Detailed vertical distribution of radiolarian assemblage (0-3000 m, fifteen layers) in the central subarctic Pacific, June 2006
The vertical distribution of radiolarians was investigated by using plankton nets with 63 $ mu $m mesh in the central subarctic Pacific (Station OS06-SA) from the surface down to 3000 m depth, which were divided into fifteen sample layers. These samples were obtained in June 2006. Radiolarian standing stocks were high in the 0-250 m interval, and they generally decreased with increasing depth. The maximum standing stocks of living radiolarians occurred in the 75-100 m depth interval. The radiolarian production is likely to be associated with temperature and dissolved oxygen. A total of 80 taxa were encountered: 33 Spumellaria, 32 Nassellaria, and 15 Phaeodaria. Six radiolarian groups were identified based on R-mode cluster analysis: Group 1: surface dwellers (0-250 m), Group 2: the taxa with pronounced abundance peaks in the 75-150 m, Group 3: subsurface to upper intermediate dwellers (750-500 m), Group 4: lower intermediate dwellers (500-1000 m), Group 5: the taxa with relatively high abundance in the 1000-2000 m; and Group 6: lower deep dwellers (2000-3000 m).
九州大学理学部紀要 32(1), 49-72, 2007-02-01