Coral Reefs Resist Climate Change with Genetic Adaptations

As our climate changes, coral reefs are becoming increasingly vulnerable to degradation. Now, though, scientists have discovered that corals may be more resilient than they thought. It turns out that coral reefs may be able to adapt to moderate climate warming, spelling new hope for those that hope to conserve these remarkable ecosystems.

Coral reefs are some of the most biodiverse areas in our oceans. They host thousands of species and act as nurseries for larger fish. Yet as temperatures warm, corals suffer from a process known as coral "bleaching." This occurs when reef-building corals eject algae living inside their tissues. Since these algae supply the coral with most of its food, bleaching can be fatal and leave vast swathes of a reef lifeless after one of these events.

Fortunately, though, it seems that the corals are adaptive. Scientists have discovered that corals possess a range of adaptations that can actually counteract the effects of warming. In order to come to these conclusions, though, the scientists used global sea surface temperature output from the NOAA/GFDL Earth System Model-2 for the pre-industrial period through 2100. This allowed them to project rates of coral bleaching. The initial results seemed to show that past temperature increases should have bleached reefs more often. The fact that they didn't seemed to indicate that corals are adapting.

In the end, scientists found that, through genetic adaptation, reefs could reduce the currently project rate of temperature-induced bleaching by 20 to 80 percent of levels expected by the year 2100--assuming that there are large reductions in carbon dioxide emissions.

"Earlier modeling work suggested that coral reefs would be gone by the middle of this century," said Cheryl Logan, one of the researchers, in a news release. "Our study shows that if corals can adapt to warming that has occurred over the past 40 to 60 years, some coral reefs may persist through the end of this century."

That's not to say that corals aren't still in danger. They face a host of other threats, including disease, acidification and sedimentation. Yet this latest study does show that corals are more resilient than previously thought. This, in turn, could give a bit more hope for the future.

The findings are published in the journal Global Change Biology.