Distribution pattern of macrobenthic composition, diversity and secondary production in Hangzhou Bay, northern East China Sea

Abstract

Based on macrobenthos collected from 18 stations in Hangzhou Bay from 2012 to 2019, the diversity and secondary production of macrobenthic communities in Hangzhou Bay were studied. The results showed that in total, 49 macrobenthic species were collected across the whole sampling period. Among the 16 dominant species determined, the polychaete Sternaspis chinensis and the bivalve Nucula faba were the dominant species across the entire sampling period. The macrobenthic community in Hangzhou Bay was at its lowest level of diversity and productivity in the Zhejiang coastal area. Correlation analysis of macrobenthic assemblages with environmental factors showed that bottom water salinity, dissolved oxygen (DO), transparency and chemical oxygen demand (COD) were the most important environmental factors affecting the macrobenthic community in Hangzhou Bay. Community parameters were negatively correlated with COD and DO but positively correlated with salinity and transparency; that is, with an increase in COD, the number of species, biomass and secondary production of the macrobenthic community decreased. However, DO was high enough for the survival and reproduction of macrobenthos, which truly reflects the frequent resuspension and deposition of sediment in Hangzhou Bay. Therefore, the macrobenthic assemblages in Hangzhou Bay were mainly controlled by severe sedimental disturbance and salinity gradients caused by freshwater input and strong ocean currents instead of water transparency and DO.