According to the ChicagoTribune, the invasive species are
--Zebra mussel, a mollusc first brought to the Great Lakes by oceangoing ships and spread by recreational boaters. The mussels filter vast amounts of water, removing nutrients needed by native organisms that fish feed on.
--Round goby, a bottom-dwelling fish native to Eurasia. It was found in 1990 in the St. Clair River, which connects Lake Huron to Lake St. Clair. The voracious eaters have spread to lakes Erie, Huron, Michigan and Superior.
--Eurasian ruffe, a spiny fish that grows and reproduces rapidly, was found in Duluth Harbor on Lake Superior more than 20 years ago. The fish have also been found in Lake Huron. Experts say they were likely transported in the ballast water of freighters on the Great Lakes.
Invasion of the Great Lakes: a Look at the Species
US - Scientists say more than 150 invasive species have been found in the Great Lakes, the largest surface freshwater system in the world, and more are threatening it.