Community characteristics of macrobenthos in the Huanghe（Yellow River） Estuary during water and sediment discharge regulation

The community characteristics of macrobenthos in the Huanghe(Yellow River) Estuary is influenced by a combination of natural and anthropogenic factors. Here, we investigated short-term changes(1-month) in macrobenthic community structure in response to water and sediment discharge regulation(WSDR) in 2011.Specifically, we sampled the macrobenthos at 18 sampling stations situated at four distances(5, 10, 20, and 40 km)from the mouth of the Huanghe Estuary before(mid-June), during(early-July), and after(mid-July) WSDR. The results showed that a total of 73, 72, and 85 species were collected before, during, and after WSDR, respectively.Then, 13, 1, and 16 dominant species were detected at this three periods. Four phyla were primarily detected at all three periods(Annelida, Mollusca, Arthropoda, and Echinodermata). However, while Mollusca and Annelida were the most important phyla in our study, Echinodermata and Annelida were the most important phyla in 1982,demonstrating major changes to community structure over a 3-decadal period. All stations were of high quality BOPA index before WSDR, whereas two and three stations were of reduced quality BOPA index during and after WSDR, respectively. The results of ABC curves showed that had incurred disturbed conditions after human activities WSDR. Most important of all, multivariate analyses and RDA analysis indicated that the structure of the macrobenthic community was closely linked to environment factors, including that organic content factor caused the distribution of macrobenthic community mostly during WSDR, while water depth after WSDR affected the macro benthos community structure seriously, and during WSDR, the environment factor influencing it was not single, including organic content, sulfide content, Hg and As. These differences may have been due to changes in water transparency negatively impacting the growth and development of macrobenthos, due to specific lifehistory requirements. Our results demonstrate that anthropogenic activity is having both long-term(3 d