Functional Groups And Ecological Significance Research Of Benthos In The Intertidal Wetland, The Yangtze River Estuary

The biotic components and their ecological process in estuarine wetland ecosystem had become one of research focus which was paid close attention to day by day. Used relatively large spatial scale and the method based on functional feeding groups, including all types of representative intertidal wetland in the Yangtze RiverEstuary-the wetland along the river and sea ( south bank of the estuary) and thewetland of shoal island (Dongtan of Chongming island, east of Hengsha island, Jiuduansha shoals) , this study systematically analyzed the benthos community structure, strengthened the discussion about the variety of natural environmental gradients and the influence mechanisms which anthropogenic disturbance impacted on ecological process for the first time. Combined with the Shannon-wiener diversityindex, the foreign advanced benthos pollution index-Biotic Coefficient was firstadopted to evaluate the pollution condition in the intertidal wetland of the Yangtze River Estuary. The benthos resource function in ecosystem of the Yangtze River Estuary was primarily discussed and we estimated and calculated their products (natural resources ) value for the first time.The main conclusions in this research are the following:Included salinity, sedimentary particle diameter was also important factor in influencing the benthos distribution along the environmental gradients in the estuary intertidal wetland. The trend of the benthos distribution was increasing with these two factors increased. Along the estuary environmental gradients, the structure of benthos community had some differences. In the upper region (Liuhekou, Gaodong), since the habitat condition was more simple and the beach was interfered highly by the anthropogenic disturbance, the species and individuals numbers of benthos were obviously less than others'. In the lower region (beach of Nanhui, Luchaogang) , the elevation of beach was higher, the plant density and biomass increased and the habitat space was enlarged, so the species and individuals numbers of benthos were both more than the upper's. And in the shoal island wetland (Dongtan of Chongming, east of Hengsha island, Jiuduansha shoals ) , it showed the characteristic of the intermediate zone that mixed with the salty and fresh water. The habitat condition was more diversifiable and complicate. The anthropogenic disturbance was relative lower. So, the species and individuals numbers of benthos were both higher. The study demonstrated further that the benthos community had significant differences at each tidal zone. Multidimensional scaling analysis showed that the benthos community hadsignificant differences in gradient patterns. From the lower tidal zone, the middle tidal zone to the higher tidal zone, the plant height and biomass of above the ground were crescent, the primary productivity was constantly enhanced, the stability of sedimentary environment was strengthened, the benthos biodiversity and abundance were corresponding to increase.Along the environmental gradient of the estuary, species numbers within each function feeding groups presented a trend of increasing gradually from the upper to the lower region of the estuary. In the upper region, Diking by a large area and environmental pollution were the main reasons that decreased the diversity of benthos functional feeding groups, it lacked in Omnivorous and Detritivorous group and there was few species in Carnivorous group. It showed that the obviously fragmental habitat led to the reduction of nutrition source and the simplification of food chain. In other regions, the development of beach was comparatively perfect, the area was broad, primary productivity was higher, the structure of food web was more complicate, food source was more abundant. So, the numbers of functional feeding groups and species numbers within each function feeding groups were more. Because the perturbations of the water in the upper region and the tide in the lower, the beach was rose and eroded in varying degrees and limited the existence and development of...