Distribution Of Living Coccolithophores And Phytoplankton Community In The South China Sea

The community of living coccolithophores in South China Sea from winter 2006 to summer 2007 were studied by this research, including species composition, dominant species, cell abundance, partical inorganic carbonate, spatial and temporal distribution, seasonal variation. This paper expounded the distribution of living coccolithophores and ti's influence to carbonate cycle of South China Sea.South China Sea is the biggest tropical marginal sea of western Pacific.It is wide and close relatively with own currents systems. There are many meso-scale eddies in these currents systems.There're low nutrition concentration in the surface water of South China Sea.Nutrition of the bottom water will be taken to the surface of sea by up-wellings which drived by the eddy and current system to be available to coccolithophores.21 living coccolithophores species were recognized by polarizing microscope from the community.In summer, the average cell abundance is about 3.30×10~3 cells per liter. The dominant species are Emiliania huxleyi, Gephyrocapsa oceanica, Florisphaera profunda, Umbellosphaera tenuis, Gephyrocapsa ericsonii, Syracosphaera pulchra. E. huxleyi and G. oceanica reached 36.14% and 35.53% by relative cell abundance respectively, both with high appear frequency. In winter, the average cell abundance reached 3.13×10~3 cells per liter,with the dominate species-Emiliania huxleyi, Gephyrocapsa oceanic, Florisphaera profunda, Umbellosphaera tenuis, Syracosphaera pulchra and Algirosphaera robusta. E. huxleyi and G. oceanica have the highest relative cell abundance 55.29% and 24.98% respectively.Coccolith carbon of living coccolithophores in South China Sea were calculated based on the theory of Young. In the upper 200m water column of summer South China Sea, the standing crop of coccolith carbon was between 0.18 mg C/m~2 to 39.78 mg C/m~2,with highest values occurring in the northern area. In the upper 200m water column of winter, the standing crop of coccolith carbon was between 0.19 mg C/m~2 and 23.51 mg C/m~2. The standing crop of the POC of coccolithophre cells was between 0.46 and 156.45 mg C/m2. The POC of coccolithophores in winter were lower than those in summer.The phytoplankton community of South China Sea were studied using the Uterm?hl method. 157 phytoplankton were identified in summer of 2007 with average cell abundance about 3.64×10~2 cells/L. In winter, there were 92 species identified,and the average abundance was 1.26×10~2 cells/L.Our results matched the historied studies in South China Sea and the studies of other seas. To know more about the coccolithophore community in South China Sea needs more works in laboratory and fields, as it's so complex the area is.