Hemolymph osmolality and cation concentrations in Litopenaeus vannamei during exposure to artificial sea salt or a mixed-ion solution: Relationship to potassium flux

Interest in culturing the Pacific white shrimp Litopenaeus vannamei in low-salinity and brackish-well waters has led to questions about the ability of this species to osmo- and ionoregulate in environments containing low concentrations of ions and in environments with ionic ratios that differ from those found in sea water. After seven days, hemolymph osmolality and potassium, sodium and calcium values were all significantly affected by salinity (as artificial sea salt) with values decreasing with decreasing salinity. These decreases were small, however, relative to decreases in salinity, indicating iono- and osmoregulation with adjustment for gradients. The hemolymph osmolality and sodium and calcium concentrations in shrimp exposed to either 2 g/L artificial sea salt or 2 g/L mixed-ion solution (a mixture of sodium, potassium, calcium, and magnesium chlorides that approximate the concentrations and ratios of these cations found in 2 g/L dilute seawater) did not differ significantly. However, hemolymph potassium levels were significantly lower in shrimp held in the mixed-ion environment. Potassium influx rates were similar in shrimp held in either artificial sea salt or mixed ions. The results of this study indicate that salinity affects hemolymph-cation concentrations and osmolality. Further, differential potassium-influx rates do not appear to be the basis for low hemolymph potassium levels observed in shrimp held in mixed-ion environments

Maturation performance of <i>Penaeus vannamei</i> co-fed <i>Artemia</i> biomass preparations

Few shrimp hatcheries successfully propagate captive broodstock on a commercial scale. Diets for acceptable maturation performance of Penaeus vannamei have typically relied on the inclusion of marine polychaetes (bloodworm) from Panama or Maine, USA, which are expensive and are of unpredictable supply. Studies were therefore undertaken at experimental and commercial scale to replace or supplement the polychaetes by frozen ongrown Artemia which were either non-enriched or bioencapsulated with specific boosters. In experiment 1 the control diet consisted of frozen squid only and was evaluated against broodstock diets where 60% of the squid was substituted by bloodworm or enriched Artemia biomass. Effects were evaluated for males and females as sexes were kept in separate broodstock tanks. In experiment 2 the control treatment received a mixture of natural feed, including bloodworm. For the two other treatments, the bloodworm fraction was replaced by non-enriched Artemia adults, respectively. Finally, an evaluation at commercial scale was made comparing two feeding regimes based on a combination of semi-moist pellets and fresh-frozen marine organisms. In one of the treatments a portion of the natural food was replaced by an equal amount of enriched, frozen Artemia biomass. Dietary effects on the reproductive performance of the broodstock were evaluated and egg characteristics were monitored. Results from the three experiments confirm that dietary conditions affect the reproductive performance of P. vannamei. Even in a maturation diet consisting of multiple natural food products, frozen adult brine shrimp biomass appears to increase reproduction performance. Although the male diet did not appear to significantly affect mating or fertilization, there was a clear tendency towards improved mating success and hatching when Artemia biomass was included in a mixed diet. Combined effects of improved mating and hatching resulted in significant differences in overall nauplii production. It is therefore concluded that Artemia biomass may be useful as a supplement to or as a replacement for polychaetes in Penaeus vannamei maturation diets

Inactivation of White Spot Syndrome Virus (WSSV) by normal rabbit serum: Implications for the role of the envelope protein VP28 in WSSV infection of shrimp

White Spot Syndrome Virus (WSSV) is a highly pathogenic and prevalent virus affecting crustacea. A number of WSSV envelope proteins, including vp28, have been proposed to be involved in viral infectivity based on the ability of specific antibodies to attenuate WSSV-induced mortality in vivo. In the present study, a series of monoclonal and polyclonal antibodies targeting vp28 were tested for their ability to neutralize WSSV infectivity, with the purpose of identifying epitopes potentially involved in vp28-mediated infection of shrimp. Surprisingly, when used as protein A-purified immunoglobulin, none of the antibodies tested were capable of inhibiting WSSV infectivity. This included one polyclonal preparation that has been previously shown to inactivate WSSV, when used as whole rabbit serum. Moreover, strong inactivation of WSSV by some rabbit sera was observed, in a manner independent of anti-vp28 antibodies. These results underscore the problems associated with using heterogeneous reagents (e.g. whole rabbit antiserum) in viral neutralization experiments aimed at defining proteins involved in infection by WSSV. In light of this, the potential of anti-vp28 antibodies to specifically neutralize WSSV should be reconsidered

Avanços da maricultura na primeira década do século XXI: piscicultura e carcinocultura marinha Advances in mariculture on the first decade of the XXI century: marine fish and shrimp culture

A piscicultura marinha é um setor pouco desenvolvido na maricultura brasileira. Por vários anos foi avaliado o potencial de cultivo de algumas espécies como o robalo-peva Centropomus parallelus e o linguado Paralichtys orbignyanus. Entretanto, somente a partir do investimento sobre o bijupirá Rachycentron canadum é que empresas privadas passaram a demonstrar maior interesse na atividade. Além dos sistemas tradicionais de piscicultura, o bijupirá pode ser criado em tanques-rede oceânicos. Esta espécie apresenta crescimento rápido, atingindo entre 4 e 8 kg em um ano de vida, e carne de excelente qualidade. A carcinocultura tem sido questionada por questões ambientais, uso de insumos como farinha e óleo de peixe e disseminação de doenças. A criação de camarões em sistemas sem renovação de água "ZEAH" (Zero Exchange, Aerobic, Heterotrophic Culture Systems) ou cultivo em meio aos Bioflocos (BFT) aplica métodos que minimizam estes problemas, contribuindo para uma maricultura mais saudável.<br>Marine fish culture is still in its infancy in Brazil. For several years the snook Centropomus parallelus and the flounder Paralicithys orbignyanus were considered for aquaculture, but their commercial application has not yet been achieved. However, once technology for culture of cobia Rachycentron canadum became available, several private companies showed interest for marine fish culture. Besides traditional rearing technologes, cobia is suitable for open ocean culture in cages. This species shows fast growth rates, fish can achieve 4 or 8 kg within one year of age and its flesh is highly appreciated. Shrimp farming has been questioned for environmental issues, use of fish oil and fish meal, and spreading diseases. Rearing shrimp in systems without water exchange, know as ZEAH (Zero Exchange Aerobic Heterotrophic Culture systems) or bioflocs applies methods that minimize these problems, contributing for the development of sustainable shrimp farming