How is parental care impacted by pharmaceutical pollution in Neolamprologus multifasciatus? : behavioural and reproductive responses to diazepam exposure in a shell-dwelling cichlid

Sammanfattning

Pharmaceutical pollutants are increasingly recognized as a threat to aquatic ecosystems due to their potential to alter animal behaviour. This experiment investigated the effects of the anxiolytic drug diazepam exposure on reproduction and parental care in the social cichlid Neolamprologus multifasciatus. Using replicate aquariums stocked with males and females, the fish were exposed to either a control concentration, a low treatment at 1 μg/L, or a high treatment at 50 μg/L of diazepam in a laboratory setting for 96 days. I monitored which females reproduced over this time, and quantified maternal aggression using mirror trials. The proportion of females that produced fry did not differ between diazepam treatments, although the number of fry that they produced was higher in the high compared to low treatment. I found that diazepam exposure significantly reduced display aggression at high doses by mothers in response to a presented mirror, but had no effect on overt aggression. Additionally, females in the high treatment swam in front of the mirror more times and emerged faster from their shelter shells, suggesting increased activity or exploratory behaviour. These findings indicate that diazepam alters parental behaviours, and also significantly impacts reproductive output, highlighting the importance of including behavioural endpoints in ecotoxicological assessments.