Eating your competitor: on the triangle between turbulence, copepod escape behaviour and predation from mussels

Clearance on different stages of the calanoid copepod Acartia tonsa by blue mussels Mytilus edulis was measured at different turbulence intensities. Turbulence enhanced consumption of all stages of the calanoid copepod A. tonsa by the benthic suspension feeder M. edulis, although with significant ontogenetic differences. Clearance on eggs increased significantly with turbulence; without turbulence, eggs sank to the bottom of the experimental cylinder and became unavailable to the mussels. In general, adult copepods escaped a filtrating mussel better than nauplii and copepodites. Experiments showed that the presence of copepodites and adult copepods reduced mussel clearance rate. The present study documents the interaction between turbulence and mussel predation on copepods and illustrates the potential of benthic suspension feeders in shaping the pelagic food web.