16:15 〜 16:30
[SCG52-19] トカラ列島における黒潮の底層環境と底生生物相への影響
キーワード：貝形虫、黒潮、トカラ列島、生物地理
A well-known biogeographic boundary, Watase-line, is recognized between Kodakarajima and Akusekijima Islands, Japan (Komaki, 2021). This boundary is placed on the Tokara gap (submarine canyon), and it is essential for understanding the biogeography. We studied the modern ostracodes in the Tokara gap and the adjacent seas as indicators of submarine- ecosystem, and biodiversity. This study examined the ostracode assemblages in surface sediments collected by GB21-1 and GB21-3 cruise (AIST).
As a result, most ostracods were subtropical and tropical water species reported from the East China Sea (Ruan and Hao, 1988; Hou and Gou, 2007). This study conducted statistical analyses using the spatial distribution information of modern ostracodes in the research area. It is suggested that the modern distribution of ostracode biofacies is unchanged between the Kodakarajima and Akusekijima Islands. We compared ostracode fauna and several bottom-environmental factors (e.g., mud content, water temperature, salinity, turbidity, DO, and pH), and the fauna tended to vary with the mud content. Tokara Islands are under the strong influence of the Kuroshio (Nagai et al., 2021). Thus, we compared Kuroshio intensity with the distribution of bottom sediments. As a result, the fine sediments were restricted in the low-velocity regions. Kuroshio intensity likely affects the sedimentary environments and benthos around the Tokara gap.
References
Hou, Y. and Gou, Y. (2007) Fossil Ostracoda of China (Vol .2) Cytheracea and Cytherellidae. 798pp, Science Pub, Beijing. (in Chinese with English abst.)
Komaki, S. (2021) Widespread misperception about a major East Asian biogeographic boundary exposed through bibliographic survey and biogeographic meta-analysis. Journal of Biogeography, 48, 2375–2386.
Nagai, T., Hasegawa, D., Tsutsumi, E., Nakamura, H., Nishina, A., Senjyu, T., Endoh, T., Matsuno, T., Inoue, R. and Tandon, A. (2021) The Kuroshio flowing over seamounts and associated submesoscale flows drive 100-km-wide 100-1000- fold enhancement of turbulence. Communications earth & environment, 2, 170.
Ruan, P. and Hao, Y. (1988), Ⅱ. Descriptions of ostracode genera and species. In Research Party of Marine Geology, Ministry of Geology and Mineral Resources and Chinese University of Geosciences eds., Quaternary Microbiotas in the Okinawa Trough and Their Geological Significance, Geological Publishing House, Beijing. 227–395, 33–74. (in Chinese)
As a result, most ostracods were subtropical and tropical water species reported from the East China Sea (Ruan and Hao, 1988; Hou and Gou, 2007). This study conducted statistical analyses using the spatial distribution information of modern ostracodes in the research area. It is suggested that the modern distribution of ostracode biofacies is unchanged between the Kodakarajima and Akusekijima Islands. We compared ostracode fauna and several bottom-environmental factors (e.g., mud content, water temperature, salinity, turbidity, DO, and pH), and the fauna tended to vary with the mud content. Tokara Islands are under the strong influence of the Kuroshio (Nagai et al., 2021). Thus, we compared Kuroshio intensity with the distribution of bottom sediments. As a result, the fine sediments were restricted in the low-velocity regions. Kuroshio intensity likely affects the sedimentary environments and benthos around the Tokara gap.
References
Hou, Y. and Gou, Y. (2007) Fossil Ostracoda of China (Vol .2) Cytheracea and Cytherellidae. 798pp, Science Pub, Beijing. (in Chinese with English abst.)
Komaki, S. (2021) Widespread misperception about a major East Asian biogeographic boundary exposed through bibliographic survey and biogeographic meta-analysis. Journal of Biogeography, 48, 2375–2386.
Nagai, T., Hasegawa, D., Tsutsumi, E., Nakamura, H., Nishina, A., Senjyu, T., Endoh, T., Matsuno, T., Inoue, R. and Tandon, A. (2021) The Kuroshio flowing over seamounts and associated submesoscale flows drive 100-km-wide 100-1000- fold enhancement of turbulence. Communications earth & environment, 2, 170.
Ruan, P. and Hao, Y. (1988), Ⅱ. Descriptions of ostracode genera and species. In Research Party of Marine Geology, Ministry of Geology and Mineral Resources and Chinese University of Geosciences eds., Quaternary Microbiotas in the Okinawa Trough and Their Geological Significance, Geological Publishing House, Beijing. 227–395, 33–74. (in Chinese)