An Observation of Primary Production Enhanced by Coastal Upwelling in the Southwest East/Japan Sea

초록

Coastal upwelling (CU) is an important process that causes changes in physical and chemical properties,resulting in variation of biological processes in a coastal area. In the southwestern part of the East/JapanSea (SWES), CU has been alleged as one of the mechanisms responsible for higher net primaryproduction (NPP) than the rest of the East/Japan Sea. We provide, for the first time, high spatialresolution underway observations of sea surface temperature, salinity, chlorophyll-a fluorescence andΔ(O2/Ar), revealing the physical and biological characteristics of the upwelled waters in the SWES. Thecold, upwelled waters retained high fluorescence and Δ(O2/Ar), consistent with enhanced phytoplanktonbiomass and biological O2 production by CU. The net community production (NCP) in the ambient andupwelled waters were 33 ± 19 and 77 ± 41 mmol O2 m-1 d-1, respectively. The latter should beconsidered as a lower bound, containing a significant fraction of low O2 waters from subsurface. Satelliteobservation indicated that NPP in the upwelled waters were higher than the ambient waters by 51%.This implies that up to half of higher NPP in the SWES than the rest of the East/Japan Sea can beascribed to CU events.