Maturation of the Biofloc System in Litopenaeus Vannamei Culture Under Different Salinities and its Effects on the Microbial Communities

Abstract

The purpose of the study is to evaluate the impact of various levels of salinity on bacterial communities that influence the maturation of the biofloc technology system (BFT) in Litopenaeus vannamei culture. The experiment involved four water treatments with different salinities:  seawater from the Arabian Gulf with 44 psu (M44), seawater diluted to 22 psu (M22), well water with 22 psu (W22), and seawater diluted to 11 psu (M11), respectively. The experiment was designed in triplicate following a completely randomized arrangement at a stocking density of 240 shrimps/m3 for 45 days until BFT reached a mature state. Water quality parameters were monitored daily and the bacterial communities in the biofloc system were evaluated every 15 days. Results have shown that salinity has an impact on the water parameters and nutritional composition of the biofloc culture. The bacteria that convert ammonia to nitrite were found to mature early at low salinity (11 psu), while bacteria that convert nitrite to nitrate were found to mature faster at high salinity (44 psu). Also, this study shows that microbial communities can shift drastically through the maturation process depending on the competitive dynamics and metabolic requirements of bacteria. This study indicates the crucial role of salinity in affecting the microbial community and maturation functionality of the BFT. The results further highlight the significance of preserving a varied and well-balanced bacterial community in biofloc aquaculture systems to maximize nitrification and water quality control.

Keywords: Nitrification, Sustainability, White shrimp, Bacteria, Integrated aquaculture