Long-term exposure to sediment-associated antidepressants impacts life-history traits in an estuarine deposit-feeding worm

Hydrophobic pollutants, such as the antidepressant sertraline (SER), tend to sorb to particles in the water column and subsequently accumulate in the sediment. Long-term exposure to these pollutants may significantly affect sediment-dwelling organisms´ fitness and behavior. To address this knowledge gap, we investigated the impact of chronic exposure to a range of environmentally relevant and higher concentrations of sediment-associated SER on the deposit-feeding polychaete Capitella teleta. Since certain antidepressants can function as neurotoxic chemicals and endocrine disruptors on non-target species, we examined feeding rate and burrowing behavior in adult worms after 23 days of exposure (Experiment 1), and key life-history traits in juvenile worms during 35 days of exposure (Experiment 2) to sediment-associated SER (0.33 - 100 µg/g dw sediment). SER did not affect survival but reduced maturation and time to first reproduction: 37%, 50%, and 29% of the worms exposed respectively to SER 0.33, 3.3 and 33 µg/g reached maturation on day 21, whereas worms in the other treatments did not mature (0%; control) or reached a lower maturation degree (6%; 100 µg/g). Although not statistically significant, growth, feeding, and burrowing manifested non-monotonic trends: at environmentally relevant SER concentrations adults increased feeding and extended time to fully burrow into the sediment, and juveniles increased growth, whereas high concentrations had an inhibitory or no effect. Reproductive endpoints appeared most sensitive to chronic SER exposure. Even at low environmental concentrations, antidepressants can cause sublethal effects in non-target species, potentially affecting population dynamics and ecosystem functioning. Further research is key to fully understanding the ecological impact of hydrophobic chemicals in natural environments.