ABSTRACT Biofloc technology is a culture system that intensively uses microbial communities. Most bacteria can form aggregates around organic or inorganic surfaces. The high adsorption capacity, surface area, and flocculant properties of clay minerals make these compounds good candidates to stimulate biofloc formation, increase bacterial biomass, and improve nitrification. The objective of this study was to evaluate the addition of clay minerals to biofloc formation and its influence on the microbial community, nitrification, and zootechnical performance of Penaeus vannamei cultivated in a biofloc technology system. Experiment 1 involved the following treatments: control (without adding clay minerals), 10, 50, and 100 mg L−1, applied daily in the water. The treatments in experiment 2 were: control without product and inoculum, control without product and with inoculum, 50 mg L−1 clay mineral without inoculum and 50 mg L−1 clay mineral with inoculum. Both experiments with a density of 400 ind m−3. NO2 levels, total suspended solids, turbidity, differed significantly (P < 0.05) between treatments in experiment 1 and zootechnical performance parameters, where higher flocculant concentrations negatively affected these indices. In experiment 2, statistical differences were verified for NH3 and NO2 concentrations and the proximate composition of the bioflocs (P < 0.05), the addition of the inoculum of bioflocs influenced these results. In summary, the addition of clay minerals influenced biofloc formation, proximal composition, and the zootechnical performance of the cultivated shrimp but did not affect the abundance of microorganisms and nitrification.

Effects of shrimp confinement in a situation of high density stocking in a long term nursery on their growth performance in grow out ponds. Were analized two nurseries with a density of 2000 shrimp m-2 were stocked at two different times. The first nursery (LTN) lasted 144 days, and the SGR of the animals was 3.0% day-1. The second nursery (STN) lasted 18 days and the specific growth rate (SGR) was 19.9% day-1. On the same day, shrimps were transferred to six lined ponds at a density of 20 shrimp m-2 where they remained for 101 days. In the first biometry, the SGR in the LTN treatment, increased to 6.7% day-1 and in the STN it decreased to 5.0% day-1. At the end, shrimps of the LTN and STN treatments reached weights of 8.46 and 6.72 g and had productivities of 1287 and 1015 kg ha-1, respectively. Shrimps reared in nurseries for long periods showed growth and survival rates similar to those obtained using conventional management practices in grow out structures.

Se analizó el efecto del confinamiento de camarones en una situación de alta densidad de población en una pre-engorda, sobre su crecimiento a largo plazo en los estanques de engorde. Dos estanques de pre-engorda con densidad de 2,000 camarones m-2 fueron sembrados en dos momentos diferentes. La primera crianza de largo plazo (LTN) duró 144 días, y la tasa de crecimiento específico (SGR) de los animales fue 3,0% día-1. La segunda crianza de corto plazo (STN) duró 18 días y el SGR fue 19,9% día-1. En el mismo día, los camarones fueron trasladados a seis estanques en una densidad de 20 camarones m-2, donde permanecieron durante 101 días. En la primera biometría, la SGR en el tratamiento LTN aumentó a 6,7% día-1 y STN disminuyó a 5,0% día-1. Al final, los camarones de los tratamientos LTN y STN llegaron a 8,46 y 6,72 g con productividad de 1.287 y 1.015 kg ha-1, respectivamente. Los camarones cultivados en pre-engorda durante largos períodos presentaron crecimiento y supervivencia similares a los obtenidos mediante prácticas de manejo convencionales en los estanques de engorda.

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.

O presente estudo comparou os métodos manual e elétrico de extrusão do espermatóforo do camarão-rosa Farfantepenaeus paulensis com o objetivo de verificar se os métodos de extrusão exercem influência na quantidade de células espermáticas e na regeneração de novos espermatóforos. Os machos foram extrusados no início (dia zero) e no final do experimento (dia 43) para verificação da eficiência dos métodos no processo de regeneração. A extrusão manual foi realizada por meio de pressão na região do quinto par de pereiópodos e o método elétrico com uso de eletrodo para transmissão de impulso elétrico de 9 volts na mesma região. Os dois métodos foram considerados eficientes, não sendo encontradas diferenças significativas entre estes (P>0,05) para o número de células espermáticas. Entretanto, foi verificada, no final do experimento, a perda de peso corporal, peso de espermatóforo e menor índice espermatossomático (IES) (P<0,05) nos animais submetidos a extrusão do espermatóforo por estímulo elétrico. Os valores médios finais (±DP) do número de espermatozóides foram 1,46 (±0,84) e 3,25 milhões (±2,12) para os tratamentos com método elétrico e manual, respectivamente. Os resultados indicam que ambos os métodos podem ser utilizados para a coleta inicial de espermatóforos e testes de qualidade de espermatozóide. Entretanto, para a reutilização dos machos após a extrusão inicial do espermatóforo, o método manual é mais indicado pela manutenção do número de células espermáticas, peso do espermatóforo, peso corporal e índice espermatossomático após a regeneração.

The present study compared manual and electrical methods to extrude the spermatophore of the pink shrimp Farfantepenaeus paulensis aiming to analyze their influence on the number of spermatic cells and spermatophore regeneration. The males were extruded in the beginning (day zero) and in the end (43rd day) of the experiment to evaluate the efficiency of these methods in the regeneration process. For the extrusion, a gentle pressure was applied manually in the fifth pair of pereiopods or electrically by a 9 volt pulse in the same area. Both methods were efficient in removing the spermatophore and no significant differences were found (P>0.05) in the number of sperm cells. Nevertheless, significant decreases (P<0.05) in the body weight, spermatophore weight and spermatosomatic index (ESI) at the end of the experimental period were observed by using the electrical stimulation. The mean values (±SD) of the number of sperm cells were 1.46 (±0.84) and 3.25 (±2.12) millions for the electrical and manual treatments, respectively. Results indicate that both methods may be applied to collect initial samples of spermatophores as well as for sperm quality testing. However, when previously spermatophore-extruded males are to be used, the manual method is indicated as the number of spermatic cells, spermatophore weight, body weight, and ESI are maintained after regeneration.

Neste trabalho, foi estudada a possibilidade de cultivar o camarão-rosa Farfantepenaeus paulensis em gaiolas com diferentes densidades de estocagem durante o outono (abril a junho) no estuário da Lagoa dos Patos, RS. Juvenis com peso médio de 4,95g (± 1,69 dp foram estocados em gaiolas nas densidades de 20, 40, 80, 100 e 120 ind/m². Os camarões foram alimentados diariamente ad libitum com pedaços de Corvina (Micropogonias furnieri). As sobrevivências e os pesos foram observados nos tempos 20, 40 e 60 dias de experimento. Durante o período de cultivo a temperatura da água decresceu de 24 para 11°C (média = 17,1°C) e a salinidade oscilou entre 3 e 26 (média = 17,5). As taxas de sobrevivência nas densidades de 20, 40, 80, 100 e 120 ind/m² foram 65%, 68%, 46%, 52% e 43,3% respectivamente, sendo significativamente maiores nas densidades de 20 e 40 ind/m². Após 60 dias, os camarões estocados em 20 e 40 ind/m² atingiram peso superior a 8,0g, sendo significativamente maiores (P<0,05) que nos demais tratamentos. A maior biomassa (356g) foi obtida na densidade de 120 ind/m². Foram produzidos de 250 a 350g de camarões com peso médio de 6,5 a 8,0g por m², mesmo em altas densidades de estocagem (40 a 120 ind/m²). As taxas de sobrevivência dos camarões mantidos em 20 e 40 ind/m² podem ser consideradas satisfatórias, contudo, após a temperatura ficar abaixo de 18°C, as taxas de crescimento foram reduzidas. Os resultados confirmam o efeito negativo da densidade de estocagem sobre o crescimento dos camarões, sendo recomendada a estocagem de 40 a 120 juvenis/m². Foi, contudo, comprovada a possibilidade de cultivar F. paulensis durante o outono no sul do Brasil.

In this study, we assessed the feasibility of culturing Farfantepenaeus paulensis in cages at different stocking densities during autumn (from April to June) in the Patos Lagoon estuary. Juveniles with mean weight of 4.95g (± 1.69 SD) were stocked in cages at densities of 20, 40, 80, 100 and 120 ind/m² of bottom. Shrimp were fed daily by-catch items (Micropogonias furnieri) ad libitum. Survival and wet weight were estimated at 20, 40 and 60 days after the beginning of the trial. Water temperature varied from 11 to 24°C (mean = 17.1°C), whiles salinity ranged from 3 to 26 (mean = 17.5). Survival rates at densities of 20, 40, 80, 100 and 120 ind/m² were 65%, 68%, 46%, 52% and 43,3%, respectively, being significantly higher at 20 and 40 ind/m². After 60 days, shrimp stocked at 20 and 40 ind/m² reached over 8.0g, which were significantly higher than those reared at 80, 100 and 120ind/m². The highest biomass (356g/m²) was obtained at 120 shrimp per m². Up to 250 to 350 g of shrimp with mean weight of 6.5 to 8.0g were produced per m² even at the highest stocking densities (40 to 120 ind/m²). Survival rates of shrimp reared at 20 and 40 ind/m² may be considered satisfactory, whereas growth rates where negligible after temperature dropped below 18°C. The present results confirmed the negative effect of stocking density on shrimp growth, being recommended the stocking of at the most 40 to 120 ind/m². Although the feasibility of culturing F. paulensis in cages during autumn in southern Brazil was demonstrated.