Influence of Spartina alterniflora salt marsh at its different development stages on macrobenthos

In 2004-2006,the community characteristics of macrobenthos in Phragmites australis salt marsh and in Spartina alterniflora salt marsh at its different development stages were investigated in Chongming Dongtan of Yangtze River estuary.At the early development stages of S.alterniflora salt marsh,macrobenthos were mainly composed of gastropod,and the species richness(D=2.18) and diversity(H'=2.19) were lower than those in P.australis salt marsh(D=2.61,H'=2.29).With the shift of time,S.alterniflora gradually interacted with native species and formed stable pattern,and the species numbers of polychaeta increased from 3 to 6.The species number and abundance of macrobenthos increased,and a new pattern of macrobenthos community was formed.The species richness(D=2.70) and diversity(H'=2.48) of macrobenthos were higher in S.alterniflora salt marsh than in P.australis salt marsh(D=2.19,H'=2.09).It would take several years for the establishment of new and stable macrobenthos community.