Can increased structural complexity decrease the predation of an alien crayfish on a native fish?

Abstract

Interactions between predators and their prey are influenced by the habitats they occupy. In freshwater ecosystems, submerged vegetation provides protection for prey compared to unvegetated substrata. Using submerged plants (Hydrilla verticillata) as a refuge for Chinese bitterling (Rhodeus sinensis), a native fish, we conducted a series of laboratory experiments to test the impact of structural complexity and prey density on predation rate. We found that the number of Chinese bitterling eaten by alien crayfish (Procambarus clarkii) decreased with the increasing structural complexity and increased with prey density. Similar reductions in predation rate with increased habitat complexity occurred at all three different prey densities. Our study indicates that structural complexity can decrease the crayfish predation on freshwater fishes.