River sediments, functioning as sink and source for nutrients, are one of the most diverse bacteria habitats in freshwater ecosystems. Recently, more attention has been paid to the sediment bacteria because of their important roles in biogeochemical cycling. Our study addresses the question of how sediment bacterial community varies taxonomically and functionally along one of the largest plateau river in the world (the Yarlung Tsangpo River) subject to anthropogenic pressures, including wastewater discharge and river damming, as they may lead to adverse impacts on river ecosystems. The results indicated that river damming retained biogeochemical nutrients of carbon, silica and nitrogen in the reservoir, while phosphorus was more sensitive to wastewater discharge. Besides, wastewater discharge resulted in asynchronous change of biomass and diversity in sediment bacteria while they were both inhibited by the construction of dam. Moreover, significant alterations in the community composition were observed in dam-associated sites, while according to exploratory bioinformatics prediction tool of PICRUSt, functional variation was not detected between upstream and downstream of the dam due to functional redundancy. In addition, revealed by General Additive Model (GAM) and Mantel test results, elevation was the endemic driver shaping the sediment bacterial community diversity and composition along with pH, while nutrient concentrations were responsible for functional variation. Furthermore, little synchronized dynamics of co-occurrence was exhibited in the sediment bacteria in the Yarlung Tsangpo River. Therefore, our study proposed that sediment bacterial community should be defined taxonomically and functionally when studying its variation in river ecosystems.

中文翻译：

---

青藏高原雅鲁藏布江沉积物细菌群落对人为干扰的分类学和功能响应

河流沉积物作为养分的汇和源，是淡水生态系统中最多样化的细菌栖息地之一。近年来，沉积物细菌因其在生物地球化学循环中的重要作用而受到更多关注。我们的研究解决了世界上最大的高原河流之一（雅鲁藏布江）的沉积物细菌群落在分类学和功能上如何变化的问题，这些河流受到人为压力，包括废水排放和河流筑坝，因为它们可能导致不利影响河流生态系统。结果表明，河流筑坝保留了水库中碳、硅和氮的生物地球化学养分，而磷对废水排放更为敏感。除了，废水排放导致生物量和沉积物细菌多样性的不同步变化，而两者都受到大坝建设的抑制。此外，在与大坝相关的站点中观察到群落组成的显着变化，而根据 PICRUSt 的探索性生物信息学预测工具，由于功能冗余，未检测到大坝上游和下游之间的功能变化。此外，通用加性模型 (GAM) 和 Mantel 测试结果显示，海拔是影响沉积物细菌群落多样性和组成以及 pH 值的地方性驱动因素，而营养浓度则是功能变异的原因。此外，在雅鲁藏布江沉积物细菌中几乎没有表现出共存的同步动态。所以，