DISTRIBUTION OF DINOFLAGELLATE CYSTS IN SURFACE SEDIMENTS FROM SOUTH CHINA SEA

Surface sediment samples at 38 sites of the South China Sea were collected and analyzed to study the contents and assemblage distributions of dinoflagellate cysts. A total of 27 species(16 genera) are identified. The dinocyst contents range from 8 to 925 cysts per gram. The high values are found in the samples from the northern part of the research area and near the Bashi Strait, while the low ones in the southern part of the South China Sea. The distribution pattern of dinocyst con tents is concordant with that of the phytoplankton in the surface water of the South China Sea, which seems to be controlled by nutrient content of the surface water. The dinocyst assemblages are dominated by Spiniferites, mainly including S.ramosus, S. hyperacanthus and S. mirabilis. The other significant genera or species are Impagidinium, Operculodinium centrocarpum,Polysphaeridium zoharyi, Lingulodinium machaerophorum,Protoperidinium and Tuberculodinium vancampoae. The cyst contents of Spiniferites and Impagidinium show an increasing trend whereas those of others decrease from the continental slope towards the deep sea.