The Consequences of Exposure to an Environmental Concentration of Antidepressant in the Eurasian Starling

Pharmaceuticals are vital to individual and societal health, yet there is growing concern regarding the effects they have on environmental health. Any pharmaceutical that is incompletely metabolised by humans can enter sewage systems following excretion. At wastewater treatment plants, many bird species are known to forage on invertebrates containing a mixture of pharmaceuticals. Psychotropic pharmaceuticals such as antidepressants, that are designed to modulate human behaviour, are predicted to elicit comparable effects in birds. In this thesis, the effects of a maximally relevant concentration of fluoxetine on ecologically relevant avian behavioural and physiological endpoints were assessed. Wild-caught Eurasian starling (Sturnus vulgaris), a species that forages at wastewater treatment plants, were exposed chronically to fluoxetine (2.7 µg day-1) from winter to early summer, for 28 weeks. During the breeding season, male starlings sang less to and behaved more aggressively towards fluoxetine-treated than control females. Over the exposure period, control birds became less bold over time, whilst boldness was unchanging in fluoxetine-treated birds. No effects of treatment were observed on activity, exploration or neophobia. Controls regrew feathers of poorer quality during the exposure period than fluoxetine-treated individuals and the concentration of glucocorticoid metabolites in faecal samples increased over time in controls but decreased in fluoxetine-treated birds. Further, the leg skin temperature of fluoxetine-treated birds was unresponsive to changes in air temperature, whereas leg skin temperature varied with air temperature in control birds. Finally, fluoxetine was detected in all fluoxetine-treated bird tissue and feather samples analysed. In future, effects on free-living individuals and populations should be assessed, as should the effects of potentially additive environmentally relevant mixtures of antidepressants. My findings suggest that environmental concentrations of fluoxetine can alter multiple traits important for reproduction and survival in individual birds, and could consequently impact on exposed local populations.