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    Community Structure of copepods in epipelagic layers in the Ross Sea and neighboring waters

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    Y. Watanabe, S. Sawamoto, T. Ishimaru and M. Naganobu (Japan)

    During the 9th research cruise of the R/V Kaiyo-maru, copepod samples were collected from three layers between the surface and 200 m with RMT 8m2 along the three longitudinal lines in the Ross Sea and its neighboring waters. Twenty three copepod species belonging to 13 families were identified and 8 unidentified taxa appeared in the study area. Samples were categorized into four major groups by cluster analysis based on species abundance and composition. Group 1 located in the north of the Southern Boundary of the Antarctic Circumpolar Current was characterized by high abundance (157.5-2279.5; mean 610.5 inds. 1000 m-3) and dominance of Rhincalanus gigas (mean 88.4%). Group 2 located off the Ross Sea (175°E; north of 72°S, 170°W; north of 75°S) was characterized by high abundance (22.6-1542.1; mean 301.9 inds. 1000 m-3) and high composition of Calanus plopinquus (mean 19.0%), Rhincalanus gigas (mean 23.2%) and Calanoides acutus (mean 38.7%). Group 3 and 4 located in the Ross Sea (175°E; south of 72°S, 170°W; south of 75°S) were characterized with low abundances (2.6-5.2; mean 3.6 inds. 1000 m-3, 6.5-50.6; mean 18.5 inds. 1000 m-3).