Performance of the agarophyte Gracilariopsis tenuifrons in a multi-trophic aquaculture system with Litopenaeus vannamei using water recirculation

This study aimed to evaluate the performance of the red alga Gracilariopsis tenuifrons as a biofilter in a multi-trophic cultivation system with Litopenaeus vannamei , using recirculation by zero water exchange. The species were cultivated for 4 weeks, while measurements were taken of the chemical and physical characteristics of water, the development of the cultivated organisms (biomass and growth rate), and the carbon, nitrogen, and phosphorus content assimilated by the seaweeds. The water enrichment produced by shrimp farming favored the seaweed development, which increased on average by 2.6 % day -1 ± 0.24 (0.4 to 4.08 % day -1 ). The seaweed species was able to remove up to 35.1% of the ammonium ion and increased its tissue nitrogen by about 4.8 times by the end of the experiment (1.2–4.8%). The shrimp presented an increase in biomass (8.0 to 12.7 g), with an average growth rate of 1.7% day -1 ± 0.1 and a survival of 100% at the end of the experiment. Based on these results, the cultivation of L. vannamei in a recirculating water system using Gp. tenuifrons as a biofilter can be an advantageous alternative, helping to reduce water usage and remove the main metabolites produced by shrimp cultivation.