The effect of warming and seasonality on bioaccumulation of selected pharmaceuticals in freshwater invertebrates

Multiple human-induced environmental stressors significantly threaten global biodiversity and ecosystem functioning. Climate warming and chemical pollution are two widespread stressors whose impact on freshwaters is likely to increase. However, little is known about the combined effects of warming on the bioaccumulation of environmentally relevant mixtures of emerging contaminants, such as pharmaceutically active compounds (PhACs) in freshwater biota. This study investigated the bioaccumulation of a mixture of 15 selected PhACs at environmentally relevant concentrations in common freshwater macroinvertebrate taxa, exposed to ambient temperatures and warming (+4 C-degrees) during the warm and cold seasons in two outdoor mesocosm experiments. Nine PhACs (carbamazepine, cetirizine, clarithromycin, clindamycin, fexofenadine, telmisartan, trimethoprim, valsartan and venlafaxine) were dissipated faster in the warm season experiment than in the cold season experiment, while lamotrigine showed the opposite trend. The most bioaccumulated PhACs in macroinvertebrates were tramadol, carbamazepine, telmisartan, venlafaxine, citalopram and cetirizine. The bioaccumulation was taxon, season and temperature dependent, but differences could not be fully explained by the different water stability of the PhACs and their partitioning between water and leaf litter. The highest waterbased bioaccumulation factors were found in Asellus and Planorbarius. Moreover, the bioaccumulation of some PhACs increased with warming in Planorbarius, suggesting that it could be used as a sentinel taxon in environmental studies of the effects of climate warming on PhAC bioaccumulation.