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Photosynthesis‐Irradiance Response in the Eddy Dipole in the Western South China Sea
Author(s) -
Liao Jianzu,
Xu Jie,
Li Ruihuan,
Shi Zhen
Publication year - 2021
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1029/2020jc016986
Subject(s) - eddy , phytoplankton , environmental science , atmospheric sciences , chlorophyll a , irradiance , oceanography , mesoscale meteorology , sea surface temperature , eddy covariance , photic zone , photosynthesis , geology , physics , nutrient , meteorology , ecosystem , biology , ecology , optics , botany , turbulence
Photosynthesis‐irradiance (P‐E) parameters, such as the maximum photosynthetic rate ( P m B ) and maximum light utilization coefficient ( α ), are key parameters of primary production (PP) models. It is necessary to understand the response of P‐E parameters to mesoscale eddies to accurately model PP in eddies. The P‐E parameters and phytoplankton communities were examined at the surface and the deep chlorophyll maximum (DCM) of the eddy dipole in the western South China Sea. The surfaceP m Bdiffered significantly between the edge and center of both eddies. TheP m Bat the center was significantly higher than that at the edge of the cyclonic eddy (CE), while the opposite trend was observed in the anticyclonic eddy (AE). Phytoplankton community composition modulated variability in P‐E parameters in the eddy dipole. Over 75% of the variance in surface P‐E parameters could be explained by the pico‐phytoplankton communities and environmental factors (nutrients and temperature). In contrast, the ratio of Synechococcus abundance to chlorophyll a concentration was primarily responsible for the variability in P‐E parameters at the DCM. These relationships allowed us to modelP m Band α at all stations and depths sampled. The integrated primary production (IPP) determined from these modeled P‐E parameters was coincident with the IPP determined from on‐deck incubations. The modeledP m B‐ α ‐based IPP exhibited a higher IPP at the CE center than that at the AE center. Our findings can improve the parameterization of the physical‐biogeochemical coupling models of eddies.