Linking Movement to Feeding Behavior in Gyrodinium spirale: Does Prey Type Matter?

Microzooplankton (<200 µm) are significant grazers of primary production and thus play an important role in oceanic food webs. The athecate dinoflagellate Gyrodinium spirale is known to feed on a wide range of prey items including much larger chain-forming diatoms. Grazing experiments were combined with behavioral studies to investigate the feeding response of G. spirale to different prey. Swimming behavior and population distribution of G. spirale exposed to chemical prey stimuli were tracked via high-resolution video analysis. Maximum growth rate of G. spirale was higher when fed the dinoflagellate Heterocapsa triquetra (0.46 d^-1) versus the diatom Skeletonema maranoi (0.19 d^-1). G. spirale had a higher maximum ingestion rate (4.48 ng C grazer^-1 d^-1) when fed H. triquetra. Responses of G. spirale to different prey stimuli will help identify potential prey-specific movement and feeding behavior. Determining prey preference of G. spirale through swimming metrics and growth and ingestion rates may help to infer feeding strategies in situ.