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Exotic invaders
 by Rebecca Goetz
For millions of years, ecological change in Indiana came slowly. The balance of plants, animals and microbes shifted as tectonic plates moved, glaciers flowed and climates changed.
Then people came.
People brought thousands of new, exotic (non-native) plants, animals and microbes. And with them came faster changes in the ecology.
And the balance changed.
Approximately one out of seven exotics causes trouble by eating, crowding out or sickening native fauna and flora. Exotics have even wiped out some native species.
To protect the native wildlife that's left, we need to do our best to control already-established invaders and keep out new ones, says Pat Charlebois of Illinois-Indiana Sea Grant, who monitors exotics in Midwestern lakes and streams. An endangered songbird, flower, clam or toad may contain the key to curing a disease. Or it may be the anchoring thread in an ecological web that keeps the air or water clean.
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The zebra mussel, found in all five Great Lakes, kills native mussels and clogs water supply pipes. (Purdue Ag Comm photo) |
"In the Great Lakes alone, we have more than 140 exotic species," says Charlebois. "Most of them don't cause much harm, but just one exotic can have a whole suite of impacts on native species."
Exotics also cost us money. Researchers at the Nature Conservancy estimate that the 79 most invasive exotics have cost the U.S. economy $97 billion. Utility companies along Lake Michigan spent $120 million between 1989 and 1994 just to keep one exotic--the zebra mussel--out of water intake pipes, says Charlebois. Indiana farmers are spending $100,000 each year fighting a Chinese weed called giant foxtail, says Purdue University weed scientist Merrill Ross. Other exotic invaders add to the bill.
Purdue researchers are trying to cut these costs, keep track of exotic threats and curb future invasions to save the native species that we have left.
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