Feeding by common heterotrophic protists on the phototrophic dinoflagellate Biecheleriopsis adriatica (suessiaceae) compared to that of other suessioid dinoflagellates

Abstract

The species in the dinoflagellate order Suessiales have 5-24 latitudinal paraplate series and include many fossil and extant species. There have been a few studies on the ecophysiology of the phototrophic species Biecheleriopsis adriatica, and no study on its predators. Thus, we explored the feeding occurrence by common heterotrophic protists on B. adriatica and the growth and ingestion rates of the heterotrophic dinoflagellate Oxyrrhis marina on B. adriatica BATY06 as a function of prey concentration. The common heterotrophic dinoflagellates Aduncodinium glandula, O. marina, Gyrodinium dominans, Gyrodinium moestrupii, Luciella masanensis, Pfiesteria piscicida, and Oblea rotunda and two naked ciliates Strombidinopsis sp. and Pelagostrobilidiutn sp. were able to feed on B. adriatica, but the heterotrophic dinoflagellate Polykrikos kofoidii was not. However, B. adriatica supported the positive growth of O. marina, but did not support that of G. dominans and O. rotunda. With increasing prey concentrations, the growth and ingestion rates of O. marina on B. adriatica increased and became saturated. The maximum growth rate of O. marina on B. adriatica was 0.162 d(-1). Furthermore, the maximum ingestion rate of O. marina on B. adriatica was 0.2 ng C predator(-1) d(-1) (2.0 cells predator(-1) d(-1)). In the order Suessiales, the feeding occurrence by common heterotrophic protists on B. adriatica is similar to that on Effrenium voratum and Biecheleria cincta, but different from that on Yihiella yeosuensis. However, the growth and ingestion rates of O. marina on B. adriatica are considerably lower than those on E. voratum and B. cincta, but higher than those on Y. yeosuensis. Therefore, B. adriatica may be less preferred prey for O. marina than E. voratum and B. cincta, but more preferred prey than Y. yeosuensis.