Continuous use of settling chamber in saltwort Batis maritima and marine shrimp Penaeus vannamei biofloc-based aquaponics

Abstract

This study evaluated the continuous use of settling chamber in saltwort Batis maritima and marine shrimp Penaeus vannamei biofloc-based aquaponics, as regards shrimp and plant growth performance, water quality, biofloc size, and phytochemical analysis. Two treatments were assessed in triplicate for 55 days: continuous use of settling chamber before the shrimp tank water was sent to the plant channels compared to no settling chamber. The shrimp (250 animals m⁻³) were cultivated in 800-L tanks equipped with heating and aeration systems, whereas the plants were cultivated in hydroponic channels that received the shrimp tank water through pumping. The continuous use of the settling chamber resulted in significantly higher values of ammonia and nitrite, in addition to lower concentrations of nitrate and total suspended solids in the aquaponics system (p < 0.05). Lower biofloc size (p < 0.05) in the treatment with settling chamber suggests the shear effect of the pump could have contributed to the instability in the concentrations of ammonia and nitrite due to destabilizing the bacterial community in the bioflocs. No significant differences in shrimp and plant performance were observed (p > 0.05), whereas the plants cultivated in the treatment with settling chamber exhibited higher values of antioxidant capacity and total phenolics compounds (p < 0.05), suggesting a higher stress environment.