The effects of prey disturbance on the susceptibility of Zebra Mussels (Dreissena polymorpha) to predation.

Abstract

Dreissena polymorpha is an invasive mollusk in the freshwaters of eastern North America. Because of its abundance and its increased natural vulnerability to predation, Dreissena can be an important food source for predators. I studied the effects of disturbance (meaning removal, shell damage, or both) of the mussel on its vulnerability to predation in two settings: controlled aquarium experiments with the Rusty Crayfish (Orconectes rusticus) as sole predator, and open water feeding trials in Douglas Lake, Michigan, USA. In both settings, both removal or and damage to zebra mussel shells increased their vulnerability, shell damage having the greatest effect. This effect was more pronounced in the laboratory than in the lake, probably owing to the presence in the lake of alternative prey, greater relevant water volume, and predators with different feeding habitas than O. rusticus. While Dreissena can provide an important food resource for molluscivores, its availability is an important limiting consideration when assessing potential predation impacts.