Top predators and habitat complexity alter an intraguild predation module in pond communities.

Predator diversity and habitat complexity frequently influence species interactions at lower trophic levels, yet their joint investigation has been performed infrequently despite the demonstrated importance of each individual factor. We investigated how different top predators and varying habitat complexity influence the function of an intraguild predation module consisting of two larval salamanders, intraguild predator Ambystoma annulatum and intraguild prey A. maculatum. We manipulated predator food webs and habitat complexity in outdoor mesocosms. Top predators significantly influenced body condition and survival of A. annulatum, but habitat complexity had minimal effects on either response. A three-way interaction among the covariates top predator identity, habitat complexity and A. annulatum survival influenced body condition and survival of A. maculatum via a density-mediated indirect effect. Different top predator combinations had variable effects in different habitat complexity treatments on intraguild predator (A. annulatum) survival that subsequently influenced intraguild prey (A. maculatum) body condition and survival. Future work should consider how different top predators influence other food web components, which should vary due to predator attributes and the physical environments in which they co-occur.