Marine explorers have discovered an “ancient” 3 km (2-mile) coral reef at a depth of 30 m (100 ft) off the coast of Tahiti, French Polynesia
The United Nations Educational, Scientific and Cultural Organization, which led the mission, says it is one of the largest discoveries at that depth.
Dr Julian Barbierre of UNESCO said there are probably many more of these ecosystems “we just don’t know about”.
“We must work to map them and protect them,” he said.
UNESCO Director-General Audrey Azoulay said the “remarkable” discovery increased our knowledge of “what lies beneath”.
The reef was found in November during a diving expedition to a depth known as the “twilight zone” of the ocean – part of a global sea floor-mapping mission.
French underwater photographer Alexis Rosenfeld said it was “magical to see the huge, beautiful rose corals spread as far as the eye can see”.
“It was like a work of art,” he said.
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Coral reefs are among the ocean’s most threatened ecosystems – vulnerable to pollution, changes in chemistry due to rising ocean temperatures and dissolved carbon-dioxide emissions.
Professor Murray Roberts, a leading marine scientist at the University of Edinburgh, said the discovery brought home how much we still have to learn about the ocean.
“We still associate corals with most shallow tropical seas, but here we find a vast previously unknown coral reef system.
“Since shallow waters warm faster than deeper waters, we may find that these deep reef systems are future refuges for corals. We need to map these particular locations, understand their ecological role, and prepare for the future There is a need to get out there to ensure their protection.”
There is currently “no evidence” the rock was damaged by those pressures and, Dr Barbier said, its unusual depth was one reason it remained in such “very good condition”.
“Normally we find them at lower depths,” he told BBC News, because the algae that live within the bodies of corals require light.
“But here we are in that part of the ocean that is [further] from land, so there is less sediment that ends up in the ocean here.”
Barbiere said the discovery provided an important insight into ocean biodiversity.
“We know that about 25% of marine species can be found in coral reefs,” he said.
“So the next step is to find out what species live around this type of rock.”
More investigations will be seen in the coming months.
Dr Letitia Hedouin, one of the expert divers from France’s National Center of Scientific Research, said: “We would expect such a reef to take about 25 years to grow and develop.
“We think deeper reefs may be better protected from global warming.
“So the discovery of this rock in such a pristine condition is good news and may inspire future conservation.”
Source: Victoria Gill, BBC NEWS