Elevated temperature increases the susceptibility of D. magna to environmental mixtures of carbamazepine, tramadol and citalopram

The joint risks assessment of thermal stress and rising loads of pharmaceuticals (PhACs) in surface waters is a relevant topic in aquatic ecotoxicology. This study investigated the relevance of increased water temperature to alter the acute toxicity of environmentally relevant carbamazepine (CBZ), citalopram (CIT) and tramadol (TRA) concentrations as mixtures (ECs) and delayed outcomes in Daphnia magna. Responses of detoxification and antioxidant pathways in premature daphnids post an acute 24 h (pulsed) exposure to the PhACs mixtures and delayed responses as the reproductive output over 14 days recovery were investigated under 21- and 26 °C incubation. Biphasic modulation in glutathione S-transferase (GST) activity and significant inhibition of superoxide dismutase (SOD) activity were observed in both thermal regimes with significant shift in effective thresholds from 10-fold ECs at 21 °C to ECs at 26 °C incubation. Significant induction in catalase (CAT) activity and oxidative stress development were recorded at elevated temperatures from the 10-fold ECs dose onward. Pulsed exposures at 26 °C also led to significant decrease in the reproduction of daphnids above the 10-fold ECs of PhACs. The Integrated Biomarker Response scoring (IBRv2) approach outlined a 1.8-fold increase in alterations of daphnids exposed to 100-fold ECs of PhACs at 26 °C.