Aspects of grazing behaviour of the marine dinoflagellate Oxyrrhis marina, Dujardin
Year: 1991
Type: dissertation
Abstract: The feeding biology and aspects of the grazing behaviour of the dinoflagellate Oxyrrhis marina were studied in a variety of laboratory-based experiments. Video studies on the mode of prey capture revealed that it involved primary capture via Oxyrrhis' transverse flagellum. Further entanglement in the transverse flagellum brought the prey close to the body where trichocysts were ejected to hold the prey while it was phagocytosed. Phagocytosis occurred all over the flagellar and of the body, not being limited to the sulcal region. Capture and ingestion time was dependent on the size of prey, large (20μm) particles taking longer to capture and ingest than small (1μm) particles. Grazing studies were carried out a wide range of autotrophs in batch culture. Food selection experiments identified the ability of Oxyrrhis to discriminate between live prey and inert spheres of the same size, but only after most of the spheres had first been ingested, indicating a form of learning process. Grazing in mixed autotroph populations also indicated selection for a certain autotroph, the cryptomonad Rhodomonas sp. being grazed more heavily than the prasinophyte Tetraselmis suecica and the diatom Phaeodactylum tricornutum. The grazing ability of Oxyrrhis was affected by its nutritional history. Oxyrrhis prefed with T.suecica or Pyramimonas obovata grazed and grew less well than Oxyrrhis prefed with Dunaliella tertiolecta, Rhodomonas sp. or Hemiselmis rufescens. Food quality, in terms of nitrogen available was not found to affect Oxyrrhis growth efficiency but was found to influence growth. The total carbon available was important, both in terms of Oxyrrhis growth and growth efficiency. At low prey biovolumes (< 60x106μm^3 ml^-1) the increase in Oxyrrhis biovolume due to grazing was greater than the biovolume of prey available, indicating that osmotrophy might play a significant role in Oxyrrhis nutrition.
Author: Tarran, G.A
Language: English
Domain: Life Sciences
SDG: Life below water
Open Access status: green
OpenAlex ID: W6989423214