Analysis of the development of nitrifying bacteria in biofloc systems and culture strategies for Penaeus vannamei in BFT and RAS
Author: Bianca de Oliveira Ramiro (Currículo Lattes)
Advisor: Dr. Dariano Krummenauer
Abstract
In Penaeus vannamei production systems that utilize Biofloc Technology (BFT), nitrification plays a key role in controlling nitrogenous compound concentrations. However, the establishment and efficiency of nitrifying bacteria in these systems can be influenced by physical, chemical, and biological factors, especially during the cultivation process. This thesis aimed to evaluate the effects of different aeration systems and artificial substrate management strategies on the development of nitrifying bacteria present in the biofilm and water column, as well as to establish more efficient management practices for biofilm reuse during super-intensive P. vannamei culture in BFT systems. Additionally, water quality and shrimp growth performance were assessed in BFT and Recirculating Aquaculture Systems (RAS) under high stocking density. The first study investigated the impact of using nano- and microbubbles as aeration strategies on the nitrification process and shrimp growth in super-intensive BFT systems. Results showed that the combined nano- and microbubble treatment was the most effective, offering better ammonia control, higher abundance of beneficial bacteria in the biofilm, and improved shrimp growth and survival. The second study evaluated different management strategies for artificial substrates in the nitrification process and P. vannamei growth, conducted in two phases using pre-colonized artificial substrates. Maintaining substrates submerged in water proved to be an effective approach that did not compromise nitrification between production cycles. Air exposure of the substrates also did not impair nitrification and promoted the recovery of the nitrifying bacterial community. Finally, the third study compared BFT and RAS systems in terms of water quality, shrimp growth performance, and economic viability. BFT resulted in higher final weight, productivity, and Vibrio control, as well as greater economic advantage compared to RAS. While RAS demonstrated better control of nitrogenous compounds, BFT stood out for its greater feed and water use efficiency and yielded higher profitability.
.