Character of zooplankton community and its variation in the water near the Yangtze River estuary

Based on the data of 8 voyages' investigation in May and August from 2000 to 2003 in the fisheries water near the Yangtze River estuary,this paper dealt with the variation trend of species composition and diversity of zooplankton.The results showed that species number of Heteropoda,Chaetognatha and Copepods in August was higher than that in May.The force of warm current enhanced with the enforcing Yangtze River freshwater in August.At the converge of different water current,isoline of species number and diversity of zooplankton were closely arranged.The rich species brought by warm current in August increased the species number and diversity value in August and were higher than those in May.Salinity was the most important environmental factor affecting community character of zooplankton in the water near the Yangtze River estuary.