长江口湿地三个演替阶段大型底栖动物群落特征

2001—2005年对长江口新生沙洲九段沙(上沙、中沙、下沙)盐沼演替序列不同阶段盐渍藻类阶段(SA)、海三棱草(Scirpusmariqueter)—草(Scirpustriqueter)阶段(MT)、芦苇(Phragmitesaus-tralis)—互花米草(Spartinaalterniflora)阶段(AA)]的大型底栖动物群落特征进行了分析研究。大型底栖动物群落的物种数、Shannon-Wiener多样性指数、Pielou均匀度指数、密度及生物量都是MT>AA>SA。SA、AA优势种的生活型分别是底内型、穴居型;MT优势种的生活型是底上附着型和穴居型。不同沙洲相同盐沼演替阶段大型底栖动物群落结构都较为相似,盐渍藻类阶段的相似性最高;不同演替阶段间差别明显,SA和AA间差别最大。不同盐沼演替阶段大型底栖动物群落特征的明显差异,既反映了环境沿盐沼演替序列的梯度变化,也体现了不同盐沼对底栖动物群落作用的差别,同时也显示了大型底栖动物对不同盐沼演替阶段生境的适应。

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.