Controls on the interannual variability of hypoxia in a subtropical embayment and its adjacent waters in the Guangdong coastal upwelling system, northern South China Sea

AbstractCoastal upwelling occurred along the west coast of Guangdong in the northern South China Sea during the summer of 2006. The effects of upwelling on the vertical and horizontal distributions of Prochlorococcus and Synechococcus were investigated. A distinct vertical temperature difference between the surface water and water at a depth of 30 m was observed in the coastal upwelling region. There was a clear spatial variability of temperature, and an increasingly obvious horizontal gradient was created from the coast to offshore waters. Picophytoplankton communities observed from the coast to offshore waters were significantly different. In the coastal upwelling waters, the picophytoplankton community was dominated by Synechococcus within the euphotic zone. Prochlorococcus dominated the picophytoplankton community in the euphotic zone in the non-upwelling region. This difference in the picophytoplankton community structure was due to different hydrodynamics. The results of canonical correspondence analysis demonstrate that temperature, salinity, and phosphate concentration may be important factors affecting the distribution of Prochlorococcus and Synechococcus.

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Physical modulation to the biological productivity in the summer Vietnam upwelling system

Ocean Science ◽

10.5194/os-14-1303-2018 ◽

2018 ◽

Vol 14 (5) ◽

pp. 1303-1320 ◽

Cited By ~ 4

Author(s):

Wenfang Lu ◽

Lie-Yauw Oey ◽

Enhui Liao ◽

Wei Zhuang ◽

Xiao-Hai Yan ◽

...

Keyword(s):

Kinetic Energy ◽

South China Sea ◽

Ocean Circulation ◽

South China ◽

Coastal Upwelling ◽

Coupled Model ◽

Biological Productivity ◽

High Productivity ◽

China Sea ◽

Upwelling System

Abstract. Biological productivity in the summer Vietnam boundary upwelling system in the western South China Sea, as in many coastal upwelling systems, is strongly modulated by wind. However, the role of ocean circulation and mesoscale eddies has not been elucidated. Here, we show a close spatiotemporal covariability between primary production and kinetic energy. High productivity is associated with high kinetic energy, which accounts for ∼15 % of the production variability. Results from a physical–biological coupled model reveal that the elevated kinetic energy is linked to the strength of the current separation from the coast. In the low production scenario, the circulation is not only weaker but also shows weak separation. In the higher production case, the separated current forms an eastward jet into the interior South China Sea, and the associated southern recirculation traps nutrients and favors productivity. When separation is absent, the model shows weakened circulation and eddy activity, with ∼21 % less nitrate inventory and ∼16 % weaker primary productivity.

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Physical Modulation to the Biological Productivity in the Summer Vietnam Upwelling System

10.5194/os-2018-9 ◽

2018 ◽

Author(s):

Wenfang Lu ◽

Enhui Liao ◽

Xiao-Hai Yan ◽

Lie-Yauw Oey ◽

Wei Zhuang ◽

...

Keyword(s):

Kinetic Energy ◽

South China Sea ◽

Ocean Circulation ◽

South China ◽

Coastal Upwelling ◽

Current System ◽

Coupled Model ◽

Biological Productivity ◽

China Sea ◽

Upwelling System

Abstract. Biological productivity in the summer Vietnam boundary upwelling system in the western South China Sea, as in many coastal upwelling systems, is strongly modulated by wind. However, the role of ocean circulation and mesoscale eddies has not been elucidated. Here we show a close spatio-temporal covariability between primary production and kinetic energy. High productivity is associated with high kinetic energy, which accounts for ~ 15 % of the production variability. Results from a physical-biological coupled model reveal that the elevated kinetic energy and intensified circulation can be explained by the separation of the upwelling current system. The separated current forms an eastward jet into the interior South China Sea, and the associated southern gyre traps nutrient and favors productivity. When separation is absent, the model shows weakened circulation and eddy activity, with ~ 21 % less nitrate inventory and ~ 16 % weaker primary productivity.

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