Marveling at the beauty of nature is perhaps the first step towards the desire to preserve it. In any case, this is what Séverine Martini thinks. Researcher at the Mediterranean Institute of Oceanology, she is a specialist in the bioluminescence of marine animals, an amazing phenomenon that has not yet revealed all its secrets. She shares her passion for the oceans with Diraxe.
Did you know that three quarters of marine organisms are bioluminescent? Of the jellyfishjellyfishof the PiscesPiscesof the bacteriabacteria. All able to produce their own lightlight by chemical reactionschemical reactions. A bit like the fireflies that enchant our summer evenings. “Our oceans are wonderful. » This is the message that Séverine Martini wants to convey to us. His specialty, precisely, is the bioluminescencebioluminescence.
“The oceans are dark. So emitting light is a real advantage. To communicate, to escape a predator, to attract prey or to find a sexual partner.explains the CNRS researcher at the Mediterranean Institute of Oceanology, winner in 2015 of the Bettencourt Prize for young researchers from the Bettencourt Schueller Foundation. “And not just in the abyss. Bioluminescence is also observed near the surface. » To enjoy the magic, it is sometimes enough to bathe in the middle of the night.
But, beyond the magic, there could well be hiding behind bioluminescence some processes of scientific interest. “It is so widespread that we say to ourselves that there are necessarily things that we still do not know”, says Séverine Martini. Among these things is the link between bioluminescence and what scientists call the biological carbon pump.
Did you know ?
At the surface of the ocean live organisms — phytoplankton — that use the sun’s energy to transform CO2 in oxygen. They also transform the inorganic carbon dissolved in the water into organic matter on which others will feed. Some of this organic matter will end up being stored at the bottom of the ocean. Nearly 10 billion tons of carbon stored each year, all the same. By what scientists call the biological carbon pump.
“There are an incredible number of bioluminescent bacteria attached to the particles of carbonecarbone organic matter that fall along the water column. These particles are clumps of detritus from phytoplanktonphytoplankton, corpses of organisms sinking to the bottom. These bacteria could act as visual markers. Making these particles more « visible » than the others. And thus increasing their chance of being ingested. »
Yes, because for a bacterium, being eaten is a chance. A chance to find yourself warm in an intestine rich in nutrient resources. To proliferate more easily than in the somewhat hostile waters of the ocean. “The ins and outs of anthropogenic climate change is like a puzzle. And bioluminescence, finally, as a piece of this puzzle”concludes Séverine Martini.
Pollution and global warming hurt the ocean
A part that it is all the more important today to succeed in placing correctly that “what is happening in the ocean is catastrophic”. We are of course thinking of plastic pollution. » There is plasticplastic on the beaches. But that’s only the tip of the iceberg. In the depths at which we work, between 200 and 1,000 meters, even beyond 2,000 meters sometimes, we have been able to observe bottles, bags and all kinds of other plastic waste., confides the researcher. This is without even mentioning the even more invisible pollution. Those of microplasticsmicroplastics.
“The other emergency, of course, is that linked to climate change. The theme is extremely important. Especially in oceanography. Because as we have just mentioned, the ocean plays a role in carbon sequestration. It captures atmospheric carbon and sequesters it in its depths on millennial scales. »
Ocean mining, a real threat
But the subject which is still little talked about and which nevertheless greatly worries scientists, is that of the mining of the seabed. “Extracting minerals from the ocean takes sedimentsediment in suspension, it increases the turbidityturbidity, it creates noise. With potentially extremely harmful consequences on a ecosystemecosystem that we are just getting to know”, underlines Séverine Martini. An ecosystem that researchers know is already delicate. With extremely slow reaction times to change.
“It really scares us”
With the evolution of means and technologies, the exploitation of the seabed has become accessible. Especially since demand is exploding. Rare minerals are sought for the manufacture of the batteries of our electric carselectric cars et hybridshybridsof the LEDLEDchips from our smartphonessmartphonesscreens of our computerscomputers laptops, photovoltaic solar panels or even wind turbineswind turbines. Projects have been validated in India. Others are under development. Including in France. And “It really scares us”, confides the researcher. First, because these projects concern areas that seem to play a key role in the biological pump process. “If the ocean captures more or less atmospheric carbon, that has a direct impact on climate change. About our everyday life. »
The other reason why we should be careful not to exploit the seabed too quickly is because, perhaps even more than elsewhere, it is important to preserve the balance of these ecosystems. “There is, at the bottom of the ocean, a biodiversity that we do not yet know. There could be hiding moleculesmolecules useful, which would allow us to manufacture medicines. The ocean floor is also part of our fishery resources. Keeping a good balance between what we take and what lives in these environments is important”points out Séverine Martini.
“During my post-doctorate, each time we dived, we came across a species that had never been described before.she remembers, a hint of emotion in her voice. It is absolutely incredible to think that the organism that we observe has almost never been seen before. In 2022. I’m not even talking about microorganismsmicroorganisms, but some fish, squid, etc. We should all be aware that changing our smartphone every year — and more broadly our way of consuming technology, and therefore rare materials — is pushing us down the wrong path.