Driving Effects of Large-Scale Sand Mining Activities on Bacterial Communities in Subtropical River Sediments—A Case Study of the Jialing River

Sand mining activities can significantly impact the microecology of rivers. Scientific studies are needed for the effective protection and restoration of river ecosystems impacted by sand mining activities. In this study, we used high-throughput sequencing technology to analyse the structure and function of sediment bacterial communities in three river habitats of the Jialing River Basin, namely, a natural river channel (no sand mining activities), a channel with continuous large-scale sand mining activities, and a channel in which sand mining had been terminated one year prior, as well as to analyse the main constraints leading to changes in sediment bacterial communities. The results revealed that the dominant bacteria in the different sand mining environments of the Jialing River were Proteobacteria, Chloroflexi, and Acidobacteria, and that total organic carbon (TOC), moisture content (MC) and total nitrogen (TN) were the main limiting factors affecting the structure of the bacterial community. In addition, large-scale sand mining activities caused significant changes (<i>p</i> < 0.05) in major secondary functions, such as energy metabolism, cofactor and vitamin metabolism, and translation. In summary, the persistence of large-scale sand mining activities led to heterogeneous changes in sediment bacterial community structure and function, which had an important impact on the stability of the ecosystem in the Jialing River Basin.