Journal of Oceanography, Vol. 61 (No. 5), pp. 857-869, 2005
Keiko Yamada1, Joji Ishizaka2* and Hiroshi Nagata3
1Graduate School of Science and Technology, Nagasaki University, Bunkyo, Nagasaki 852-8521, Japan
2Faculty of Fisheries, Nagasaki University, Bunkyo, Nagasaki 852-8521, Japan
3Seikai National Fisheries Research Institute, Fisheries Research Agency, Taira, Nagasaki 851-2213, Japan
(Received 17 June 2004; in revised form 24 January 2005; accepted 25 January 2005)
Abstract: The spatial and seasonal variability of primary production in the Japan Sea from 1998 to 2002 was estimated using a satellite primary production model. A size-fractionated primary production model was validated by In situ primary production data measured in the Japan Sea. Estimated primary production and In situ primary production showed a good positive correlation. Estimated primary production showed spatial variability. Annual primary production levels were 170, 161, 191 and 222 gC m-2year-1 at the Russian coast, in the middle of the Japan Basin, the southeastern area and the southwestern area, respectively. It was higher to the south around 40°N than to the north, and higher in the western area than in the eastern one. Peaks of primary production appeared twice, in spring and fall, in the southern area, while a single peak appeared in the northern area. Primary production along the Russian coast was higher than in other areas during summer. The spring bloom contributed 42% to the annual primary production in these four areas. Furthermore, estimated primary production showed an interannual variability that was largest in spring. Primary production in fall also showed interannual variability, especially in the middle of the Japan Basin and the southwestern area. This corresponded mainly to the size of the phytoplankton bloom in each year. Winter convection by wind and the depth of nutrient-rich, cold subsurface water underlying the Tsushima Current may contribute to the nutrient supply to upper layer and interannual variations of primary production in spring.