The response of riverine fish communties to Dreissena-induced benthification

Since their original introduction to the Great Lakes in the late 1980’s, zebra and quagga mussels (Dreissena polymorpha and D. bugensis) have become “ecosystem engineers”, bringing about drastic ecological changes to the aquatic systems they invade. Their voracious filter-feeding activity increases water clarity and contributes to the process of benthification, in which the majority ecosystem’s energy becomes concentrated in the benthos. This phenomenon has been documented in lakes, but less is known about the effects of this invasive species on riverine systems with swift currents. This study investigates the impact of zebra mussels on communities of fishes and benthic invertebrates in the Huron River, a medium-sized system located in southeastern Michigan. The data demonstrates a definite trend toward benthification in areas with dense colonies of zebra mussels, with a marked increase in the abundance of species that are able to take advantage of the changes induced by zebra mussels. Given the expanding range of this invasive species within North America, this research has implications for the management of wildlife in other watersheds.