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Consistent predictable patterns in the hydrogen and oxygen stable isotope ratios of animal proteins consumed by modern humans in the USA



Published datasets of proteinaceous animal tissues suggest that co-variation between amino acid hydrogen (δ2H) and oxygen (δ18O) isotope ratios is a common feature in systems where isotopic variation is driven by geographic or temporal variation in the δ2H and δ18O values of environmental water. This has led to the development of models relating tissue δ2H and δ18O values to those of water, with potential application in a number of fields. However, the strength and ubiquity of the influence of environmental water on protein isotope ratios across taxonomic groups, and thus the relevance of predictive models, is an open question. Here we report strong co-variation of δ2H and δ18O values across a suite of terrestrial and aquatic animal meats purchased in American food markets, including beef, poultry (chicken and turkey), chicken eggs, pork, lamb, freshwater fish, and marine fish. Significant isotope co-variation was not found for small collections of marine bivalves and crustaceans. These results imply that isotopic signals from environmental water were propagated similarly through most of the diverse natural and human-managed foodwebs represented by our samples. Freshwater fish had the largest variation in δ2H and δ18O values, with ranges of 121 ‰ and 19.2 ‰, respectively, reflecting the large isotopic variation in environmental freshwaters. In contrast marine animals had the smallest variation for both δ2H (7 ‰ range, crustaceans) and δ18O (3.0 ‰ range, bivalves) values. Known-origin beef samples demonstrated direct relationships between the variance of environmental water isotope ratios and that of collected meats. Copyright © 2011 John Wiley & Sons, Ltd.