Magnesium Isotopes in Enamel Hydroxyapatite as Trophic Indicator

Trophic information is crucial for interpreting the structure of an ecosystem, subsequently, changes in trophic relationships reflect perturbation in ecological and climatic regime. In the absence of organic components and associated nitrogen isotopic signatures, past trophic levels of an ecosystem in deep geological time are elusive. This research is to study magnesium isotopes in enamel hydroxyapatite as a quantitative geochemical proxy to indicate past trophic information in terrestrial ecosystems. Results from our current study suggests observable variation of trophic levels within an extant savannah ecosystem. Browsers and grazers exhibit different magnesium isotope ratios, which complicates interpretations of omnivory and absolute trophic level. Thus, further inquiry of natural Magnesium isotopic ratios of the representative fauna in combination with other isotope studies are critical in the interpretation of paleo-trophic system of terrestrial mammals.