The impact of pharmaceuticals on personality in sea anemones

Abstract

Pharmaceutical drugs along with other human derived contaminants are prevalent in natural water bodies due to many anthropological factors and they eventually end up reaching coastal waters. The pharmaceuticals have impacts on the behaviour and physiology of humans, thus it is important to understand what impact they have on animals. The sea anemone, Metridium senile, is found throughout the world such as in the shore regions of the west coast of Sweden. Three commonly found pharmaceuticals, caffeine, propranolol and diazepam were examined to understand their impact upon the sea anemones by measuring risk-taking behaviour; also termed shyness and boldness. M. senile were exposed to 0.01 mg/L of caffeine, 0.01 mg/L of propranolol and 20 ng/L of diazepam in artificial sea water for two weeks. Risk taking was measured as the startle response where anemones had a fast jet of artificial seawater or drug-containing seawater directly jetted onto the oral disk of the anemones. The time to re-extend the tentacles is a measure of boldness. Measures were made prior to, during and after the two week drug exposure. In the first three weeks, from baseline to the end of exposure week 2, the pharmaceuticals propranolol, diazepam and the controls did not affect the startle response. In the final week, all anemones that were exposed to one of the three drugs exhibited an increase in startle response in comparison to the controls. Caffeine was the only drug that elicited a significantly faster startle response than other pharmaceuticals compared to the control group. Therefore, caffeine exposure at environmentally relevant concentrations may increase risk taking in M.senile.