Interacting Effects of Polystyrene Microplastics and the Antidepressant Amitriptyline on Early Life Stages of Brown Trout (Salmo trutta f. fario)

Whether microplastics themselves or their interactions with chemicals influence the health and development of aquatic organisms has become a matter of scientific discussion. In aquatic environments, several groups of chemicals are abundant in parallel to microplastics. The tricyclic antidepressant amitriptyline is frequently prescribed, and residues of it are regularly found in surface waters. In the present study, the influence of irregularly shaped polystyrene microplastics (<50 µm), amitriptyline, and their mixture on early life-stages of brown trout were investigated. In a first experiment, the impacts of 100, 104, and 105 particles/L were studied from the fertilization of eggs until one month after yolk-sac consumption. In a second experiment, eggs were exposed in eyed ova stages to 105, 106 particles/L, to amitriptyline (pulse-spiked, average 48 ± 33 µg/L) or to two mixtures for two months. Microplastics alone did neither influence the development of fish nor the oxidative stress level or the acetylcholinesterase activity. Solely, a slight effect on the resting behavior of fry exposed to 106 particles/L was observed. Amitriptyline exposure exerted a significant effect on development, caused elevated acetylcholinesterase activity and inhibition of two carboxylesterases. Most obvious was the severely altered swimming and resting behavior. However, effects of amitriptyline were not modulated by microplastics.