May 18, 2022 10:37 am

Rare new coral reef discovered in Tahiti




A UNESCO-supported scientific research mission has discovered a 3km-long reef with giant rose-shaped corals off the coast of Tahiti.. It is one of the largest coral reefs in the world located at depths greater than 30 meters. The pristine state and extensive surface area covered by the rose-shaped corals make this discovery highly unusual. It also highlights the limited knowledge we have of the oceans. “To date, we know better the surface of the moon than the depths of the ocean. Only 20% of the seabed has been mapped. This remarkable discovery in Tahiti demonstrates the incredible work of scientists who, with the support of UNESCO, are expanding our understanding of what lies below,” said Audrey Azoulay, Director-General of UNESCO.

The researchers highlight how unusual it is to find such a large reef (about 3 km long and between 30 and 60/65 m wide) located at this type of depth (between 35 and 70 meters), in such a spotless and healthy. Lhe giant rose-shaped corals (some of them 2 meters in diameter) are healthy and there is no evidence that they have been impacted by human activity. «It is, therefore, a fascinating discovery that shows us how much we still have to discover in this type of depth. It is one of the largest known coral reefs in the so-called “twilight zone” of the ocean, at depths between 30 and 120 meters. This zone is beyond shallow depths, but still has access to sufficient light for coral to grow and reproduce,” the researchers note.

So far, the vast majority of the world’s known coral reefs lie at depths of up to 25 meters, so this discovery suggests there are many more large reefs in our ocean., at depths of more than 30 meters that we simply do not know.

The discovery has been made possible by innovative diving teams – @alexis.rosenfeld

The diving expedition that located and studied the reef in November 2021 was carried out within the framework of the UN Decade of Ocean Science for Sustainable Development, led by UNESCO, the United Nations agency in charge of the ocean. French photographer Alexis Rosenfeld, who is dedicated to exploring the oceans through the 1 Ocean campaign, supported by UNESCO, led the team of international divers, which also included Dr. Laetitia Hedouin, from the National Center for Scientific Research (CNRS) of France, and its marine environmental research organization CRIOBE. “It was magical to witness the gigantic and beautiful pink corals that stretch as far as the eye can see. It was like a work of art,” says Alexis Rosenfeld.

New technologies, keys

Until now, very few scientists have been able to locate, investigate and study coral reefs deeper than 30 meters. However, new technologies are allowing longer dives to these depths. ANDThis exploratory mission was made possible by state-of-the-art computer-controlled diving equipment known as rebreathers, which provide divers with a special helium-based gas mixture. This mixture protects against narcosis and allows deeper dives for longer periods. In all, the team conducted dives totaling about 200 hours to study the reef and were able to witness coral spawning.

In the coming months, more dives are planned to continue investigating the reef. The fact that such an extensive reef, in the ‘twilight zone’, is in such a pristine state raises interesting questions. “We would expect a reef like this to take about 25 years to grow and develop like this. French Polynesia suffered a major coral bleaching event in 2019, but this reef does not appear to have been significantly affected. We believe that deeper reefs may be better protected from global warming. So the discovery of this reef in such a pristine condition is good news and may inspire further protection in the future,’ says Dr Laetitia Hedouin.

Our lack of knowledge about the ocean is clearly illustrated by the fact that so far only 20% of the global seabed has been mapped. The Intergovernmental Oceanographic Committee (IOC), part of UNESCO, and its partners are working with governments and companies with the goal of completing mapping of the entire seabed by 2030.Seabed mapping can help us better understand glacial melting, allowing us to better predict sea level rise. Also to improve our management of fish stocks and our tsunami warning systems. Coral reefs are an important food source for other organisms, so their location can contribute to biodiversity research. Organisms that live on reefs can be important for medicinal research, and reefs can also provide protection against coastal erosion and even tsunamis.

UNESCO in favor of the ocean

UNESCO’s Intergovernmental Oceanographic Commission (IOC), founded in 1960 and joined by 150 countries, coordinates global programs such as ocean mapping and tsunami risk prevention, as well as numerous scientific research projects. The agency is also the guardian of unique ocean locations, through 232 marine biosphere reserves and 50 World Heritage marine sites of Outstanding Universal Value. UNESCO has led the United Nations Decade of Ocean Science for Sustainable Development, from 2021 to 2030, which this year is reflected in the organization of several major international summits that will increase collective mobilization.

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