Ecotoxicological effects on a food-web exposed to pharmaceuticals : Uptake and effects of oxazepam, fexofenadine and a mixture of both in algae, zooplankton and sticklebacks.

Abstract: Complex mixtures of biologically active pharmaceutical residues continuously enter aquatic environments via wastewater, where it can affect species through preserved human drug targets or cause unexpected effects in non-target species. Benzodiazepines and antihistamines are two highly consumed groups of pharmaceuticals that have been shown to bioconcentrate in aquatic organisms and induce behavioural alterations affecting individual fitness. Few studies have investigated bioaccumulation and possible ecological effects of co-occurring pharmaceuticals in food-webs. The aim of this study was to: 1) quantify and compare species-specific bioconcentration and bioaccumulation, by exposing a tri-trophic system consisting of algae, zooplankton and three-spined sticklebacks to oxazepam (benzodiazepine), fexofenadine (antihistamine) and a mixture of both, and 2) analyse if exposure to these pharmaceuticals induce behavioural alterations in sticklebacks, by using standardized behavioural experiments. Species-specific bioconcentration of both oxazepam and fexofenadine was confirmed (F3,98 = 3.061, p = 0.03) were algae and zooplankton bioconcentrated substantially more pharmaceuticals (~50-1800 μg kg-1) compared to sticklebacks (~0.1-6 μg kg-1). Uptake of oxazepam in both zooplankton and sticklebacks was significantly higher compared to fexofenadine (p < 0.001).  Zooplankton and sticklebacks retained 16 and 0.3%, respectively, of fexofenadine from the consumed contaminated prey. Sticklebacks showed no direct behavioural alterations, but possible direct and indirect cascading effects might occur in co-occurrence with fish species exhibiting pharmaceutical-induced alterations. These findings highlight the importance of including consumption of contaminated prey as an important exposure route, when assessing effects of pharmaceuticals in the environment. Contamination magnitudes and subsequent effects are species-specific and vary depending on type of pharmaceuticals.