Salinity and alkalinity as potential controls for pCO2 reduction in an experimental shrimp (Litopenaeus vannamei) farming

Abstract

Shrimp farming, once limited to coastal areas, is now thriving in non-coastal regions as well, due to the success of the whiteleg shrimp (Litopenaeus vannamei) cultivation across a wide range of salinity. The purpose of this study was to evaluate the influence of salinity on the CO₂-carbonate system during experimental shrimp farm cultivation aiming sustainable crustacean aquaculture. The evaluation involved two shrimp production systems, where water samples were collected periodically from seven tanks of hypersaline water (M1) and seven tanks of brackish water (M2), making a total of fourteen semi-closed experimental units. Both treatments used the same feeding method. Carbonate system parameters (TA and pH) and ancillary data (including temperature, salinity, dissolved oxygen, and phosphorus fractions) were all sampled during the rearing cycle of these aquatic organisms. Additionally, pCO₂ and dissolved inorganic carbon (DIC) were estimated for a complete evaluation of CO₂-carbonate system parameters. The results indicate that the hypersaline treatment (M1) resulted in lower pCO₂. In contrast, the mesohaline treatment (M2) led to higher pCO₂. The total alkalinity (TA) varied from 2420 to 3469 µmol. kg-1 in M1 and from 3589 to 4463 µmol. kg-1 in M2. Since the addition of lime is a common practice in aquaculture, our results suggest that it also should be managed as an approach for removing CO₂ in shrimp farming, besides the use of hypersaline waters, or to improve the carbon sustainability of brackish water shrimp farms, in search for greater sustainability of this activity in accordance with Sustainable Development Goal 14 – Life Below Water.