Six-hundred
miles west of Rochester, in suburban Chicago, is a structure that just might
save Lake Ontario.
Connecting
the Chicago and Des Plaines Rivers, the Chicago Ship and Sanitary Canal links
up two of the continent’s largest water systems: the Mississippi River and the
Great Lakes watersheds. At the bottom of that canal lies a $9 million
underwater electric fence that’s keeping species on one side from migrating to
the other.
Specifically,
Asian carp. Brought to this continent in the 1970s by catfish farmers, they
escaped during floods, spreading throughout the Mississippi River and its
system of tributaries. A bigger, badder version of the homegrown carp we always
had, these fish can grow up to four feet and 100 pounds according to the
federal Environmental Protection Agency. And their ability to leap up to six
feet out of the water — often frightening and sometimes injuring fisherman
and biologists — has garnered plenty of headlines.
The
fish are already thriving in the Mississippi system and nearly everyone is
petrified about the possibilities if they reach the Great Lakes.
“Due
to their large size, ravenous appetites, and rapid rate of reproduction, these
fish could pose a significant risk to the Great Lakes Ecosystem,” the EPA’s
website reads. “Eventually, they could become a dominant species in the Great
Lakes.”
But Asian carp are just one
of an estimated 50,000 species from beyond our shores who’ve taken up permanent
residency here. And some of them are costing us. David Pimentel, a professor of
entomology at Cornell University, estimates that those species suck more than
$125 billion from the economy. Much of Pimentel’s recent research has focused
on “aquatic nuisances,” an appellation that covers a broad range of species. In
New York alone he estimates aquatic invasive species cause about $500 million
in damages by creating problems like clogged pipes or choking off waterways.
“That
does not really include terrestrials,” says Pimentel. “I would say probably the
rest would be about $3 billion.”
Some
of these are infamous enough to be widely recognized — zebra mussels, Asian
longhorn beetle, purple loosestrife.
But
others are less obvious. Asked what the single most costly invasive species
was, Pimentel paused a moment before fingering the HIV virus, followed by the
West Nile virus.
And
73 percent of the agricultural crops used in North America are invasive, he
adds. Now those plants are struggling to cope with newer forms of invasive
plants, in other words: weeds. About 12 percent of crop production is lost to
weeds each year nationally, says Pimentel. For New York, that means $300 to
$500 million dollars gone from the pockets of the state’s already struggling
farmers. Other plants, like purple loosestrife — the flower you see in
ditches, medians, and roadsides throughout the state — cost local governments
money to keep (at least partially) under control.
For
Pimentel, weeds and other introduced plants are the worst part of the problem.
In addition to the economic harm done to farmers, landowners, and governments,
there’s the less quantifiable specter of extinctions.
“Invasives
cause 40 percent of extinctions in the US,” says Pimentel. That’s second only
to those caused by human activity. And invasive plants that out-compete native
species can have an extinction multiplier effect. That’s because plants are the
foundation of the food chain; tear them out of the equation and ecological
relationships higher up will topple. Pimentel explains: “Any time you have a
plant that’s headed for extinction, you have the extinction of a lot of the
species that are dependent on that plant.”
These days, when it
comes to fighting invasive species, the outlook is grim. Since the mid-20th
century, there’s been an explosion of new species here.
“I
think we should be worried about this because it’s rapid and increasing,”
Pimentel says. “In just half the time, the number of species coming in has more
than doubled. Evolution in natural systems can’t happen fast enough to adapt to
that.”
The
blame for that, Pimentel suggests, lies with the rapidly changing nature of the
global economy.
“We’ve
got more people traveling, traveling more rapidly, and we’ve got globalization
and increased trade,” he says. And our track record of stamping out the
invasives we’ve fought thus far is miserable.
“Out
of those 50,000 species, we’ve eradicated maybe two,” he says.
This article appears in Aug 24-30, 2005.
