Aquaponic production of Sarcocornia ambigua and Pacific white shrimp in biofloc system at different salinities

Abstract

This study aimed to evaluate the relationship between salinity in the performance of marine shrimp Litopenaeus vannamei and halophyte plant Sarcocornia ambigua in an aquaponic system with biofloc. The experiment was conducted for 57 days, and four treatments were evaluated: 8 psu (practical salinity unity), 16 psu, 24 psu, and 32 psu, with three replicates. Each experimental unit consisted of an 800 L tank for shrimp rearing, a 40 L settling chamber and a hydroponic bench of 0.3 m2 of planting area and density of 40 plants m−2. The tank water was continuously pumped to the settling chamber, and the supernatant was distributed on the hydroponic bench to irrigate the plants, returning to the tank by gravity. The tanks were stocked with 300 shrimp m−3 (1.6 ± 0.1 g). The shrimp were fed four times daily with a commercial diet containing 38% crude protein. Salinity affected shrimp survival, which was lower in 8 psu treatment (56.3 ± 4.7%). No salinity relationships were detected with any of the plant performance parameters; however, the highest biomass was produced at 16 psu, which is close to the isosmotic point of S. ambigua. The lowest concentrations of ammonia and nitrite and the highest concentrations of nitrate were found, through the interpolation of the data, near the 18 psu salinity. So, it is suggested that in this salinity, the absorption of ammonia by the plants is favored. The salinity also affected the concentration of dissolved orthophosphate. There was no relationship between salinity and the production of phenolic compounds and antioxidant activity in plants. The integrated cultivation of L. vannamei with S. ambigua can be carried out between salinities of 16 and 24 psu since the performance of the shrimp is not impaired, and the growth of the plants and the removal of nitrogen and phosphate compounds are favored in this range of salinity.