Coincident with the establishment of dreissenids in Lake Ontario, the depth distribution of alewife, a non-native predator of larval fishes, shifted deeper and the abundance of burrowing amphipod, Diporeia, declined sharply. The alewife distribution shift was followed by increased reproductive success of two native fishes, lake trout and yellow perch whereas the decline of Diporeia was followed by the appearance of emaciated lake whitefish and slimy sculpin, two native fishes that eat Diporeia.