Behavioural effects on Lymnaea stagnalis following sublethal exposure to the antidepressant fluoxetine

Abstract: The use of selective serotonin reuptake inhibitors (SSRI), a group of antidepressants, increases globally resulting in higher concentrations also in wastewater recipients. These concentrations may cause altered behaviour of aquatic organisms and have effects on whole ecosystem level. Therefore, the objective of this study was to assess if seven days of exposure to concentrations ranging between 0,01-100 μg/L of a common SSRI drug, fluoxetine, affected the behaviour of the great pond snail, Lymnaea stagnalis. The behavioural endpoints evaluated was boldness, the risk-taking propensity and activity, by performing behavioural state assays. For assessing potential effects on trophic interactions, snail grazing rate was evaluated by assessing consumption rates of spinach. None of the fluoxetine concentrations significantly affected any of the tested behaviours in Lymnaea. In this study, the repeatability of boldness and activity in Lymnaea was lower than previously reported for other aquatic species, including snails However, with time snail activity decreased, indicating reduced stress-levels. Results also revealed reduced snail grazing rate in the highest concentration. This study concludes that individual variation should get more attention to promote enhanced understanding of behavioural plasticity, an essential part for increasing knowledge regarding effects of toxicants on different organisms. However, as fluoxetine concentrations two to three orders of magnitude higher than those measured in the environment did not affect measured behaviours of Lymnaea in this study, these results indicate low risk for the aquatic environment.