DIRECT AND INDIRECT EFFECTS OF PREDATION ON TADPOLE COMMUNITY STRUCTURE IN THE AMAZON RAIN-FOREST

The relationship between the distribution of predators (fish, odonates and water beetles) and prey assemblages (amphibian larvae) was invest igated in the tropical rainforest of central Amazonas, Brasil. The anu ran community uses a variety of waterbodies for reproduction, ranging from streams and streamside ponds to isolated forest ponds. Predators in this system include fish in streams and streamside ponds, and inver tebrates (primarily odonate naiads and beetles) in forest ponds. Tadpo le species richness and assemblage structure were related to fish dens ity and species richness. No relationships between tadpole assemblages and abiotic pond characteristics were detected. The presence of fish explained much of the variation in both species composition and specie s richness within and among ponds. Some species of tadpole were consis tently found to coexist with high densities of fish. Path analyses sug gest that while fish have a strong direct effect on tadpole associatio ns and species richness, they also have an indirect effect through inv ertebrate predators (odonate larvae and coleopteran beetles). Prey sur vival-strategies such as palatability and behaviour may explain how ta dpole species composition is affected by predators at the community le vel. These findings suggest that the observed patterns of habitat use by larval anurans may be structured in response to the distribution of key predators (fish) in this system.