Net-phytoplankton community of the Bohai Sea in the autumn of 2000

Features of phytoplankton community were studied based on the data of phytoplankton net samples from 60 grid stations investigated from 29th August to 4th September 2000 in the Bohai Sea,China.Three phyla including 35 genera and 64 species (not including unidentified taxa) were found in the survey area.The main phytoplankton group is diatom,but the dinoflagellates are also important in the phytoplankton community,it can be the dominant group at some stations.The dominant species are Coscinodiscus excentricus,Ceratium tripos and Eucampia zodiacus,etc.The key species phytoplankton in this season are Coscinod iscus excentricus,Eucampia zodiacus,Ditylum brightwellii,Ceratium fusus and Ceratiumfurca.The horizontal patterns of phytoplankton cell abundance are controlled by that of diatoms,it is high in the northern central Bohai Sea,the southern Bohai Gulf and the southern Bohai Straits.The dinoflagellates abundance is high in the northern Bohai Gulf.There is a phytoplankt on ecot one formed by the Bohai Circulation Current in the northern central Bohai Sea,high species richness,high biological diversity and high cell abundance are found here.The species richness,the Shannon-Wiener index and the evenness of phy to plankton are relatively high in the central Bohai Sea.The fuzzy evaluation of biodiver sity shows that phy toplankton community biodiversity in the Bohai Sea is low.