Toward a standardised protocol for the stable isotope analysis of scleractinian corals

Rationale: The stable isotope analysis of carbon and nitrogen is a powerful tool in many ecological studies, but different sample treatments may affect stable isotope ratios and hamper comparisons among studies. The goal of this study was to determine whether treatments that are commonly used to prepare scleractinian coral samples for stable isotope analysis yield different δ15N and δ13C values, and to provide guidelines toward a standardised protocol. 

Methods: The animal tissues and Symbiodiniaceae of two symbiotic scleractinian coral species (Stylophora pistillata and Porites lutea) were divided into subsamples to test the effects of the drying method, lipid extraction, acidification treatment and water washing. All the subsamples were analysed for their δ15N and δ13C values, using continuous flow elemental analyser/isotope ratio mass spectrometry.

Results: The drying method and lipid extraction treatment had no substantial effects on the δ15N and δ13C values of Symbiodiniaceae...