Phytoplankton in Changjiang Estuary and adjacent waters in winter

The water samples of phytoplankton were selected from the grid survey around the Changjiang Estuary and adjacent waters from 19th Feb.to 5th Mar.2006.The phytoplankton commuinity and its structure were reported in this paper.A total of 116 taxa(including 17 uncertain species) belonging to 56 genera of 5 phyla were identified.The main phytoplankton group was diatom and the second was dinoflagellate.There were also a few species belonging to Chrysophyceae,Chlorophyceae and Cyanophyceae.The dominant species were Paralia sulcata,Thalassiosira excentricus,Thalassiosira rotula and Coscinodiscus radiatus.The cell abundance of phytoplankton ranged from 111.11 to 2315.56 104/m3 and the average was 914.87×104 /m3.The average cell abundance of phytoplankton in surface water was relatively high in the inshore area and northeast in the survey area.The vertical distribution of phytoplankton showed that the maximum cell abundance was found in subsurface water,and along with the increase of the depth cell abundance firstly was increased then decreased.According to the study on the diversity of phytoplankton community,the Shannon-Weaver diversity index and Pielou evenness index were high in the river mouth and low offshore.