EXPERIMENTAL EVIDENCE FOR BENTHIC FOOD WEB MODIFICATION AND EFFECTS ON THE GROWTH, PRODUCTION, AND SURVIVORSHIP OF AN AMPHIPOD BY AN EXOTIC BIVALVE IN THE OHIO RIVER

An in situ container experiment was performed in The Ohio River to determine the nature of the interaction of amphipods and zebra mussel colonies. Amphipods living on live zebra mussel substrate had significantly greater growth, production, and survivorship, in comparison to those on plain cobble or zebra mussel shells only. Benthic organic matter from the live zebra mussel containers showed a significant shift in stable isotope signatures consistent with biodeposition by mussels or senescence of mussel tissue. C:N ratios were significantly lower in the live zebra mussel treatment, indicating a higher quality food source available for amphipods. The results of this study indicate amphipods show a positive relationship to zebra mussels through several potential mechanisms; first, through increased habitat area created by mussel shells, and second, biodeposition and alteration of the benthic food web as demonstrated by the container experiment.