Invading species. They’re one of the greatest threats to ecosystems in the Great Lakes. You can learn more about this threat to Canada’s Great Lakes by visiting the Invading Species Awareness Program operated by the Ontario Federation of Anglers and Hunters and the Ontario Ministry of Natural Resources. In the Great Lakes, the charge of invasive species is being led by zebra mussels, quagga mussels, spiny water flea, sea lamprey and round gobies which are aggressive and spread rapidly to the the point where they can out-compete natives species for food. The risk is these invasive species will use their Great Lakes foothold to expand their reach to many inland lakes across the country (zebra mussels have already reached many major inland lakes).
Today, more than 185 invasive species, originating from other areas of the world, are now found in the Great Lakes. They entered the Great Lakes mostly through dumping of ballast water by cargo ships. Ballast water regulations will help stem this source of invasives. But some non-native species, such as goldfish, enter the Great Lakes because they are dumped by people no longer wishing to keep them in aquariums or small backyard ponds.
The Great Lake most at risk is Lake Erie, where warmer waters are a suitable habitat for many invasives from Asia and other warmer climates. At least another 30 non-native species are expected to enter the Great Lakes, according to a recent U.S. study.