Evaluating the Culture Condition of Marine Microalga Tetraselmis chui and Its Role in a Tilapia-microalgae-clam Semi-recirculating Culture System on the Efficiency of Removing Total Ammonia Nitrogen in Water

Abstract

The growth of Tetraselmis chui and its efficiency in taking up total ammonia nitrogen (TAN) in aquaria with an 8-cm light path in water were significantly higher than those in aquaria with a 25-cm light path in water. Similarly, the growth of T. chui and its efficiency in taking up TAN under illumination with 240 μE/m^2•s were significantly higher than those with＜180 μE/m^2•s. A higher aeration intensity enhanced the growth of the microalga and its TAN uptake. Tetraselmis chui could effectively remove TAN from a semirecirculating aquaculture system. The level of TAN in the fish-tank water of tilapia-microalgae-clams (TMC) treatment was close to that of tilapia with water exchange treatment which exchanged 37.5% of the fish tank water daily. The survival, weight gain, and feed conversion ratio of fish in TMC treatment were comparable to those in tilapia with water exchange treatment. In total, 750% of the water was recovered by this semi-recirculating aquaculture system.