Coral Chemical Affects Climate
October 24, 2013

Corals Make Chemical That Influences Local Climate

Brett Smith for - Your Universe Online

Anyone who has ever been to the ocean knows that signature smell of sea water. One of the molecules responsible for that smell is actually derived from a chemical made by tiny coral animals called dimethylsulphoniopropionate (DMSP).

According to a new study in the journal Nature, Australian marine scientists have discovered the first evidence that DMSP plays a major role in local climate. The molecule offers the coral animals cellular protection in times of heat stress and causes climate cooling by seeding cloud formation.

“The characteristic ‘smell of the ocean’ is actually derived from this compound, indicating how abundant the molecule is in the marine environment,” said study co-author Cherie Motti, a chemist at the Australian Institute of Marine Science. “In fact we could smell it in a single baby coral.”

“This is the first time that an animal has been identified as a DMSP producer. Previously it was assumed that the large concentrations of DMSP emitted from coral reefs came solely from their symbiotic algae,” said lead author Jean-Baptiste Raina, a marine biologist from the ARC Centre of Excellence for Coral Reef Studies at James Cook University (CoECRS).

In the study, corals’ production of DMSP increased when corals were subjected to stress-inducing warmer water temperatures. DMSP and its derivates act as antioxidants by shielding coral tissues from environmental stress, including stress caused by high solar radiation.

The DMSP molecules also serve as seeds for the formation of water droplets in the atmosphere – which eventually create clouds. If coral numbers drop, the study authors warn, there could be a significant fall in the generation of DMSP and this could impede cloud formation.

“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,” Raina explained. “If fewer clouds are produced, less heat will be reflected – which ultimately will lead to warmer sea surface temperatures.”

The study researchers noted that Australia’s Great Barrier Reef is a major contributor of the atmospheric sulfur 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,” the team wrote in their paper.

“Considering declining trends in coral cover and predicted increases in coral mortality worldwide caused by anthropogenic stressors, the associated decline in sulfur aerosol production from coral reefs may further destabilize local climate regulation and accelerate degradation of this globally important and diverse ecosystem," they added.

Stephen Archer, a biogeochemist at the Bigelow Laboratory for Ocean Sciences in the US, told Chemistry World that the discovery of DMSP production in an animal is exciting. He added that the effects of coral-produced DMSP are probably only regional, contributing to cloud formation around the biggest reefs but not having much of an effect on the global climate.

“I suspect the majority of DMSP still comes from phytoplankton in the open ocean,” he said.