Shellfish procurement and seasonal scheduling across the Mesolithic–Neolithic transition at Zacatín rock shelter (Gualchos-Castell de Ferro, Granada, southern Iberia)

This study investigates the intertidal shellfish exploitation by the last hunter-gatherers and the first farmers, and their role within broader subsistence strategies during the Mesolithic–Neolithic transition on the Mediterranean coast of the Alboran Sea. We conducted taxonomic, biometric, and stable oxygen isotope ratio (δ 18 O) analyses of Patella caerulea Linnaeus, 1758, shells recovered from the Zacatín rock shelter (Granada, southern Iberia). Shell δ 18 O values indicate that shellfish harvesting did not occur uniformly throughout the year but was concentrated in colder months, suggesting seasonal visits to the coast. Comparable seasonal patterns are observed in both Mesolithic and Early Neolithic levels, pointing to continuity in the timing of intertidal resource use despite the introduction of farming and herding practices. This marked seasonal collection is discussed in relation to taxonomic diversity and shell size variations observed at the site, as well as to different approaches to environmental availability and subsistence organisation within broader economic strategies.