Human land uses alter the structure and potential function of bacterial communities across an urban river of western China.

The rapid population growth and intensive anthropogenic activities have induced profound alterations in surface land covers, inevitably posing significant threats to water quality and aquatic biodiversity within river ecosystems. However, the congruent or divergent effects of human land-use patterns on planktonic versus sedimentary bacterial communities remain insufficiently elucidated. Herein, we comprehensively investigated the structure and function of planktonic and sedimentary bacterial communities among the forest, agricultural, and residential regions along the Bahe River. Regarding planktonic bacteria, we found that urban imperviousness significantly elevated ion-derived variables, posing negative effects on bacterial structure and potential function. Particularly, planktonic bacterial network topology was impaired in exchange for community stability, while predicted functional capacities related to xenobiotics biodegradation and metabolism were enriched in the residential region. For sedimentary microbes, impervious and agricultural land-uses facilitated nutrient accumulation and adversely impacted bacterial composition and potential function, despite minor differences in bacterial α-diversity and network topology/community stability across the three regions. Notably, total phosphorus exhibited robust positive correlations with multiple predicted metabolic pathways of sedimentary bacteria. Our study underscored the differentiated responses of planktonic and sedimentary bacterial communities to human land uses, emphasizing the necessity of implementing media-specific (i.e., water and sediments) pollution mitigation measures tailored to diverse land-use patterns for safeguarding riverine biodiversity.