Feeding by the newly-described heterotrophic dinoflagellate Gyrodinium jinhaense: comparison with G. dominans and G. moestrupii

Abstract

Heterotrophic dinoflagellates are major grazers of microalgae in marine food webs. The feeding of the newly described heterotrophic dinoflagellate Gyrodinium jinhaense was explored by providing 19 common microalgal prey species and the ciliate Mesodinium rubrum as prey. Furthermore, the specific growth and ingestion rates of G. jinhaense feeding on the chlorophyte Dunaliella salina were determined as a function of prey concentration. Cells of G. jinhaense were able to feed on microalgae of sizes ≤ 26 μm with the exception of the dinoflagellate Karenia mikimotoi. In contrast, G. jinhaense did not feed on microalgae > 26 μm with the exception of the dinoflagellate Lingulodinium polyedra. With increasing mean prey concentration, both the specific growth and ingestion rates of G. jinhaense feeding on D. salina rapidly increased at mean prey concentrations < 504 ng C mL−1 (6300 cells mL−1), but slowly at higher prey concentrations. The maximum growth and ingestion rates of G. jinhaense feeding on D. salina were 0.655 day−1 and 0.82 ng C predator−1 day−1 (10 cells predator−1 day−1), respectively. Gyrodinium dominans and G. moestrupii are able to feed on most microalgal prey species, including the species that G. jinhaense did not feed on. Moreover, these two Gyrodinium species have positive growth rates when feeding on the red-tide dinoflagellates Prorocentrum cordatum and Scrippsiella acuminata, which did not support growth of G. jinhaense. Therefore, G. jinhaense has an ecological niche different from that of G. dominans and G. moestrupii, and this pattern may be the result of evolution among these Gyrodinium species. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.