Ecology Of Zoobenthic Community Of Wetland In Estuarine Tidal Flat

Zoobenthic community is an important part of estuarine ecosystem, which comprise a broad assemblage of diverse forms, mostly various invertebrates. The benthic subsystem is an important dynamic center in the wetland ecosystem of the estuarine tidal flat, in which the zoobenthic community take up a connecting link between the preceding and the following, and determine many significant ecological processes in the estuarine ecosystem.Survival of zoobenthos in the tidal flat wetland of estuary is influenced by habitat stability, heterogeneity and nutrimental level that closely related to tidal dynamics, sedimentary conditions, characteristics of physiognomy and vegetation pattern. Based on the background of knowledge about estuarine and coastal dynamics, sedimentology and physiognomy, with an eye to forward field of international estuarine ecological research, according to different spatial scales, environmental heterogeneity and habitat stability, this paper studied the ecology of zoobenthic community of the tidal flat wetland in the Changjiang estuary. Major conclusions from this research are:1. This study suggests that functional group diversity of zoobenthos can reflect environmental gradients and habitat quality of estuary integrally. In the south bank of the Changjiang estuary, the changes of habitat conditions of the tidal flat wetland results in the differences of zoobenthic community structure and function along the estuarine gradients. We have categorized functional groups according to three aspects such as trophic types, mobility and food gathering techniques, so that if and how the estuarine environmental gradients are reflected in the zoobenthos is analyzed. A total of 55 species and 15 functional groups were identified, forming cline distribution pattern along longitudinal gradients of the south bank of the Changjiang estuary. There were zoogeographical pattern of zoobenthic species and functional groups which positively correlates with salinity gradient in the south bank of the Changjiang estuary. From the upper reaches to the lower reaches of an estuary along the environmental gradient, the number of zoobenthic species and functional groups increase gradually. There were 9 species of zoobenthos and 6 functional groups in the tidal flat of estuarine upper reaches respectively, and 42 species and 15 functional groups in the tidal flat of lower reaches respectively. In addition, the distribution pattern of zoobenthic species and functional groups along the estuarine gradient related to the width of tidal flat, habitat heterogeneity and primary productivity. There was difference in the dominant functional groups in various transects along estuarine gradient. The complex functional communities is located in the lower reaches of estuary in which there were various functional groups with different trophic types, mobility and food gathering techniques. Moreover, there were functional poor assemblages in the upper reaches of estuary and transect which was greatly polluted. Along estuarine gradient remarkable change reflects in a loss of sessile and tentaculate organisms from areas beyond Binghai transect towards the inner estuary. Those sessile and tentaculate organisms are sensitive to environmentaldisturbance, so they reflect the seasonal fluctuation of natural environmental factors such as salinity in the upper reach of the Changjiang estuary is greater than that of the lower reach and the upper reach of the Changjiang estuary is disturbed strongly by human activities. This study suggests the basic zoobenthic community parameters were reflected in the composition and diversity of functional group. Condensing species diversity information into the analysis of the composition and diversity of functional group will helps to understanding the changes of ecological relationship underlying the complicate community changes which are reflected in a complex environmental gradients. Using the functional group-approach, it is evident that the gradual shift in species composition is also reflected in some...