Feeding by the calanoid copepods Acartia spp. on the heterotrophic dinoflagellates Gyrodinium jinhaense, G. dominans, and G. moestrupii

Abstract

Gyrodinium jinhaense and G. moestrupii were described within the past two decades, but the interactions between these two Gyrodinium species and copepods remain to be studied. To elucidate these interactions, the ingestion rate of the calanoid copepods Acartia spp. feeding on G. jinhaense, G. dominans, and G. moestrupii was determined. The maximum ingestion rates of A. hongi/A. omorii on G. jinhaense and G. dominans (3680 and 3480 ng C predator(-1)d(-1), respectively) were similar, but they were considerably higher than that on G. moestrupii (1600 ng C predator(-1)d(-1)). The largest size and fastest swimming speed of G. moestrupii may be partially responsible for this lowest maximum ingestion rate. The ingestion rates of A. hongi/A. omorii on G. jinhaense, G. dominans, and G. moestrupii at the prey concentrations of both 50 and 100 ng C mL(-1) were higher than those on the heterotrophic dinoflagellates Pfiesteria piscicida and Luciella masanensis but lower than those on the heterotrophic dinoflagellates Stoeckeria algicida and Oxyrrhis marina. Therefore, G. jinhaense, G. dominans, and G. moestrupii are moderate heterotrophic dinoflagellate prey for Acartia spp.