Abstract
Predator-prey relationships underpin the stability of ecosystems but can be perturbed by numerous factors, such as biological invasions. Crayfish readily colonize new ecosystems and their impacts can modify food webs or ecosystem functioning. However, while crayfish exert high levels of predation pressure handling prey with their claws, claw loss is also common in their populations, which could mediate prey selection pressures. Here, we investigate how the number of claws in the marbled crayfish Procambarus virginalis modulates its preferences for two different available prey: Chironomus plumosus and Gammarus fossarum. We showed that the food preference of P. virginalis was mainly for soft, less mobile prey, such as C. plumosus, with significantly fewer G. fossarum (harder, more mobile prey) being killed. This preference was largely independent of claw presence but depended on the availability of prey, with fewer G. fossarum being targeted as the number of claws decreased. Our results highlight the complexity of predator-prey ecological relationships in invaded freshwater ecosystems and show that some biotic factors, such as the quantity and type of prey available, need to be taken into account in order to better understand their role in ecosystem dynamics.
Keywords: Chironomus plumosus • choice experiment • feeding preference • Gammarus fossarum • macroinvertebrate community • prey preference • Procambarus virginalis
