Differential stability of photosynthetic membranes and fatty acid composition at elevated temperature in Symbiodinium

• Published in: Coral reefs 2011-03, Vol.30 (1), p.217-225
• Main Authors: Díaz-Almeyda, E, Thomé, P. E, El Hafidi, M, Iglesias-Prieto, R
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Applied ecology; Aquatic life; Biological and medical sciences; Biomedical and Life Sciences; Climate change; Conservation, protection and management of environment and wildlife; Coral bleaching; Coral reefs; Environmental degradation: ecosystems survey and restoration; Fatty acid desaturation; Fatty acids; Freshwater & Marine Ecology; Fundamental and applied biological sciences. Psychology; High temperature; Life Sciences; Membranes; Ocean temperature; Oceanography; Photosynthesis; Sea water ecosystems; Seawater; Symbiodinium; Symbiosis; Symbiotic dinoflagellates; Synecology; Thermal stress; Water temperature
• ISSN: 0722-4028; 1432-0975
• DOI: 10.1007/s00338-010-0691-5

Coral reefs are threatened by increasing surface seawater temperatures resulting from climate change. Reef-building corals symbiotic with dinoflagellates in the genus Symbiodinium experience dramatic reductions in algal densities when exposed to temperatures above the long-term local summer average, leading to a phenomenon called coral bleaching. Although the temperature-dependent loss in photosynthetic function of the algal symbionts has been widely recognized as one of the early events leading to coral bleaching, there is considerable debate regarding the actual damage site. We have tested the relative thermal stability and composition of membranes in Symbiodinium exposed to high temperature. Our results show that melting curves of photosynthetic membranes from different symbiotic dinoflagellates substantiate a species-specific sensitivity to high temperature, while variations in fatty acid composition under high temperature rather suggest a complex process in which various modifications in lipid composition may be involved. Our results do not support the role of unsaturation of fatty acids of the thylakoid membrane as being mechanistically involved in bleaching nor as being a dependable tool for the diagnosis of thermal susceptibility of symbiotic reef corals.