Spatial distribution and seasonal variation of the macrobenthic community on tidal flats of Tianhe, Wenzhou Bay

From Nov. 2003 to Aug. 2004, the authors studied the macrobenthic community on the tidal flat of Tianhe, Wenzhou Bay. We found a total of 38 species, belonging to 23 families, 8 classes and 7 phyla, most of them were arthropods and mollusks. Species’ numbers did not differ significantly among seasons (F 3,9=1.76,P0.05) but were distinct among tidal flats was (F 3,9=9.56,P0.01). The density and biomass of the upper, high, middle and low tidal flat were 144.50±14.24 ind./m2, 58.56±13.23 g/m2; 171.00±16.52 ind./m2, 40.57±12.60 g/m2; 182.50±39.38 ind./m2, 50.26±10.57 g/m2 and 94.00±28.88 ind./m2, 16.55±7.27 g/m2.Densities were not significantly affected by seasons nor tidal flats (F 3, 9=2.78 and F 3, 9=2.14,P0.05) but biomass differences were marked among tidal flats (F 3,9=16.72 and F 3,9=22.24,P0.01). Margalef’s species richness indices and Shannon-Wiener’s indices were as follows: highmiddlelowupper, the Pielou’s indices were: upperhighmiddlelow, Simpson’s indexes were: upperlowhighmiddle. Using the Hierarchical Cluster of between-groups linkage method and the Non-matric Multi-dimentional Scaling method, the 16 macrobenthic communities of high and middle tidal flat had no distinct dividing line, the macrobenthic communities of upper and low tidal flat had a distinct dividing line. The paper indicated that habitat differences were most important reason for differences in the macrobenthic communities composion