Seasonality from Mg/Ca Ratios of Prehistoric Shellfish Exploitation ( <i>Patella caerulea</i> Linnaeus, 1758) at the Haua Fteah (Libya, North Africa)

Mollusc shells, commonly preserved in archaeological records worldwide, capture high-resolution, sub-annual environmental information at local scales through the incorporation of chemical elements during their formation. These geochemical signals can be used to infer the season of shellfish collection by past human populations. This study presents new seasonal data derived from magnesium-to-calcium (Mg/Ca) ratios in Patella caerulea Linnaeus, 1758 from the archaeological site of Haua Fteah in northern Cyrenaica (Libya, North Africa). Our data were obtained through elemental mapping using laser induced breakdown spectroscopy (LIBS), which enables the visualisation of intra-shell geochemical variation at high spatial resolution. The results provide detailed reconstructions of shellfish collection seasonality from the Capsian to the Neolithic periods, covering a ∼5,000 year span from the latest Pleistocene through the Early-Mid Holocene. We demonstrate that mollusc gathering occurred throughout the year, with a higher frequency in the autumn and winter seasons, suggesting that marine resource use was more consistent than previously assumed. We compare our data with previous seasonality studies of different mollusc species to demonstrate that seasonal collection patterns varied between mollusc species, suggesting differences in marine exploitation subsistence strategies, probably related to the availability of other food resources, energetic return and mollusc processing techniques.