Distributing characteristics of zooplankton in Pearl River Estuary

Based on the data collected from three cruises during the flood (August,2006) ,the mean-flow ( November,2006) and the dry (February,2007) periods,the species composition,quantitative distribution and species diversity of zooplankton in the Pearl River Estuary were determined. Results showed that total 94 species were identified. Among them crustacean was the dominant group,containing 49 species. The zooplankton community was composed of 35 copepod species,28 rotatoria species,14 cladocera species,6 protozan species and 2 species of both tunicata and euphausiacea,and one species of polychaeta,spiral,heteropoda and medusae in Pearl River Estuary. The dominant species from brackish estuarine were Acartiella sinensis,Schmackeria inopinus,Limnoithona sinensis,Apocyclops royi,Brachionus calycifloru,Brachionus falcatus,Asplanchna priodonta,Bosmina longirostris. The dominant zooplankton species were mainly pollution tolerant species which indicated that water in Pearl River Estuary has been polluted. Shannon-Wiener diversity index showed that the species diversity was lowest during the dry period and highest during the mean-flow period.