The partition coefficients (KD) guiding the uptake of Mg and Sr in the low-Mg calcite valves of ostracodes in Australian saline lakes have been reviewed in line with new information on the bicarbonate content and the αMg/αCa of the ambient waters. Strongly alkaline and very high αMg/αCa (>>20) waters cause the partition coefficients of ostracodes to differ significantly from those found in other lakes with lower αMg/αCa values. Water salinity does not affect the uptake of Mg or Sr in ostracode valves, whereas the αHCO3– of the water strongly correlates to KD[Sr], with high αHCO3– resulting in a significant KD[Sr] decrease.