After 20 years of research, you have published “The scallop, sentinel of the ocean”, which you have come to sign after the last conference on Tuesdays at the Espace des sciences, at the Champs Libres. How does this animal watch over its environment?
Many French people see Saint-Jacques as the festive Christmas dish, but CNRS de Bretagne research has made it an archive of the marine environment. It testifies in real time or a posteriori of what happened in the water. Every day, the scallop records the temperature – to the nearest 0.3 degrees -, the amount of phytoplankton, the presence of contaminants, pollutants, toxic algae or variations in salinity. This information is archived in the outer skeleton of the shell, used as a symbol for centuries. Today we have the possibility of reading a shell like a book. A 5-year-old shell has recorded all the variations in its environment.
You also study their sounds, why?
We had the idea to study its movements. By moving its two valves, like a bellows, it ventilates itself, brings in fresh water on a regular basis. But if there is a problem with the oxygen in the water or with the presence of a poison – fuel oil from the sinking of the Erika, for example – its movements become abnormal. We can use these movements to detect pollution, but the difficulty is to bring it to the surface. We first placed accelerometers to record long, very precise movements, and then we thought of less intrusive ways of listening to the sound of his movements.
The starting point of your research was an alert from the fishermen of the harbor of Brest on their rarefaction. What is the situation today in Brittany, particularly in the face of the presence of octopus?
The fishing statistics are excellent, the Saint-Jacques is not sick and the way of managing and sowing the shells is mastered. There are indeed problems related to sea bream and octopus, and on that we will see what the future will tell us. As the scallops are very sensitive to oxygen, toxic algae are also potential problems, especially in the larval stage.
What did you spot in the waters through the scallop?
A study carried out with Jean-Alix Barrat, a specialist in micrometeorites and Professor Douraied Ben Salem, for example showed the arrival on the catchment basins of the harbor of Brest, through the memory of the shells, of gadolinium, which is a toxicant. present in the contrast used in hospital MRI scans. This knowledge and reading, acquired in the harbor of Brest, has been exported all over the planet. In tropical environments, such as in New Caledonia, we have studied the contamination of nickel mines with scallops. We also studied the Antarctic scallop and been under the Arctic ice to find incredible information on how the ecosystem works.
Phenomena on an oceanic scale and the movement of the stars are inscribed on an 8 cm animal
Can the scallop help investigate climate change?
Under the ice of the poles, the bivalves have already reacted to the new distribution of the ice linked to the melting. Underwater, the rules of the game change in the spring because it appears earlier than 40 years ago. The problem is that we open a short window, even though the shells have been there for 25 million years and already registering their daily lives, they only grow and live for a few years, maximum 12 years in Norway. In Brest, we have been collecting shells for 40 years, this allows us to predict what we will have in the near future, knowing that the shells will stay on the coastal strip, because they accept almost all temperatures and do not go flow back to the North like abalone.
Do some species live longer?
Arctica islandica is magical. It is the oldest animal on earth, which lives 500 years. It records the activities of the Labrador Current: phenomena that take place on the scale of the Atlantic Ocean are recorded on an animal 8 cm in diameter! He was in Brittany at the last ice age, from Brest to Aber Vrac, and we now find him in Saint-Pierre-et-Miquelon. This creature even registers the variations of the axis of the Moon, and gives a cycle of 18 years. Through it, we see at a depth of 500 m the movement of the stars which surround us. In one of the most beautiful marine ecosystems in the world, the arches of Mauritania also record the sandstorms of the Sahara. The rare earths contained in the sand are imprinted in the shells of these mollusks. It has become a scientific tool.
You are in conference this evening in Rennes, is this an exercise that you like?
Beyond the public’s lack of knowledge of the sea – which is much less true in Brittany – we need to raise awareness. Through the exhibition, the marriage between art and science with the objective, beyond popularization, to make more sensitive to the ocean. Perhaps once the general public is imbued with a maritime impetus, we can explain how this is a common good, necessary, which does not belong to any industry and how much it must now be protected. . For the exhibition, three musicians composed on the basis of our recordings in different ecosystems of the planet. Going to music to feel an emotion is something other than a graph with anxiety-provoking figures. Because we are in denial of the truth: we are ravaging the ocean.
How did you manage to make all these discoveries?
I opened my eyes, worked a lot and got lucky. What saved me was also the relationship with diving, the immersion did me a lot of good to test what I thought was the truth. This scallop, which was a festive dish, becomes a sentinel, a source of understanding of how the sea works and of inspiration for musicians. I think it can extend to all biodiversity. Finally, the value of a species is measured by the level of scientific knowledge we have of it and the energy put into understanding it. The reasons for protecting a species are certainly not economic, it is a duty of precaution.
The conference will take place at 8:30 p.m. on Tuesday, December 14 at the Hubert Curien auditorium, at the Champs Libres in Rennes. She can also be followed by videoconference via this link. From December 18, the researcher’s work will also be on display through the Artic Blues exhibition, in the Anita Conti room of the Champs Libres.
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