Large-scale spatial patterns in the community structure of benthic harpacticoid copepods in the Bohai Sea, China

To determine the effects of natural and anthropogenic variables on the benthic harpacticoid copepod assemblages of the Bohai Sea, China, samples were collected on two occasions from an extensive grid of 20 stations. Differences among stations between sampling periods, although significant, were a consequence of small changes in abundances of dominant species. This is interpreted as a seasonal effect. Differences between stations were significant, and were used to cluster stations into groups with similar species composition. These station groupings reveal a weak faunal gradient leading from the mouth of the Huanghe (Yellow River) to the Bohai Strait. Analyses relating faunal composition to environmental variables showed that there were significant differences in environmental variables between faunally defined groups of stations. The variables most closely correlated with community structure were those related to natural processes within the Bohai Sea, namely silt/clay content, depth and phaeopigment concentrations at the sediment surface. The Huanghe is the most turbid river in the world, and its inputs into the Bohai Sea are the primary factors affecting variation in community structure of the copepods. A suite of univariate measures are related to distance from the river mouth. Analyses do not suggest strong large-scale pollution gradients within the study area.