Taxonomic and Functional Responses of Sediment Bacterial Community to Anthropogenic Disturbances in the Yarlung Tsangpo River on the Tibetan Plateau

摘要

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 rivers in the world (the Yarlung Tsangpo River) subject to anthropogenic pressures. The results indicated that wastewater discharge resulted in asynchronous change of biomass and diversity in sediment bacteria, and they were both inhibited by the construction of dam. Moreover, significant alterations in the community composition were observed between upstream and down-stream of the dam, while functional variation was not detected due to the bacterial functional redundancy. In addition, revealed by General Additive Model (GAM) and Canonical Correspondence Analysis (CCA), elevation was the endemic driver on the Tibetan Pla-teau shaping the sediment bacterial community diversity and composition along with pH, while nutrient condition was responsible for functional variation. Furthermore, little synchronized dynamics of co-occurrence was exhibited in sediment bacteria in the Yarlung Tsangpo River. In conclusion, anthropogenic disturbances influenced the sediment bacterial community at the compositional level rather than the functional level in the typical high-elevation river. Therefore, our study provides potential evidence that diversity, composition and function of sediment bacterial community should all be taken into consideration on the Tibetan Plateau.