Membrane lipids of symbiotic algae are diagnostic of sensitivity to thermal bleaching in corals

• DOI: 10.1073/pnas.0402907101
• Publication Date: 2004-08-31T00:14:24Z
• Authors: Dan Tchernov; Maxim Y. Gorbunov; Colomban de Vargas; Swati Narayan Yadav; Allen J. Milligan; Max Häggblom; Paul G. Falkowski
• Keywords: Zooxanthellae; Coral bleaching; Symbiodinium; Stylophora pistillata; Hermatypic coral

Over the past three decades, massive bleaching events of zooxanthellate corals have been documented across range global distribution. Although phenomenon is correlated with relatively small increases in sea-surface temperature and enhanced light intensity, underlying physiological mechanism remains unknown. In this article we demonstrate that thylakoid membrane lipid composition a key determinate thermal-stress sensitivity symbiotic algae cnidarians. Analyses membranes reveal critical threshold separating thermally tolerant from sensitive species zooxanthellae determined by saturation lipids. The potentially diagnostic differential nature induced found scleractinian corals. Measurements variable chlorophyll fluorescence kinetic transients indicate damaged are energetically uncoupled but remain capable splitting water. Consequently, fraction photosynthetically produced oxygen reduced photosystem I through Mehler reaction to form reactive species, which rapidly accumulate at high irradiance levels trigger death expulsion endosymbiotic algae. Differential thermal stress among various Symbiodinium seems be distributed all clades. A clocked molecular phylogenetic analysis suggests evolutionary history cnidarians selected for tolerance elevated temperatures latter portion Cenozoic.