The spatial-temporal distribution and its biodiversity of intertidal macro benthos in Dongtou Archipelago

In this paper, 4 sections in Dongtou Archipelago were chosen to investigate the spatial-temporal distribution and the biodiversity of intertidal macrobenthos in autumn (Oct.) 2006 and spring (Apr.) 2007, respectively. The total number of macrobenthos in four sampling sites was 72, which included 44 species of mollusc, 13 species of crustacean, 11 species of macro algae, 2 species of polychetes, 1 species of echinoderm, and 1 species of the other group. Compared with the data in autumn and in spring, the number of species in the former (66 species) was slightly higher than that in latter (63 species), whereas the average biomass and abundance in the former (576.98 g/m²,461 ind/m²) were obviously lower than that in latter (1 129.23 g/m²,707 ind/m²). For all of the sections, Thais clavigera Kuster, Tetraclita japonica Pilsbry, Tectarius granularis Gray, were the dominant species and accounted for over 60% of the whole biomass and abundance. For the average index of biodiversity, the species biodiversity index was 1.73?0.47(0.83-2.10), the index of Margalef’s species richness was 2.26?0.33(1.99-2.95), the Pielou’s evenness was 0.62?0.19(0.29-0.85), and the index of Simpson’s dominance was 0.70?0.18(0.36-0.87). The whole result indicated human activities were the main factor to lead to the extremely unstable community in the intertidal macrobenthos with the lower biodiversity in Dongtou Archipelago. And there was a trend of evolving into the secondary type community structure.