Performance of Penaeus paulensis (Perez-Farfante) broodstock under longterm exposure to ammonia

摘要

The effects of total ammonia (TAN; NH4+ + NH3) on the reproductive performance, survival, growth and moulting of wild Penaeus paulensis (Perez-Farfante) broodstock were studied to determine optimal rearing conditions, Based on previously established 'safe levels' for P. paulensis adults (3.4 and 4.2 mg L-1 TAN), two 46-day trials were performed. In the first trial, six females and four males were stocked in 700-L tanks under three treatments (0.37, 2.53 and 6.86 mg L-1 TAN) with at least two replicates per treatment. In trial 2, ammonia levels of 0.68, 1.55 and 2.62 mg L-1 TAN were assigned to three 6000-L tanks, each stocked with 36 females and 24 males, Ammonia only influenced the survival of females and the growth of males exposed to 6.86 mg L-1 TAN (0.21 mg L-1 NH3). No further effects of ammonia on moulting and reproductive performance were detected, The present results demonstrate that up to 2.62 mg L-1 TAN, coupled with 0.07 mg L-1 NH3 and 1.50 mg L-1 NO2, will not impair reproductive performance of P. paulensis. It is suggested that water quality for the maturation of P. paulensis may be maintained through lower daily water exchange rates instead of the usual high levels (150-300%) employed on penaeid shrimp maturation systems.