Ecological consequences of amphibian larvae and their native and alien predators on the community structure of temporary ponds

1. Connections between consumers and resources in food webs are complex and affect the structure and functioning of ecosystems. We assessed the influence of amphibians as consumers on the structure and functioning of temporary ponds, determining their impact on macrophyte abundance, zooplankton diversity and water chemistry. 2. The effect of amphibians may be modulated by interactions with predators or competitors that alter tadpole density or behaviour. Therefore, we also investigated the consumptive and non-consumptive effects of native and invasive predators on amphibian larvae and pond ecosystems. 3. High amphibian density decreased macrophyte biomass and zooplankton diversity and increased water turbidity and nutrient content. These effects were largely attributable to tadpoles of the largest herbivorous species, spadefoot toads (Pelobates cultripes). In the absence of spadefoot toads, amphibians unexpectedly affected plant biomass positively. 4. Invasive crayfish (Procambarus clarkii) altered community structure in similar ways to high densities of amphibians and caused greater mortality of amphibian larvae than did native predators. 5. The high herbivorous impact of spadefoot toads and invasive crayfish carried over to the following hydrological cycle.