Abstracts (first author)
Invasive crayfish have a greater impact on amphibian larval survival and pond structure than native predators
The efficiency of induced antipredator responses critically depends upon accurate cue recognition and hence requires some joint predator-prey evolutionary history because otherwise preys may fail to recognize or respond efficiently against alien predators. Thus, amphibian larvae often fail to trigger antipredator responses against invasive predators. Few studies analyzed the ecological consequences of predator-tadpole interactions on the rest of the aquatic communities of temporary ponds, but amphibians’ impact on the community structure and dynamics of aquatic systems may be conditioned by their interactions with competitors and predators. Thus, predators can potentially have cascading effects on pond communities via alterations in amphibian larval density and/or their phenotype. We used a mesocosm array at Doñana National Park to test for density dependent and density-independent effects of native and invasive predators on survival and growth rate of amphibian larvae, also quantifying its consequences on the food web. Invasive predators caused greater mortalities of amphibian larvae than native predators, hence having a stronger potential for direct density-dependent effects on amphibian guilds and their interactions in the trophic web. Moreover, crayfish increased turbidity and nutrient content in the water and had a direct negative impact on plants that was carried over into the following hydrological cycle. Thus, our results highlight how this invasive species poses a greater predatory threat to amphibians than other native predators, and can also be highly disruptive of the entire pond structure.