Seasonal Change of Phytoplankton and Its Relations to Environmental Factors in Shenzhen Bay from November 2010 to July 2011

From November 2010 to July 2011,seasonal investigations for phytoplankton community were conducted in Shenzhen Bay of Guangdong province,China.Eight-three species in 45 genera of 5phyla had been identified.Among all species,Bacillariophyta accounted for 83.1% and 10.8% of species belonged to Pyrrophyta.Skeletonema costatum were the perennial dominant species to the area.Phytoplankton cells densities ranged from 9.63×103 cells/L to 19904.0×103 cells/L and averaged964.5×103cells/L.Obvious seasonal variations of phytoplankton abundance were found with a descending order from autumn to summer,winter,and spring in this area.The diversity index and evenness indices were rather lower,which indicated that the community compositions were rather brittle and the community stabilities were rather fragile.In spring,under the influence of Shenzhen River and precipitation,phytoplankton abundance reached to their minimum.In autumn,the environmental factors were very appropriate and phytoplankton abundance surged,while in winter low temperature became the primary factor inhabiting the growth of phytoplankton.