Seasonal variability of surface phytoplankton in the Northern South China Sea: A one-dimensional coupled physical-biogeochemical modeling study

Geng, Bingxu; Li, Shiyu; Wang, Dongxiao; Hu, Jiatang; Luo, Lin; Wang, Siying

doi:10.1080/14634988.2012.689600

Cited by 7 publications

(3 citation statements)

References 23 publications

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“…The comparison between modeled and remotely sensed SChl is similar to that shown in Geng et al (2012), who used the same model configuration at SEATS. Here we also show comparisons of model results and in situ observations.…”

Section: Modeled Distributions In the Northern And Central Scssupporting

confidence: 61%

“…driven by local processes, especially on a seasonal time scale (e.g., Du et al, 2017;Li et al, 2015;Tseng et al, 2009). Previous 1D modeling studies conducted for the SCS basin have been able to simulate the vertical structures of biogeochemical variables reasonably well (e.g., Geng et al, 2012;Gong et al, 2014;Li et al, 2015).…”

Section: Uncertainties In the Modelmentioning

confidence: 99%

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Evaluating the Roles of Wind‐ and Buoyancy Flux‐Induced Mixing on Phytoplankton Dynamics in the Northern and Central South China Sea

et al. 2019

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Observations from two Bio-Argo floats deployed in the northern and central South China Sea (SCS) show distinct seasonal patterns of vertical chlorophyll distribution. There is a permanent subsurface chlorophyll maximum (SCM) located between 60 and 80 m throughout the year and a weak seasonality of surface chlorophyll in the central SCS. In the northern SCS, the SCM shoals to the upper mixed layer in winter and surface phytoplankton shows a clear winter bloom pattern. The mechanism driving the spatial and seasonal differences in phytoplankton dynamics in the euphotic zone remains unclear. Here a coupled physical-biological model is developed and applied to the northern and central SCS. With model and satellite data, we show that the contrasting patterns in chlorophyll are induced by the spatial variability in winter mixing dynamics. In the northern SCS, the buoyancy flux-induced mixing plays a dominant role in controlling the seasonal variability of vertical nutrient transport and phytoplankton production, which leads to the peak of surface chlorophyll and the significant shoaling of the SCM in winter. In the central SCS, the intensity of the buoyancy flux is reduced and both buoyancy fluxand wind-induced mixing control the winter mixing dynamics. However, the combination of these two mixing processes is weaker than in the northern SCS and the vertical nutrient transport is limited to the layer above the SCM, resulting in the reduced seasonality of surface chlorophyll and the relatively stable SCM all year round in the central SCS.Plain Language Summary Both satellite and Bio-Argo floats show a significant increase of surface chlorophyll concentration in winter in the northern South China Sea (SCS) but a very weak seasonal change in the central SCS. We used a coupled physical-biological model to systematically study the mechanism driving these spatial and seasonal differences. The model can reasonably simulate the different chlorophyll distribution patterns identified by observations. We found that the buoyancy flux-induced mixing plays a dominant role in controlling the seasonal change of chlorophyll in the northern SCS. In the central SCS, both buoyancy fluxand wind-induced mixing control the winter mixing dynamics. However, the combination of these two mixing dynamics is not as strong as that in the northern SCS and the vertical nutrient transport is only limited to the layer above the SCM, resulting in the reduced seasonality of surface chlorophyll and the relatively stable SCM all year round in the central SCS.

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Section: Modeled Distributions In the Northern And Central Scssupporting

confidence: 61%

Section: Uncertainties In the Modelmentioning

confidence: 99%

Evaluating the Roles of Wind‐ and Buoyancy Flux‐Induced Mixing on Phytoplankton Dynamics in the Northern and Central South China Sea

et al. 2019

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“…Oceanographic processes cause strong spatiotemporal variations of physical and biogeochemical factors, forming sharp gradients between rivers and the ocean, which eventually determine phytoplankton distribution in terms of biomass and community composition (Cullen et al, 2002;Margalef, 1978). Many studies have focused on phytoplankton dynamics in systems that are mainly controlled by riverine inputs, including the East China Sea (eg., Chen et al, 2003;Gao & Song, 2005;Zhou et al, 2017;Zhu et al, 2009), Baltic Sea (eg., Lips et al, 2014;Stipa, 2004;Tamminen & Andersen, 2007;Wasmund et al, 1998), Chesapeake Bay (eg., Adolf et al, 2006;Harding, 1994;Jiang & Xia, 2017), northern South China Sea (eg., Chen et al, 2004;Geng et al, 2012Geng et al, , 2019Pan et al, 2015), and northern Gulf of Mexico (eg., Bargu et al, 2016;Camacho et al, 2014;Lohrenz et al, 1997Lohrenz et al, , 2008. The mechanisms controlling the algal blooms can be generalized as physical and biological controls.…”

Section: Introductionmentioning

confidence: 99%

Phytoplankton Blooms off a High Turbidity Estuary: A Case Study in the Changjiang River Estuary

Wang

Lin

et al. 2019

JGR Oceans

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The occurrence of phytoplankton blooms in estuarine and coastal waters is codetermined by the export of fluvial nutrients and other water properties such as turbidity. In this study, the Changjiang River Estuary was used as an example to investigate the intrinsic link between river plume dynamics, riverine nutrient loading, suspended sediment concentration, and phytoplankton blooms with a coupled hydrodynamic-sediment-ecosystem numerical model. Suspended sediment concentration from the sediment module was used to parameterize light attenuation in waters, which, in association with river plume dynamics, was found to impact phytoplankton distribution. Data that was collected in situ, in addition to satellite data for chlorophyll, nutrients, and suspended sediments, were used to validate the model, which performed well. The surface high chlorophyll centers exhibited a patch-like pattern from the northeast to the south off the Changjiang River mouth. The high chlorophyll concentration within the river plume was mainly determined by riverine nutrient exports, and potential phosphate limitation occurred away from the river mouth. The chlorophyll concentration decreased dramatically shoreward of the sediment front, which was controlled by the bottom river plume front. The bottom plume front was an intrinsic feature of the Changjiang River plume and similar river plume systems, which set a boundary separating the well-mixed (turbid) nearshore waters and stratified (clear) offshore waters. Without considering the sediment shading effect, the model yielded an unrealistic chlorophyll distribution with artificially high values in the turbid area. This indicated that light attenuation was a key factor limiting phytoplankton blooms in turbid river estuaries.Plain Language Summary In estuaries and coastal waters, the aquatic environment is affected by both riverine nutrient input and water properties such as turbidity. The associated river plume may play an essential role in controlling water properties, thus influencing the aquatic environment such as the algal blooms. In the current study, a well-validated hydrodynamic-sediment-ecosystem model was used to simulate phytoplankton blooms and the dynamic link with the Changjiang River plume. The results showed that the surface suspended sediment front was of vital importance in determining the shoreward boundary of the phytoplankton bloom area. Light attenuation due to high turbidity became a major factor limiting phytoplankton blooms in turbid nearshore waters. In environments with a strong tidal influence, the surface suspended sediment front was closely related to the bottom river plume front, which gave rise to differences in water stabilization and thus resulted in turbid conditions on either side. The results of this study provided a good reference for understanding the phytoplankton distribution characteristics in estuaries with high turbidity.

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Influence of mesoscale eddies on primary production in the South China Sea during spring inter-monsoon period

Tan

Song

et al. 2014

Acta Oceanol. Sin.

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Seasonal variability of surface phytoplankton in the Northern South China Sea: A one-dimensional coupled physical-biogeochemical modeling study

Abstract: The South China Sea is an oligotrophic marginal sea located in the tropical-subtropical Northwestern

Cited by 7 publications

References 23 publications

Evaluating the Roles of Wind‐ and Buoyancy Flux‐Induced Mixing on Phytoplankton Dynamics in the Northern and Central South China Sea

Evaluating the Roles of Wind‐ and Buoyancy Flux‐Induced Mixing on Phytoplankton Dynamics in the Northern and Central South China Sea

Phytoplankton Blooms off a High Turbidity Estuary: A Case Study in the Changjiang River Estuary

Influence of mesoscale eddies on primary production in the South China Sea during spring inter-monsoon period

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