A test of long-term and dose-dependent effects of fluoxetine exposure on the velocity of the invasive crayfish<i>Procambarus clarkii</i>

Fluoxetine, a selective serotonin reuptake inhibitor (SSRI), is one of the most detected antidepressants in wastewater, managing to enter watersheds where it is taken up by freshwater fauna. Here we asked if the serotonergic system affects the dispersal capabilities of Procambarus clarkii , a prolific worldwide invasive freshwater crayfish species, thanks in part due to its dispersal rates. For this, we exposed adult crayfish to fluoxetine (serotonin facilitator) and para-chlorophenylalanine (PCPA, serotonin inhibitor) at two concentrations, and measured their velocity after 8 and 16 days, on a two-meter-long metal gutter. Overall, our treatment effects revealed to be non-significant, however the lowest dosage of fluoxetine seem to decrease crayfish mean velocity between the 8th and 16th day of exposure, thus shedding some light on the putative importance of the long-term exposure to environment dosage-dependent fluoxetine in modulating the dispersal capabilities of P. clarkii . Though further research is needed, these results can help us better understand the impact of ambient fluoxetine to this invasive species.