Anthropogenic activities usually contaminate water environments, and have led to the eutrophication of many estuaries and shifts in microbial communities. In this study, the temporal and spatial changes of the microbial community in an industrial effluent receiving area in Hangzhou Bay were investigated by 454 pyrosequencing. The bacterial community showed higher richness and biodiversity than the archaeal community in all sediments. Proteobacteria dominated in the bacterial communities of all the samples; Marine_Group_I and Methanomicrobia were the two dominant archaeal classes in the effluent receiving area. PCoA and ANOVA revealed strong seasonal but minor spatial changes in both bacterial and archaeal communities in the sediments. The seasonal changes of the bacterial community were less significant than those of the archaeal community, which mainly consisted of fluctuations inabundance of a large proportion of longstanding species rather than the appearance and disappearance ofmajor archaeal species. Temperaturewas found to positively correlatewith the dominant bacteria, Betaproteobacteria, and negatively correlate with the dominant archaea,Marine_Group_I; and might be the primary driving force for the seasonal variation of the microbial community.

Human activities usually leave footprints in the environment. By using 454 pyrosequencing, the impact of effluent from an industrial park on the coastal microecology in Hangzhou Bay, China, was interpreted by analysing the microbial communities of the activated sludge from three wastewater treatment plants and the sediment from the effluent receiving area. Based on richness and biodiversity, the sediments were more diversified than the activated sludge, although the seawater environment was highly contaminated. Both bacterial and archaeal communities were niche-determined. The bacterial phylum Proteobacteria dominated in all samples; and certain pollutant-resistant genera, such as Thauera and Truepera, were found in all samples. Archaeal phyla Euryarchaeota and Thaumarchaeota dominated the activated sludge and sediment samples, respectively. According to the analysis of shared operational taxonomic units (OTUs) and reads among different samples, more bacterial OTUs and reads were shared between two samples from sites with a direct effluent connection, showing a clear correlation between the wastewater treatment plants and the effluent receiving bay area. The impact of second-hand pollution can be evaluated by comparing the bacterial community in different eco-environments with a direct effluent connection, especially when pristine samples are not available.