Effect of temperature, stocking density and total suspended solids on the oxygen consumption of white shrimp Litopenaeus vannamei (Boone, 1931) in a biofloc system
The creation of new cultivation systems for shrimp such as biofloc technology (BFT) has allowed to increase the cultivation densities, and together with this increase, the dissolved oxygen (DO) requirement has increased. Since these systems rely on technologies such as blowers and hydraulic pumps, they have the potential risk of failure that could lead to a drop in the DO. The objective of this work is to generate a safety protocol for OD in shrimp L. vannamei cultures in BFT systems after the occurrence of a break in the aeration supply, under different environmental conditions of cultivation. The experimental design consisted of 2 phases. The first with 5 temperatures (22, 24, 26, 28, 30°C) to check the time to reach hypoxia with different densities of shrimp (150, 300, 450 and 600 cam/m3) and total suspended solids (0 , 100, 500 and 1000 mg/L), with three repetitions. In the second phase, reoxygenation at 28°C was tested. Shrimp juveniles had individual weight of ≈12g. The time required to reach the critical point (OD ≤ 0.6 mg/L) and to the alarm point (OD ≤ 2.0 mg/L) was determined. The results showed that both shrimp density, TSS and temperature had significant effects on oxygen consumption. Lipid peroxidation analysis (TBARS) showed that after hypoxia the muscle recovers in 72 hours, while in the hepatopancreas in 72 hours the damage was maintained. The results showed that in a cultivation in a BFT system currently used by producers with densities ranging between 300-450 cm/m3, at temperatures from 30 to 28°C and with SST at 500 mg/L, the DO can drastically decrease after a breakdown in the aeration supply causing large mortalities, between 60 minutes and 100 minutes.