Noémie Coulon, voice of the ocean

Noémie Coulon recounts that her initial findings have had " the effect of a sledgehammer " on the marine scientific community. In her thesis, defended at the end of 2024 at the Muséum National d'Histoire Naturelle (MNHN), the marine ecologist shows the worrying effects of climate change on sharks and rays in Europe, species hitherto perceived as resilient. " There is a relative scientific consensus on the ability of these species, which are a few hundred million years old and have survived numerous climatic crises, to get through this new crisis. Several results show that this is not the case.

The young researcher first highlighted the northward migration of rays and sharks as a result of climate change. To arrive at this conclusion, she used catch data from scientific bottom trawling campaigns in European seas. A time series spanning a quarter-century for nine fished species provides her with a valuable dataset. " I found the presence of six species in the southern North Sea, although they had never been observed there, even going back to historical texts throughout the 20th century.

89% mortality at + 4°C

Even more worrying is the impact of warming and acidification of the water on the reproduction of these large predators. The rearing of small dogfish eggs in tanks shows that, when water temperature is varied, while nothing happens at +2°C, mortality rises to 89% at +4°C! Beyond eggs, " there could be impacts at every level: gamete production, the signals needed for males and females to meet, sperm storage by females..." adds Noémie Coulon. These are very worrying results, confirmed by other work on the greater spotted dogfish, which is more sensitive to environmental changes, showing a possible collapse of populations at +4°C. "

France is home to over a hundred species of shark and ray, " so these questions are not anecdotal", stresses the young researcher, who insists on the unique and irreplaceable functions of these large predators, already threatened by fishing. In addition to their place at the very top of the trophic chain, these species play a role in the carbon cycle by making daily migrations in the depths. " Some rays are burrowers, stirring up the sand and thus energizing the ecosystem by putting particles in suspension and preventing anoxia in the environment ", adds the woman who makes no secret of her pleasure at working on these large fish, a grail for young marine ecologists.

"Mobilization strategy

A post-doctoral fellow at the Marbec laboratory until 2027, Noémie Coulon is currently working on the current monitoring of fish in marine protected areas in the French Mediterranean. Using dive observations and DNA sampling in the environment - two non-invasive approaches - she is working in particular to model the characterization of fish in these habitats.

For the time being, however, she is dedicated to another task: defending the cause of marine species by relaying the scientific findings of the two thousand researchers taking part in the One Ocean Science Congress. Winner of the L'Oréal-UNESCO Young Talent Award for Women in Science 2024, Noémie Coulon is one of nine "ECOP insiders" - in other words, "early career ocean professionals" - who have infiltrated the congress, to be held ahead of the UNOC in Nice at the beginning of June. Each of them has been chosen to share information with the nine major language communities: Mandarin, English, Spanish, Arabic, Hindi, Portuguese, French, Russian and German. " There's both a need to make the information more accessible to the general public, and a strategy for mobilizing people around these issues, so as to influence the negotiations that follow," says the scientist.