Researcher
"Making the invisible depths of our oceans visible" is the mission that Miriam Brandt accomplished with her thesis devoted to studying the incredible biodiversity of the deep ocean. Portrait of a researcher who gets to the bottom of things.
During her thesis, Miriam Brandt hit rock bottom. The very bottom, in fact, at a depth of 8,000 meters below sea level. Was the doctoral student feeling a little blue? Not at all, it was actually her goal: to collect mud from the seabed to study the incredible little creatures that inhabit the abyss. "They are an important link in the ocean food chain because they help recycle matter that falls from the surface," explains the young researcher, who defended her thesis in July 2020. It's an essential role for a distant and little-known ecosystem.
In order to lift the veil on this mysterious world, Miriam Brandt turned to environmental DNA analysis, extracting samples directly from deep-sea mud. And to wade through this sludge, you need to bring out the big guns. "We took samples from depths of 330 to 8,000 meters, lowering core samplers and sending down robots to collect a few grams of mud from the very bottom," explains the researcher, recalling a 35-day expedition in the Pacific Ocean: "a wonderful experience, living on the boat with 50 researchers and 20 crew members." Wonderful and intense: "When we bring up sediment from the seabed, it goes from 4 degrees to 25 degrees in a matter of hours, so we have to process it quickly to prevent the DNA from degrading. We cut the cores, take samples, freeze them, and then send them in dry ice to the laboratory in Sète to extract the DNA ."
For a few grams of mud
But how do these few grams of mud enable Miriam Brandt to determine who inhabits the abyss? " By studying DNA, I looked at specific genes, genes common to all living organisms, to you, to me, and to these tiny creatures. These are barcode genes: reading them allows us to identify the species present. Using this method, by analyzing deep-sea mud samples collected from around the world, I was able to make progress in mapping the biodiversity of the deep sea."
This ambitious project immediately caught Miriam Brandt's attention when she was looking for a thesis topic. She has been familiar with the seabed since she was a child. First through diving, which she has been doing since she was 12 years old: "My grandfather was a diver, it's a family thing."Then, at the end of middle school, she watched the documentary Deep Blue,which showcases the richness of marine biodiversity, and discovered "a fascinating world populated by animals that live in incredible ways, without light." Then came Claire Nouvian's book Abysses, which cemented her high school dream: "I want to work in the sea."
A decisive encounter
This certainty was not always easy to translate into a study plan when it came to choosing a career path. Unable to find the right guidance, the student enrolled in a biology preparatory course in Marseille. A good student, she passed her first year with flying colors, but found herself sadly "moving away from the sea." To get closer to it, Miriam Brandt traveled across the globe to Australia for a summer road trip on the island continent, where she had a decisive encounter: "a French woman whose name I don't even remember, who told me around a campfire at James Cook University where her nephew was studying marine biology."Seduced by the freedom and the oceans, Miriam Brandt was tempted to stay in Australia... "But my father wanted me to return to France, so we made a deal: I would go back, finish my prep school, and then return to Australia."
It was a good deal, because once shehad completed her second year, the young woman headed to Townsville to study for a bachelor's degree in marine biology and chemistry. "I discovered tropical marine ecology, met passionate people, and dived on the Great Barrier Reef!" recalls the German student, who was born in Frankfurt.
Once she had her bachelor's degree in hand, however, she began to feel nostalgic for the old continent. "Either I went back then, or I would never go back." The decision was made: she would return to Europe. She ended up in Bremen, "Germany's marine science city," where she found a place in an international master's program in ecology. She wrote her master's thesis at the Max Planck Institute for Marine Microbiology on the symbiosis between marine invertebrates and bacteria.
Total crisis
"Discovering molecular biology forced me to step outside my comfort zone,"she recalls. But it also forced her to stray from what she really enjoyed. "With my background in ecology, I felt out of step with microbiology. I was losing sight of what had always motivated me. From ecology to microbiology, I was no longer on the right track."So after her master's degree, she was in " total crisis." Miriam Brandt turned down a thesis in Bremen and, after a short detour to the tropics, returned to Ardèche, where she grew up, and found herself teaching science in a middle school. Then the biology bug caught up with her again: "I realized that not only did I love it, but I could also inspire this passion in others!" Convinced that this was where her professional future lay, Miriam Brandt set out to find a thesis in France.
So when she came across the topic "Why not the deep sea? Environmental DNA for studying biodiversity in the deep sea" at the Marbec laboratory, proposed by Sophie Arnaud-Haond, Miriam Brandt said yes. "The presence of Ifremer and many other research institutes and groups makes Montpellier a stronghold of marine ecology in France, which reinforced my decision to do my doctoral research at the University of Montpellier."
He is particularly interested in this subject because this work has real societal implications. "It is not yet widely known, but there is a real arms race to exploit our abyssal plains! Humans are prepared to bulldoze the seabed to extract minerals such as lithium, rare earths, and cobalt, which are used in new technologies. We therefore need to learn more about this biodiversity in order to establish regulations to protect this wonderful but mysterious ecosystem."
Protecting the seabed
It was to raise public awareness of this risk that Miriam Brandt decided in 2019 to take part in the My Thesis in 180 Seconds competition. Although she did not win, Miriam Brandt deserves credit for raising awareness of deep-sea mining. "For now, we are in the exploration phase, but starting in 2024, mining permits will be issued for areas as large as France in the middle of the Pacific Ocean!" says the researcher with concern."It's a distant and invisible environment, with small creatures that we have little emotional connection to, so it's harder to raise awareness about this cause,"laments Miriam Brandt, who has found herself fighting an uphill battle.
She will soon continue this fight from Norway, where she will begin a post-doctoral fellowship in Bergen in August, dedicated to studying the consequences of offshore gas and oil exploitation on biodiversity. This is a logical continuation of an already rich career, with the sea as a common thread and the desire to protect it as a backdrop.