Are you anxious yet? Investigating the effects of citalopram on the physiology and behavior of the rusty crayfish (Faxonius rusticus)

Selective serotonin reuptake inhibitors (SSRI) are a growing group of pollutants that are increasingly causing detrimental changes to aquatic ecosystems. Upon entering aquatic habitats, these chemicals affect both vertebrates and invertebrates by influencing fecundity, aggression, exploration, and mortality in non-target organisms. In crustaceans, more specifically in crayfish and lobsters, since serotonin (5-Hydroxytryptamine, 5-HT) has been linked to a suite of stress responses and agonistic behaviors, SSRIs have the potential to harm these organisms significantly. In this study, we aimed to quantify the effects of a twenty-one day exposure of citalopram on the behavior and physiology of the rusty crayfish (Faxonius rusticus). Crayfish were exposed to an environmentally relevant concentration (1 μg / L) of citalopram in their tank water for 21 days and perform physiological (oxygen consumption and stress analysis) and behavioral (flight initiation distance) assays. Changes in behavior (reaction distance), physiology (oxygen consumption), and neurotransmitter levels (stress) were used to quantify any effects due to citalopram exposure. We found that as the length of exposure increased, regardless of citalopram presence, the oxygen consumption rate decreased significantly. Females that were injected with supplemental 5-HT froze closer to a novel stimulus than males or individuals from other treatment groups. Females also took longer to explore the arena than males, regardless of treatment. The amount of 5-HT present in individuals increased with mass, but this was not observed in individuals exposed to an external stressor regardless of the presence or absence of citalopram in their system. Exposure to 1 μg / L of citalopram for 21 days did not significantly impact crayfish behavior, but behavior and oxygen consumption were impacted by sex and isolation length, respectively. While this concentration of citalopram did not alter behavior or physiology, further work is needed to quantify the effects of various concentrations and modes of delivery.