http://www.nytimes.com/2008/06/17/science/17muss.html
Biologists also warn that the vector behind the quaggas' spread, to the Great Lakes by oceanic freighter and to the West on recreational boats, remains open to exploitation by other potentially destructive species. An estimated 180 alien species have reproducing populations in the Great Lakes Basin, with new ones added almost yearly. Most recently, viral hemorrhagic septicemia, a European virus that can cause large fish kills, has spread to three Great Lakes: Huron, Michigan and Ontario.
"Everybody
in North America needs to be concerned about what species come into the
Great Lakes," Dr. Fahnenstiel said. "There's no system that's
geographically isolated anymore. We're all linked."