NET-PHYTOPLANKTON COMMUNITY IN THE NEARSHORE WATERS OF BOHAI IN 2011

Features of the phytoplankton community were studied using the netz-phytoplankton data in spring and summer in 2011,total 3phyla including 13genera and 37species of phytoplankton in spring and total 4phyla including 24genera and 46species of phytoplankton in summer were commonly found in the survey area.The main phytoplankton groups were eurythemal and neritic autochthonous species,the dominant species were Chaetoceros borealis,Noctiluca scintillans,Skeletonema costatum and Chaetoceros curvisetus in spring and Skeletonema costatum,Nitzschia pungens in Summer.A comparison with the historical data obtained in spring,diatom was also the dominant species in these two data sets,but the ratio of red tide dinoflagellates increased,especially,cell abundance of Ceratium furca,Ceratium tripos,Ceratium fusus and Noctiluca scintillans increased,in which the Noctilluca scintillans was near to the density criterion and should be paid more attention to.The distribution of phytoplankton cell abundance was mainly due to the diatom distribution.The Shannon-Wiener index was deceasing from inshore waters to offshore waters in spring and deceasing from south to north in summer,the Shannon-Wiener index was low in the survey area and red tide is easy to occur.