Acute toxicity test of ammonia nitrogen to Litopenaeus annamei juveniles under low salinity and high alkalinity

Under static water conditions with low salt and high alkalinity(salinity 5,total alkalinity 250 mg/L),the acute toxicity test was conducted to examine the effect of ammonia nitrogen on Litopenaeus annamei juveniles with body length of(1.12±0.45) cm.Results showed that median lethal concentrations(LC₅₀) of ammonia nitrogen were 1 001.17,63.41,47.98,28.30 mg/L at the time point of 24,48,72,96 h respectively under low salt and high alkalinity conditions,so that its safe concentrations of total ammonia nitrogen and ionic ammonia nitrogen for Litopenaeus annamei juveniles were 2.83 mg/L and 0.22 mg/L,respectively.Ammonia nitrogen is highly toxic to Litopenaeus annamei,and measures to reduce the content of ammonia nitrogen have been proposed.