Biofloc Systems for Sustainable Production of Economically Important Aquatic Species: a review
Biofloc-Based Integrated Multi-Trophic Aquaculture
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| 5. Biofloc-Based Integrated Multi-Trophic Aquaculture
Much as BFT systems facilitate the maintenance of good water quality suitable for the survival and general wellbeing of reared aquatic species without the use of high water volumes and exchange rate, the accumulation of total suspended solids (TSS) and organic matter in the rearing units might result in several ecological problems in the surrounding environment. Therefore, there is an urgent need for sustainable utilization of the accumulated substances, which might pose a danger to the aquatic ecosystems and surrounding environment. BFT systems permit the installation of integrated multi-trophic aquaculture (IMTA) systems in which the wastes of one organism are utilized as feed by another organ- ism [ 89
94 ]. In other words, filter-feeding organisms such as Oreochromis sp. and Mugil liza are utilized for the assimilation of suspended solids and organic matter that accumulate at the bottom of rearing units. However, the choice of these organisms will depend on certain factors, as reported by Borges et al. [ 89 ]. These include: • The absence of competition for food between the co-cultured species; • The filter feeders should be able to consume the suspended solids and organic matter without detrimental effects on their general wellbeing; • The filter feeders should not negatively affect the growth performance and general wellbeing of a co-cultured species in the rearing unit. Previous studies on the integration of shrimp and Nile tilapia (Oreochromis niloticus) have reported increased N and P recovery, yields, growth, growth performance, and immunity in shrimp or tilapia under different stocking densities [ 4 ,
, 91 , 93 ]. Borges et al. [ 89 ] demonstrated that the integrated culture of mullet (Mugil liza) and white shrimp (Litopenaeus vannamei) in the same rearing unit or two separate units for 41 days resulted in a reduction in sludge, thus indicating the utilization of organic matter in the rearing units by mullet. Holanda et al. [ 94 ] also showed that integrating mullet and shrimp culture not only reduces the concentration of TSS in rearing water but also improves the water quality and growth performance of shrimp. However, Hoang et al. [ 95 ] found
that gray mullet (Mugil cephalus) is not an efficient biofloc consumer under the shrimp polyculture BFT system. The discrepancy in results could be attributed to differences in mullet species and rearing conditions. Furthermore, de Oliveira Costa et al. [ 12 ] have Sustainability 2021, 13, 7255 9 of 15
recently shown that the integration of oyster (Crassostrea gasar) and shrimp (Litopenaeus vannamei) in BFT systems did not influence the concentrations of TSS in the rearing units. The authors hence suggested that larger stocking densities could result in more noticeable changes in TSS concentrations. Therefore, the choice of species and rearing conditions is vital for the maintenance of good water quality and to increase crop production. Sometimes, photoautotrophs (halophytes) are used for the absorption of N and P, all of which lead to the maintenance of good water quality and the improved survival and growth performance of the reared species [ 92 ]. For example, Legarda et al. [ 96 ] found that an integrated BFT system (L. vannamei and Ulva fasciata) facilitated N and P recovery at 5.5% and 7.6%, respectively, compared to the control (without Ulva fasciata). Moreover, shrimp yields were 2.91 kg m −3 with a survival rate of 90.6% and FCR of 1.84. Likewise, Pinheiro et al. [ 97 ] observed that integrating L. vannamei and Sarcocornia ambigua at different water salinities (16 and 24 psu) favored the elimination of N and phosphate compounds and did not negatively affect the growth of shrimp or plant growth. tải về 0.71 Mb. Chia sẻ với bạn bè của bạn:
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