Australasian Science: Australia's authority on science since 1938

Corals a Major Source of Climate Gas at Low Tide

Researchers believe that climate models have ignored an important gas emitted by corals at low tide.

Tropical reef-building corals exposed at low tide emit large amounts of the important climate gas dimethylsulfide (DMS), which has a key role in cloud formation and may reduce transient light and heat stress on reefs. The research, published in Nature Scientific Reports, concludes that this source, which has so far been overlooked by climate models, may be critically important in regulating the tropical atmosphere.

Past research has shown that the vast amounts of DMS produced by coral continually seeps into the surrounding water but is broken down before it reaches the sea surface. However, DMS concentrations in the atmosphere above coral reefs rise when the corals are exposed at low tide.

“Our experiments suggest that DMS emissions from coral reefs may be in the same order of magnitude as other marine DMS hotspots, such as transient phytoplankton blooms,” says lead investigator Dr Frances Hopkins from Plymouth Marine Laboratory in the UK. “This large input of DMS from coral reefs is currently unrecognised in climate models, so we now need in situ measurements of DMS above reefs to really get a handle on how much they may contribute to global DMS fluxes.”

Co-author A/Prof David Suggett of The University of Technology, Sydney adds: “Our physiological data showed that corals were not stressed during exposure to air whilst emitting DMS. Our combined observations are consistent with how corals use sulfur compounds that are precursors to DMS to accelerate their stress tolerance pathways.”

The novel findings are highly relevant to the Great Barrier Reef. With an estimated 30% of all corals killed in the northern Great Barrier Reef alone this year, loss of the ability for corals to further regulate local climates leaves the remaining corals more exposed than ever to further stressors.

“This work provides yet more evidence that the future of coral reefs are inextricably linked to the health of our climate,” Suggett says. “As climate change destroys our reefs, the capacity for corals to contribute to Earth’s natural climate regulation capacity will further diminish.”