Aug 21, 2006 — There are over 160 non-native species in the Great lakes and St.Lawrence Seaway. If they impact native species, they're called "invasive." It's estimated that invasive species already cost the Great Lakes basin billions of dollars a year. The Great Lakes Radio Consortium's Zach Peterson reports that invasive species are also changing the ecosystem, crowding out the native species, and disrupting the natural food chain. And there will likely be more coming.