Zebra mussels (Dreissena polymorpha), habitat alteration, and yellow perch (Perca flavescens) foraging: system-wide effects and behavioural mechanisms

Abstract

The aggregate impact of an exotic species introduction, such as the zebra mussel (Dreissena polymorpha), may involve a large number of biotic and abiotic interactions within the recipient ecosystem. We used laboratory experiments and field data to assess effects of zebra mussels on both foraging success of yellow perch (Perca flavescens) and activity of the amphipod Gammarus fasciatus. In two laboratory experiments zebra mussel clusters reduced the rate at which yellow perch captured amphipods. Yellow perch captured fewer amphipods when zebra mussels were present at two light levels (<2.1 and >214 lx) and across a range of prey densities (76–1500 amphipods·m–2). The effect of zebra mussels on amphipod activity depended on light level. Yellow perch captured fewer amphipods in the presence of mussel clusters than when plants were present. The frequency of amphipods in the diets of adult yellow perch in Oneida Lake increased after zebra mussel introduction, but the increase was greater in low mussel density habitats. Our laboratory results and field observations suggest that zebra mussels affect yellow perch foraging on amphipods through increased structural complexity (negative) and increased light penetration ( positive), but not through increased prey density.