In a future shaped by climate change, where will ocean life still thrive? Are there heat resistant organisms that can survive a warmer ocean? A recent study from Stanford University published this week in the Proceedings of the National Academy of Sciences opens a window into how some reef-building corals can live in unusually high temperatures, and may hold a key to species survival for organisms around the world.
“If we can find populations most likely to resist climate change and map where they are, then we can protect them,” said Stephen Palumbi, director of Stanford University’s Hopkins Marine Station and leader of the research team. “It’s of paramount importance, because climate change is here.”
Coral reefs are crucial sources of fisheries, aquaculture and storm protection for about 1 billion people worldwide. These highly productive ecosystems are constructed by reef-building corals; tiny animals that grow to form colonies so big they can be seen from space. But overfishing and pollution, plus rising temperatures and acidity, have destroyed half of the world’s corals during the past 20 years. The growing threat of climate change makes it imperative to understand how corals respond to extreme temperatures and other environmental stresses.
Corals are tropical animals that live in perpetual danger of overheating. If the temperature goes up just 1-2 degrees they begin to suffer, Yet there are patches of live and healthy coral that break the rules. “Researchers in the US National Park of American Samoa discovered something amazing,” Palumbi recounts. “Some of the reefs there heat up to lethal temperatures in the summer. But corals there surprised everyone by thriving, not dying.” Palumbi, lead author Daniel Barshis, a Stanford postdoctoral scholar, and other researchers have spent the last five years mapping the heat resistant corals in Samoa. They found what they call the world’s strongest corals near the Ofu runway, and are they are using the Ofu reef as a natural laboratory to discover the mechanism that corals use to overcome temperature limits. Recent advances in DNA sequencing technology and the first coral genome sequence let the group chart how the corals change how they use their genome during heat stress, and what makes a heat resistant coral.
Heat-resistant and heat-sensitive corals had a similar reaction to experimental heat: hundreds of genes “changed expression” or turned on to reduce and repair damage. However, the heat-resistant corals showed an unexpected pattern. “About sixty heat stress genes were already turned on even before the experiment began,” Barshis explained, These genes are “frontloaded” by heat resistant corals – already turned on and ready to work even before the heat stress began. “It's like having already charged batteries in your flashlight before a hurricane arrives” Palumbi said. “instead of going out to get them in the storm.”
The findings show that DNA sequencing can offer broad insights into the differences that may allow some organisms to persist longer amid future changes to global climate. “We’re going to put a lot of effort into protecting coral reefs, but what happens if we wake up in 30 years and all our efforts are in vain because those corals have succumbed to climate change?” Barshis asked.
As with strong corals, finding species most likely to endure climate change – “resilience mapping” – is the first step toward protecting them, Palumbi said. “Some of the solutions that we’re looking for must already be out there in the world”.
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Steve Palumbi cell phone 831-601-7002
Dan Barshis: firstname.lastname@example.org