‘Remarkable’ giant coral reef found off Tahiti

This handout picture taken on December 12, 2021 by French Photographer Alexis Rosenfeld shows a newly-discovered reef of giant rose-shaped corals at a depth of over 30 meters off Tahiti, in French Polynesia. – A team led by the photographer Alexis Rosenfeld and the scientist Laetitia Hedouin, researcher at CNRS – CRIOBE, supported by UNESCO, has just carried out a large-scale exploration mission on a deep coral reef in the heart of the Pacific. With an exceptionally high coral cover, this site is of great interest to scientists. This unique coral reef extends over several hectares and inspires an indescribable sense of magic in its viewer. “As far as the eye can see, it is covered with these corals in the shape of giant roses. They remind me of the work of a great fashion designer”, explains the photographer. (Photo by Alexis ROSENFELD / Alexis Rosenfeld / AFP)

by Kelly MACNAMARA
Agence France-Presse

PARIS, France (AFP) – Scientists have discovered a vast reef of “pristine” rose-shaped corals apparently unharmed by climate change in deep water off the coast of Tahiti, UNESCO announced Thursday.

Mapping approximately three kilometres (two miles) long and up to 65 metres (213 feet) wide, UNESCO said it was “one of the most extensive healthy coral reefs on record”.

The UN heritage agency said it was “highly unusual” to find healthy coral in cooler waters between 30 and 65 metres deep and that it could suggest that there are more reefs in the ocean depth that are safer from the impacts of warming waters.

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 which stretch for as far as the eye can see. It was like a work of art,” said Alexis Rosenfeld, a French photographer and founder of the UNESCO partner 1 Ocean campaign.

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

“To date, we know the surface of the moon better than the deep ocean,” said UNESCO Director-General Audrey Azoulay, adding that only 20 percent of the world’s seabed has been mapped.

‘Inspire’

“The discovery of this reef in such a pristine condition is good news and can inspire future conservation,” said Laetitia Hedouin, a marine biologist at French research agency (CNRS).

“We think that deeper reefs may be better protected from global warming.”

Most of the world’s known reefs have been found at depths of up to 25 metres and the UN heritage body said the Tahiti reef could suggest there are more areas of healthy coral in the ocean’s unmapped “twilight zone”.

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

French Polynesia suffered a significant bleaching event back in 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 become stressed by spikes in ocean temperatures, causing them to expel algae living in their tissues, leaving graveyards of bleached skeletons where vibrant ecosystems once thrived.

Warming threat

This handout photo taken on May 28, 2013, and released by the Protected Areas and Wildlife Bureau (PAWB) on May 31, 2013 shows volunteers removing coral-killing starfish in Verde Island Passage off Pagkilatan village in the province of Batangas, south of Manila. A coral-killing starfish has begun infesting a channel of water in the Philippines famed for having some of the most diverse marine life in the world, the government said on May 31, 2013. (Photo by PAWB / AFP)

Starfish can also ravage corals by eating them.

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

Coral reefs cover only a tiny fraction of the ocean floor, but they are home to at least a quarter of all marine animals and plants.

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

Hardest hit were corals in South 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, shielding land surfaces but generating huge, long-lasting marine heatwaves that are pushing many species of corals past their limits of tolerance.

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