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General Session 3: Biological oceanography & global change |
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Group-specific growth and grazing rates for phytoplankton in the South China Sea basin
GS3-37
Xin Liu* , State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, Fujian, China
Siyu Jiang, State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, Fujian, China
Bangiqn Huang, State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, Fujian, China
Presenter Email: liuxin1983@xmu.edu.cn
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| The grazing of microzooplankton on phytoplankton is the main factor to maintain the high growth rate and low biomass of phytoplankton in the ocean, and also has important impacts on marine biogeochemical cycles. However, the variations and regulatory mechanism on group-specific growth and grazing mortality rates for phytoplankton are still unclear. Here, we report the comparisons on the growth and grazing mortality rates between different phytoplankton groups, and their relationships with environment factors in the northern South China Sea basin. Using the microscope method and dilution experiment combined with flow cytometry and high performance liquid chromatography techniques, community structure of microzooplankton and phytoplankton, phytoplankton growth and microzooplankton grazing rates were studied. The correlations among the growth rates of picophytoplankton were significant, while the growth rates of Prochlorococcus and Synechococcus were the highest in the summer and spring, respectively. Besides, the correlations of the grazing mortality rates among them were also significant but no significant difference was found. Positive correlations between growth and grazing mortality rates of five dominant phytoplankton groups (diatoms, haptophytes_6, haptophytes_8, Synechococcus and Prochlorococcus) were found. However, the grazing rates on prokaryotic phytoplankton were only positively correlated with prokaryotic phytoplankton and those of eukaryotic phytoplankton were also just positively correlated with themselves. These results indicate different microzooplankton grazing processes on prokaryotic and eukaryotic phytoplankton. |
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