Acute toxicity of ammonia to larvae of the tiger prawn, Penaeus monodon

Abstract

The tolerance of larval Penaeus monodon to ammonia increased as the larvae metamorphosed from the nauplius to the postlarva stage. The 24-h LC50 values of ammonia for nauplius, zoea, mysis and postlarva were 6.00, 8.48, 24.04, and 52.11 mg/l ammonia-N (0.54, 0.76, 2.17, and 4.70 mg/l NH3N). The 48-h LC50 values of ammonia for mysis and postlarvae were 14.39 and 27.73 mg/l ammonia-N (1.30 and 2.50 mg/l NH3N). The 72-h and 96-h LC50 values of ammonia for postlarva were 17.05 and 11.51 mg/l ammonia-N (1.54 and 1.04 mg/l NH3N). A “safe level” of ammonia was 1.15 mg/l ammonia-N (0.10 mg/l NH3N) on the basis of the 96-h LC50 value for postlarvae. A more conservative estimate of the “safe level” for rearing larval P. monodon was calculated on the basis of an estimated 96-h LC50 for the nauplius to be 0.13 mg/l ammonia-N (0.01 mg/l NH3N).