Red Sea could be world’s ‘last coral refuge’ as global warming bleaches reefs elsewhere, researchers say

  • Scientists hope that at least some of the Red Sea corals – five per cent of the corals left worldwide – can survive amid a looming global collapse
  • Most shallow-water corals affected by coral bleaching because of repeated marine heatwaves are unlikely to last the century
Doris Wai |

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Striated surgeonfish and royal angelfish swim by a coral reef along Egypt’s southern Red Sea coast. Photo: AFP

Beneath the waters off Egypt’s Red Sea coast, a kaleidoscopic ecosystem teems with life. It could become the world’s “last coral refuge” as global heating eradicates reefs elsewhere, researchers say.

The Intergovernmental Panel on Climate Change said this year that most shallow-water corals affected by coral bleaching because of repeated marine heatwaves would be unlikely to last the century.

Even if global warming is kept within Paris climate goals of 1.5 degrees Celsius above pre-industrial levels, 99 per cent of the world’s corals would not recover. But Red Sea coral reefs, unlike those elsewhere, were “highly tolerant to rising sea temperatures”, said Mahmoud Hanafy, professor of marine biology at Egypt’s Suez Canal University.

Scientists hope that at least some of the Red Sea corals – five per cent of the corals left worldwide – could survive amid a looming global collapse. “There’s very strong evidence to suggest that this reef is humanity’s hope for having a coral reef ecosystem in the future,” Hanafy said.

Eslam Osman from the King Abdullah University of Science and Technology in Saudi Arabia said: “It is crucial that we preserve the northern Red Sea as one of the last standing coral refuges because it could be a seed bank for any future restoration effort.”

Global warming, as well as dynamite fishing and pollution, wiped out a startling 14 per cent of the world’s coral reefs between 2009 and 2018. Graveyards of bleached coral skeletons are now left where once vibrant and species-rich ecosystems thrived.

Recent studies have shown the northern Red Sea corals are better able to resist the dire impact of heating waters. “We have a buffer temperature before the coral sees bleaching,” Osman said. “One, two, even three degrees [Celsius] of warming, we’re still on the safe side.”

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One theory explaining the corals’ apparent resilience to heat is because of “evolutionary memory” developed many thousands of years ago, when coral larvae migrated north from the Indian Ocean. “In the southern Red Sea, coral larvae had to pass through very warm waters, which acted as a filter, only letting through species that could survive up to 32 degrees Celsius,” Osman said.

However, even if Red Sea corals survive rising water temperatures, they risk being damaged by non-climate threats – pollution, overfishing and habitat destruction.

“When non-climate threats increase, the vulnerability to climate change increases as well,” Osman said.

The waters off Egypt’s Red Sea coast could become the world’s “last coral refuge” as global warming destroys reefs elsewhere. Photo: AFP

Reefs off Egypt are hugely popular among divers, and some Red Sea dive sites are operating at up to 40 times their recommended capacity, according to Hanafy. Fishing must also drop to a sixth of current rates to be sustainable.

For Hanafy, protecting the reef is a “global responsibility” and one which Red Sea tourism businesses must share. Local professionals say they have already witnessed damage to parts of the delicate ecosystem.

One solution, Hanafy said, would be for the environment ministry to boost protection over a 400-square-kilometre area of corals known as Egypt’s Great Fringing Reef. More than half of it already lies within nature reserves. But creating one continuous protected area would support the coral by “regulating activities and fishing ... and banning pollution”, Hanafy said.

Agence France-Presse

Why are coral reefs important?

Coral reefs are some of the most diverse ecosystems on Earth, and they are often called the “rainforests of the sea”. About one-quarter of the ocean’s fish depend on coral reefs for food and shelter. Many sea creatures also rear their young within coral reefs.

Australia’s Great Barrier Reef alone contains more than 400 coral species, and these support 1,500 fish species, 4,000 mollusc species and six of the world’s seven sea turtle species.

At least 500 million people rely on coral reefs for food, coastal protection and livelihoods. Coral reefs also act as natural barriers that protect coastlines from tsunami and storms. Their survival is important for workers in the fishing and tourism industries.

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