Prey subsidy or predator cue? Direct and indirect effects of caged predators on aquatic consumers and resources

摘要: The non-consumptive effects of predators on prey can affect phenotypes, potentially having important consequences for communities due to trait-mediated indirect interactions. Predicting and their impacts be difficult because resources directly through nutrient cycling indirectly by altering resource use, which lead complex interactions among consumers. In this study we examined the caged dragonfly aquatic in presence absence two focal herbivores, tadpoles Neotropical tree frogs Agalychnis callidryas Dendropsophus ebraccatus. We crossed presence/absence dragonflies with four tadpole treatments: no tadpoles, each species alone, both together examine composition, predator presence, time growth, resources, zooplankton abundances. Predator growth changed ontogeny was species-dependent. Predators initially reduced then dramatically increased A. but had effect D. also abundances periphyton phytoplankton. However, there evidence a trophic cascade (i.e., interaction). Instead, nutrients from carcass subsidies likely played an increasingly role facilitating shaping competitive interactions, time. nutrient-poor systems release via consumption terrestrially derived items may have food webs independent cascades.