Benthic macroinvertebrate communities in
Spartina alterniflora
zones in the Yangtze Estuary, in China, were investigated seasonally in 2005, and their structure and biodiversity were analyzed. Twenty-one species were identified, across four Classes; 10 species of Crustacea, five species of Polychaeta, five species of Gastropoda, and one species of Lamellibranchia. Dominant species included:
Assiminea
sp.,
Notomastus latericeus
,
Cerithidea largillierl
,
Glauconome chinensi
and
Gammaridae
sp. Functional groups were comprised of a phytophagous group and a detritivorous group. The average density of all benthic macroinvertebrates was 650.5±719.2 inds/m
2 in the survey area. The high value of the standard deviation of the average density was a result of abundant
Assiminea
sp. at Beihu tidal flats. The average density of macroinvertebrates from Beihu tidal flat, Chongming Dongtan to Jinshanwei tidal flat decreased gradually. There was significant difference between compositions and abundance of macroinvertebrates along the estuary gradient (P<0.05). The density and biodiversity were highest in summer and lowest in winter. The mean biomass of macroinvertebrates was 20.8±6.1 g/m
2. Biomass changed seasonally in the same way as density, with the change in biomass being: summer (Aug.) >autumn (Oct.) >spring (Apr.) > winter (Dec.). A BIO-ENV analysis showed that the mean grain size of sediment, height of Spartina and salinity were the major factors which affected the structure of the macroinvertebrate community. Variations in the community structure were probably caused by the population dynamics of S.alterniflora along with the variation in sampling time and location.