Effect of the addition of diatoms (Navicula spp.) and rotifers (Brachionus plicatilis) on water quality and growth of the Litopenaeus vannamei postlarvae reared in a biofloc system Abstract The aim of this study was to evaluate the effect of the addition of Navicula spp. and Brachionus plicatilis on water quality and growth of postlarvae shrimp Litopenaeus vannamei reared in a biofloc system. Four treatments were considered: a control (biofloc system -BFT); BFT with the addition of Navicula spp. (BFT-N); BFT with the addition of Brachionus plicatilis (BFT-B) and BFT with the addition of Navicula spp. and Brachionus plicatilis (BFT-NB), each in triplicate. Shrimp (16.2 AE 0.03 mg) were stocked at a density of 2500 shrimp m À3 and plankton were added on days 1, 5, 10, 15, 20, 25 and 30 at a density of 5 9 10 4 cells mL À1 (Navicula spp.) and 30 organisms L À1 (Brachionus plicatilis). The shrimp were fed a formulated feed in four daily rations composed of 40% crude protein and 8% lipids. Significant differences between treatments were observed for final weight, yield, feed conversion ratio, specific growth rate, protein efficiency ratio and protein content of the shrimp. The combined plankton addition of Navicula spp. and B. plicatilis had better performance parameters, indicating their benefit as natural food sources for postlarvae L. vannamei in biofloc systems.

A 42-day trial was conducted to evaluate the effects of a low-salinity biofloc system with different stocking densities on water quality and zootechnical performance of Nile tilapia fingerlings (10 g/L). Four treatments were tested at different densities: 500 fish/m³, 750 fish/m³, 1,000 fish/m³ and 1,250 fish/m³, all in triplicate. Fingerlings of Oreochromis niloticus (initial mean weight of 1.17 ± 0.05 g) were stocked in twelve experimental black-plastic tanks (40 L) with no water exchange during the experimental period. Molasses was added daily to the system at 30% of the amount of feed, and fish were given four daily rations of a formulated feed composed of 36% crude protein and 9% lipids. Water quality variables (dissolved oxygen, pH, salinity, TAN, NO2, NO3 and PO43) did not demonstrate significant differences between the treatments. However, significant influences (α ≤ 0.05) of the stocking densities were observed for total suspended solids, settleable solids, final weight, yield, and protein efficiency ratio. The results showed survival over 96%, final weight values between 12 and 18 g, yield between 9.49 and 15.27 kg/m3, water consumption of 52 to 101 L/kg fish, and total time of settling chambers between 238 and 305 h/kg fish. These results indicate a negative effect of stocking density on final weight, survival, alkalinity, NO2, PO43 and water consumption, and a positive effect on yield in Nile tilapia fingerling culture (1-20 g) in a low-salinity biofloc system with densities up to 1000 fish/m³.

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The objective of this study was to evaluate the effect of the addition of Navicula sp. on the growth and fatty acids profile of Litopenaeus vannamei postlarvae in a biofloc system (BFT). Four treatments were used: BFT; BFT 2.5N (addition of 2.5 × 10 4 cells/ ml of Navicula sp.); BFT 5N (addition of 5 × 10 4 cells/ml of Navicula sp.) and BFT 10N (addition of 10 × 10 4 cells/ml of Navicula sp.), all in triplicate. The shrimp (1 ± 0.01 mg) were stocked at a density of 3,000 postlarvae/m 3 and fed with commercial feed. The diatom was added every 10 days, and at the end of 42 days, shrimp performance, water quality and proximal composition were evaluated. The BFT 5N and BFT 10N treatments had higher performance values, highlighting the values of productivity (2.30 and 2.42 kg/m 3 ) and specific growth rate (15.92 and 16.08%/day), which were higher than the other treatments. In addition, the highest levels of fatty acids were observed in treatments with diatom (BFT 5N and BFT 10N), indicating the benefits of Navicula sp. on growth enhancement and fatty acid content of L. vannamei postlarvae grown in biofloc systems. K E Y W O R D Sdiatoms, presumptive diagnosis, proximal composition, stress response, water quality

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O objetivo do trabalho foi avaliar o crescimento da microalga Navicula sp. utilizando resíduo sólido de um cultivo em sistema de bioflocos como meio de cultura em comparação ao meio Conway. Foram realizados dois experimentos, com e sem adição de metais traços, sendo que cada experimento teve cinco tratamentos com três repetições cada um: R0C100 (100% Conway); R25C75 (25% resíduo e 75% Conway); R50C50 (50% resíduo e 50% Conway), R75C25 (75% resíduo e 25% Conway) e R100C0 (100% resíduo). Os cultivos de alga foram realizados em erlenmeyers de 1 L durante 10 dias, com fotoperíodo integral e inóculo inicial de 5x10 4 cél. mL-1. Realizaram-se contagens diárias para acompanhamento da densidade celular máxima, tempo de duplicação e velocidade de crescimento. O pH e a temperatura foram mensurados no início e no final dos experimentos. Para as análises estatísticas, utilizaram-se os testes de Cochran, Shapiro Wilk, ANOVA e Tukey (P < 0,05). O pH e a temperatura mantiveram-se dentro dos padrões de cultivo nos dois experimentos. O meio de cultura com resíduo de cultivo de camarão em biofloco apresentou resultado semelhante ao do meio Conway e mostrou-se satisfatório para o desenvolvimento da microalga Navicula sp., ressaltando que a presença de metais traços favoreceu o crescimento da espécie. Palavras-chave: tratamento de efluente; microalga; crescimento.

A trial was conducted for 42 days to evaluate the effects of two commercial feeds with high and low crude protein content on the performance of white shrimp Litopenaeus vannamei cultivated in an integrated biofloc system with the seaweed Gracilaria birdiae. The experiment had a 2 × 2 factorial design (a biofloc monoculture or an integrated system with 32% (low) or 40% (high) crude protein content) with the following treatments: IS32 (an integrated system using low protein commercial feed); IS40 (an integrated system using high protein commercial feed); M32 (a monoculture system using low protein commercial feed); and M40 (a monoculture system using high protein commercial feed), all in triplicate. Shrimp individuals (0.23 ± 0.04 g) were stocked at a density of 500 shrimp/m 3 and no water exchange was carried out during the experimental period. No significant influence (p > 0.05) was found to be caused by the integrated system or the crude protein levels on water quality. However, a significant influence (p < 0.05) was found for final weight (3.21-4.12 g), weight gain (2.97-3.89 g), yield (1.39-1.96 kg/m 3 ) and feed conversion ratio (1.47-1.74). Growth was similar in IS32, M40 and IS40, indicating that crude protein levels can be reduced with no adverse effect on shrimp performance variables in integrated biofloc systems with G. birdiae.Additional keywords: growth; nutrition; seaweed; shrimp; water quality. Abbreviations used: FCR (feed conversion ratio); IS32 (an integrated system using low protein commercial feed); IS40 (an integrated system using high protein commercial feed); M32 (a monoculture system using low protein commercial feed); M40 (a monoculture system using high protein commercial feed); PL (postlarvae); TSS (total suspended solids).Authors' contributions: All authors contributed equally to this work (conception; acquisition, analysis, interpretation of data; drafting of the manuscript; critical revision of the manuscript and statistical analysis).Citation: Brito, L. O.; Junior, L. C.; Abreu, J. L.; Severi, W.; Moraes, L. B. S.; Galvez, A. O. (2018). Effects of two commercial feeds with high and low crude protein content on the performance of white shrimp Litopenaeus vannamei raised in an integrated biofloc system with the seaweed Gracilaria birdiae.

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