Effects of decalcification, species, and mammalian order on bulk stable isotope values from marine mammal teeth
The stable carbon (δ13C) and nitrogen (δ15N) isotope analysis of marine mammal teeth are useful for reconstructing their past foraging ecology and habitat use, among other things. Fossilized teeth require removal of inorganic compounds via a decalcification process before the stable isotope analysis of the organic collagen. To test for the necessity of decalcification for the proper analysis of the δ13C and δ15N values from modern marine mammal teeth, I compared the δ13C and δ15N values from decalcified vs. intact dentin sampled from multiple individuals (n=23 total) of seven species of marine mammals. I found no differences in the δ13C (mean±SD: -14.1±1.3‰ vs. -14.2±1.2‰) or δ15N (mean±SD: 16.6±2.4‰ vs. 16.7±2.3‰) values from intact vs. decalcified samples, respectively. The C:N ratios were slightly higher for intact (3.0±0.2) vs. decalcified (2.8±0.1) teeth. My results follow those of a previous study examining effects of decalcification from one sperm whale tooth and underscore the recommendation that decalcification is not necessary before the stable isotope analysis of dentin from modern carnivorous marine mammal teeth.