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.

Resource availability affects intraguild interactions between larval salamanders.

Yurewicz, Kerry¹, ¹

ABSTRACT- Resource availability is expected to influence the outcome of interactions between species that can interact as both competitors and as predator and prey. I raised larvae of an intraguild predator, Ambystoma laterale, and an intraguild prey, Ambystoma maculatum, separately and together in outdoor wading pools under two fully-crossed resource manipulations. Zooplankton, a shared resource, was present at low or high levels. Rana sylvatica tadpoles, an alternate prey for the intraguild predator, were present or absent. Salamander growth and survival were measured after six weeks. When raised separately, survival of each species was high and unaffected by resource treatment. Both species responded to increased zooplankton with increased growth. When both salamander species were raised together, interspecific competition resulted in decreased growth for each species. Ambystoma maculatum survival was also higher when raised alone than with A. laterale. Further, both resource manipulations affected salamander performance. In the absence of tadpoles, the growth of each species increased with zooplankton level. Intraguild prey survival also increased with zooplankton abundance. When tadpole prey were available to the intraguild predator, the survival of the intraguild predator was lower, but growth was high and unaffected by zooplankton level. Intraguild prey survival tended to be lower but increased with zooplankton level, while growth was lower and unaffected by zooplankton level. These results illustrate how the availability of different resources can affect coexistence between intraguild predators and prey.

KEY WORDS: Ambystoma, competition, intraguild, predation