Stocking density at rearing phase for white shrimp farmed in a biofloc system

O objetivo deste trabalho foi determinar a densidade de estocagem ideal para o cultivo de camarão‑branco, em sistema de biofloco sem renovação de água. Foram realizados dois experimentos inteiramente casualizados, com três repetições para cada tratamento. No primeiro, juvenis de camarão‑branco, com peso médio inicial de 1,23±0,09 g, foram cultivados a densidades de estocagem de 833, 1.250, 1.667, 2.083 e 2.500 camarões por m3. No segundo experimento, o peso médio inicial foi de 6,32±0,7 g, e as densidades foram de 566, 833, 1.111, 1.388 e 1.667 camarões por m3. Os melhores resultados de produtividade, com médias de 9,92 e 10,77 kg m-3, foram obtidos com 1.667 e 1.111 camarões por m3, respectivamente, no primeiro e segundo experimentos. O aumento da densidade de estocagem afeta o crescimento e a sobrevivência do camarão‑branco em sistema de biofloco.The objective of this work was to determine the optimal stocking density for Pacific white shrimp farming, in biofloc culture system (BFT) without water exchange. Two completely randomized experiments were carried out, with three replicates for each treatment. In the first experiment, juveniles with 1.23±0.09 g initial mean weight were reared at the stocking densities of 833, 1,250, 1,667, 2,083, and 2,500 shrimp per m3. In the second experiment, the initial mean weight was 6.32 ± 0,7 g, and the densities were 566, 833, 1,111, 1,388, and 1,667 shrimps per m3. The best productivity results, with the means 9.92 and 10.77 kg m-3, were obtained at 1,667 and 1,111 shrimp per m3, respectively, in the first and second experiments. Increasing stocking density affects growth and survival of white shrimp farmed in biofloc system

Toxicidade aguda do nitrito na larvicultura do camarão-rosa Penaeus paulensis Pérez-Farfante, 1967

Através de bioensaios em sistema semi-estático, analisou-se a toxicidade aguda do nitrito para ovos e estágios larvais de Penaeus paulensis. Os ovos mostraram-se bastante susceptíveis ao nitrito, além de diminuir a taxa de eclosão o nitrito causou uma série de deformações morfológicas nos náuplios eclodidos. As CL’s50 24h para ovos, náuplios, zoéas, misis e pós-larvas foram de, respectivamente, 0,94; 21,91; 340,57; 197,75 e 277,80 mg/l de N-NO2’. Houve um aumento acentuado da ação tóxica do nitrito sobre as larvas após 24h. Em 96h, as CL’s50 passaram para 8,6; 8,21 e 10,71 mg/l de N-NO2' para, pela ordem, zoéa, misis e pós-larva. O nível de segurança ("safe levei") recomendado para que o nitrito não interfira na larvicultura de P. paulensis foi estimado em 0,094 mg/l de N- NO2*.The acute toxicity of nitrite on eggs and larval stages of pink shrimp Penaeus paulensis was investigated using semistatic bioassays systems. The eggs are highly susceptible to nitrite, besides decreasing the hatching rate nitrite induced serious morphological deformities in hatched nauplii. The 24-h LC50 on eggs, nauplii, zoea, mysis, and post-larvae were, respectively, 0.94; 21.91; 340.57; 197.75; and 277.80 mg/1 NO2 -N. There was an increase in the toxic action of nitrite on larvae after 24 hours. The 96-h LC50 were 8.6, 8.21, and 10.71 mg/i N02-N for, respectively, zoea, mysis, and post-larvae. A "safe level" of nitrite was estimated at 0.094 mg/l N02 -N, on the basis of 24-h LC50 for eggs. Such studies on larval prawns are relevant to water management practices in hatcheries producing prawn seed for aquaculture purpose

Plankton and water quality variability in an estuary before and after the shrimp farming effluents: possible impacts and regeneration

Abstract Water quality, chlorophyll a, phytoplankton, proto and mezo-zooplankton abundance were spatiotemporally evaluated in an estuary receiving effluents from a Pacific white shrimp Litopenaeus vannamei farm in Patos Lagoon estuary, Southern Brazil. Samples were taken before (BD) and; 1 day (1 PD) 5 days (5 PD), 10 days (10 PD), 20 days (20 PD) and 30 days (30 PD) after the effluents discharge. Some water quality parameters were affected by the effluents discharge; however, these changes were restricted to a distance of 20 m from the effluent discharge channel for a period of 5 days. The microbial community was dominated by chlorophyceae, followed by diatoms, cyanobacteria and ciliates. There was an increase in the abundance of different groups on the 1 PD sampling compared to BD. The zooplankton abundance was low in practically all sites, except for 30 PD sampling. The meso-zooplanktonic organisms were represented by copepods, mostly Acartia tonsa. Despite some effects on water quality and phytoplankton and protozooplankton abundance until 5 PD sampling, these alterations dissipated in a short period of time. We conclude that the environment quickly assimilated the effluents discharge, and the water quality parameters remained within the limits stipulated by standard guidelines

Plankton and water quality variability in an estuary before and after the shrimp farming effluents: possible impacts and regeneration

<div><p>Abstract Water quality, chlorophyll a, phytoplankton, proto and mezo-zooplankton abundance were spatiotemporally evaluated in an estuary receiving effluents from a Pacific white shrimp Litopenaeus vannamei farm in Patos Lagoon estuary, Southern Brazil. Samples were taken before (BD) and; 1 day (1 PD) 5 days (5 PD), 10 days (10 PD), 20 days (20 PD) and 30 days (30 PD) after the effluents discharge. Some water quality parameters were affected by the effluents discharge; however, these changes were restricted to a distance of 20 m from the effluent discharge channel for a period of 5 days. The microbial community was dominated by chlorophyceae, followed by diatoms, cyanobacteria and ciliates. There was an increase in the abundance of different groups on the 1 PD sampling compared to BD. The zooplankton abundance was low in practically all sites, except for 30 PD sampling. The meso-zooplanktonic organisms were represented by copepods, mostly Acartia tonsa. Despite some effects on water quality and phytoplankton and protozooplankton abundance until 5 PD sampling, these alterations dissipated in a short period of time. We conclude that the environment quickly assimilated the effluents discharge, and the water quality parameters remained within the limits stipulated by standard guidelines.</p></div