Epsilon Archive for Student Projects

Abstract

Pharmaceutical waste products are increasingly being detected in the environment where their behaviour-altering effects may impact wild animals. Yet, we have a poor understanding of how these pollutants affect the reproductive success of exposed animals and ultimately the evolutionary selection pressures they experience. In this laboratory experiment, we exposed groups of a highly social fish, Neolamprologus multifasciatus, to environmentally realistic concentrations of the pharmaceutical oxazepam over a one-month period. We monitored how offspring production and division of reproduction were affected. This represents one of the first experiments to assess these endpoints under controlled yet naturalistic conditions, where fish were able to create social groups under different exposure scenarios. High doses of oxazepam significantly reduced aggressive behaviours in both reproductive and non-reproductive fish. Larger males and females had higher reproductive success. Specifically high treatment allowed smaller males to become reproductively successful, whereas they were unable to reproduce under control conditions. Reproductive males exhibit more aggressive behaviours than non-reproductive males, while reproductive females show more submissive behaviours than non-reproductive females. Males have larger home ranges, and reproductive females have smaller home ranges than their non-reproductive ones. Overall spatial dynamics, such as home range size and shell selection, remained unchanged by the treatment. These findings suggest that environmentally realistic concentrations of oxazepam can significantly alter social behaviours and reproductive dynamics in Neolamprologus multifasciatus.