Performance of Penaeus paulensis (Pérez-Farfante) broodstock under long-term exposure to ammonia

Abstract

The effects of total ammonia (TAN; NH4* + NH j) on the reproductive performance, survival, growth and moulting of wild Penaeus paulensis (Perez-I'arfantcl broodstock were studied lo determine optimal rearing conditions. Based on previously established 'safe levels' for P. paulensis adults (3.4 and 4.2mgir' TAN), two 46-day trials were performed. In the tirst trial, six females and four males were stocked in 700-L tank.s under three treatments (0,37. 2.5 3 and 6.86mgL"' TAN) with at least two replicates per treatment, fn trial 2. ammonia levels of 0.68, 1.55 and 2.62 mg L~' 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.H6mgL" TAN (0.21 mgL ' NHj), No further eflects of ammonia on moulting and reproductive performance were detected. The present results demonstrate that up to 2.62mgL"^ TAN. coupled with 0.07mgL"' NHâ nd 1.50mgL"' NO^. 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 (lSO-i()07n) employed on penaeid shrimp maturation systems.199S Biackweli Science Lid

The influence of water renewal rates on the reproductive and molting cycles of Penaeus paulensis in captivity

“…Sub-lethal concentrations of ammonia have been shown to decrease growth and molting rates of penaeid juveniles (Chen and Kou, 1992;Wasielesky et al, 1994). However, under longterm exposure to ammonia concentrations (up to 6.86 mg/l), no influence were detected on P. paulensis molting or reproductive performance, affecting only survival of females and growth of males (Cavalli et al, 1998). In accordance, no influences on molt cycle or reproductive performance could be related to ammonia concentration or any of the water quality parameters.…”

“…In accordance, no influences on molt cycle or reproductive performance could be related to ammonia concentration or any of the water quality parameters. The present results reinforced a trend towards reduced water exchange for shrimp reproduction and maintenance of a more stable environment, which might result in reduction of labour and overall water requirements (Cavalli et al, 1998) and less stress to the breeding population (Bray and Lawrence, 1992). The only fertilized spawns were those obtained at the beginning of the experimental period (first week).…”

“…The mean number of eggs per spawn was relatively low (16,000-40,000 eggs/spawn) compared with those usually obtained when larger maturation tanks are applied. Although the potential fecundity of P. paulensis reported by Iwai (1978) under field (Southeast Brazilian off-shore areas) was up to 500,000 eggs per spawn, when eyestalk ablated wild females were maintained in captivity for at least 45 days, the mean number of eggs per spawning event ranged from 16,000 to 160,000 (Marchiori and Boff, 1983;Cavalli et al, 1997;Cavalli et al, 1998), while the number of nauplii per spawn ranged from 60,000 to 140,000 (Beltrame and Andreatta, 1991;Marchiori and Cavalli, 1993;Vinatea et al, 1993;Petersen et al, 1996;Reis et al, 1998). In the present study, the number of eggs per spawning event was in agreement with those usually observed for wild broodstock maintained in larger circular tanks, but again a relative decrease was observed in the number of eggs per spawn in this tank shape/size.…”

“…Generally high water exchange rates (100-400% per day) are adopted in the maturation of penaeid shrimps (Bray and Lawrence, 1992;Ogle, 1991), mainly to reduce the levels of nitrogenous compounds. However, lower water exchange might result in a more stable environment, since no further effects of ammonia on molting and reproductive performance of P. paulensis were detected under long-term exposure (Cavalli et al, 1998). Accordingly, the present study describes the influence of water renewal on the reproductive and molt cycles of a wild-caught broodstock.…”

Chronic effects of nitrogenous compounds on survival and growth of juvenile pink shrimp

“…For example, Cavalli et al (1998) analyzed the effect of ammonia on adults of F. paulensis reporting lower growth rates in females in the treatment containing 6.86 mg/L TA-N. However, this effect was not observed in males.…”