Uptake of Urea Nitrogen by Oocystis borgei in Prawn (Litopenaeus vannamei) Aquaculture Ponds

Abstract

The goal of this study was to assess the rate of urea nitrogen uptake (ρ) by Oocystis borgei and the relationship between environmental factors and ρ. Light intensity, temperature, pH, salinity, and algal concentration, were used to construct an empirical model. The results showed that light intensity, algal concentration, pH and salinity had significant effects on ρ, and the optimal combination of environmental conditions for ρ was a temperature of 25°C, pH of 7.0, light intensity of 81 µmol m^-2 s^-1, salinity of 15‰, and algal concentration of 4.5 × 10⁸ cell L^-1-5.5 × 10⁸ cell L^-1. The model equation was ρ = 2 × 10^-5 × (A^0.363B^0.783C^0.045D^-0.503E) + 0.0017, with a coefficient of determination (R²) of 0.83. No significant difference in variance was observed between the model-predicted values and the measured values (F = 0.238, p > 0.05), which demonstrated the high fitting degree of the simulation equation. This study provided valuable insight into the reduction of urea nitrogen levels in aquaculture water by O. borgei.

Keywords: Aquaculture; Model; Oocystis borgei; Uptake rate; Urea nitrogen.