Morphology and distribution of heterotrophic protists along 75゜E in the Southern Ocean

• Main Authors: Shigemitsu Hara, Eiichiro Tanoue, Michio Zenimoto, Yuzo Komaki, Eiji Takahashi
• Format: Report
• Language: English
• Published: Division of Environmental Science, The Graduate School of Science and Technology, Kobe University/Division of Environmental Science, The Graduate School of Science and Technology, Kobe University/Faculty of Applied Biological Science, Hiroshima University/Far Seas Fisheries Research Laboratory/Department of Biology, Faculty of Science, Kobe University 1986
• Subjects: Antarctic; Austral; Indian; Southern Ocean; Antarc*; Memoirs of National Institute of Polar Research; Polar Research
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=1877; http://id.nii.ac.jp/1291/00001877/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=1877&item_no=1&attribute_id=18&file_no=1

Seawater samples were collected from the 0 and 50m layers along the transect of 75°E in the Indian sector of the Southern Ocean in the austral summer of 1983-84 during the BIOMASS SIBEX I cruise of the R. V. KAIYO MARU of Japan Fisheries Agency. Distribution and taxonomy of heterotrophic protists were investigated. Naked amoebae and choanoflagellates were the dominant heterotrophic protists in the Indian sector of the Southern Ocean. The total cell volume of heterotrophic protists was larger at 50m than at 0m. The ratio of the cell volume of heterotrophic protists to the total cell volume (heterotrophic and autotrophic protists) was found to be reverse correlation to the total cell volume in the 0m layer. Species of choanoflagellates invested in siliceous loricae (Acanthoecidae) were distributed only in the 0m layer. Choanoflagellates invested in organic sheaths (Salpingoecidae), naked choanoflagellates (Codonosigidae) and amoebae were distributed in both 0 and 50m layers. Importances of choanoflagellates and amoebae in the detritus food chain in the pelagic Antarctic ecosystem were suggested. Three species of choanoflagellates, Monosiga ovata KENT, Pleurasiga cupula LEADBEATER and Savillea parva (ELLIS) LOEBLICH, were firstly reported from the Southern Ocean.