The effect of an anti-depressant on responses to predation in an isopod

Abstract: A lot of chemicals and pharmaceutical substances used by humans, are released into the waste-water and end up in lakes and ponds. Further, because pharmaceutical substances are increasing worldwide, the problem increases. A very common human anti-depressant is fluoxetine which is found in lakes, ponds and even in the bodies of aquatic organisms. This study is focusing on how fluoxetine might change antipredation behaviour in the aquatic organism Asellus aquaticus. A. aquaticus live worldwide and are important for aquatic ecosystems because of its leaf litter decomposition degradation and hence nutrient cycling. A. aquaticus used in this study were wild-caught in lake Tåkern. In the lab, A. aquaticus were experimentally exposed to fluoxetine in an environmental relevant concentration, 20 ng/l, or kept in normal water as a control, for 28 days. After this exposure, A. aquaticus went through simulated predation attacks, and their responses were measured. I found no difference in anti-predation behaviour after the simulated predation attack in A. aquaticus, between the group exposed to fluoxetine and the control group. I found that males tended to be more active and explorative than females, but this was not affected by fluoxetine exposure. My results suggest that the dose of fluoxetine here used, did not cause behavioural changes as observed in other studies. Nevertheless, substance like fluoxetine are not the only pharmaceutical organisms in the wild are exposed to, and such cocktail effects may be additive. Future studies should therefore investigate how these substances both individually (in varying doses) and together, can affect aquatic organisms and ecosystems.