Behavioural effects of psychopharmaceuticals and their ecological relevance in aquatic environments

Human medicines like antidepressants and neuroactive drugs are increasingly found in rivers and lakes. These substances can influence the behaviour of aquatic organisms, potentially disrupting ecosystems. My research explores how movement behaviour in freshwater species responds to two pharmaceuticals, carbamazepine and citalopram, compared to traditional toxicity measures like mortality. Laboratory tests showed that behavioural changes could be early warning signs of pharmaceutical effects, occurring at lower concentrations than lethal effects. Since behaviour plays a crucial role in survival and reproduction, changes in organism behaviour could potentially result in shifts at the population or ecosystem level. However, long-term outdoor experiments (mesocosms) revealed that these behavioural changes did not translate into significant population- or community-level impacts at environmentally realistic concentrations. While it remains complex to link individual behavioural responses to broader ecological consequences, the results raise important questions about how we assess the environmental risks of pharmaceuticals.