Exotic species threaten environment
Foreign invaders thriving in the
July 26, 2002
BY BOB DART
WASHINGTON -- Walking catfish. Fruit bats. Red-whiskered
bulbuls. Brown tree snakes. Brushtail possum. Chinese
mitten crabs. Asian longhorn beetles. Zebra mussels. Round
goby. Asian swamp eels.
The newly notorious snakehead fish is only the latest
exotic foreign creature to threaten the U.S. environment
enough to alarm federal officials.
"We talk a lot about endangered species, but, at the
other end of the scale, invasive species" pose at least
as great a danger, Interior Secretary Gale Norton said
Like the snakehead, a rapidly reproducing Asian fish
that can slither across land and eat virtually every small
animal it encounters, the other threatening creatures
thrive in the U.S. wilds where they have no natural predators.
They can quickly upset the balance of nature. Indeed,
these foreign invaders could hasten the extinction of
some endangered species of native American animals, warned
As if that catalog of invaders was not enough, the government
warned of a particularly nasty plant this week, prompted
in part by an incident in Massachusetts that could have
been the basis for a minor horror story.
The offending life form: a stinging, 15-foot-tall poisonous
weed from Iran sighted in Massachusetts and found in about
a half-dozen other states that packs a sap capable of
causing acute pain, severe blisters, scarring and perhaps
"This thing looks like it's right out of the 'Little
Shop of Horrors,' " said Richard Mytkowicz of the U.S.
Department of Agriculture (USDA). "Don't worry; it won't
run after you and eat your children. But take it very
Several weeks ago, Doug and Nancy Roberts decided to
hack away at the overgrowth on a recently purchased farm
in Granville, a small town about 20 miles west of Springfield,
Mass. Nancy attacked a "gigantic, ugly" weed with a small
pruning knife, Doug Roberts said. A day or two later,
she came down with "horrible, big huge blisters on her
legs that have begun to scar," he said.
"I'll give the plant this much: It's impressively bold.
It's also evil," said Craig Hollingsworth of the University
The sap of the plant contains furomarin, a chemical
that destroys the skin's ability to block the ultraviolet
rays of the sun. Cases of contact in England, where the
weed is more common, have sent some children to the hospital
with severe blistering. Although British scientific literature
warns that the sap can blind if it gets in the eyes, U.S.
scientists knew of no documented cases.
Setting down roots
The influx of intruders indicates how small the globe
is getting, said Alan Tasker of the animal and plant health
inspection division of the USDA.
"Pangea is what we called the clump of land before it
split into continents," Tasker said. "The pace and frequency
of international travel is turning us into another Pangea."
And once here, the intruders are hard to eradicate.
The Asian swamp eel, for example, has found a home around
lakes, swamps and rivers in Florida and Georgia. Capable
of breathing air and surviving cold and drought, the 3-foot-long
eels have even become established near metro Atlanta,
according to the U.S. Fish and Wildlife Service.
The live eels were imported as a food and could have
been released in the wild in an effort at fish farming.
They are voracious predators and can slither across land
if forced out of water. Uncontained, they could spread
as far north as Virginia and Maryland, the agency said.
Kudzu, of course, is perhaps the Southern poster child
of invasive plants. Native to China and Japan, kudzu was
purposely introduced to United States at the 1876 Centennial
Exposition in Philadelphia. In the 1930s, Southern farmers
were urged to plant the ever-spreading vines to prevent
Since then, kudzu has taken over more than 7 million
acres of land -- about 10,938 square miles -- and causes
$100 million in damages a year to crops, forests and property
in the South, the Wildlife Service reported.
Norton said the "celebrity of the snakehead" is focusing
attention on the overall problem. The Bush administration
wants to ban the importation and interstate transportation
of the voracious Asian fish.
Among the other animals and plants whose importation
is banned under the Lacey Act, which outlaws the importation
of certain so-called injurious species and their transportation
across state lines:
- Zebra mussels. Native to the Caspian
Sea and Ural River, the distinctively striped shellfish
were probably brought to the Great Lakes through ballast
water discharged by international freighters. They are
capable of corroding wood, steel and concrete and fouling
water intake pipes for industry and ship engines. They
have spread across 20 states and are a big problem in
- Raccoon dogs. Native to woodlands of
Russia, China and Japan, they are called tanuki in
their homelands. An unusual canine, it is basically
a dog that looks like a raccoon in markings and body
structure. It eats whatever it can find -- rodents,
lizards, frogs, ground birds, seeds, fruit, berries,
insects, and spiders.
- Asian longhorn beetles. Native to China,
they have shiny black wings splotched with white, and
blue feet and legs. In the United States, they first
appeared in Brooklyn in 1996 and have since been found
in Chicago. They probably arrived on wooden pallets
made in China. "These beetles literally eat trees to
death," the Wildlife Service warned.
- Round goby. Native to Europe, these
bottom-feeding fish have spread across the Great Lakes
eating the eggs of bass, walleye and perch. Because
they absorb toxic contamination such as PCBs, they pose
risk to humans who consume them or other fish that ate
the goby. They've been found in the St. Clair and Detroit
rivers, as well as Lake St. Clair.