Study on species diversity of dinoflagellate cysts in the central of north Yellow Sea and Sishili Bay

During years of 2008 to 2011,49 surface sediment samples were collected in the Sishili Bay of Yantai and in the central of north Yellow Sea.The identification of dinoflagellate cysts in the collected samples was undertaken.In this research,41 dinoflagellate cyst taxa of 16 genera were identified,in which Brigantedinium aymmetricum Matsuoka(Protoperidinium sp.) was the newly recorded species in the sea area of China.Spiniferites bentori var.truncata,Spiniferites hyperacanthus and Operculodinium centrocarpum were the dominant cyst taxa in Sishili Bay,while cysts of Alexandrium tamarense / catenella,Alexandrium minutum / affine,Protoceratium reticulatum and Gonyaulax spp.were dominant in the central northern Yellow Sea.Moreover,three toxic dinoflagellate cysts were found highly abundant from Zhifu Island to the central of north Yellow Sea,namely,Gonyaulax spinifera,Lingulodinium polyedrum and P.reticulatum,which produced Yessotoxin(YTX).And also,in the central of north Yellow Sea,there were other three toxic cysts(A.tamarense / catenella,A.minutum / affine and Gymnodinium catenatum) with high cyst abundances,secreting paralytic shellfish poison(PSP).Therefore,it demanded more monitoring and research of dinoflagellate cysts in these areas,to prevent the bloom of toxic dinoflagellates.Besides,it was further proved that human activities had impacted the coastal eco-system,by the analysis and comparison in terms of dinoflagellate cyst distribution and the environmental characteristics in two areas,including the Sishili Bay and the central of north Yellow Sea.