First indication of deleterious impacts in white-seabream larvae (Diplodus sargus) survival and behaviour following acute venlafaxine exposure.

Wastewater effluents are teeming with organisms, nutrients and chemical substances which water treatment processes fail to remove. Among these substances, pharmaceuticals such as antidepressants are a frequent occurrence, and have been reported to lead to severe effects in the physiology and behaviour of non-target marine species across taxa. Venlafaxine (VFX) is one of the most consistently prescribed substances for the treatment of human depressive disorders, acting as a serotonin and norepinephrine reuptake inhibitor. In the present study, the potential effects of this antidepressant on the survival and key behaviours (i.e. movement, aggression and foraging) of white seabream (Diplodus sargus) larvae were addressed. Larvae were submitted to an acute exposure of two different VFX treatments (low concentration, 10 µg L; and high concentration, 100 µg L) for a total of 48 h. Sampling took place after 24 and 48 h of exposure. Overall, results showed a significant effect of a two-day exposure to VFX in larvae of D. sargus. Survival was significantly reduced by exposure to a high concentration, but behavioural effects of antidepressant exposure were subtle: i.e. increased attack frequency and temporary modulation of capture success. Further research efforts should be directed towards evaluating the potential chronic effects of antidepressants in marine species, if we are to anticipate possible pressures on natural populations, and effectively advice policymakers towards the investment in new and more efficient methods of wastewater treatments.