Nine stations were established to investigate the macrobenthos in Quanzhou bay in May, August, November of 2001 and February of 2002. Samples were collected by a grab with an area of 0.05 m2,five times in each station. Samples were washed with a 〈WSB〉 model macrobenthos whirler and isolated by using a sieve set of 1mm and 0.5mm mesh to isolate specimens. Treatment and storage of specimens followed the national standard detailed in the Specification for Oceanographic Survey. Margalef’s species richness index (d), Shannon-Wiener information index diversity (H′), Pielou’s evenness index (J) and Simpson’s dominance index (D) of species were calculated respectively; the community was divided according to cluster analysis by Bray-Curtis’s similarity coefficient and multidimensional scaling ordination; the community was analyzed by Abundance Biomass Comparison (ABC) method, and data were processed by computers. In Quanzhou bay 256 species were identified in the macrobenthos,among which there were 66 species of Polychaeta, 74 species of Mollusca, 77 species of Crustacea, 12 species of Echinodermata, and 27 other species. Species belonging to Polychaeta, Mollusca and Crustacea account for 84.76% of the total species, thus constituting the main population of macrobenthos. The dominant species includes Prionospio malmgreni, Sthenolepis japonica, Lumbrineris sp., Patamocorbula laevis,and Neoxenophthalmus obscurus. In spring, summer, autumn and winter, the average biomass is 23.13g/m2，and the average inhabiting density is 144 inds./m².As to the quantity composition, mollusks have the greatest biomass (10.28g/m²) followed by echinoderms (5.44g/m2) mollusks also have the greatest the inhabiting density (78 inds./m2) followed by species of Polychaeta (37inds./m2). As to the seasonal change of quantity composition, the biomass in spring (34.22g/m²)>that in winter (29.96g/m²)>that in summer (16.14g/m²)>that in autumn (12.21g/m²); the inhabiting density in summer (235 inds./m²)>that in spring (197 inds./m²)>that in autumn (74 inds./m²)>that in winter (68 inds./m²). In respect of the quantity composition, mollusks have the greatest biomass in spring and summer by 18.76g/m² and 10.94g/m² respectively, whereas the biomass of echinoderms is the greatest in autumn and winter by 5.94g/m2 and 15.50g/m2 respectively; mollusks have the highest inhabiting density in spring and summer by 126 inds./m2 and 171 inds./m² respectively, whereas species of Polychaeta have the highest inhabiting density in autumn and winter.
Two communities contribute to Macrobenthos in Quanzhou bay.community Ⅰ: Prionospio malmgren-Patamocorbula laevis-Ogyrides striaticauda and community Ⅱ: Mediomastus californiensis-Patamocorbula laevis-Neoxenophthalmus obscurus. For community Ⅰ, species abundance (d=3.1473) and diversity (H′=2.2162) are higher than those for communityⅡ（d=1.6981 and H′=1.1419）, evenness (J=0.7637) is higher than that for community Ⅱ（J=0.4229），dominance (D=0.1476) is higher than that for community Ⅱ（D=0.1302）. The accumulative dominance of biomass for community Ⅰ and Ⅱ reaches 82% and 65% respectively, and the accumulative dominance of abundance for these two communities reaches 60% and 55% respectively. Especially, in stations Q1, Q2, and Q3, the combined k-dominance curves for abundance and biomass of community Ⅰ show intersection and inversion, indicating a poor habitat, low biomass and inhabiting density, and uneven distribution of quantity inside the bay. In station Q2, the accumulative dominance of abundance and biomass amounts up to 88% and 94% respectively, which may be attributable to biomass (140.95g/m2) and inhabiting density (490 inds./m2) of Patamocorbula laevis. To sum up, fluctuation in the communities of macrobenthos in Quanzhou bay is mainly caused by the seasonal succession.