Zebra mussel called worst of Great Lakes' invaders

Two decades after zebra mussels were discovered in the Great Lakes, some scientists are calling the foreign mollusks the most harmful exotic species ever to invade the world's largest freshwater ecosystem. Several prominent researchers contend dreissenid mussels--zebra and quagga mussels--have caused more profound changes in the lakes than the sea lamprey and other non-native species. In the Muskegon Chronicle.