Structure of Macrobenthic Communities in Different Habitats at the Diked Tidal Flat in Winter

Based on the data collected from 9 types of habitat samplings on the macrobenthic community in the diked tidal flat at the south bank of Hangzhou Bay in Jan. 2004,the composition of species,diversity,and community structure were studied,and 9 types of habitats selected were Spartina alterniflora moist soil (SAMS),Phragmites communis moist soil (PCMS),S.alterniflora dry soil (SADS),P.communis dry soil (PCDS),S.alterniflora inundated soil (SAIS),P.communis inundated soil (PCIS),admixture dry soil (ADS),using pond (UP),and desolation pond (DP).From 9 types of habitats,total 13 species were collected,which are belonged to 7 order,3 classes,2 phylums and dominated by the living types of surface and surface below,and most of them are the arthropod and crustacea.Shannon-Wiener indexes (H') of the macrobenthic communities are followed SAMS>PCMS>SADS>PCDS=SAIS>PCIS>ADS>DP>UP,Pielou indexes (J) are SAMS>PCMS>SADS>PCDS>ADS>SAIS>PCIS>DP>UP,and Simpson indexes (D) are PCMS>SAMS>SADS>PCDS>ADS>SAIS>PCIS>DP>UP.Base on the data of four times extracting from the density of macrobenthic communities,using the hierarchical cluster of between-groups linkage method,9 types of habitats are classed 4 groups,I.e.the moist soil,dry soil,water soil and pond groups.The numbers of species of the moist soil,dry soil,water soil and pond are 10,6,10 and 5,the average densities are 45,40,87 and 240 ind/m2,and the biomasses are 23.67,15.11,14.81 and 8.23 g/m2,respectively;H', J and D tend towards moist soil>dry soil>water soil>pond.Using the Non-matric Multi-dimensional Scaling method,9 macrobenthic communities are displayed in the 2-dimensional ordinal configuration,and the dimension 1 implies being concern to the hydrology,the dimension 2 to the complexity of habitats.Also the analysis suggests that the macrobenthic community at the diked tidal flat may be affected by the complex power of hydrology condition,characteristics of sediment,succession of vegetation and relation among the species