Major environmental variables related to north-south differences in the macrozoobenthic community in adjacent sea areas of the Yangtze River estuary, China

Main environmental variables of the bottom water and the macrozoobenthic community were compared between northern and southern adjacent sea areas of the Yangtze River estuary, China, using data of ten months from 2015 to 2016. The PCA (principal component analysis) results showed significant north-south differences in the environmental variables. Results of PCO (principal coordinates) analysis and cluster analysis revealed an obvious north-south distribution pattern of the macrozoobenthic community, and a phenomenon of patchy distribution of macrozoobenthos was also found in the study area. Relationships of environmental variables and the macrozoobenthic community dissimilarities were analysed by BIOENV analysis and CCA (canonical correspondence analysis). Depth, salinity and turbidity were revealed as major environmental factors related to the north-south differences in the macrozoobenthic community in adjacent sea areas of the Yangtze River estuary, and among them, depth contributed most to the differences. The CDW (Changjiang Diluted Water) was suggested as an important driving factor related to the north-south differences of both environmental variables and the macrozoobenthic community. ABC (abundance/biomass comparison) curves indicated that macrozoobenthos in the north suffered a higher level of disturbance than those in the south, probably due to suffering more interference from the Yangtze River.