Pharmaceuticals and personal care products (PPCPs) are contaminants of concern in aquatic ecosystems and are now detected in surface waters receiving wastewater. PPCPs pose a considerable risk to aquatic biota as they are biologically active by design, and have largely unknown effects on non-target organisms including aquatic microbes. Research indicates that select pharmaceuticals can inhibit functioning of aquatic organisms at low, environmentally relevant concentrations. However, the effects of PPCPs on whole-ecosystem structure and function are only now being investigated.
We conducted a 21d artificial stream experiment to examine the effects of 3 commonly detected PPCPs (fluoxetine, diphenhydramine and ciprofloxacin) on stream ecosystem function. We examine effects on biogeochemical processes, including denitrification, primary production and respiration. We also explore how PPCPs alter the relationship between community composition and algal exudate quality of biofilms and the structure and function of denitrifying bacteria. Our results suggest that although subtle, PPCPs are capable of altering ecosystem processes and we highlight important risks of PPCPs posed to freshwater systems and aquatic biota.