Isotope incorporation in broad-snouted caimans (crocodilians)

Abstract

The trophic ecology and migration of vertebrate species have been increasingly studied using stable isotope analysis. However, this approach requires knowledge on how dietary isotopic values are reflected in consumers' tissues. To date, this information has only been obtained for a handful of ectotherms; in particular, little is known about crocodilians. In this study, diet-tissue discrimination factors (DTDFs) and carbon and nitrogen stable isotope turnover rates were estimated for plasma, red blood cells (RBCs), and muscle obtained from broad-snouted caimans (Caiman latirostris). Individuals were fed two different control diets for 189 days. DTDFs for δ15N (Δ15N) and δ13C (Δ13C) ranged from -2.24‰ to 0.39‰ and from -0.52‰ to 1.06‰, respectively. Isotope turnover rates in tissues, expressed as half-lives, ranged from 11 to 71 days, with plasma