Researchers, including A/Prof. Peta Clode from the AMMRF at the University of Western Australia, have discovered that coral produces an important sulphur molecule, called dimethylsulphoniopropionate (DMSP) and that its production increases when corals are subjected to water temperatures that cause them thermal stress. This molecule has significant properties ranging from cellular protection in times of temperature stress, to local climate-cooling through the formation of clouds in the sky above the ocean. Their work was published recently in Nature.
Previously it was assumed that the large concentrations of DMSP emitted from coral reefs came from the symbiotic algae that are intimately associated with the corals. However, the team found that this is not the full story and that the coral cells themselves produce much of the DMSP. This is the first example of DMSP being produced by an animal of any kind. A/Prof. Clode used transmission electron microscopy in the AMMRF at UWA to help to demonstrate this. Compared with algae in normal temperatures, after thermal stress, algal cells in coral tissue show massive deterioration of their cellular components and are not able to produce DMSP. This molecule and its breakdown products, act as antioxidants protecting coral from the damaging effects of environmental stresses such as increased ocean temperature. It also contributes to the cooling of local climate by providing nuclei for the formation of water droplets in the atmosphere above coral –helping to create clouds.
Australia’s Great Barrier Reef (GBR) is a major hotspot for the emission of sulphur aerosol particles. The GBR is the largest biological structure on the planet and the release of these particles along its 2600 km length could constitute a major source of cloud condensation nuclei. If coral numbers continue to decline, cloud formation could be impeded, less heat will be reflected and sea surface temperatures will rise. Human activities that cause a decline in coral cover may therefore further destabilise climate regulation creating a vicious circle of ocean warming.