Seasonal fluctuation of macrobenthos community in Jiuduansha intertidal wetland of Yangtze River Estuary

From November 2004 to October 2005, an investigation was made on the seasonal fluctuation of macrobenthos community in the Jiuduansha intertidal wetland of Yangtze River Estuary, with the correlations between this fluctuation and sediment factors studied. 864 samples were collected seasonally from 216 sites in 7 sampling transects. A total of 30 species were identified, mainly belonging to Mollusca, Annelida, Crustacea and insect. The dominant species were Stenothyra glabra, Assiminea violacea, Potamocorbula ustulata, Glaucomya chinensis, and Ilyrplax deschampsi. In spring, macrobenthos had the highest density and biomass and the richest diversity, but in summer, the density and biomass were the lowest, the diversity was on a lower level, and the distribution was uneven. There were no significant differences in the species number and biomass between autumn and winter, but the density was higher in winter than in autumn. In spring, summer and autumn, the species number, density, and biomass of macrobenthos had no significant correlations with sediment factors, but in winter, macrobenthos density had significant correlations with the humidity and organic matter content of sediment.