The Ecological Research On The Characters Of Macrobenthos Communities In Jiuduansha Wetland

The estuary wetland is a kind of transition zone among the sea, freshwater and land. It is an important object in the research of the nature protection and the changing world. There is abundance wetland resource in Yangtze River estuary, and the community of macrobenthos with the habitats composed a macrobenthos sub-system in the ecosystem. The macrobenthos distribution has high correlation with the environment factors. As the indicator species, the macrobenthos is the most direct and valuable subject in the estuary ecosystem research. Additionally, in the last 90's, the invasive species Spartina alterniflora were induced to the Yangtze River estuary, there were no accordant conclusions about the effect of invasive species on the original wetland ecosystem.During the year 2004-2005, the relevant research was taken on the new-form wetland (Jiuduansha) in Yangtze River estuary. The main contents were: (1) The spacial-temporal pattern of macrobenthos in the different habitats in Jiuduansha; (2) The impact ion of the introduced species Spartina alterniflora to the community characteristic of macrobenthos; (3) The wetland environment factors relationship with the community of macrobenthos.We selected the three main shoals of Jiuduansha wetland with six main habitat types including Phragmites australis zone, Scirpus×mariqueter zone, S. triqueter zone, and Spartina alterniflora zone, low tidal mudflats and high tidal mudflats. A total of 864 samples in 216 sites from 7 transects were sellected annually. The species composition, density, biomass, Shannon-Wiener diversity index and Pielou even index were used to describe the characters of the macrobenthos community. Meanwhile, the wet, salinity, pH, nutrition factors (NH₄⁺-N, NO₃^--N & K⁺) and the organic matter (O.M.) of wetland sediment were measured.The main conclusions as follows:A total of 31 macrobethos species were found, consisting of Mollusca, Annelida, Crustacea, and Insect larva, with the dominant species being Ilyrplax deschampsi, Stenothyra glabra, Assiminea violacea, Potamocorbula ustulata, Glaucomya chinensis and Limnodriu hoffmeisteri. The seasonal Fluctuation of the macrobenthos density was obvious. The spatial grads of macrobenthos density and biomass were Xiasha>Shangsha>Zhongsha. The density of macrobenthos in Shangsha and Zhongsha were significantly different in summer (One-Way ANOVA).