| During Nov. 2008 to Oct. 2009, in the wetland of Yancheng national rare bird reserve, we studied the macrobenthos communities of this area. In this study, according to the characteristics of tide and vegetation, we divided the study area into 6 kinds of basic habitat as supralittoral zone with Spartina alterniflora, supralittoral zone without plants, intertidal zone with Spartina alterniflora, intertidal zone without plants, bank of creek and bottom of creek, by use the methods such as diversity-analysis and communit-cluster, we analysed and compared the characteristics of macrobenthos communities in each basic habitat in a whole year. The major result of this study is the following:1) There were total 22 living sample species and 11 debris species of macrobenthos have been collected in the study area. The living sample species includ 17 families, 4 classes and 3 phyla, and 17 of them were eurythermal widespread species, 4 of them were temperate cold-water species, 1 of them were subtropical warm water species. The dominant species of the study area were Potamocorbula ustulata, Cerithidea sinensis, Sesarma dehaani, Helice tridens.2) The different ecological characteristics of each basic habitat can influence the species and functional group composition of macrobenthos. The vegetation and tide were the two main effect factors on macrobenthos communities.3) The hightest average density and biomass of macrobenthos community in a year were appeared in the intertidal zone without plants habitat (the hightest average density is 744.88ind/m~2, the hightest average biomass is 1156.64g/m~2); the lowest average density and biomass of macrobenthos community in a year were appeared in the intertidal zone with Spartina alterniflora habitat (the lowest average density is 15.27ind/m~2,the lowest average biomass is 20.96g/m~2). By compared the change situation of macrobenthos density and biomass between the intertidal habitats and the no-tidal habitats in a whole year, we found the change situation of these two main types habitats were opposite. It possibly caused by the different climatic conditions and the different physical properties between the land and sea.4) The influence on macrobenthos communities by Spartina invasion was depends on the coverage density of Spartina. In the habitats that with high coverage density of Spartina, the diversity of macrobenthos communities were lower than that in the habitats without any plant; but in the habitats with the Spartina in patch distributed, the diversity of macrobenthos communities were higher than the habitats without any plant. This situation possibly caused by the different substrate hardness, substrate organic content, and substrate oxygen content between the two main type habitats. The influence on macrobenthos communities by Spartina invasion was also depended on the tidal characteristics, in the intertidal habitats, the influence was much more seriously.5) The hightest average Shannon-Wiener diversity index of macrobenthos communities appeared in the supralittoral zone without plants habitat (H=1.657±0.099); the lowest average Shannon-Wiener diversity index of macrobenthos communities appeared in the intertidal zone with Spartina alterniflora habitat(H=0.286±0.276). Diversity analysis showed that the diversity of macrobenthos communities had no seasonal variations in most habitats except the intertidal zone without plants. Because the human disturbance, the normal distribution of macrobenthos were interfered, the diversity of macrobenthos communities did not showed a seasonally change in the habitats with a high-level human disturbance; but in the intertidal zone without plants, the human disturbance level was much lower, the diversity of macrobenthos communities showed a seasonally change obviously.6) The communities cluster and NMDS sorting showed that the similarity of macrobenthos communities in each habitat did not change seriously in a year. The similarity of macrobenthos communities was mainly depended on the existence of tide.
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