Influence of stocking density on water quality and growth performance in production of juvenile pirarucu, Arapaima gigas, in irrigation canals Influência da densidade de estocagem na qualidade da água e na performance de crescimento na produção de juvenis de pirarucu, Arapaima gigas, em canais de irrigação
Phycocyanins are water-soluble proteins that work as accessory pigments and have several properties, such as immunostimulant action, cholesterol reducing effect, anti-inflammatory, antiviral, anticancer, antioxidant effects, among other uses. This study aimed to evaluate the accumulation of phycocyanin and biomass production of the microalgae Arthrospira (Spirulina) platensis grownin fish effluent. The experiment was carried out in two phases. The first developed in an indoor environment with controlled conditions, while the second, in a recirculation system, in an outdoor environment, using for both phases the Venkataraman media (control) and Nile tilapia effluent. There was no significant difference (p>0.05) between the performance of algae grown under the same conditions. Phycocyanin concentrations were higher for the treatments using modified Venkataraman medium. The purification process by ion exchange chromatography resulted in higher pigment concentrations for the eluted fractions with 0.2 M NaCl for all crude phycocyanin extracts.
Despite the economic importance of shrimp farming, a number of technical problems have been widely reported in the literature. This article focuses on the environmental and socioeconomic impacts of semi-intensive/intensive shrimp farming in the Acaraú river estuary. This estuary has the second largest number of farms in the Ceará state. Currently, the industry has 31 participating farms with a total area devoted to shrimp farming of 1,571.58 ha. In 2013, total production was 7,853.92 tons of shrimp with an average yield of 5.88 t ha-1 year-1 in an earth pond area of 1,335.49 ha. This industry employs 1,382 people, representing 17.3% of the jobs generated in the two municipalities where the Acaraú river estuary is located. The main environmental impacts of this industry are water pollution and loss of mangroves. However, no changes in water quality parameters were observed during the period 2011-2013, indicating that this estuary has some nutrient processing capacity derived from nurseries, while 159.4 ha of mangrove forests were occupied by In the same period of the establishment of the farms, this estuary presented an increase of 987.41 ha of this landscape unit. The results of this research demonstrate that the Brazilian shrimp industry requires an improvement in management practices to achieve sustainable growth.
Effect of sodium nitrate concentration on the lipid content of Chlorella vulgarisEfeito da concentração de nitrato de sódio no conteúdo lipídico de Chlorella vulgaris
In Brazil, Penaeus vannamei breeding is performed in specialized hatcheries. In the reproduction phase of larviculture, most of the time, it is used broodstock that undergo a maturation induction by eyestalk ablation. However, the use of this technique may present different disadvantages, as other physiological and metabolic processes are also affected by the removal of the eyestalk. This study aimed to perform a comparative analysis between ablation and non-ablation effects on the reproductive process of P. vannamei females. It was observed that the NAF showed higher values (p<0.05) for mating frequency (16.5 ± 4.7 days), spawning frequency (17.8 ± 4.8 days), number of eggs/female (297,208 ± 24,827), number of nauplii/female (210,625 ± 21,681). On the other hand, the AF group presented higher values for mortality rate (39.1 ± 0.3%) and daily mating rate (11.7 ± 2.8%). Spawning rate (92.7 ± 5.3%) and hatch rate (70.8 ± 2.7%) were not affected by non-ablation. This study has shown that the use of NAF results in a superior reproductive performance when compared to the AF performance, and that the use of NAF does not compromise the zootechnical performance in the larval stage.
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