Explore the Impact of Reclaimed Water Reuse on the Assembly and Coexistence Patterns of Bacterioplankton and Bacteriobenthos Community in the Receiving River Sections

Abstract

To address water scarcity, reclaimed water is an essential supplement, yet its potential ecological impacts, especially on microbial communities in different habitats, remain largely unknown. This study investigates the effects of reclaimed water on bacterioplankton and bacteriobenthos in five river sections receiving treated effluents. Findings reveal that reclaimed water significantly suppresses bacterioplankton but has little effect on sediment. Bacterioplankton co-occurrence networks exhibit greater variability than bacteriobenthos in response to reclaimed water, indicating stronger resilience in the latter. Both community assembly mechanisms are driven by stochastic processes, with reclaimed water reinforcing the dominance of dispersal limitation. Post-reclaimed water use, genes for nitrate assimilation increase in water, and those for denitrification rise in sediment. Mantel and Redundancy Analysis (RDA) indicate that TN, NH4+, and NO3- are key environmental drivers of bacterial community assembly and species coexistence in river sections, with bacteriobenthos showing greater nitrogen metabolic potential. These results indicate that planktonic bacteria adapt to the environmental pressures brought about by the inflow of reclaimed water through succession, while benthic bacterial communities are relatively stable and sufficient to absorb the impact of reclaimed water.

Keywords: Reclaimed water, microbial community, Habitat heterogeneity, assembly mechanism, species coexistence