Five dozen scientists call invasive species the most urgent environmental threat to the Great Lakes & Mississippi River Basin: Barriers urged for area rivers
Thursday, May 15, 2003
Chicago Tribune, By John Biemer
Calling invasive species the most urgent environmental threat to the Great Lakes and the Mississippi River Basin, five dozen scientists laid out some extreme measures Wednesday to choke off a "revolving door" through Chicago that alien animals use to expand their devastating influence.
The two-day summit, organized by Mayor Richard Daley and the U.S. Fish and Wildlife Service, is focusing on the Chicago Sanitary and Ship Canal and the Cal-Sag Channel, which links the two regions by connecting Lake Michigan and the Illinois River.
Invading creatures come in a wide range of sizes, from 100-pound carp to the tiniest microbes, so different techniques may be necessary to keep them from spreading. But many of the scientists at the summit decided the most effective way to pinch off that corridor to everything would be to construct physical barriers where the Chicago and Calumet Rivers and the North Shore Channel meet Lake Michigan. Such barriers would draw heavy opposition because they would block recreational boats and cargo ships.
But scientists favor barriers as the most clear-cut way to keep unwanted plants and animals from making that journey, said John Fogner of the Fish and Wildlife Service office in Barrington.
"It's pretty radical, it would be pretty expensive," he said. "What this group did is continuously weigh that against the extent of the invasive species problem."
Biologists say aquatic animals from as far away as the Caspian Sea--most of which arrived in the ballast water of transoceanic cargo ships--have taken advantage of improving water quality in Chicago's man-made waterways resulting from enforcement of the Clean Water Act of the 1970s. Before then, the polluted water blocked fish, mollusks and microscopic animal species from slipping between the two enormous watersheds.
Zebra mussels traveled the canal from the Great Lakes to the Mississippi River, spreading all the way south to the Gulf of Mexico. The mollusks are responsible for causing billions of dollars in damage since the late 1980s by clogging water filtration systems, altering the natural ecosystem and encrusting themselves by the million over docks and ships.
$137 billion a year in losses
Worldwide commerce has accelerated the spread of invasive species across the United States. By 2000, they were blamed for $137 billion a year in cumulative economic losses nationwide, according to the U.S. Fish and Wildlife Service.
"In short, invasive species are the No. 1 threat to both the ecology and economy of the Great Lakes," said Dennis L. Schornack, the chairman of the U.S. section of the International Joint Commission, which manages water bodies along the U.S.-Canadian border.
Already, more than 160 non-native species live in the Great Lakes watershed, and almost 150 live in the Mississippi watershed. Not all of them have wreaked havoc on native ecosystems, but a few alien species with destructive potential have established themselves in one of the two watersheds--and are now knocking on that revolving door.
That includes two huge and prolific species of Asian carp that have worked their way up the Mississippi to within 55 miles of Lake Michigan.
From the north, there is the quagga mussel, which could be as troublesome as the zebra mussel. Another looming threat is ruffe, an aggressive perch relative native to Eurasia that's a potential competitor to the native walleye, sauger and yellow perch. And then there are the spiny water fleas: tiny crustaceans that biologists fear will devour the plankton that sustains young native fish.
Last year, the Army Corps of Engineers laid underwater cables on the base of the Sanitary and Ship Canal to generate an electric field to deter the advance of another invasive species, the round goby, a small predatory fish. It wasn't erected in time to stop the gobies, but scientists expect it to work on the Asian carp.
Still, the electric barrier has not been 100 percent successful in tests run on common carp already established in the vicinity, with one of 70 fish tracked by the Illinois Department of Natural Resources slipping through.
`All you need is 2 fish'
That's a concern for DNR biologist John Dettmers, who's helping fine-tune barriers for the expected arrival of the carp, now no more than 25 miles away.
"The bottom line is all you need is two fish, one of each sex, to start a population," he said.
The electric "fence" near Romeoville is expected to last just three years. A second electrical barrier, 1,000 feet south of the first one, is slated to be in place by the summer of 2004. Still, the electricity does not stop smaller animals.
So, by today, scientists at the summit are expected to finish a menu of suggestions for long-term methods to stop a wider variety of species along the canal. Among other ideas explored were creating "biological control zones" on designated stretches of water to repel or kill organisms that come through. Such zones could be created by injecting hot water or toxicants into the system or by removing oxygen from the water. Other options include emitting a piercing sound to deter fish.
Daley, who addressed the group Wednesday, encouraged the biologists to think big.
"Sometimes, we have to be bold about it and be not afraid of taking some active steps protecting us against invasive species and other threats" to the region's water quality, said the mayor, who sees the battle as part of the water initiatives he announced last month.
If Congress approves the now pending National Aquatic Invasive Species Act of 2003, the Corps of Engineers will be given the authority to conduct studies to test such ideas.
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