The reef is not only huge, but also completely intact. And that’s pretty special, at a time when most reefs are struggling to survive.

During a diving expedition, a three kilometer large coral reef was discovered off the coast of the island of Tahiti in the South Pacific. A stunning find. The newly discovered coral reef is located at depths between 30 and 65 meters and appears to be in particularly good condition. “It was magical to see gigantic, beautiful rose corals stretching as far as the eye can see,” recalls Alexis Rosenfeld, who led the diving mission. “It’s a work of art.”

Great coral reef

The beautiful coral reef, consisting of rose-like corals with a diameter of up to two meters, is one of the largest coral reefs in the world. Such gigantic coral reefs are very important because they are a food source for other organisms. In addition, they protect against coastal erosion and even tsunamis.

Photo of the newly discovered coral reef off the coast of Tahiti, which is one of the largest coral reefs in the world. Image: Alexis Rosenfeld

Intact

The reef is not only huge, but also completely intact. And that’s pretty special, at a time when most reefs are struggling to survive. “French Polynesia has been ravaged by a period of extreme bleaching in 2019,” said researcher Laetitia Hedouin. “But this reef does not appear to be significantly affected.”

More about bleaching
Coral lives in symbiosis with microscopic algae that provide the coral with food and color. When the coral is exposed to stress (due to higher water temperatures or pollution), the algae leave the coral tissue. As a result, the coral not only loses an important source of food, but also color. The coral weakens and becomes more susceptible to disease. One of the biggest stress factors facing coral at the moment is the warming of the seawater. As a result, bleaching has become a rapidly spreading problem.

How is that possible? Researchers suspect that the reef off the coast of Tahiti is well protected from bleaching because of its deep location. And so the reef has taken the worst blows. “Discovering this reef in such a pristine condition is good news,” continues Hedouin. “It can serve as a source of inspiration for future conservation.”

Great depth

The fact that a reef has been found at a depth of more than 30 meters is very special. The vast majority of the world’s known coral reefs can be found at depths of up to about 25 meters. It could therefore mean that there are many more reefs at great depths, in an area known as the ‘twilight zone’ of the ocean.

Moon

That nickname is not for nothing. At the moment, only 20 percent of the entire seabed has been mapped. “We know the surface of the moon better than the deep ocean,” said Audrey Azoulay, UNESCO director general. Fortunately, advances in technology have meant that longer dives at great depths are now possible. “The remarkable discovery near Tahiti demonstrates the incredible work of scientists who are expanding our understanding of the ocean,” Azoulay said.

In total, researchers made several dives and spent about 200 hours near the reef to study it properly. More diving expeditions will be launched in the coming months to continue research on the newly discovered reef.