Abstract: A serial of concentration gradient of enrofloxacin were used to evaluate the effect of acute toxicity of enrofloxacin on Artemia nauplius. Nine different concentrations of enrofloxacin were tested in the study， which were 0， 2， 4， 6， 8， 10， 11， 12 and 14 mg·mL-1. The 24 hEC50 and 48 hEC50 (effective concentration for 50% reduction)， and 24 hLC50 and 48 hLC50 (lethal concentration for 50%) of enrofloxacin were calculated by the method of probability unit. The results showed that， at 24 h and 48 h， the maximum concentrations of enrofloxacin that could not make Artemia nauplius die were 04 mg·mL-1 and 02 mg·mL-1， respectively. The minimum concentrations that made Artemia nauplius to die entirely were 14 mg·mL-1 and 11 mg·mL-1， respectively. The 24 hEC50 and 48 hEC50 of enrofloxacin to Artemia nauplius were (1066 ± 033) mg·mL-1 and (1054±033) mg·mL-1， respectively. The 24 hLC50 and 48 hLC50 of enrofloxacin to Artemia nauplius were (946 ± 033) mg·mL-1 and (771 ± 033) mg·mL-1， respectively. The results suggested that Artemia nauplius was not sensitive to enrofloxacin.

Key words: Artemia nauplius, enrofloxacin, EC50, LC50