The zebra mussel is just one of 115 "exotic" species introduced to nutrient-rich Lake Erie since 1810 -- and while its impact may be formidable, it may someday find a balanced niche in the lake's ecology.
That was one message from the first "state of Lake Erie" conference Wednesday in Dunkirk's Harbourfront Sheraton.
Sponsored by New York's Sea Grant Extension Service, the conference attracted researchers from New York and Ontario who offered an update on contaminants, fish populations and exotic newcomers, such as the "spiny water flea."
Among the surprises:
Lake Erie fish are safe to eat. And older people worried about heart disease may be "safer" eating even Lake Ontario salmon for the "Omega-3 fatty acids," despite fears of trace levels of mirex or PCBs.
The zebra mussel continues to spread in spectacular fashion, but so far, no ill effects have been found on fish-spawning beds. And recent research indicates that zebra mussel colonies may actually filter and eat some of their new offspring each breeding season.
The experimental lamprey-control program in Lake Erie caused a dramatic increase in mature lake trout, giving fisheries biologists hope they can someday re-establish breeding populations of this native species.
The lake's "forage base" is adequate to support all the game and food fish now present and diverse enough so that lean years for one forage species, like the emerald shiner, are compensated by "booms" of another, like gizzard shad.
"We saw zebra mussel veligers increase 45-fold between 1989 and 1990 in the Buffalo-Dunkirk area," said Dr. Howard P. Reissen, an assistant professor of biology at Buffalo State College. "And we expect to see far more next summer."
These colonizing early stages of the mollusk float downstream, and managed to go the length of Lake Erie in about two years, he said.
"Now the mussel stretches from Cornwall on the St. Lawrence (River) to Duluth (Minn.) in the west," said Dr. Joe Leach of the Ontario Ministry of Natural Resources.
However, while some of these shellfish are affecting industry, power plants and drinking-water intakes, they are not a matter for panic, the scientists said.
The zebra mussel, introduced here from European ship ballast discharges, reproduces rapidly, fouling water plant intakes. Decreased water flow can lead to overheated pumps and generally disrupt water and industrial plant operations.
"When the zebra mussel story broke, I could only think that never had there been such media hype by so many over so small an organism," Leach said.
According to Dr. Edward Mills of Cornell University, the mussel is just another in a long list of "exotics" brought to the lakes -- including the salmon, carp and brown trout.
"About half the exotics never got established," he said. "About half the 115 species introduced here came in since 1960, most of them borne in water ballast of ships.
"But even before that, new species were brought in by ships or even purposely planted -- like purple loosestrife, which is now a real problem plant in much of the Northeast.
"In the last 10 years we've seen the Atlantic white perch become widespread," Mills said. "We don't know its real impact yet.
"But an earlier migrant, which also came in via the canal system -- the alewife herring -- made it possible to plant the steelhead, coho and Chinook salmon that have meant so much to sportfishing in the lakes."
Since those fish were introduced 25 years ago there has been controversy over eating them, said Dr. Michael Voiland, Sea Grant's director.
"But pollution levels have dropped markedly in the last 15 years, and we have found that no game fish exceeds federal 'thresholds' for the chemicals -- except some carp and channel catfish caught in areas like Buffalo Creek.
"Some groups with their own agendas have made an issue over fish consumption," Voiland added.