Ghislain Bardout, could you tell us about the overall objectives of the DeepHope program currently on-going ?


© Franck Gazzola / Under The Pole

We are currently half-way though the DeepHope program, a scientific project surveying the deep corals ecosystems. It started in July 2018 and will be ending in June 2019, when the WHY will be back in Tahiti after 12 months of sailing across five archipelagos and surveying 15 islands.

DeepHope has been designed together with Laëtitia Hédouin, Researcher from the CNRS at the CRIOBE. The CRIOBE is the Insular Research Center and Environment Observatory based in Moorea, French Polynesia.

DeepHope is focusing on mesophotic corals. The word mesophotic comes from the ancient greek. Meso means ”median’’ and photic means ‘’light’’. The mesophotic zone is therefore this zone named also twilight zone located where the sun struggles to penetrate the water, which is between -30m and -150m. Generally speaking, researchers cannot dive past the -30m mark and this is exactly we are busy working on: everything coral past the -30m depth down to -150m.


© Maxime Horlaville / Under The Pole

 Where are you at in this program and how is it happening concretely?

Today, we are mid-March. We have already dived in the Society islands, more specifically in Bora-Bora and Moorea. Coming into the Tuamotus, we have surveyed Makatea, Tikehau, Rangiroa and Rarohia. Then we headed to the Marquesas: Faut Hiva, Tahuata and Hiva Oha and we are standing-by to keep sailing towards the Gambier archipelago. After that we will have to stop in the Australs archipelago with the islands of Raivavae and Tubuai, before making our way back to Tahiti in June 2019.\

So far, we have over 4000 samples that have collected, sampled and conditionned. We have also shot thousands of photo-quadrats on the six depths at which we operate the scientific work: -6m, -20m, -40m, -60m, -90m and -120m.

© Franck Gazzola / Under The Pole

On top of that we have been going futher down to -150m, sometimes deeper, in order to find the deepest corals we could find. We regularly found the samples specie: the Leptoseris, which we have found down to -150m. We think that those corals could be living even deeper than -150m…but it is indeed difficult to confirm. Collecting samples at those depths can only be occasional.

Beyond the samples, we also collect a great amount of oceanographic data which help us to put characterise the environment where corals live: temperature, light, salinity, pH, etc…

The amount of data collected by the DeepHope program is absolutely unprecedented, whether it’s on the density, diversity and partition of the different coral species.

For instance, some species can easily be found at -20m, but we can also find them way below that depth too, like the Pachyseris which we have found down to -90m on several occasions.

This can also vary from one region to another: in the Marquesas we have found some corals that we haven’t found anywhere else. And vice-versa. We have discovered noticeable differences in density and diversity. 

We have essentially taking like a large picture, a portrait if you will, of the deep corals of Polynesia.

© Franck Gazzola / Under The Pole

 What was the preparation like for this intense program of diving?

This scientific program can only be done through deep diving. It’s a full year of field work, of diving but more specifically deep-diving. The dives are done gas mixes: helium, oxygen and nitrogen. We call this type of mix ‘’trimix’’ in diving terms. These dives are pretty committing, very deep with a changing team. There is some kind of roster onboard.


© Maxime Horlaville / Under The Pole

There is also a great degree of repetition, day after day, month after month, during a whole year. Let’s not forget that French Polynesia is as wide as the greater Europe. The WHY helps us navigate this vast region but is also our technical and logistical platform for everything diving related. All those elements make the DeepHope program a really intense one.

Therefore we have to prepare the team to manage this project in the best possible conditions. This is where all the work that we have done upstream was critical in regards to the preparation of the equipment and the logistical organisation of the expedition.


© Franck Gazzola / Under The Pole

The team from the CRIOBE has managed the scientific fold of the project, like the equipment and everything relating to the sampling of corals for instance. We all gathered last August for a workshop with both teams (Under The Pole and the CRIOBE). The idea was to get to know each other, to learn from one another, and to define the scientific and diving protocols, as well as the difficulties, potential risks and limitations.

We, the divers, also received a training on coral taxonomy, as it was a new concept for most of us. Even if we knew some bits, we didn’t know as much as the scientists. Today, we’ve closed that gap.


© Franck Gazzola / Under The Pole

An regarding the diving preparation ?

For the diving side of things, we have had a gradual progression. We started with one month of intense training with a renowned instructor: Aldo Ferrucci.


© Franck Gazzola / Under The Pole

Repetition is really important. It is critical to constantly challenge oneself, remain open, seek to maintain one’s skill level, especially when doing such an activity: deep diving. Technics evolve over time, and it is really key to train and repeat those new gestures or drills to stay on top of our game. It is absolutely vital to be well trained.

From mid-August, we started the dives with the scientific team. We began to repeat the protocols directly on the working sites, in order to get familiar with the equipment and sampling technics. This allowed us to get direct feedback from the scientists. Our learning curve was really short and steep.


© Franck Gazzola / Under The Pole

The first working site took the longest: this was where we trained if you will, but once we got to Bora Bora, the team really hit the ground running.

Since then, we’ve just rolled-out the program. Onboard we have two scientists, sometimes three, or even four, with some specialists who come here on short-term basis. Before we’ve even realised, it’s March already and we have already completed two-third of the program.

We already have some promising results. In four months, when this year long on-field phase will be completed, the second phase of the project will start in the laboratories for the analysis of all the data. This should result in a large number of publications and reports on the mesophotic corals of French Polynesia. But beyond this, it may trigger some similar programs, maybe of comparable scope, in Polynesia or else where in the world. 


© Franck Gazzola / Under The Pole

 What are the inherent risks of this kind of diving ?

A deep diving program with the use of gas mixes like DeepHope are certainly requires a lot of commitment. It’s a matter of being well trained and never loose sight on the organisational elements and what we are there for. We have to constantly maintain this fine balance between life onboard and the physical exertion, to keep as far away from certain limits. The main risk is called routine.

We should never consider any of the dives we do on this program as standard. Those are out of the ordinary and will remain so. Every single dive must be correctly prepared, and everyone must stay within one’s own adequate depth corresponding to one’s level of experience. Only gradually, the experience will slowly allow to go deeper, down to -120m and more.


© Franck Gazzola / Under The Pole

Other the risk is to get exposed to accidents which could quickly become disastrous, especially talking about decompression incidents.

Of course, we dive with procedures that have been tested, with sufficiently reasonable margins, but decompression is not an exact science. If we look at the number of dives we do, we are statistically more exposed that occasional divers.

But beyond decompression, we have to have a decent knowledge of the environment. We do these exceptional dives in spectacularly clear waters, so rich, with a reef that is home to a lot of fish from the smallest to the largest ones. It is a whole ecosystem of life and biodiversity. Moreover, we dive on the places less travelled, in waters and depths never dived. There are apex predators like sharks that you have to know. We have witnessed some inquisitive or even territorial behaviours. When you dive in wild waters, you have to understand the inhabitants of those waters to maximise your own safety.


© Franck Gazzola / Under The Pole

 What is your weekly frequency of diving ?

One island means two working sites. This requires about 12 to 15 days of work. To complete one site, 3 or 4 days of diving are necessary, with a no-dive day in the middle. This day is usually dedicated to the collection of bathymetric data, which is done from the surface, with sonars.


© Franck Gazzola / Under The Pole

Between the two sites, we generally assign one education day. We spend one day on every island to work on pedagogy and raise awareness by sharing with the youngest one in the local schools. This represents over a dozen days per site with at least 8 days of diving.

 Are you satisfied with the diving from a technical point of view ?

Technically, yes. The dives are going really well. The month of training allowed to align all technics and procedures. From the get-go, the team spoke the same language. This improved greatly our efficiency but more importantly our safety. During this period of training we have define our standards for this program, in order to reduce any unnecessary exposure. From a scientific point of view, the workshop has been also very beneficial.


© Franck Gazzola / Under The Pole

From mid-August, we got straight into the program and gradually gained in experience. We quickly became really efficient. We have crossed one island after another on our list with the same protocols and it always went smoothly.

Of course, sometimes we had to face challenges. The weather has caused some delays, but overall the program is rolling-out really smoothly. The scientists are enthusiast, and they see groundbreaking perspectives for the science and for the corals. This reinforces the grounds and the relevance of this program which we had identified as one with great potential with Laëtitia Hédouin over three years ago now.

 From a scientific point of view, how is everything going? Have you made some discoveries ?

We can already say that we have discovered a new family of corals that was not known in French Polynesia before. We might also have found a new specie. But before making announcements, the scientists want to complete their research for like taxonomic/genetic analysis. We cannot share non-verified data. This scientific rigour is key and we should not cut corners here.

However, we can already present a first mid-term assessment of the Deephope programme.

 What has been your most amazing moment on this first part of the expedition ?

It is hard to pick one on such a long time on expedition. I would actually have at least two.

© Maxime Horlaville / Under The Pole

I can think of a strong memory whilst diving over -150m with Julien Leblond, to see where would be the low limit for the corals on this site. At the bottom, we were making a u-turn alongside this steep cliff. Of course it was dark but the water was really clear. We looked down to try to see below our fins, and we could see like a change in the cliff face, probably around the -200m mark. Rather that dropping straight down to the abyss like it is usually the case, it actually looked like it was flat, like a plain or a plateau. It was very different from what we generally witness here in Polynesia where we mainly see verticality. Of couse, we wanted to go and check it out. Every diver would want that: to see what’s further down. But we had to make our ascent towards the surface. This moment will forever feel like a dream, a vision. This is what I find extraordinary with diving. It is like an endless world that will never be fully explored. So, during every dive, we look further down and try to imagine what we could find.


© Franck Gazzola / Under The Pole

Another great memory is in Makatea.

This island is very different from all the other islands in Polynesia. It’s a high island, with unique geological characteristics. There are vertical cliffs all around it and inside lies a tropical primary forest covering almost the entire island. It is very difficult to access this place: there is no airport or protected shelter for boats. Only a couple of exposed buoys for short-term mooring. We did a first dive to scout the place and see what we could hope to find. And we found the most extraordinary reef, particularly rich, with a Leptoseris coral cover close to 100% at depths of 80-90m.

We didn’t see that anywhere else. It was an unprecedented discovery. This naturally asks the question: why such fields of corals that deep? Normally we’d see corals scattered around at those depths. Here, the place was just fully covered. On top of that we also found cave and overhangs booming with life. This site ended up being one of the most interesting one from a scientific standpoint, very promising. We have therefore planned to go back again in June, just before the end of the expedition, and to treat it as a proper scientific dive site.

Ghislain Bardout


© Franck Gazzola / Under The Pole