Crayfish predation on amphibian eggs and larvae

We experimentally evaluated the impact of the introduced signal crayfish (Pacifastacus leniusculus) and the native noble crayfish (Astacus astacus) on eggs and larvae of seven species of amphibians, likely to co-occur with crayfish in southern Sweden. In aquarium experiments eggs and tadpoles of all amphibian species were consumed by both crayfish species. The consumption of amphibian eggs by signal crayfish increased with temperature. The noble crayfish consumed more tadpoles than the signal crayfish, but the latter caused more sub-lethal damage to tadpoles. Tadpoles of the common toad (Bufo bufo) were sometimes killed but left uneaten by both crayfish species. In pool experiments, signal crayfish consumed more tadpoles of Hyla arborea in a less complex habitat and significantly reduced survival of Hyla tadpoles and the biomass of aquatic macrophytes.