Sublethal effects of the toxic dinoflagellate Karenza brevis on marine copepod behavior

Apart from grazing interactions, little is known regarding the sublethal effects of Karenia brevis cells on copepod behavior We conducted grazing and mortality experiments with K. brevis cells and brevetoxins (PbTx-2), establishing routes of toxicity for the copepods Acartia tonsa, Temora turbinata and Centropages typicus. Subsequent behavioral experiments determined whether copepod swimming and photobehavior both behaviors involved in predator avoidance, were impaired at sublethal K. brevis and PbTx-2 levels. Copepods variably grazed toxic K. brevis and non-toxic Prorocentrum minimum at bloom concentrations. Although copepods accumulated brevetoxins, significant mortality was only observed in T turbinata at the highest test concentration (1 X 10(7) K. brevis cells L-1). Acartia tonsa exhibited minimal sublethal behavioral effects. However, there were significant effects on the swimming and photobehavior of T turbinata and C. typicus at the lowest sublethal concentrations tested (0. 15 mu g PbTx-2 L-1, I X 105 K. brevis cells L-1). Although physiological incapacitation may have altered copepod behavior, starvation likely played a major role as well. These data suggest that sublethal effects of K. brevis and brevetoxin on copepod behavior occur and predicting the role of zooplankton grazers in trophic transfer of algal toxins requires knowledge of species-specific sublethal effects.