Local isotopic ecologies matter in the Pacific: an example from Waya Island, Fiji

The use of stable isotope analysis (SIA) has contributed significantly to our understanding of the diets of people who lived in Oceania in the past. While this work has relied extensively on Pacific-wide baselines, in this study, we demonstrate the importance of understanding local isotopic ecologies for the application of SIA to the interpretation of past human diets across the Pacific Islands. We expand on previous isotopic analysis from Waya Island, Fiji, by analysing additional human (n = 3) and faunal (n = 15) remains using δ13C and δ15N data from bone collagen. The analysed samples come from human and faunal individuals excavated from two different sites, Y2-25 “Olo” (2800-2400BP) and Y2-39 “Qaranicagi” (760-660 BP). We used a multispecies approach to SIA to capture aspects of the local isotope ecology of Waya Island, informing our interpretation of the human isotopic data. Through a re-analysis of previously published data alongside these new contributions, we demonstrate how intra-regional isotopic variation in marine environments may complicate the use of Pacific-wide baselines for understanding past human diets.