Meeting Abstract

P1.12  Friday, Jan. 4  Hiding from the enemy: behavioral responses of isopods to bluegill sunfish kairomones TESSITORE, K.A.; CONTINO, G.J.; IYENGAR, E.V.*; Muhlenberg College; Muhlenberg College; Muhlenberg College iyengar@muhlenberg.edu

Inducible defenses are triggered by biotic cues, such as the presence of a predator. We investigated whether aquatic isopods (Caecidotea communis) from ponds show behavioral changes in habitat preference when exposed to water with and without chemical cues from predatory fish (bluegill sunfish: Lepomis macrochirus). Isopods are thigmotactic, and are often found burrowing under or within leaf litter. We provided single isopods a checkerboard pattern of four choices of habitat (four replicates of each habitat within a single container): elevated shelters that provided shade, food pouches that disallowed thigmotaxis, and two benthic sources of layered mesh allowing thigmotaxis: a dark one providing shading and a translucent one allowing light penetration. We monitored the habitat choice of each isopod over an eight minute period and calculated the overall percentage of time spent in each habitat. Each individual isopod was tested in both water with and without fish cue and we examined the responses of small (N = 24) and large (N = 20) isopods separately. There was no significant effect of fish cue on habitat choice. The small isopods tended to spend more time in the mesh habitats than in shade or with food, while the large isopods used all habitats to the same extent. Our experimental animals came from a fishless pond. We are now repeating the experiment with a subpopulation from a pond with fish, to see if the natal environment affects behavioral responses in isopods.