Ecologists Fighting Exotic Species

 

 
6,000 Alien Plant and Animal Species Have Invaded U.S.; Dozens More Arrive 
Each Year 

By JOSEPH B. VERRENGIAA 
 The Associated Press 

BLACKWATER NATIONAL WILDLIFE REFUGE, Md..

Bill Geise has met 
the enemy. It's a swamp rat as big as a pit bull, and about as affable. A 
quartet of orange buckteeth jut from its pinched face like a mouthful of 
Doritos. 

Those chisels are good for one thingg: tearing out acres of tender salt 
marsh plants by the roots. 

The nutria is native to South America but has invaded this tranquil, tawny 
fringe of Chesapeake Bay where Geise wandered as a boy. 

Safe from predators a hemisphere away, flotillas of the web-footed rodents 
are defoliating one of America's richest preserves. One-third of the 
refuge's original 23,000 acres of whispering bull rush and cordgrass now 
are silent mud flats and sterile bays that stretch for miles into the hazy 
horizon. 

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 European settlers 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. 

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. 

''We have inaugurated a new era of ecological chaos,'' said Chris Bright of 
the Worldwatch Institute in Washington, D.C. ''When an exotic establishes a 
new beachhead, it can spread to new areas and adapt. This is happening all 
the time, virtually everywhere.'' 

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 leftover to combat emergencies. 

In February, President Clinton formed a Cabinet-level task force to more 
strenuously defend against exotic species. Three departments - Interior, 
Agriculture and Commerce - are seeking $28.8 million in fiscal year 2000 
for a wider battle. 

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 has already 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. Spraying weeds from aircraft 
like it was Vietnam, not North Dakota. 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. 

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 historical 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 infected trees. The U.S. Department of Agriculture says the insect 
could cause about $130 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. 

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 next 
to Disney World after the tiger mosquito was found deep within the piles. 

In the Great Lakes and 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 a study by 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. 

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 eco-disasters 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 bugs appear to 
be devouring only the alien weed, but it could take years before scientists 
can be sure. 

The leafy spurge, a Eurasian herb that infests 5 million acres from 
California to Maine, is believe 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. 

''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 
one-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 22 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. 

Over 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. 

Nutria scatter into the heart of a wetland, and randomly chew into its 
thick carpet of starchy roots. Biologists call those ''eat-outs.'' 

Aerial photos show the marsh damage blistering until the eat-outs merge 
into open bays. Then saltier water from the Chesapeake seeps in with the 
tide, strangling stands of loblolly pine and accelerating erosion. 

''It's a cancer,'' said refuge biologist Keith Weaver. 

To these researchers, the only question is how best to kill nutria. 

Louisiana's eradication program failed despite extensive trapping and 
poisoning campaigns; now it's motto is population control. One agency posts 
Cajun recipes on its Internet site. (Nutria gumbo? Pass the Tabasco.) A 
sheriff's SWAT team blasts the rodents for nocturnal target practice. 

But the nutria are growing cagey. ''They've gotten real suspicious of a 
boat motor,'' Colona said. ''The dumb ones already have been weeded out.'' 

Next year, Blackwater and state agencies will launch a $2.9 million 
eradication campaign over three years. 

Geise still relies on the paths and false channels he memorized as a boy to 
navigate the refuge. He'll guide biologists who plan to fit males with 
radio transmitters to map their wanderlust. They'll test traps, poisons and 
some unconventional biological lures - vocalizations and sex hormone scents 
- that put a modernist twist on the Pied Piper legend. 

Their ace-in-the-hole? Cold weather. A nutria in Brazil rarely encounters a 
snowflake. 

Geise hankers for a winter like 1978, when much of the Chesapeake froze 
solid. Out on the marsh, he would find nutria huddling 15 or 20 deep. 

''Kick the piles apart, and underneath you could find a few still alive, 
trying to keep warm,'' Geise recalled. 

Hardhearted? Geise offers no apology. The South American interlopers have 
forded a creek to infest the swamp behind his ancestral farm, too. 

''I grew up on the Blackwater,'' he declares, ''and I'm watching it 
disappear. It's really sad.'' 

Spoken like a true native. 

 AP


 

 
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