Dreissena-Shell Habitat and Antipredator Behavior: Combined Effects on Survivorship of Snails Co-Occurring with Molluscivorous Fish

Abstract

Prey employ various strategies to avoid predators, including use of structurally complex habitat where predator foraging efficiency can be reduced. We used laboratory experiments to quantify combined effects of antipredator behavior and habitat provided by zebra mussel (Dreissena polymorpha) shells on survivorship of snails (Physella heterostropha) co-occurring with molluscivorous fish. First we determined predator effects on prey habitat use in aquaria with and without Dreissena-shell beds (i.e., ceramic tiles with and without shells attached to them, respectively) by comparing snail distribution in the absence of fish and in the presence of chemical cues produced from redear sunfish (Lepomis microlophus) preying on snails. Effectiveness of shell beds and other habitats as refuges from actual predation were then evaluated by introducing fish to aquaria that previously received chemical cues, and recording numbers of snails remaining in various habitats 24 h later. Shells and fish had strong independent a...