Effects of forest disturbance on breeding habitat availability for two species of anurans in the Amazon

Abstract

Deforestation may cause substantial changes in community structure along freshwater habitat gradients. This study evaluated how biotic and abiotic factors affect the distribution and reproductive success of two frog species in Central Amazon. Ponds in continuous and disturbed forest were surveyed to determine the distribution of their associated aquatic predators and the production of newly metamorphosed frogs. The effect of each predator assemblage on tadpole survival was tested using mesocosms. Newly metamorphosed Osteocephalus taurinus occurred in short hydroperiod ponds in disturbed forest, where they had lower encounter frequencies with aquatic insects and no fish were detected. In contrast, newly metamorphosed Phyllomedusa tarsius were associated with longer hydroperiod ponds in continuous forest where fish and aquatic insects were prevalent. In the experimental study, O. taurinus tadpoles had lower survival rates than P. tarsius tadpoles, suggesting that O. taurinus is more vulnerable to fish and insect predators. These results are consistent with the pattern of metamorphic success along the hydroperiod gradient in the study area. If intact continuous forest continues to be harvested, species that require ponds with longer hydroperiods for successful metamorphosis would be prone to population declines.