Duarte_2019_Mar.Environ.Res_147_24

Antidepressants such as fluoxetine are frequently detected in estuaries and can have profound effects on non-target organisms by interfering with the neural system and affecting essential physiological processes and behaviours. In this context, short-term effects of fluoxetine exposure were analysed in the common goby Pomatoschistus microps, an estuarine resident fish species. Two experiments were conducted with fish exposed to: i) fluoxetine concentrations within the mug/L range for 96h (0.1, 0.5, 10 and 100mug/L) and ii) fluoxetine concentrations within the mg/L range for 1h (1, 5 and 10mg/L). Acute toxicity was assessed via multiple biomarker responses, namely: activity levels of antioxidant (superoxide dismutase and catalase) and detoxification enzymes (ethoxyresorufin O-deethylase and glutathione S-transferase); and biomarkers of effects (lipid peroxidation and DNA damage) and of neurotoxicity (acetylcholinesterase inhibition). Furthermore, behavioural responses concerning activity (active time, movement delay and number of active individuals) and feeding (number of feeding individuals) were also recorded and analysed. Acute fluoxetine exposure for 96h (in the mug/L range) reduced antioxidant CAT activity with increasing concentrations but had no significant effect on SOD activity. Biotransformation enzymes showed bell-shaped response curves, suggesting efficient fluoxetine metabolism at concentrations up to 10mug/L. No significant damage (LPO and DNAd) was observed at both concentration ranges (mug/L and mg/L), yet 1h exposure to higher fluoxetine concentrations (mg/L range) inhibited acetylcholinesterase activity (up to 37%). Fluoxetine (at mg/L) also decreased the number of both feeding and active individuals (by 67%), decreased fish active time (up to 93%) and increased movement delay almost 3-fold (274%). Overall, acutely exposed P. microps were able to cope with fluoxetine toxicity at the mug/L range but higher concentrations (mg/L) affected fish cholinergic system and behavioural responses.