Characteristics of Macrobenthic Fauna Communities in Three Successional Stages of the New Emergent Salt Marsh in an Estuary of the Yangtze River

The characteristics of macrobenthic fauna communities in the three salt marsh successional stages [saline algae stage (SA), Scirpus mariqueter-Scirpus triqueter stage (MT) and Phragmites australis-Spartina alternflora stage (AA)] were studied during 2001 to 2005, in new emergent shoals, Jiuduansha (Shangsha, Zhongsha and Xiasha), an estuary of the Yangtze River. The results showed that the Shannon-Wiener index, the Pielous Evenness index, the density and the biomass of the communities in each shoal all had the same sequence for these successional stages. This sequence was MT>AA>SA. The dominant life forms at SA and AA stages were infaunal and caving respectively, while those at MT were adhering and caving. The community structures at the same successional stage in the three different shoals were all quite similar and those at the SA stages had even more similarities. However, there were obvious differences among the community structures at the three successional stages, especially between those at SA and AA. These results implied that there was some environmental gradient variation along the successional sequence, and that the salt marsh of the different successional stages had different effects on the macrobenthic fauna communities. Accordingly, the macrobenthic fauna had some adaptation properties to the specific habitats of the different stages.