The variation of biodiversity of macrobenthic fauna with salinity and water depth near the Pearl Estuary of the northern South China Sea

To study the relationship between macrobenthic fauna and environmental factors, we investigated four transects from coast to deep-sea waters near the Pearl Estuary in the northern South China Sea from July –August 2006 (Summer, wet season), April–May 2007 (Spring, normal water season), and October–December 2007 (Autumn, dry season). A total of 273 species, 256 species and 148 species were identified in spring, summer and autumn, respectively. Macrobenthic fauna belonging to the Annelida phylum had the greatest species richest, followed by Arthropoda, Mollusca, and Echinodermata. The species richness, abundance and biomass of macrobenthic fauna increased from estuary sites to coastal sites, and decreased from coastal sites to deep-sea sites. The Shannon-Wiener index of macrobenthic fauna was higher in coastal sites than those in estuary and deep-sea sites. The species evenness of macrobenthic fauna was the highest in deep-sea sites, followed by coast and estuary sites. The k-dominance curves of macrobenthic fauna were higher in estuary and deep-sea sites than that in coastal sites. These results show that the macrobenthic biodiversity was the highest in coastal sites. Species richness, abundance, and biomass of macrobenthic fauna are negatively correlated with water depth in spring and autumn, but only biomass of macrobenthic fauna is negatively correlated with water depth in summer. The species richness, abundance, Shannon-Wiener index, and species evenness of macrobenthic fauna are positively correlated with salinity in the bottom of the water column in summer, but are not correlated in spring and autumn. 第 3期 张敬怀: 珠江口及邻近海域大型底栖动物多样性随盐度、水深的变化趋势 303