PARENT SESSION
Wednesday, August 9, 1:30-5:00 pm
COS 72 - Prey preference and prey defense mechanisms
Plantation Room, Cook Convention Center
Presiders: G Wang and S Raghu

Assessing the potential impact of African jewelfish Hemichromis letourneuxi in Everglades marshes: prey selectivity and antipredator response by native prey.

Rehage, Jennifer^*,, Loftus, William,

ABSTRACT- Predation is often a major mechanism underlying impact by non-indigenous species. We examined the susceptibility of Everglades fishes and macroinvertebrates to predation by a recent invader, the African jewelfish Hemichromis letourneuxi. Susceptibility to predation should intimately relate to predator foraging preferences, as well as to prey antipredator responses. Non-indigenous species may predate opportunistically on naive prey that have no common evolutionary history with the non-indigenous predator, and thus lack antipredator responses or show behavioral responses that are ineffective against novel predation. We conducted a prey selectivity experiment in outdoor mesocosms followed by behavioral assays of antipredator response in aquaria. Survivorship of several species was quantified in the presence of a native predator, warmouth, of the non-indigenous jewelfish, and in the absence of predators. The prey included species abundant across a variety of Everglades habitats, stocked in equal densities: eastern mosquitofish, sailfin molly, Florida flagfish, least killifish, bluefin killifish, and grass shrimp. We then quantified foraging behavior, activity, and refuge use of each prey species in the absence and presence of the two predators in timed trials. Predators had similar predation rates but different preferences. Both predators avoided mosquitofish, jewels preferentially consumed shrimp and avoided flagfish. Warmouth behaved as diet generalists, and exhibited no preferences. Antipredator responses differed among prey and in response to predator type. These results suggest that the role jewels may play in the community may be distinct from that of native predators and deserving further attention.

Key words: predation, wetland, fishes