Can domoic acid affect escape response in copepods?

Abstract

Copepods are important grazers on toxic phytoplankton and serve as vectors for algal toxins up the marine food web. Success of phytoplankton depends among other factors on protection against grazers like copepods, and same way copepod survival and population resilience relies on their ability to escape predators. Little is, however, known about the effect of toxins on the escape response of copepods. In this study we experimentally tested the hypothesis that the neurotoxin domoic acid (DA) produced by the diatom Pseudo-nitzschia affects escape responses of planktonic copepods. We found that the arctic copepods Calanus hyperboreus and C. glacialis reduced their escape response after feeding on a DA-producing diatom. The two species were not affected the same way; C. hyperboreus was affected after shorter exposure and less intake of DA. The negative effect on escape response was not related to the amount of DA accumulated in the copepods. Our results suggest that further research on the effects of DA on copepod behavior and DA toxicity mechanisms is required to evaluate the anti-grazing function of DA.