Predation vulnerability of planktonic copepods: consequences of predator foraging strategies and prey sensory abilities

We investigated the vulnerability of 2 copepod species (Eurytemora affinis and Temora longicornis) to predation by predators with different foraging modes, three-spined stickleback Gasterosteus aculeatus juveniles and mysid shrimps Neomysis integer. Copepods were videofilmed escaping from predators and from an artificial flow field, and the results were used in a model of hydrodynamic disturbance generated by a predator. The copepods detected mysids from a significantly larger distance than they detected sticklebacks (0.45 and 0.24 cm, respectively). Consequently, the capture success of the sticklebacks was higher than that of mysids. In the case of sticklebacks foraging on E. affinis, copepod reaction distance was significantly correlated with stickleback approaching speed; sticklebacks captured a copepod only if they were able to slowly approach to within a strike distance of