Dataset: Stable oxygen and carbon isotopes in freshwater pearl mussels from ultrastructurally distinct shell portions

Oxygen isotopes in stream water can serve as natural tracers of watershed dynamics. Freshwater pearl mussels provide δ18Owater estimates that overcome temporal and spatial limitations of instrumental records. The reliability of shell‑based δ18Owater reconstructions depends on understanding which shell layer biomineralizes closer to oxygen isotopic equilibrium with ambient water.

This dataset contains isotope data obtained from freshwater pearl mussel shells, as discussed in the article titled "Biologically driven isotope fractionation in ultrastructurally different shell portions of freshwater pearl mussels (Margaritifera margaritifera): Implications for stream water δ18O reconstructions".

The dataset includes δ18O and δ13C values from field-collected and tank-reared bivalve shells, complemented by in-situ δ18Owater measurements from the tanks and shell growth rates of the tank-reared specimens.