Community characteristics and influencing factors of macrobenthos in Pearl River Estuary

The Pearl River Estuary is the largest estuary in Guangdong Province, and plays an important role in China's estuarine ecosystem. In order to explore the seasonal variation of macrobenthic community, we conducted four surveys in Pearl River Estuary waters in summer 2020 (August), winter 2019 (December), spring 2021 (March) and autumn 2021 (October). The species composition, biomass and diversity of the collected macrobenthic fauna were analyzed by multivariate statistical analysis. A total of 138 benthic species were recorded. The number of macrobenthic species  was higher in spring (45) than that in the other three seasons. The highest density was observed in spring and the lowest in summer; the highest biomass was obsered in winter and the lowest in autumn. Amphiopholis laevis was the dominant species in spring, summer and autumn. One-way analysis of variance (ANOVA) shows that the changes of Margalef richness index (D), Shannon index (H') and Pielou evenness index (J') were all significantly different in different seasons (P<0.05), and the Pearson correlation analysis shows that the diversity of macrobenthic fauna was significantly correlated with pH, suspended solids, chemical oxygen demand (COD) and other environmental factors. The results indicate that the seasonal variation of macrobenthic community results from the combined effect of multiple environmental factors. Thus, it is necessary to strengthen the long-term monitoring and protection of biodiversity in this area.