Hydrogen isotope ratios in animal body protein reflect trophic level

1Carbon and nitrogen isotope ratios in consumer tissues are known to correlate with diet isotope composition, and nitrogen isotope ratios are observed to increase with increasing trophic level.2We analysed nitrogen and hydrogen isotope ratios of collagen from 19 species of British fish, birds and mammals to investigate how δD also correlated with trophic level and with feeding environment (terrestrial or aquatic).3A strong relationship between trophic level and δD was discovered for both terrestrial and aquatic consumers.4The correlation between trophic level and δ15N was apparent for terrestrial consumers, but less so for aquatic consumers.5No differentiation was found between δD of aquatic and terrestrial consumers at the same trophic level.6This observation should provide an additional tool in the study of current and ancient animal and human food web ecology