Clove essential oil from Eugenia caryophyllus Induces Anesthesia, Alters Swimming Performance, Heart functioning and Decreases Survival Rate During Recovery of Daphnia magna

The results showed that the oil induced anesthesia at three highest concentrations: 150, 100 and 50 μl/L. TtA and TtR were dependent on the size of the animal and concentration of the oil. The shortest TtA and the longest TtR were noted for the smallest daphnids anaesthetized for 45 minutes at 150, 100 and 50 ul/L. Lethality of small and large daphnids previously exposed to anesthetic concentrations for both times was observed at 24th hour of recovery period suggesting latent toxicity of clove oil. The oil inhibited heart rate, heart muscle contraction and swimming velocity at anesthetic (150, 100, 50 μl/L) and at non-anesthetic concentrations of 25, 10 and 1μl/L. Recovery period after previous 45-min anesthesia showed temporal increase however and subsequent decrease of Daphnia swimming velocity and heart activity resulting probably from latent toxicity.

The results of the present study indicate that clove oil induces rapid immobilization and latent toxicity in Daphnia magna, at lower concentrations that those recommended for fish anesthesia and suggest that excessive use of the oil in natural ponds or other water reservoirs may be detrimental to coexisting cladocerans leading to disturbance of ecological balance. Keywords : Daphnia, clove oil, anesthesia, swimming behavior, heart activity