Widespread psychoactive pollutant augments daytime restfulness and disrupts diurnal activity rhythms in fish

• Published in: Chemosphere (Oxford) Vol. 326; p. 138446
• Main Authors: Tan, Hung, Martin, Jake M., Alton, Lesley A., Lesku, John A., Wong, Bob B.M.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.06.2023
• Subjects: Activity; Animals; Animals, Wild; Anthropogenic change; Antidepressive Agents; Behavioural ecotoxicology; Circadian Rhythm; Cyprinodontiformes - physiology; Environmental Pollutants; Environmental Sciences; Fluoxetine - toxicity; Gambusia holbrooki; Humans; Miljövetenskap; Prozac; Selective serotonin reuptake inhibitor; Water Pollutants, Chemical - toxicity; Prozac; Activity; Anthropogenic change; Gambusia holbrooki; Behavioural ecotoxicology; Selective serotonin reuptake inhibitor
• ISSN: 0045-6535; 1879-1298; 1879-1298
• DOI: 10.1016/j.chemosphere.2023.138446

Pharmaceutical pollution is a major driver of global change, with the capacity to alter key behavioural and physiological traits in exposed animals. Antidepressants are among the most commonly detected pharmaceuticals in the environment. Despite well-documented pharmacological effects of antidepressants on sleep in humans and other vertebrates, very little is known about their ecologically relevant impacts as pollutants on non-target wildlife. Accordingly, we investigated the effects of acute 3-day exposure of eastern mosquitofish (Gambusia holbrooki) to field-realistic levels (nominal concentrations: 30 and 300 ng/L) of the widespread psychoactive pollutant, fluoxetine, on diurnal activity patterns and restfulness, as indicators of disruptions to sleep. We show that exposure to fluoxetine disrupted diel activity patterns, which was driven by augmentation of daytime inactivity. Specifically, unexposed control fish were markedly diurnal, swimming farther during the day and exhibiting longer periods and more bouts of inactivity at night. However, in fluoxetine-exposed fish, this natural diel rhythm was eroded, with no differences in activity or restfulness observed between the day and night. As a misalignment in the circadian rhythm has been shown to adversely affect fecundity and lifespan in animals, our findings reveal a potentially serious threat to the survival and reproductive success of pollutant-exposed wildlife. [Display omitted] •Pharmaceutical compounds are entering the environment at an unprecedented rate.•The pharmaceutical pollutant fluoxetine disrupts circadian rhythms of wild fish.•Disruptions to diel activity patterns was driven by increased daytime inactivity.•Misalignments in circadian rhythms have been shown to adversely affect lifespan.