北运河浮游细菌集合群落空间变化的环境解释

环境选择在精细地理尺度河流浮游细菌多样性构建机制中的贡献已得到普遍认同.为回答浮游细菌集合群落中核心分类操作单元(Core Operational Taxonomic Units,Core OTUs)和特有分类操作单元(Unique Operational Taxonomic Units,Unique OTUs)是否具...

Environmental interpretation of spatial variation of planktonic bacterial communities in the North Canal River

The contribution of environmental selection to the construction mechanism of phytoplankton diversity in fine geographical scale rivers has been widely recognized. According to ecological theory of metacommunity, the determinant factors between the Core Operational Taxonomic Units (core OTUs) and the Unique Operational Taxonomic Units (unique OTUs) are potential to be different, as these two key components of microbial community in river ecosystems vary in dispersal ability and biological responses. To test this hypothesis, the Beijing-Tianjin-Hebei section of the Northern Canal River, which is highly artificial, was selected as the study area. To interpret the spatial variation of the core OTUs in local-community and the unique OTUs, the water quality monitoring results and high-throughput sequencing results were combined for comprehensive analysis. The results showed that inorganic nitrogen, cation such as Ca²⁺, Mg²⁺ induced by reclaimed water recharge and organic pollution caused by physical disturbance of reclaimed water recharge port were the key pollutants in the North Canal River. The intra-group similarity of the core OTUs in local-community was significantly higher than that of the unique OTUs, and the geographical distribution pattern and environmental divers differed a lot between these two key components. The spatial distribution law of core OTUs in local community was significantly consistent with geographic spatial distribution pattern, and environmental variables most closely related to spatial changes were TN, nitrate nitrogen (NO₃^--N), K⁺, Ca²⁺, Na⁺ and Mg²⁺. Specifically, these critical environmental variables showed a significant decrease trend with the direction of water flow and showed a strong synergistic change with the geographical diffusion distance. While, unique OTUs in local-communities did not have a significant geographic spatial distribution pattern, and the crucial environmental variables determining the spatial distribution of the unique OTUs in local-communities were temperature, oxidation-reduction potential and pH, which were caused by the indirect effects of physical disturbance on hydrological quality of reclaimed water supply.