Antidepressants in surface waters: fluoxetine influences mosquitofish anxiety-related behavior at environmentally relevant levels

Pharmaceutical contamination is an increasing problem globally. In this regard, the selective serotonin reuptake inhibitors (SSRIs)—a group of antidepressants—are particularly concerning. By disrupting the serotonergic system, SSRIs have the potential to affect ecologically important behaviors in exposed wildlife. Despite this, the nature and magnitude of behavioral perturbations resulting from environmentally relevant SSRI exposure among species is poorly understood. Accordingly, we investigated effects of two field-realistic levels of the SSRI fluoxetine (61 and 352 ng/L) on sociability and anxiety-related behaviors in eastern mosquitofish (Gambusia holbrooki) for 28 days. Additionally, we measured whole-body tissue concentrations of fluoxetine and norfluoxetine. We found that fluoxetine altered anxiety-related behavior but not sociability. Specifically, female fish showed reduced anxiety-related behavior at the lower treatment level, while males showed an increase at the higher treatment level. In addi...