PARENT SESSION
Oral Session #46: Animal Community Ecology: Pools, Foodwebs, Structure. Presiding: D. Post.
Wednesday, August 8, 2001. 8:00 AM to 12:00 PM. Hall of Ideas I.
Effect of risk of predation on two temporary pool species (Bufo viridis and Culiseta longiareolata).
Stav, Gil1, Kotler, Burt1, Blaustein, Leon2, 1 2
ABSTRACT- Green toad (Bufo viridis) tadpoles and mosquito larvae (Culiseta longiareolata) are highly vulnerable to predation by the dragonfly nymph, Anax imperator. We assessed various responses of tadpole and mosquito larva to caged Anax in artificial pools. We compared responses in seven treatments (five replicate pools each) of various combinations of presence or absence of: one caged Anax, 30 Bufo tadpoles and 100 Culiseta larvae. Caged Anax were fed with 1 tadpole and 3 mosquito larvae once a week. Culiseta females oviposited more in pools without Bufo. Bufo were more prevalent farther from Anax in the absence of Culiseta, but closer to Anax when Culiseta were also present. Culiseta larvae did not respond spatially to caged Anax in the absence of Bufo, but when Bufo were present, they were more prevalent closer to the predator. The presence of Culiseta, but not Anax, affected time to and size at metamorphosis, and survival of Bufo tadpoles. Both the presence of Anax and water turbidity affected color of Bufo tadpoles. When Anax was present or when water was cloudy, Bufo tadpoles were lighter in color. In the lab, lighter colored tadpoles were more vulnerable to Anax in clear water, while no difference was found in cloudy water. This study shows the complexity of predation risk on prey species, and it's potential effect on temporary pool community.
KEY WORDS: Predation, Bufo viridis, Culiseta longiareolata, Anax imperator