The scientists increased the heat above the lethal threshold and waited for the corals to die.
“We were heating the water one degree above the maximum summer temperature,” says Anders Meibom, a researcher at the Institute of Earth Sciences at the University of Lausanne. “At the Great Barrier Reef, after a couple of weeks, they would start to die.”
But the corals taken from the Gulf of Aqaba, a trench of water protruding from the Red Sea, licking Jordan, Israel, Saudi Arabia and Egypt, did not seem concerned about the temperature.
“So we increased to two degrees,” recalls Meibom. Now, they are supposed to die. Instead, they seemed happier. “
The heat went up again. “Three degrees now, this is ridiculous,” says Meibom. “We were thinking, this doesn’t make sense, they’re supposed to be dead. But they didn’t even seem stressed. So we go up to four degrees. “
Coral science in recent years has become the study of a free-falling ecosystem. Coral reefs, some of the richest environments in the world, regularly undergo massive “bleaching” as a result of abnormally high ocean surface temperatures and increased acidification, both consequences of global warming. The loss of color, the result of an expulsion of the microscopic algae that support the creatures, is a vivid sign that corals have become very vulnerable to more heat and disease.
Half of the world’s coral reefs are believed to have died in the past three decades, and up to 90% of existing coral reefs may die by the middle of the century, according to February research.
However, the coral in the experiment at Eilat University survived, even as temperatures rose to five, then six, then seven degrees. “They even showed improved physiological performance at higher temperatures,” says Maoz Fine, the marine science professor who led the research. “At first we weren’t so sure we were doing everything right, experimentally.”
Their results confirmed years of reports of divers in the Gulf of Aqaba and the northern Red Sea. Despite the fact that ocean surface temperatures in the area heat up at the same rate as elsewhere, coral species have never suffered a documented bleaching event. A growing body of research from across the region is leading marine scientists to a compelling possibility: that a wide variety of corals along the 4,000 km of Red Sea reefs are exceptionally resilient to the climate crisis.
“We realized, shit, we have an incredible situation,” says Meibom. “This is the only coral reef ecosystem that has a chance to withstand the two to three degrees of extra heat that we will now inevitably have by the turn of the century.”
If you can survive the neighborhood. Protecting the reef from other threats like pollution and overpopulation will require one thing above all, scientists say. Persuading at least four governments in the Middle East, not all of which acknowledge the existence of the other, to work together.
The Red Sea feeds from the Indian Ocean through a shallow strait between Djibouti and Yemen about 30 km wide. More than 2.5 million years ago, during the last ice age, the strait receded, slicing through the Red Sea and rendering it inhospitable. “It got very hot, very salty and almost everything died,” says Karine Kleinhaus, a professor of marine science at Stony Brook University in New York.
When the ice sheets melted, the strait reappeared and plant and animal life flooded. The coral species that made the arduous journey north through the Red Sea underwent generations of evolutionary selection. “Only those who could withstand salinity and very high temperatures could move north and colonize,” says Kleinhaus.
Many scientists believe that many of the coral species that inhabit the Red Sea reef today were forged by that migration, and can survive, and even thrive, in oceanic temperatures higher than predicted in the coming decades.
The implications for coral reefs in other parts of the world are still being studied. Transplanting resistant coral species to other reefs has generally not worked in the past, says Meibom. “The salinity of the water and the ecosystem of the microbes is different,” he says. “Some species survive, but they are not happy, and many of them die.”
Another possibility is to discover exactly how the Red Sea corals survive extreme conditions, and then direct the evolution of the species elsewhere to select those qualities.
The problem is that scientifically assisted evolution still takes time, and reefs are being hit by heat waves at an accelerated rate.
Research on the Red Sea corals is still in its early stages. “We really don’t know what is happening biologically that allows these corals to thrive with temperature disruptions that are killing corals elsewhere,” says Kleinhaus.
Progress is slowing down due to lack of funds and closings and travel restrictions as a result of the coronavirus, but also due to tense politics in the region. The gathering of scientists from across the region to mount a research expedition to different points on the reef, for example, has been hampered by Saudi Arabia’s reluctance to allow Israeli scientists to enter its territorial waters. “Everything is a challenge in this region,” says Fine.
Threats to the reef will accumulate in the coming decades. Populations along the Red Sea in Israel, Egypt and Jordan are expected to increase. Saudi Arabia plans to build a futuristic megacity at the edge of its waters. “Although the reef is resistant to climate change, it will not be immune to unsustainable development, pollution, sewage, or hypersaline discharge from desalination plants,” says Kleinhaus.
No country can protect it alone, says Olivier Küttel of the Swiss Federal Institute of Technology in Lausanne. “Egypt can do well, but if Saudi Arabia, Israel or Jordan do poorly, they can quickly destroy the entire ecosystem,” he says.
King Abdullah II of Jordan is among lobbyists for the reef to be recognized on the Unesco Marine World Heritage List, which advocates hope will elevate the state of the area, facilitate attracting research funds and pressure governments to protect it.
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