Isotopically anomalous metabolic oxygen in marine vertebrates as physiology and atmospheric proxy

Triple oxygen isotope data of tooth enamel (phosphate) from 16 modern marine vertebrates (sharks, mammals) from different marine habitats are presented. Marine mammal data show a clear signature of isotopically anomalous metabolic oxygen in their bioapatite. This is related to a low flux ratio of isotopically normal drinking and food water to anomalous metabolic oxygen. Traces of anomalous metabolic oxygen are also observed in shark bioapatite. Sharks and mammals have overlapping O-18/O-16 ratios, but distinct O-17 signatures. Our new data suggest that triple oxygen isotopes are a valuable new tracer to assess the physiology of extant and extinct marine vertebrates and may provide a new proxy for past atmospheric CO2 mixing ratios and global primary biosphere production. (C) 2022 Elsevier Ltd. All rights reserved.

Automated summary

The triple oxygen isotope data of tooth enamel (phosphate) from 16 modern marine vertebrates (sharks, mammals) from different marine habitats indicate the presence of isotopically anomalous metabolic oxygen in the bioapatite of marine mammals and traces of anomalous metabolic oxygen in shark bioapatite. This suggests that triple oxygen isotopes can be used as a valuable tracer to assess the physiology of extant and extinct marine vertebrates and provide a new proxy for past atmospheric CO2 mixing ratios and global primary biosphere production.