January 6, 2006
Aquarium Opens Invasive Species Exhibit
CHICAGO -- The huge Asian carp are real, the gape-mouthed round gobies are real, but organizers of a new exhibit that opened Thursday at the Shedd Aquarium decided not to mess with real zebra mussels - they're just replicas.
The exhibit concerns threats to the Great Lakes from invasive species - plants or animals that arrive in spots where they didn't originate. They then multiply, spread and harm the balance of their new environment by eating or competing with native species.An example is zebra mussels, already notorious pests in the Great Lakes. They are voracious eaters, multiply quickly and are so stubborn once entrenched that the Shedd staff worried they could end up clogging the aquarium's pipes - hence, the models that climb the side of one of the exhibit's aquariums.
Scientists believe at least 170 aquatic invasive species currently live in the Great Lakes basin, according to the exhibit, and a new species is introduced on average once every eight months.
"These species are not inherently bad. They're just in the wrong place," said David Lodge, director of the Center for Aquatic Conservation at the University of Notre Dame, who provided advice to the Shedd.
Staff at the Shedd said visitors who have read about the threat of invasive species often ask to see them. The exhibit is also designed to provide visitors with tips about how they can help prevent introducing or spreading invasive species.
The plants and animals arrive in the Great Lakes region - the world's largest surface freshwater system - in multiple ways. Some are carried in the ballast water of cargo ships, others hitchhike rides on fishing gear or are dumped into sewers and lakes by owners who are tired of caring for an exotic animal or plant around the house.
"The damages are far reaching - from the shoreline, to the pipes of power plants and municipal waterworks, to the many other lakes and rivers that are under threat and indeed under harm as zebra mussels and many other species spread from the Great Lakes across the continent," Lodge said.
The exhibit is a permanent one, and it takes the place occupied by several aquariums previously devoted to aquatic life in the Great Lakes and Midwestern rivers and lakes.
It includes a mix of plants and fish that are native to the Great Lakes, such as lake sturgeon, the prehistoric-looking fish with a snout-like mouth and dull brown color.
The non-invasive exhibits include hydrilla, an Asian plant common used to decorate aquariums, and round gobies, which eat trout and bass eggs.
One of the exhibit's highlights is an aquarium filled with Asian carp, which are currently being kept out of the Great Lakes by electric barriers.
An accompanying videotape shows dozens of carp jumping four feet in the air out of the Illinois and Mississippi rivers - where they've multiplied quickly because of a lack of natural predators. Some of the carp land in boats, others hit passengers; in one shot, at least eight are seen flying in the background.
The carp are "filter feeders" that consume plankton that would normally be eaten by juvenile minnows, walleyes and blue gill bass, said Kurt Hettiger, a senior aquarist at the Shedd.
Hettiger went out on a boat on the Illinois River near Havana, about 200 miles southwest of Chicago, to collect the carp for the exhibit. He was dismayed by what he saw.
"It was sort of devastating to see how many of these fish there were in a small area," he said. "In some areas, where you sort of start crowding them in, the water is literally erupting with these fish. It's sadly amazing."
On the Net:
Shedd Aquarium: http://www.sheddaquarium.org