Preliminary Study on Net-phytoplankton Community Structure and Red Tide Causative Species in Tianjin Sea Area,Bohai Sea

Phytoplankton species composition, species succession and red tide causative species were analyzed from 2002-05 to 2003-09 in Tianjin red tide monitoring section, Bohai Sea. Total 68 taxa belong to 37 genus were recorded. The results showe that diatoms (51species, accounted for 75.00%) and dinoflagellates (11 species) are the major components of phytoplankton community in the survey region. The ecotype of these phytoplankters is temperate and neritic species. In Tianjin Sea area, Coscinodiscus species are abundant and dominant throughout the whole year, they contribute 63.41% of total bio-mass in cell number. The phytoplankton community is characterized by big cell diatom coexisting with dinoflagellates, its horizontal distribution is related to environmental factors. The species succession is the major process of seasonal changes of phytoplankton community development pathway in the Bohai Sea.