Abstract:

The effect of ammonia on Penaeus monodon postlarvae (5.7 ± 0.9 mg, 12.0 ± 1.4 mm) varied with pH level. As the postlarvae were exposed to 250 mg•l^-1 ammonia-N, the LT₅₀ and LT₁₀₀ values decreased with pH increases. Postlarvae exposed to 60 mg•l^-1 ammonia-N and a pH of 9.10 had less tolerance than those exposed to 250 mg•l^-1 ammonia-N and a pH of 8.31. The LT50 value of postlarvae exposed to 0.07 mg•l^-1 ammonia-N and pH of 9.10 was less than half of the LT₅₀ value of postlarvae exposed to the same concentration of ammonia-N but a pH of 8.31. Increasing pH level in a given ammonia solution increased the proportion of NH₃ and increased the ammonia toxicity on P. monodon postlarvae. Monitoring the ammonia level and preventing an increase of pH are suggested for shrimp culture.

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Date 1989/06/01

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