The universal imprint of oxygen isotopes can track the origins of seafood

Abstract

AbstractIdentifying the source of seafood is critical for combatting seafood fraud, but current tools are predominantly developed and applied on a species‐specific basis. This study investigates how multiple marine taxa could be geolocated at global scales by exploiting stable oxygen isotope compositions in carbonate biominerals (δ18Obiomin), where we expect to see universally expressed and predictable spatial variation in δ18Obiomin values across taxa. We constructed global ocean isoscapes of predicted δ18Obiomin values specific to fish (otoliths), cephalopod (statoliths) and shellfish (shells), and a fourth combined “universal” isoscape, and evaluated their capacity to derive δ18Obiomin values among known‐origin samples. High correspondence between isoscape‐predicted δ18Obiomin values and a compiled database of measured, georeferenced values (3954 datapoints encompassing 68 species) indicated that this δ18Obiomin approach works effectively, particularly in regions with highly resolved projections of seawater δ18O composition. When compared to taxon‐specific isoscapes, the universal isoscape demonstrated similar accuracy, indicating exciting potential for universal provenance applications. We tested the universal framework via a case study, using machine‐learning models to identify sample origins amongst regions of divergent (Tropical Asia vs Temperate Australasia) and similar (Temperate Asia vs Temperate Australasia) climates and latitudes. Classification accuracy averaged 75.3% between divergent regions, and 66% between similar regions. When endothermic tuna species were excluded from the analysis, the accuracy between divergent regions increased up to 90% between divergent regions. This study presents the first empirical step towards developing universal chemical markers, which have the potential to support a more inclusive and global approach of validating provenance of seafood.