Species composition and quantitative distribution of phytoplankton near the Jiuduansha waters of Yangtze River estuary

The phytoplankton between Wusongkou and Lower Jiuduansha of Yangtze River estuary was investigated in Sep.2005. 135 species of phytoplankton belonging to 70 genera were found in the survey area.The species of diatom,including 82 species in 42 genera,was the most and took 60.8% of all species.Green algae involving 24 species in 14 genera and 14 genera of other algae were also detected.The quantitative distribution of phytoplankton in the sampling sites in Upper Jiuduansha and Middle Ji- uduansha were more abundant than other sites,and that decreased sharply in the Lower Jiuduansha sampling sites.Skeletonema costatum (Grev.) Cleve was the dominant species and took about 71.8% of the total quantity of phytoplankton.Some factors which affected distribution of phytoplankton quantity were also investigated in this paper.