Toxicidade aguda da amônia no processo produtivo de pós-larvas de Penaeus paulensis Pérez-Farfante, 1967 / Acute toxicity of ammonia in the productivity process of postlarvae of Penaeus paulensis Pérez-Farfante, 1967

Larval shrimp Penaeus paulensis showed a tendency to decrease in ammonia tolerance as the larva metamorphosed from nauplius to postlarvae stage. The 24-h LC50 were 4.04, 1.70, 2.72, and 1.42mg/l NH3-N on nauplii, zoea, mysis and postlarvae, respectively. The zoea stage and the initial postlarvae substages were very susceptible to ammonia. The 96-h LC50 values on zoea and postlarvae were 0.69 mg/l and 0.32 mg/l, against 0.80 mg/l NH3-N on mysis. The eggs of Penaeus paulensis were affected by ammnia, which provoked a progressive decrease in the hatching rate and induced morphological deformities in hatched nauplii. A "safe level" of ammonia was estimated at 0.032 mg/l NH3-N on the basis of 24-h LC50 for eggs