Article

Biofloc technology in aquaculture: Beneficial effects and future challenges

Aquaculture (Impact Factor: 1.83). 08/2012; 356-357:351-356. DOI: 10.1016/j.aquaculture.2012.04.046

ABSTRACT As the human population continues to grow, food production industries such as aquaculture will need to expand as well. In order to preserve the environment and the natural resources, this expansion will need to take place in a sustainable way. Biofloc technology is a technique of enhancing water quality in aquaculture through balancing carbon and nitrogen in the system. The technology has recently gained attention as a sustainable method to control water quality, with the added value of producing proteinaceous feed in situ. In this review, we will discuss the beneficial effects of the technology and identify some challenges for future research.

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    • "Recent evidence suggests that bioflocs 'seem' to prevent disease outbreaks (Avnimelech 2012); evidence suggests that bioflocs may not produce growth-inhibitory substances in the presence of Vibrio harveyi, but instead cause a decrease in quorum-sensing-regulated bioluminescence of the pathogen. Thus, bioflocs in this particular case may downregulate the virulence of Vibrio to different hosts, improving the survival of the cultured species (Crab et al. 2012). Despite this evidence, the magnitude and the importance of such an assertion ought to be demonstrated by both bioassays to monitor antimicrobial activities and metagenomic approaches. "
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    ABSTRACT: The use and study of microbes in aquaculture has become a common practice in the last decade. Metagenomics is a relative recent genomics subdiscipline that has emerged as a promising scientific tool to analyse the complex genomes contained within microbial communities. However, despite the potential of metagenomics, its use is not yet common in some agro-industrial disciplines such as aquaculture. In this review, we analyse some of the potential uses of metagenomics in aquaculture to highlight the microbial diversity and dynamics of the culture systems. This review addresses some potential uses of metagenomics in the study of microbial diversity, microbial roles in microcosms, antibiotic resistance genes, novel and potential pathogens, microbial communities forming bioflocs, probiotics and other applications.
    Reviews in Aquaculture 07/2015; DOI:10.1111/raq.12102 · 3.92 Impact Factor
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    • "They are incorporated into tissue (approximately 20 %), and the remainder is converted into nitrogen through direct excretion and decomposition of organic debris (Colt and Armstrong 1981; Avnimelech 1999). Therefore, the BFT (Biofloc Technology Culture System) is characterized by the conversion of the nitrogen supplied by food that is not consumed and by the excreta of cultivated organisms, which, together with the addition of organic carbon sources, will be converted into microbial protein available as additional food in the culture environment and allowing for improvement in the feed conversion rates (Wasielesky et al. 2006a; Crab et al. 2012). The advantages that these systems provide are a reduction in the demand for water and a consequent reduction in the emission of effluents, minimizing the impact on the environment. "
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    ABSTRACT: The carbon sources such as molasses cane sugar, dextrose and rice bran were tested in growing Pacific white shrimp, Litopenaeus vannamei, using the Biofloc Technology System, and the reduction in the concentration of total ammonia nitrogen in the experimental nursery and grow-out phases were assessed in tanks with a volume of 800 L at 35 and 70 days, respectively. In the nursery experiment, postlarvae with an average weight of 0.024 ± 0.01 g were stocked at 1200 m−2 and shrimp with an average weight of 4.09 ± 0.51 g and stocking density of 300 m−2 was used in the grow-out. The carbon sources used in the nursery were molasses (M) and rice bran (R) and in the grow-out were dextrose (D) and rice bran (R). In the nursery experiment, using molasses, the ammonia concentration was significantly lower (p < 0.05). In the grow-out experiment with dextrose, the ammonia concentration was significantly lower (p < 0.05), but performance data were significantly better (p < 0.05) in the rice bran treatment. The faster degradation of dextrose and molasses sources may have provided higher levels of carbon as a substrate for heterotrophic bacteria to use in metabolizing ammonia, thereby improving the water quality.
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    • "In contrast, Ray et al. (2010) observed no difference in TSS production when Pacific white shrimp were given fish meal diets versus vegetable meal diets. Increases in TSS commonly affect the respiration of cultured organisms (gill obstruction) and dissolved oxygen diffusion into the water column (Crab et al. 2012; Moreira de Souza et al. 2013). Nevertheless, the TSS values reported here (400– 500 mg/L) are within the recommended range (200–500 mg/L) for a good productive response in biofloc cultures (Avnimelech 2009). "
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    ABSTRACT: Biofloc culture systems,which are based on the development of microorganisms that recycle inorganic nutrients and organic matter, may contribute to the nutrition of some farmed species. Juvenile red tilapia (Nile Tilapia Oreochromis niloticus × Mozambique Tilapia O. mossambicus) cultured in saltwater were fed pelleted diets in which 0, 33, 67, or 100% of the fish meal was substituted with a vegetable meal mix (corn, wheat, and sorghum meals). The proximate composition of the biofloc produced in the culture systems was evaluated. Four experimental diets and one control diet (isocaloric and isoproteic) were randomly assigned to 15 experimental tanks. Samples of biofloc were periodically collected to measure the total suspended solids, organic matter, and ash content and to determine the protein, lipid, and carbohydrate contents. At the end of the study, variables describing red tilapia production were determined. The biofloc volume, total suspended solids, ash, and organic matter showed significant differences among treatments, but carbohydrate (33.0–39.0%), lipid (2.6–3.5%), and protein (23.7–25.4%) levels were similar. No significant differences were observed in red tilapia survival, final biomass, or feed conversion ratio.We conclude that the substitution of fish meal with vegetable meal in the pelleted feed had no adverse effect on the production response of saltwater-cultured red tilapia.
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