The Under the Pole III expedition initiated in May 2017, is an extraordinary adventure exploring the ocean depths. A team of divers and scientists are travelling the globe on board a scientific polar schooner called WHY, crossing from the Arctic to the Antarctic, the Pacific to the Atlantic. The objective is to study the underwater environment, from the surface to depths exceeding 150m. They have made some exceptional observations of deep-water corals in French Polynesia.
During the month of May 2019, in Paris the Intergovernmental Science-Policy Platform for Biodiversity and Ecosystem Services presented its first global assessment report to the public. The findings give a distressing overview of the state of life on Earth. The group of international experts estimate that 66 % of the marine environment has been “severely altered” by human activities today, this even though a large amount of its biodiversity is as yet unknown to man. It’s a telling figure that 90 % of the world’s oceans remain unexplored… This vast unexplored expanse includes the Twilight Zone, or “mesophotic” level where only just enough light penetrates for photosynthesis to occur, at a depth of 30 to 150 meters below the surface, a zone that has only just become accessible to scientists thanks to technological advances and improved diving techniques. Thanks to the presence of the Under the Pole III team in French Polynesian waters for the last year, it has been possible to send expert divers with state of the art equipment to explore the depths of the ocean, as far as physically feasible.
A unique opportunity to carry out detailed scientific research on the so-called “mesophotic” corals. Little visited previously, this zone that lies between 30 and 150m below sea-level, has a great potential for new discoveries. “As we face ecological crisis, it is vital to use all possible means to acquire knowledge that will allow us to better protect the oceans and sustainably manage its resources”, explains Ghislain Bardout, cofounder of the Under the Pole expeditions. The sailboat Why and its crew arrived in French Polynesian waters in mid-2018, with the mission of exploring the depths of the reef face in thirty different locations on fifteen islands: Moorea and Tahiti (Windward Islands); Huahine, Raiatea and Bora Boara (Leeward Islands); Tikehau, Rangiroa, Raroia and Makatea (Tuamotu Islands); Hiva Oa, Tahuata and Fatuiva (Marquesas Islands) ; Raivavae (Austral Islands), and Mangareva (Gambier Islands).
This represents more than 1,000 dives in total. Samples of the discoveries are going to be examined in the laboratory, and it is expected to result in at least ten scientific publications. Since the month of June, for the first time, the expedition has also been using a unique experimental facility called the Capsule, installed in the ocean near Moorea, in the Windward Society Islands. It is a miniature and self-contained underwater living unit, which allows three divers to spend 72 hours (or even longer…) continuously underwater and so alternate scuba dives with periods of rest and observation.
Under the Pole III : gaining insight into French Polynesia's deep water reefs
Since July 2018, in between two polar expeditions – one in the Arctic, which they’ve completed and one in the Antarctic, which will begin in 2020, after some time for maintenance to be carried out on the Why – the expedition team have been working on a research program called DeepHope, that focuses on studying mesophotic corals in French Polynesia. The program is carried out in collaboration with Criobe (Centre de recherche insulaire et observatoire de l’environnement, Island Research Center and Environment Observatory). Thousands of coral samples have been collected, most of them unique specimens, never previously collected. “It provides critical and vital information about these corals, a source of knowledge that will help develop preservation strategies, but also a source of hope for the future”, explains Laetitia Hédouin, director of research at the CNRS (Centre national de la recherche scientifique, French National Center for Scientific Research) who is coordinating this scientific program along with Michel Pichon, another coral reef expert.
The underlying objective is to get a handle on their diversity and their vulnerability, in order to develop protection strategies. In any case the variety of samples that have been collected clearly demonstrates that the diversity and density of these types of coral species in French Polynesia have been hugely underestimated thus far, they are the highest in the world. The analyses that will be carried out over two years, will investigate the idea of an ecological safeguard “these discoveries contribute to supporting the hypothesis that the ocean depths provide a refuge for surface corals and provide hope for restoring the reefs”, Michel Pichon predicts optimistically.
A life-raft for surface reefs ?
On April 4th 2019, in the Gambier Islands, Ghislain Bardout and two equipped divers from their team brought up samples of a mesophotic coral, Leptoseris hawaiiensis growing at the greatest depths ever recorded (– 172 meters). Scientists from Criobe, who were there, immediately identified the species and confirmed the record. It’s a discovery “that we’ve been waiting 40 years for”, Michel Pichon notes enthusiastically. “The scientific results that are beginning to emerge, as well as their impact, are clearly of paramount interest on a global scale.” Finding living coral at this depth, along with the impressive collections made, prove that surface corals can also colonize the ocean depths, both developing there and finding a refuge. This has given rise to a hypothesis that mesophotic habitats could serve as a life-raft, a potential source for regenerating damaged shallow reefs (bleached, weakened or destroyed in different ways…), impacted by broader changes occurring in the marine environment (increasing water temperatures, acidification, cyclones…). Up to now, it was thought that only 25 % of corals could migrate from the surface to deeper water. Today, the expedition’s discoveries show that the trend is much more pronounced, with more than 60 % of surface species being capable of colonizing the deeper water. “We are no longer going to consider coral reefs without also taking into account the life that occurs further below and, which could constitute a liferaft for the reefs at the surface”, Laetitia Hédouin reckons. “Today they represent a genuine source of hope for reef restoration …”
The Under The Pole expeditions
The Under the Pole expeditions endeavor to push back the frontiers of human underwater exploration, using a bold and relentlessly innovative approach. This program of expeditions has already been gaining international recognition since 2010, for their expertise in polar diving (Under the Pole I spent 45 days diving at the geographic North Pole; Under the Pole II, 21 months in central Greenland), bringing together 150 team members and 180 partner research institutes and companies. The program is headed by Ghislain Bardout and Émmanuelle PériéBardout a couple that have turned their passion for exploration into a career and a way of life. The Under the Pole III expedition, that is currently underway, will be heading to the Antarctic after finishing exploring Polynesian waters. The current expedition will continue until June 2021, the date it is expected to return to Concarneau in mainland France, the Why’s home port.
Source : Reva Tahiti Magazine
Text : Claude Jacques-Bourgeat
Pictures : Franck Gazzola, Julien Leblond