Scientists discover one of the world’s largest coral reefs in the waters off Tahiti

Researchers have discovered a large reef of “untouched” rose-shaped corals that are apparently undamaged by climate change in deep water off the coast of Tahiti, UNESCO announced on Thursday.

By mapping about three kilometers (two miles) long and up to 65 meters (213 feet) wide, UNESCO said it was “one of the most extensive healthy coral reefs recorded”.

The UN’s cultural heritage agency said that it was “highly unusual” to find healthy corals in colder waters between 30 and 65 meters deep and that this may indicate that there are more reefs at sea depth that are safer from the effects of warming.

The discovery was made in November by divers with special equipment that allowed them to go deeper and spend 200 hours at the reef.

“It was magical to witness giant, beautiful rose corals that stretch as far as the eye can see. It was like a work of art,” said Alexis Rosenfeld, a French photographer and founder of UNESCO’s partner 1 Ocean Campaign.

The giant rose-shaped corals are each up to two meters in diameter.

– So far, we know the moon’s surface better than the deep sea, says UNESCO Director – General Audrey Azoulay, adding that only 20 percent of the world’s seabed has been mapped.


“The discovery of this reef in such a pristine state is good news and could inspire future conservation,” said Laetitia Hedouin, a marine biologist at the French Research Bureau (CNRS).

“We believe that deeper reefs can be better protected from global warming.”

Most of the world’s famous reefs have been found at depths of up to 25 meters, and the UN’s cultural heritage agency said that the Tahiti reef may indicate that there are more areas with healthy corals in the sea’s degenerate “twilight zone”.

“This remarkable discovery in Tahiti demonstrates the incredible work of scientists who, with the support of UNESCO, are promoting the extent of our knowledge of what lies beneath,” said Azoulay.

French Polynesia was hit by a significant bleaching incident as early as 2019, but this newly discovered reef does not appear to have been significantly affected.

“These corals do not show signs of stress or disease,” Hedouin told AFP.

Bleaching occurs when healthy corals are stressed by peaks in sea temperatures, causing them to expel algae that live in their tissues, leaving cemeteries of bleached skeletons where living ecosystems once flourished.

Heating threat

Starfish can also ravage corals by eating them.

Temperature sensors have been placed in the area as part of a program to analyze why corals appear to be unaffected by climate change and to monitor their population dynamics.

Coral reefs cover only a small part of the seabed, but they are home to at least a quarter of all marine animals and plants.

In October, the Global Coral Reef Monitoring Network said that dynamite fishing, pollution, but mostly global warming, had wiped out 14 percent of the world’s coral reefs between 2009 and 2018.

The hardest hit were corals in southern Asia and the Pacific, around the Arabian Peninsula and off the coast of Australia.

Oceans absorb more than 90 percent of the excess heat from greenhouse gas emissions, protect land surfaces but generate huge, long-lasting marine heat waves that push many species of corals past their tolerance limits.

A single bleaching event in 1998 caused by warming water wiped out eight percent of all corals.


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