Temporal and spatial fluctuation of macrobenthos community in a newly established wetland in Yangtze River Estuary

To understand the temporal and spatial fluctuations of macrobenthos community in a newly established Jiuduansha wetland in Yangtze River Estuary,an investigation was made on the main habitats of three shoals in the wetland from November 2004 to October 2005.The results showed that the macrobenthos community in the wetland had the highest biomass and density in spring,which declined in summer and autumn and went up in late autumn and winter.The overall diversity of macrobenthos species was relatively low and distributed unevenly.There was a significant difference in macrobenthos densities between Shangsha and Zhongsha in summer,and the spatial grads of macrobenthos density and biomass was in the sequence of XiashaShangshaZhongsha in all seasons.The trade-off of dominant species groups had a significant effect on the temporal and spatial fluctuations of macrobenthos community.The density and biomass of macrobenthos were the highest in Scirpus mariqueter and S.triqueter and the second in Phragmites australis and Spartina alterniflora zones during the whole year,and the lowest with extensive seasonal fluctuation in intertidal mudflat zones.No significant difference in the community characteristics of macrobenthos was observed between alien S.alterniflora and native P.australis zones.