Fatty acid profiles of separated host–symbiont fractions from five symbiotic corals: applications of chemotaxonomic and trophic biomarkers

Abstract

Fatty acids (FAs) are the main components of lipids in corals. We examined FAs profiles from five symbiotic coral species belonging to five different genera (Acropora, Pavona, Turbinaria, Favites, and Platygyra) and four different families (Acroporidae, Agariciidae, Dendrophyllidae, Faviidae). We separated symbionts from the coral host tissue to investigate the interaction of FA between symbionts and host tissue. After separation, we used FA profiles, in particular specific FAs (e.g. 16:0, 18:0, 18:3n-3, 20:5n-3, 22:6n-3) and their ratios (EPA:DHA, PUFA:SFA) as biomarkers (i.e. signature lipids) to examine chemotaxonomy and trophic level (autotrophy vs. heterotrophy) of each coral species. Gas chromatography–mass spectrometry (GC–MS) was performed to identify and quantify FA. For quantification, the dry weight of total lipids was used to normalize FA concentration (μg mg−1). We found that (1) the five different coral species showed define species-specific FA profiles; (2) certain FAs were valuable biomarkers to determine relative trophic strategies (i.e. autotrophy and/or heterotrophy; (3) the application of FA ratios to define trophic level requires caution in research application and data interpretation. Considering the limitations of FA ratios determined herein, we suggest it to be more appropriate to examine response to environmental change within species. Going forward, our study provides important FA baseline data that builds the foundation for future investigations on the impact of environmental changes related to nutrition and metabolism in symbiotic corals.