Ghent University. Faculty of Bioscience Engineering
Abstract
The general objective of this study was to explore the contribution of biofloc technology (BFT) application to aquaculture productivity enhancement, while maintaining sustainable practices. To increase biofloc utilization and overall nutrient utilization, the potential of biofloc utilization by some aquaculture species has been elucidated. This study shows that particle size plays an important role in the nutritional quality and in situ utilization of bioflocs by some aquaculture species. This information was used the basic knowledge to construct a BFT-based integrated culture with the aims to control suspended solids production and to increase nutrient utilization efficiency in an aquaculture system. It is demonstrated that combining BFT with an integrated culture system resulted in lower suspended solids, higher biomass production, total feed efficiency, as well as higher N and P recovery. Furthermore, it is shown in the present study that BFT application also brought about other beneficial effects for the cultured species i.e. enhancing the immunity and the reproductive performance. We demonstrated that the consumption of bioflocs by shrimp resulted in an increase of immune response leading to a higher resistance against infectious myo necrosis virus (IMNV) challenge. Similarly, higher resistance against Streptococcus agalactiae was also observed in tilapia larvae cultured in a biofloc system. Moreover, a notable beneficial effect of biofloc system on tilapia reproduction was also confirmed. It is important to note that the magnitude of the expected beneficial effects of biofloc system could be determined by the operational parameters applied in the aquaculture system. We confirmed that carbon source could affect the dissolved inorganic nitrogen profile in the cultured water, and that alkalinity should be closely monitored during the culture period. It is also observed that the addition of secondary species in a biofloc-based integrated system might influence the water quality dynamic in the culture system and did not necessarily reduce the dissolved nutrient waste. Finally, the present study demonstrated possible modifications to improve the ecological performance of a biofloc-based aquaculture system and new possible roles of this system in aquaculture production
