Temporal and spatial variability of benthic macrofauna communities in the Yangtze River estuary and adjacent area

Four cruise surveys were carried out in summer, winter, spring, and autumn from 2006 to 2007 to evaluate the seasonal distribution of macrobenthos in the Yangtze River estuary and its adjacent waters. A total of 59 sites were sampled and divided into three areas (estuary, inshore, and offshore areas). In all, 335 taxa were collected with polychaetes and mollusks being the dominant groups. Two-way ANOVA revealed significant differences among the numbers of species, densities, and biomasses in the areas. However, several differences were found among seasons. SIMPER analysis showed that the dominant species of macrobenthos varied in different areas, and the inshore area was the most complex of the three. The abundance/biomass comparison (ABC) curve of macrobenthos in the inshore area showed apparent rises and falls, which are characteristic of disturbance to macrobenthos. Canonical correspondence analysis showed that echinoids were closely related to the presence of silicates and temperature, whereas polychaetes were closely related to depth and temperature.