New preprint published: Bugs on drugs

Goede, N.J., Cerveny, D., Cebrián-Lacasa, D., Demaire, C., Zhang, N., Brendonck, L., Bertram, M.G., Gelens, L., Brodin, T., Thoré, E.S.J. Preprint. Bugs on drugs: trait-specific behavioral responses to fluoxetine and clobazam in damselfly nymphs across temperatures. SSRN http://dx.doi.org/10.2139/ssrn.7083711

ABSTRACT

Freshwater ecosystems are increasingly exposed to psychoactive pharmaceuticals while also experiencing rapid warming, two stressors known to influence aquatic organism behavior. Yet, it remains unclear how temperature shapes the behavioral effects of these environmentally persistent compounds—whether occurring individually or as mixtures—particularly in aquatic invertebrates. Therefore, we experimentally tested whether and how 2-week exposure to fluoxetine (average measured concentration: 0.31 µg/L), clobazam (0.95 µg/L), or their mixture (0.33 and 1.05 µg/L, respectively), affects the locomotor and foraging behavior of northern damselfly (Coenagrion hastulatum) nymphs at two environmentally relevant temperatures (10 °C and 16 °C). Temperature strongly influenced locomotion and foraging behavior by reducing activity and feeding after 2 weeks of exposure, accounting for much of the observed variation across treatments. Pharmaceutical effects were comparatively trait-specific. Clobazam reduced active movement speed regardless of temperature, whereas fluoxetine decreased prey-capture success at 10 °C. Combined exposure did not, however, result in stronger detectable behavioral effects than single-compound exposure. Bioconcentration analyses revealed higher accumulation of fluoxetine than clobazam, suggesting that toxicokinetic differences contributed to the observed behavioral responses. Together, these results demonstrate that warming can substantially shape baseline predator behavior and should be considered when interpreting contaminant effects in freshwater ecosystems under ongoing climate change.