Evaluation of short-term toxicity of ammonia and nitrite on the survival of whiteleg shrimp, Litopenaeus vannamei juveniles

Abstract

The effects of short-term toxicity of total ammonia nitrogen (TAN) and nitrite were estimated in juveniles of Litopenaeus vannamei under laboratory conditions. In the first experiment, L. vannamei juveniles were exposed to different concentrations of ammonia (0, 5, 10, 15, 20, 30, and 40 mg of TAN L-1) or nitrite (0, 5, 10, 20, 30, 40, and 50 mg of NO2--N L-1), using the static renewal method at a salinity of 20 ppt and pH 8.2. The survival rates of juveniles significantly decreased when exposed to increased concentrations of ammonia or nitrite during the 96 h bioassays. The 24, 48, 72, and 96 h LC50 values of TAN in juveniles were 45.5, 30.1, 13.8, and 6.3 mg L-1, respectively, while the LC50 values of NO2--N at 24, 48, 72, and 96 h were 37.6, 16.7, 8.8, and 4.8 mg L-1, respectively. Experiment 2 evaluated the tolerance of L. vannamei juveniles at various salinities (5, 10, 15, and 20 ppt) under a high concentration of ammonia or nitrite (5 mg L-1). Results showed that the survival rates of L. vannamei at 5 ppt and 10 ppt were significantly lower than those at 20 ppt after 72 h and 96 h of exposure.