Abstract Description

Freshwater systems are increasingly exposed to wastewater discharges containing excessive organic inputs. The likely outcomes of this exposure include eutrophication, impaired biogeochemical processes and reduced water quality. Despite these challenges, we lack insights regarding the impacts of direct stressors such as wastewater treatment plants (WWTPs) on microbial community composition in effluent-receiving freshwater environments. Cyanobacteria, which are key players in carbon and nitrogen cycling, provide a sensitive indication of environmental disturbances. Here, we collected samples across a river that receives effluents from four WWTPs and characterised the microbial community composition using 16S rRNA gene amplicon sequencing, together with physicochemical parameters. To further enhance cyanobacterial resolution, we will use accurate databases such as CyanoDB and Cyanoseq, allowing for clear taxonomic profiling and characterisation of Cyanobacterial responses to WWTPs responses. Statistical tests will be used for the database to compare the microbial community responses and the cyanobacteria to repeated introduction of four WWTPs’ discharges across the river. This work is expected to provide insights on how multiple WWTPs discharges affect microbial ecology in a freshwater source and evaluate the potential of Cyanobacteria as sentinel taxa for detecting wastewater-driven perturbations. Overall, these findings will contribute to develop suitable microbial indicators for ecosystem protection.