Coral reefs have more than one trick up their sleeve to cope with warming oceans according to Australian researchers.
Associate Professor Peta Clode from The University of Western was one of the team whose findings are published online today in Nature.
They discovered that coral - which is an animal - produces an important sulphur molecule with many properties. These range from cellular protection in times of temperature stress, to local climate-cooling through helping to form clouds in the sky above the ocean.
Associate Professor Clode and her fellow researchers revealed that the molecule, dimethylsulphoniopropionate (DMSP), and its production increases when corals are subjected to water temperatures causing thermal stress.
DMSP and its breakdown products act as antioxidants, protecting coral tissues from environmental stress, including the high solar radiation that corals experience.
It is the first time that an animal (the coral host) has been identified as a DMSP producer. Previously it was assumed that the large concentrations of DMSP emitted from coral reefs come solely from their symbiotic algae.
The characteristic smell of the ocean is derived from this compound, indicating how abundant the molecule is in the marine environment.
However, scientists have warned that if coral numbers decline, there could be a major decrease in production of these vital sulphur molecules (DMSP), and this will in turn, impede cloud formation. These sulphur molecules are also important as they serve as nuclei for the formation of water droplets in the atmosphere - and hence help to create clouds.
Cloud production, especially in the tropics, is an important regulator of climate - because clouds shade the Earth and reflect much of the sun's heat back into space. If fewer clouds are produced, less heat will be reflected - which ultimately will lead to warmer sea surface temperatures.
Australia's Great Barrier Reef (GBR) is a major hotspot for the emission of sulphur aerosol particles, the scientists suggest in the paper.
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. Considering declining trends in coral cover and predicted increases in coral mortality worldwide caused by anthropogenic stressors, the associated decline in sulphur aerosol production from coral reefs may further destabilise local climate regulation and accelerate degradation of this globally important and diverse ecosystem.
The team, led by researchers from the Australian Institute of Marine Science, included UWA Associate Professor Clode, and researchers from the Australian Research Council Centre of Excellence for Coral Reef Studies at James Cook University, Murdoch University, and the Australian National University.
Associate Professor Peta L. Clode (Acting Deputy Director UWA Centre for Microscopy, Characterisation and Analysis and UWA Oceans Institute) (+61 8) 6488 8098
Michael Sinclair-Jones (UWA Public Affairs) (+61 8) 6488 3229 / (+61 4) 00 700 783