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Biological Response to the Interaction of a Mesoscale Eddy and the River Plume in the Northern South China Sea
Author(s) -
Geng Bingxu,
Xiu Peng,
Liu Na,
He Xianqiang,
Chai Fei
Publication year - 2021
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1029/2021jc017244
Subject(s) - plume , upwelling , oceanography , bloom , geology , mesoscale meteorology , phytoplankton , biogeochemical cycle , pearl , algal bloom , environmental science , nutrient , meteorology , ecology , geography , archaeology , biology
The Pearl River delivers a large amount of freshwater, sediments and nutrients to the northern shelf of the South China Sea (SCS). In June 2015, an anomalously strong phytoplankton bloom was captured by satellite images in the slope region of the northern SCS, which was associated with the southeastward spreading of the river plume on the shelf and a southwestward‐moving eddy along the slope. In this study, the underlying dynamics triggering the bloom was investigated using a coupled physical‐biogeochemical model. Results show that the nutrients supporting the bloom were not directly sourced from the Pearl River, but were transported locally from subsurface. The eddy cross‐slope current advected low salinity water from the Pearl River plume, which interacted with eddy edge and enhanced frontal dynamics with vertical motions. The front‐induced upwelling injected nutrients from subsurface to surface layer and stimulated phytoplankton bloom in the upper layer. Overall, the phytoplankton bloom was attributable to the interaction of freshwater plume on top and the eddy edge induced anomaly in the subsurface. These findings suggest that the eddy‐entrained freshwater could have significant biological consequences through modifying local dynamics in the plume‐influenced region.