Species Composition and Diversity of Macrobenthos in the Intertidal Zone of Xiangshan Bay, China

Xiangshan bay is a narrow semi-closed bay and situated on the northwestern coast of the East China Sea. Over past decades, it has become to a major bay with intensive human activities, dense urbanized area, and poor water quality. The aim of this paper was to reveal the ecological status through the elucidation of the species composition, abundance, biomass and diversity of macrobenthos in this bay. Six intertidal sections were surveyed from January 2007 to November 2008 quarterly. Sections TG, HD and XH are located in the three inner bays, sections QJ and WS are located near the thermal power plants, and section XX is located at the outer part of Xiangshan Bay. Great variations in macrobenthos community were indentified, and the species composition of the community in the present study showed the dominance in the order of molluscs （bivalves and gastropods）, crustaceans and others, and only few Polychaeta were recorded. Only three dominant species, Littorina brevicula, llyplax tansuiensis, and Cerithidea cingu- lata were collected in all the sections, and a total of 19 dominant species were recorded only in one section. Two-way ANOVA analyses of abundance indicated that there were significant differences among sections or seasons. Shannon-Wiener diversity index （H＇） had its maximum （2.45） in section QJ, and minimum （1.76） in section TG Multiple irregular k-dominance plots clearly showed that the study area was polluted and the macrobenthos community was under stress. We conclude that the macrobenthos of Xiang- shan Bay have been disturbed by human activities, especially at the interior bay.