Abstract:Seasonal population changes in Gymnodinium in Daya Bay, the South China Sea, were investigated from July 1997 to June 1998. The environmental factors were analyzed at the same time, and their effects on Gymnodinium population dynamics were also evaluated. High densities of Gymnodinium were measured in April and May at Daya Bay, in which four peeks of cell concentrations were observed. The highest density of 996 cells/ml was obtained at S6 on May 2 1998. Gymnodinium only occasionally appeared...