Ammonia tolerance ofLitopenaeus vannamei(Boone) larvae

Abstract

The tolerance of Litopenaeus vannamei larvae to increasing concentrations of total ammonia nitrogen (TAN) using a short-term static renewal method at 26 degrees C, 34gL(-1) salinity and pH 8.5 was assessed. The median lethal concentration (24h LC50) for TAN in zoea (1-2-3), mysis (1-2-3) and postlarvae 1 were, respectively, 4.2-9.9-16.0; 19.0-17.3-17.5 and 13.2mgL(-1)TAN (0.6-1.5-2.4; 2.8-2.5-2.6 and 1.9mgL(-1) NH3-N). The LC50 values obtained in this study suggest that zoeal and post-larval stages are more sensitive to 24h ammonia exposure than the mysis stage of L. vannamei larvae. On the basis of the ammonia toxicity level (24h LC50) at zoea 1, we recommend that this level does not exceed 0.42mgL(-1) TAN - equivalent to 0.06mgL(-1) NH3-N - to reduce ammonia toxicity during the rearing of L. vannamei larvae.