Characteristics of Plankton Community and Its Relations with Environmental Factors in Yueqing Bay

The species composition,dominant species,and abundance of plankton were investigated in Yueqing Bay on April 13,2010.A total of 162 phytoplankton species which belonged to 6 phyla were identified.The phytoplankton community was mainly composed of Bacillariophyta(144 species,88.9%),followed by Pyrrhophyta(12 species,7.4%).On the other hand,37 zooplankton species which belonged to 10 groups were identified,51.4% of them were Copepoda(19 species).The average cell abundances of the phytoplankton and zooplankton were 38.12×104 cells/m3 and 37.26 cells/m3,respectively.The spatial distributions of phytoplankton and zooplankton abundances were decline from inner bay to open bay.The dominant species of phytoplankton were Coscinodiscus jonesianus and Biddulphia sinensis,and that of zooplankton were Labidocera euchaeta and Paracalanus aculeatus.The average diversity indexes(H') of phytoplankton and zooplankton were 2.35 and 1.16,respectively.Moreover,the plankton community in different areas was varied with the changed environmental gradients.Yueqing Bay was serious eutrophication,and the contents of DIN and DIP were 0.756mg/L and 0.038mg/L,respectively.Compared to the data of May,1982,DIN and DIP contents increased by 112% and 131%,respectively.The decline of phytoplankton abundance was observed comparing to the data of 1982,and Copepoda remained the dominant group in community of zooplankton.