Abstract: By the methods of water sampling, net sampling, and microscope identification, a seasonal investigation was conducted on the phytoplankton community in Zhanjiang Bay of Guangdong, China in February-November 2009, with the spatiotemporal distribution of Chatoceros community in the Bay and  affecting factors analyzed. A total of 32 Chatoceros species were collected, including 17 red tide causative species. The dominant species in the Chatoceros community were C. curvisetus, C. pseudocurvisetus, and C. muelleri. Temporally, the species richness and cell abundance of Chaetoceros were characterized by a typical seasonal pattern, with the highest in spring and summer and the lowest in autumn and winter. Spatially, the species richness and cell abundance decreased from outer bay to inner bay. The cell abundance of Chaetoceros was significantly positively correlated with water temperature, salinity, pH, chlorophyll a, and cell abundance of phytoplankton, and significantly negatively correlated with water DIN and silicate, but had no significant correlation with water phosphate. The seasonal variation of Chaetoceros cell abundance was mainly controlled by water temperature, and also, affected by the interspecific competition and the feeding pressure from zooplankton produced by seasonal alternation; while the spatial distribution of Chaetoceros cell abundance was affected by illumination, water salinity, pH, and the feeding pressure from high-density cultured shellfish.

Key words: Nilaparvata lugens, Chaos, Power spectrum figure, Return map, Autocorrelation function, Poincare section, Phase trajectory figure