Behavior effects of a psychotropic pharmaceutical contaminant on Atlantic salmon (Salmo salar) juveniles : Atlantic salmon juveniles exposed to two different oxazepam concentrations

Sammanfattning: Environmental pollution by pharmaceuticals is an issue of concern that is currently attracting attention around the world. Although environmental effects of pharmaceutical contaminants are not yet well documented, studies have shown that these substances may have the potential to disrupt the biotic component of an ecosystem. Particularly worrisome contaminants are the neuroactive pharmaceuticals which have the potentiality to induce behavioral modifications in non-target species. In the present study, I examined the effects of a benzodiazepine anxiolytic pharmaceutical (oxazepam) on the behavior of Atlantic salmon (Salmo salar) juveniles (fry). The hypothesis of this study was that oxazepam reduces the anxiety-like behavior of the Atlantic salmon juveniles. To test the hypothesis and assess the impact of oxazepam exposure on Atlantic salmons fry behavior, two different concentrations of this drug; a low-level (1.9 ug L-1) and a high-level concentration (1000 ug L-1) were used. Exposures lasted for 48 hours and afterwards, the fish were recorded to evaluate their behavioral responses. The results of this study reveal that oxazepam in a high concentration (1000 ug L-1 ) alters specific behavioral endpoints related to the fitness (feeding/predator avoidance) of Atlantic salmons fry. Individuals exposed to the high oxazepam concentration exhibited significant lower average speed and acceleration as well as they traveled a shorter mean distance compared to the unexposed (control) individuals. These findings confirm the hypothesis and show that psychotropic pharmaceutical contaminants modify animal behaviors, which can ultimately lead to ecological consequences. However, the concentration that generated behavioral effects in this study was three magnitudes higher than concentrations measured in the environment and thus, should not be viewed representative for oxazepam contaminated ecosystems.