One of the biggest coral reefs in the world has been discovered off the coast of Tahiti in French Polynesia. Scuba divers have been exploring the site, which is made up of giant rose-shaped hard corals, each growing up to 2m across and in pristine condition.
The reef is about 3km long and between 30 and 60/65m wide, but such surprise discoveries are always possible while only a fifth of the seabed has been mapped to date, say scientists from the UNESCO-supported research team that located it.
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The site’s sheer extent makes it a highly valuable discovery, they report, but what makes it even more unusual is that unlike the vast majority of the world’s known coral reefs, which lie no deeper than 25m, the Tahiti reef thrives at shadier depths of 30-65m.
“So this discovery suggests that there are many more large reefs out there, at depths of more than 30m – in what is known as the ocean’s ‘twilight zone’ – that we simply do not know about,” says UNESCO.
The scientific team has so far carried out some 200 hours of dives to study the reef, during which time the divers have been able to witness the coral spawning. Further investigative dives are planned in the coming months, concentrating on the marine-life species that live on the reef.
“French Polynesia suffered a significant bleaching event back in 2019 – however, this reef does not appear to have been significantly affected,“ said marine biologist Dr Laetitia Hedouin from France’s National Centre of Scientific Research (CNRS). “The discovery of this reef in such a pristine condition is good news and can inspire future conservation.
“We think that deeper reefs may be better protected from global warming.”
The Intergovernmental Oceanographic Commission of UNESCO co-ordinates global programmes such as ocean-mapping and tsunami alert systems, along with numerous scientific research projects. The agency is also the guardian of 232 marine biosphere reserves and 50 marine World Heritage sites, and through the 2020s is leading the UN Decade of Ocean Science for Sustainable Development.
The “1 Ocean” campaign, led by explorer-photographer Alexis Rosenfeld in partnership with UNESCO through the decade, sis seeing a range of investigative expeditions being carried out as part of the agency’s mission to map the ocean.
“It was magical to witness giant, beautiful rose corals which stretch for as far as the eye can see,” commented Rosenfeld of the Tahiti reef he has been documenting. “It was like a work of art.”
