Data from laboratory experiments investigating the effects of environmental calcium and magnesium concentrations, and salinity, on post-moult calcium and acid-base fluxes in whiteleg shrimp (<i>Penaeus vannamei</i>).

Both experiments were conducted in 2023 at the Aquatic Resources Centre at the University of Exeter. Shrimp (n = 30; wet mass = 0.57 ± 0.03 g) in Experiment 1 were acutely exposed (24 h) to a range of [Ca²⁺] (1.8 – 25 mmol/L) and [Mg²⁺] (10 – 119 mmol/L) levels at a constant Ca:Mg of 1:5 with all other major ions (Na⁺, Cl^-, K⁺) kept constant.

In Experiment 2, shrimp (n = 54; wet mass = 1.13 ± 0.03 g) were acclimated for 4 – 10 days to progressively lower seawater salinities (25, 20, 15, 10, 5, 2.5 and 1 ppt) under either naturally diluted or artificially enriched Ca²⁺ + Mg²⁺ seawater treatments. The aim of Exp. 1 was to characterise the relationship between divalent cation availability and Ca²⁺ uptake, while Exp. 2 aimed to assess the seawater salinity below which Ca²⁺ uptake is impaired, and whether this is a result of low Ca²⁺ + Mg²⁺ availability.