Distribution of polycystine Radiolaria, Phaeodaria and Acantharia in the Kuroshio Current off Shikoku Island and Tosa Bay during Cruise KT07-19 in August 2007




The occurrences of polycystine Radiolaria, Phaeodaria, and Acantharia are reported from plankton net samples, which were obtained in the transect covering from the Kuroshio Current off Shikoku Island to Tosa Bay during Cruise KT07-19 in August 2007. We employed 100 μm as the mesh size of the plankton nets, which was coarser than the mesh size of many recent radiolarian studies (e.g., 44 or 63 μm). The obtained specimens in the samples were categorized into 130 polycystine radiolarian, and 17 phaeodarian, and 3 acantharian taxa. The marked similarity of the polycystine radiolarian assemblages encountered in this study to those reported from the tropical and subtropical oceans in the literature clearly indicates the significant influence by the warm Kuroshio Current. Furthermore, the observed polycystine radiolarian assemblages are similar to those of the previous result from the same specific study area. However, the vertical distribution patterns of some of the major polycystine radiolarian and phaeodarian taxa are different from the previous results from the same region. The differences in vertical distribution may be primarily due to the differences in vertical water mass conditions due to different sampling seasons. In spite of the lengthy sample storage for seven months after the sampling in the shore laboratory, many acantharian specimens were still preserved and encountered in the laboratory census, representing the acantharian presence in the summer sea surface waters in the Kuroshio Current area.


  • 九州大学大学院理学研究院紀要 : Series D, Earth and planetary sciences

    九州大学大学院理学研究院紀要 : Series D, Earth and planetary sciences 32(3), 39-61, 2011-03-10

    Faculty of Science, Kyushu University


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