Thermal plasticity in coral reef symbionts is mediated by oxidation of membrane lipids

Abstract The oxidation of polyunsaturated fatty acids (PUFA) is a common stress response across biomes with potential to trigger impairment of cell growth and reproduction. The oxidative stress theory of coral bleaching induced by global warming has been widely accepted to explain coral reef decline, but its underlying physiological mechanism remains under debate. Here we used lipidomic and population density data to examine cell cultures of three coral reef symbionts after a heat shock (sudden rise of 12 °C for 4 hours). Heat tolerance in S. microadriaticum and C. goreaui was characterized by preservation of thylakoid-derived glycolipids. Conversely, heat sensitivity in B. minutum was linked to elevated concentrations of oxidized PUFA esterified to glycolipids, suggesting that culture growth had ceased due to severe oxidative damage. Our findings provide a basis to further understand the role played by oxidative stress in coral bleaching and reveal novel biomarkers for the monitoring of symbiont-coral health.