Basal autotrophic and heterotrophic food web responses to municipal wastewater effluent exposure in the Bow River, Alberta and experimental streams at Advancing Canadian Water Assets
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2024-09-19
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Abstract
Municipal wastewater effluent (MWWE) release into urban rivers act as a main point source of nutrients and environmental substances of concern (ESOCs), such as pharmaceuticals and personal care products, which can alter the water quality of receiving waters and the physiology and ecology of aquatic organisms. Over the years, there have been active efforts to reduce the impact of MWWE on the Bow River’s ecosystem health; however, understanding potential nutrient-ESOC interactions and potential impacts on aquatic organisms are still largely unknown. This study examined the changes in basal autotrophic and heterotrophic community characteristics and responses to Municipal Wastewater Effluent (MWWE) exposures both in the Bow River and in artificial streams at Advancing Canadian Water Assets (ACWA). A main goal was to better understand the responses of riverine biofilms to MWWE complex mixtures and identify potential interactions between nutrients and ESOCs. In the Bow River, increasing MWWE loadings enhanced heterotroph decomposition rates and ash free dry mass (AFDM) accumulation, and the main driver of change identified was nutrient enrichment. In contrast, experiments in the artificial streams found increasing MWWE concentration (0-15 % v/v) suppressed autotroph biomass, produced a subsidy-stress pattern in biofilm AFDM, and had no impact on organic matter decomposition rates. Nutrient-ESOC interactions were suggested as a potential cause for the patterns observed in the artificial streams. In both riverine and stream systems, MWWE impacts consistently showed a shift towards more heterotroph dominant biofilm communities with time (as quantified by the autotrophic index (AI)). The observed MWWE effects on biofilm community composition shift show potential to influence efficient energy transfer to higher trophic levels.
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Sayles, B. K. (2024). Basal autotrophic and heterotrophic food web responses to municipal wastewater effluent exposure in the Bow River, Alberta and experimental streams at Advancing Canadian Water Assets (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.