New Evidence for Late Glacial Shellfishing Seasonality and Coastal Environments in Atlantic Europe from Shell δ ¹⁸ O values

[EN] In recent decades, the role of marine resources in prehistoric hunter-gatherer diets has been widely debated. While some scholars propose that shellfish served as an emergency food supply during resource scarcity, others highlight their broader nutritional benefits. This paper applies δ18O analyses to Patella vulgata Linnaeus, 1758 shells from Cuevona de Ardines and El Cierro caves (Asturias, Spain) to determine seasonal patterns in shellfish collection during the Early Magdalenian (ca. 19,600–18,900 cal BP) and Azilian (ca. 13,600– 12,700 cal BP) periods. These data provide insights into human subsistence strategies, enhancing our understanding of coastal resources in their diets and mobility patterns. Additionally, past sea surface temperatures (SST) were estimated using δ18O values derived from shells. The results were compared with anthracological remains from Cuevona de Ardines and El Cierro, as well as other available evidence (pollen surveys, marine cores, isotopic analyses, etc.), to achieve a more accurate palaeoenvironmental reconstruction. Findings indicate that, during the Early Magdalenian, shellfishing primarily occurred in autumn, followed by summer and spring. For this period, an annual mean SST of 12.6°C is proposed. During the Azilian period, harvesting also predominantly took place in autumn, albeit to a lesser extent throughout the rest of the year, with an annual mean SST close to 14°C. These results are compared and discussed in the context of other sites with similar chronologies.