verywhere.” So far, like human immigration control, the battle against alien species has been spotty, expensive and largely ineffective.      Two dozen federal agencies have stitched together a crazy quilt of detection and eradication efforts with state and local authorities. But much of the effort is aimed at ports, borders and threats to crops. There is little left over to combat emergencies. In February, President Clinton formed a Cabinet-level task force to defend more strenuously against exotic species. Three departments, Interior, Agriculture and Commerce, are seeking $28.8 million in fiscal year 2000 for a wider battle.

Feeding the Weed Counterattack
The Agriculture Department alone spends $30 million annually on weed management. But Randy Westbrooks, the federal government’s noxious-weed coordinator, has just $450,000 to counter new outbreaks. Westbrooks’ latest foe is a Brazilian native known as floating fern, discovered in the Toledo Bend Reservoir in east Texas. He complains he lacks emergency funding to eradicate the aquatic weed while the outbreak is small. To do the job himself would exceed his annual budget.      “It’ll spread through every waterway in the South,” Westbrooks predicts. “When it starts clogging pipes and burning out irrigation pumps, we’ll pay attention to it.” Florida already has been particularly hard hit by alien species. Ecologists estimate that one in every four plant and animal species there is not native. The alien species invasion — Interior secretary Bruce Babbitt calls it an “explosion in slow motion” — is turning even staunch conservationists into stone cold killers. They’re trapping nutria. Poisoning sport fish. Ripping out saltcedar with bulldozers and chains. “Restoring the wilderness means bringing some land under tighter human control in the short term,” said ecologist Greg Aplet of the Wilderness Society.      Waiting for nature to heal itself has failed miserably, many environmental groups acknowledge. Within a few years, people wake up to find unfamiliar plants and animals growing like kudzu, the alien plant that ate the South.

Paradise Lost?
They’re in national parks and monuments. In wildlife refuges and coastal marine sanctuaries. In wilderness areas that were intended to remain living dioramas of our American paradise lost. Alien species are invading cities, too. The Formosan termite, a stowaway in crates that brought equipment back from the Pacific during World War II, has infested 90 percent of New Orleans’ gracious French Quarter, where it is causing an estimated $300 million a year in damage, repairs and pest control. The super-termite’s jaws have put the area on the National Trust for Historic Preservations’ list of the 11 most endangered historic sites. It’s the only site on the list because of a bug. The Asian longhorned beetle is destroying thousands of hardwood trees in Chicago and New York City, threatening to turn shady neighborhoods into urban deserts. The treatment has been as painful as the invasion: chopping down of infected trees. The U.S. Department of Agriculture says the insect could cause about $138 billion in damage if it breaks out of it beachheads in the two cities and becomes widely established. In some places, researchers are turning to high-tech and unorthodox weapons.

Radar Used to Spot Nests
University of Kentucky scientists fly a radar-equipped airplane over the Ohio River Valley to find the Asian tiger mosquito. The mosquitoes don’t make a radar blip, but the radar can spot hidden mounds of scrap tires, where the insects breed. Tiger mosquitoes love tires. They arrived in 1985 in a Japanese container shipment headed for a Houston recapping plant. They have spread to 25 states and followed trade routes to Africa and South America, too. Aggressive biters, tiger mosquitoes transmit 17 potentially fatal tropical viruses, including dengue fever, yellow fever and forms of encephalitis. One dengue epidemic linked to the tiger mosquito in Rio de Janeiro infected 1 million people. Outbreaks have not been reported in the United States, but public officials were concerned enough to spend $2 million removing a swampy tire dump adjacent to Disney World after the tiger mosquito was found deep within the piles.

Billions from Rogue Mussels
In the Great Lakes and in Mississippi River basins, zebra mussels are expected to cause $5 billion in damages to shipping and power plants by 2002, according to the U.S. Fish and Wildlife Service. Biologists believe the Black Sea natives were stowaways in ballast water of cargo ships that was discharged into Lake St. Clair near Detroit in the late 1980s. Damage by the thumbnail-sized mollusk represents only a fraction of the costs being rung up by invasive species. The total is $138 billion annually and growing according to Cornell University economist David Pimentel. His study, the most comprehensive of its kind, considered such factors as crop losses, depressed land values, eradication programs and medical bills covering everything from invasive pathogens like AIDS to emergency room treatments for feral dog bites. As a last resort, scientists are taking the risky step of fighting aliens with aliens. They travel to the exotics’ homelands to recruit natural born killers — predators, parasites and pathogens — that previously held the pests in check.

Even Allies Sometimes Turn Coats
Unfortunately, some biological agents turn traitor and attack native species after being released here. In Hawaii, for example, the carnivorous rosy wolf snail was imported to kill the giant African tree snail. Instead, it has pounced on 800 local mollusk species, driving more than 50 to extinction since the mid-1950s. Such ecodisasters are prompting more rigorous testing.      On the Pine Butte Swamp preserve in Montana and other northern Plains sites, managers have cautiously released a cavalry of tiny flea beetles in patches of leafy spurge since 1994. So far, the flea beetles appear to be devouring only the alien weed, but it could take years before scientists can be sure.

Hitchhiking with Immigrants
The leafy spurge, a Eurasian herb that infests 5 million acres from California to Maine, is believed to have hitchhiked in sacks of grain seed brought from Russia in 1827 by Mennonite immigrants. Give an alien species two centuries to spread and, experts say, eradication may be impossible. Some have been here longer still. Spanish conquistadors brought horses — as well as smallpox and other alien diseases — to the Americas 500 years ago. Some pests have grown so familiar that people don’t realize they’re aliens. For example, American colonists brought the dandelion from Europe. By those measures, leafy spurge is a newcomer. Still, states spend $144 million annually to fight it with little success. In Ashley National Forest in Utah, crews have drenched one patch with herbicides for 13 years. At Pine Butte, spurge is overtaking the last prairie wetland visited by grizzly bears. Perhaps the flea beetle will crawl to the rescue since it co-evolved with the weed in Eurasia. Nothing else works.

Buds May Benefit from Bugs
“There are buds in the weed’s roots,” explains Keith Fletcher of the Nature Conservancy’s Iowa chapter, who released flea beetles last summer at the Broken Kettle Grasslands Preserve in the Loess Hills near Sioux City. “If you pull it, mow it, burn it, if you take a disc and cut it up into 1-inch pieces, it stimulates these buds to make new seeds.” In the Blackwater’s fetid, brackish wetlands, nutria are the furry equivalent of leafy spurge. Swamp ranchers, who once envisioned selling their pelts as a middle-class mink, brought the rodents to 21 states in the 1930s and 1940s. In Louisiana, for example, E.A. McIlhenney of Tabasco sauce fame imported 13 nutria from Argentina. But nutria chic was doomed by fickle fashion tastes. Set free in the Blackwater and elsewhere, the rodents started doing what comes naturally — gorging and mating. In 16 months, a single female and her progeny can produce 150 offspring. In Louisiana, the Tabasco family’s baker’s dozen now number at least 3 million in the bayous. Maryland’s population is 50,000 and growing rapidly. The Blackwater is the epicenter of the boom, but nutria now infest the entire Eastern Shore. “They are furry cockroaches!” state biologist Robert Colona shouts over the racket of a motorboat. He gestures with his cigarette at a ragged stretch of half-eaten Blackwater salt marsh over the bow. “You might not see nutria very often, but their signs are everywhere — their tracks, their droppings.” They are devastating habitat for rare native species like bald eagles and eliminating nurseries for the crabs and oysters that have paid the mortgages of tidewater families for generations.