The impact of wastewater effluent on noble crayfish behaviour : insights from wastewater cue preference and shelter-seeking tasks

Sammanfattning

The increasing production of wastewater effluent has adverse effects on/poses a threat to aquatic wildlife. Although wastewater treatment plants mitigate pollution, they are not fully effective in removing all contaminants. Aquatic animals’ behaviour can indicate their physiological responses and ecological health and can thus be used to enhance understanding of how pollutants affect aquatic animals. This study investigates behavioural effects on noble crayfish (Astacus astacus) before and after seven days of exposure to wastewater effluent. Two key behavioural responses were assessed: 1) how crayfish use shelter resources, which are vital for their survival as a refuge from predators, and 2) the capacity crayfish have to detect and potentially prefer or avoid olfactory cues of wastewater effluents. The results show significant changes in crayfish behaviour after exposure. Exposed crayfish spent less time in shelters and avoided cues associated with wastewater effluent, preferring areas further away from the effluent outlet. Additionally, exposed crayfish were significantly more active than the control. The results indicate potential alterations in behavioural responses after exposure to wastewater effluent, suggesting that crayfish may need previous experience with wastewater to be able to detect the wastewater cue and actively choose to avoid it. Further, crayfish exposed to wastewater acted bolder by not seeking shelter, potentially increasing risk-taking behaviour. Further research is needed to confirm my findings in natural environments and in environments next to other wastewater treatment plants.