Model Predicts Which Coral Reefs Will Better Adapt to Global Warming

Climate change is causing coral reefs around the world to decline. According to a new study in the journal Global Change Biology, reefs that receive more heat-tolerant coral larvae from warmer ocean regions will be more likely to adapt and survive than those that receive less. The discovery was made using a computer model created by University of Texas at Austin evolutionary biologist Mikhail Matz.

"It's good news that at least some reefs in the world should be able to adapt really well," said Matz, a professor in the Department of Integrative Biology.

This positive effect of added genetic diversity on reef resilience could, according to Matz, be harnessed to help save coral reefs.

"People can promote natural coral adaptation by mixing and matching corals from distant populations, combining their genetic diversity," Matz said. "This so-called 'assisted gene flow' provides fuel for natural evolution."

While an artificial assist to evolution could delay coral reef demise in high risk areas, Matz said measures should still be taken to protect reefs at a lower risk.

"The first priority should be protecting the reefs which have the best chance to adapt," he said. "Our model only deals with a single risk factor - lack of evolutionary potential - but we must not let them die from other hazards."

These additional hazards include predator outbreaks, pollution, disease, ocean acidification and severe storms. This means the reefs still face plenty of threats, even if they could adapt to warming.

The model represents an important step forward in coral reef research because it has predictive power. Once the current temperature and level of coral immigration from warmer regions is known, the computer can predict how the corals in an area will fare.

The researchers also made projections using this predictive model under different carbon emission scenarios and found that if the world keeps emissions, and thus the warming rate sufficiently low, many more coral reefs would be able to adapt successfully. If emissions stay on their current trajectory, far fewer reefs would survive global temperature rise.

"If we are able to reduce carbon emissions and follow the lower warming trajectory, things look massively better," Matz said. "This would put the majority of the reefs out of risk."

The computer model was run using the Lonestar 5 supercomputer at UT Austin's Texas Advanced Computing Center.

The research was done in partnership with Eric Treml from Deakin University in Australia, and Benjamin Haller from Cornell University.