Natural abundance of nitrogen stable isotopes in intertidal mussels off NW Spain between 2002 and 2023

This dataset contains the values of natural abundance of stable isotopes (carbon and nitrogen) in bulk tissues of intertidal mussels (Mytilus galloprovicialis) collected between 2002 and 2023 along the NW coast of Spain. Stable isotopes were determined in the aductor muscle of mussels. Stable nitrogen isotope values were also mesured in amino acids in some samples in 2023. Stable isotope determinations were made by isotope-ratio mass spectrometry using an elemental analyzer (bulk samples; Viana et al. 2011) or a gas-chromatograph (derivatized amino acids; García-Seoane et al. 2023) as the inlet device.