Utilização de Navicula sp. no cultivo de camarões marinhos Litopenaeus vannamei nafase berçário em sistema de bioflocos

Abstract

The use of the BFT system (Biofloc Technology) is being implemented in the nursery and commercial grow-out phases of shrimp in Brazil. However, little is known about the role of the combination of bacteria and microalgae in this system. In this sense, the objective of the study was to evaluate the use of the BFT system in marine shrimp nurseries with different frequencies and densities of inoculation of the diatom Navicula sp. on growth, water quality and microbial floc composition. Two experiments were carried out, in which the density of addition of Navicula sp. in the culture system and the second one evaluated the best frequency of addition of the diatom. Both experiments had four treatments, all in triplicate. The first experiment: BFT (without addition of Navicula sp.); 2.5N BFT (with the addition of 2.5 x 104 cells.mL Navicula sp.); BFT 5N (with the addition of 5 x 104 cells.mL Navicula sp.) and BFT 10N (with the addition of 10 x 104 cells.mL Navicula sp.). The cultivation lasted 42 days and zootechnical performance and water quality were evaluated. The shrimp (1 ± 0.01 mg) were stored at a density of 3,000 post-larvae.m³ and they were fed with commercial feed. The microalgae was inoculated in the experimental units according to the density described for each treatment on the first, tenth, twentieth and thirtieth days of culture. The treatments BFT 5N and BFT 10N presented superior performance values, with emphasis on the values of productivity (2.30 and 2.42 kg.m3) and specific growth rate (15.92 and 16.08%.day), which were superior to the other treatments. In addition, the highest levels of fatty acids were observed in treatments with diatoms (BFT 5N and BFT 10N), indicating the benefits of Navicula sp. in increasing the growth and fatty acid content of L. vannamei post-larvae grown in biofloc systems. In the second experiment, four treatments were evaluated: BFT (without the addition of Navicula sp.); BFT 5D (with the addition of Navicula sp. every 5 days); BFT 10D (with addition of Navicula sp. every 10 days) and BFT 15D (with addition of Navicula sp. every 15 days), all in triplicate. The cultivation lasted 35 days and zootechnical performance and water quality were evaluated. The shrimp (5 ± 0.01 mg) were stored at a density of 3,000 post-larvae.m³ and they were fed with commercial feed. The microalgae was inoculated in the experimental units at a cell density of 10 x 104 cells.mL. All data were submitted to ANOVA (α≥0.05) where no significant differences were observed for the data of water quality. FCA, survival, final weight, productivity and SGR differed significantly, where Navicula BFT treatments were superior to the control treatment (BFT without the addition of Navicula sp.), highlighting the BFT 10D treatment that presented higher values for final weight (0.50 ± 0.06 g), productivity (1.41 ± 0.03 kg.m3) and specific growth rate (13.17 ± 0.03% / day) in relation to the other treatments. Finally, it is concluded that the concentrations of 5 x 104 cells.mL and 10 x 104 cells.mL of Navicula sp. when inoculated every 10 days they showed the best performance, which indicates the benefits of Navicula sp. in the growth of post-larvae L. vannamei grown in biofloc systems.