Senior Researcher
“Bringing to light the unseen depths of our oceans”—that is the mission Miriam Brandt fulfilled with her dissertation, which focused on the incredible biodiversity of the deep ocean. A portrait of a researcher who gets to the bottom of things.
While working on her dissertation, Miriam Brandt hit rock bottom—or rather, the deep sea, down to 8,000 meters below sea level. Was this just a case of the doctoral student’s blues? Not at all—it was actually her goal: to collect the mud covering the seafloor to study the incredible tiny creatures that inhabit the abyss.“They are an important link in the ocean’s food chain because they help recycle material that falls from the surface,” explains the young researcher, who defended her dissertation in July 2020. It’s an essential role in a distant and little-known ecosystem.
To lift a corner of the veil on this mysterious world, Miriam Brandt turned to the study of environmental DNA, extracted directly from deep-sea mud. And to wade through this sludge, you have to pull out all the stops.“We collected samples from depths ranging from 330 to 8,000 meters; we lower core samplers or send down robots to retrieve a few grams of mud from the very bottom,” explains the researcher, recalling a 35-day expedition in the Pacific Ocean:“It was a wonderful experience—life on the ship with 50 researchers and 20 crew members.” Wonderful and intense:“When we bring the sediment up from the seafloor, its temperature rises from 4 degrees to 25 degrees in just a few hours, so we have to process it quickly to prevent the DNA from degrading: we cut the cores, take samples, freeze them, and then ship them on dry ice to the laboratory in Sète to extract the DNA .”
For a few grams of mud
But how do those few grams of mud allow Miriam Brandt to know who inhabits the deep sea? “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 sediment samples collected from all over the world, I’ve been able to make progress toward mapping the biodiversity of the deep sea.”
An ambitious project that immediately caught Miriam Brandt’s attention as she was searching for a thesis topic. She knows the ocean floor well—and has since she was a little girl. First through scuba diving, which she’s been doing since she was 12:“My grandfather was a diver; it runs in the family.”Then, toward 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 there in incredible ways, without light.” Next came reading Claire Nouvian’s book *Abysses*, which solidified her high school dream:“I want to work in the ocean.”
A Decisive Encounter
This certainty wasn’t always easy to translate into a study plan when it came time to choose a major. Unable to find the right guidance, the student enrolled in a biology prep program in Marseille. A good student, she passed her first year with flying colors, but found herself“drifting away from the sea” with sadness. To get closer to it, Miriam Brandt traveled across the globe to Australia for a summer-long road trip across the island continent, where she had a fateful encounter:“a French woman—whose name I don’t even remember anymore—who spoke to me around a campfire at James Cook University, where her nephew was studying marine biology.”Captivated 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 struck a deal: I’d go back, finish my preparatory program, and then head back to Australia afterward.”
It was a great opportunity, because once she completed her second year, the young woman headed to Townsville to pursue a bachelor’s degree in marine biology and chemistry.“There, I discovered tropical marine ecology, met some passionate people, and went scuba diving on the Great Barrier Reef!” recalls the German student, who was born in Frankfurt.
Once she had earned her bachelor’s degree, however, she began to feel nostalgic for the Old Continent.“Either I went back then, or I wouldn’t go back at all.” Her mind was made up: she would return to Europe. She ended up in Bremen, “Germany’s city of marine science,” where she secured a spot in an international master’s program in ecology. She would write her second-year 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 distance herself from what she truly 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 scale.”So after her master’s degree, she hit “a total crisis.” Miriam Brandt turned down a thesis opportunity in Bremen, and after a brief detour to the tropics, she returned to the Ardèche, where she grew up, and found herself teaching life and earth sciences at a middle school. That’s when the biology bug caught up with her:“I realized that not only did I love it, but I could also spark that passion in others!” Fully convinced that this was where her professional future lay, Miriam Brandt set out to find a thesis opportunity in France.
So when she came across the topic “Why Not the Abyss? Environmental DNA for Studying Deep-Sea Biodiversity” at the Marbec laboratory, proposed by Sophie Arnaud-Haond, Miriam Brandt jumped at the chance.“The presence of Ifremer and numerous other research institutes and groups makes Montpellier a hub for marine ecology in France, which reinforced my decision to conduct my doctoral research at the University of Montpellier.”
He is all the more interested in the subject because this research has taken on a genuine societal dimension.“People aren’t yet fully aware of it, but there’s a real arms race underway to exploit our abyssal plains! Humans are ready to bulldoze the ocean floor to extract minerals like lithium, rare earth elements, and cobalt, which are used in new technologies. We therefore need to better understand this biodiversity in order to establish regulations to protect this wonderful yet mysterious ecosystem.”
Protecting the seabed
To better raise public awareness of this risk, Miriam Brandt decided in 2019 to enter the “My Thesis in 180 Seconds” competition. Although she did not win, Miriam Brandt deserves credit for raising awareness about deep-sea mining.“Right now we’re in the exploration phase, but starting in 2024, mining permits will be issued covering areas as large as France right in the middle of the Pacific Ocean!” the researcher warns.“It’s a distant and invisible environment; these are tiny creatures with which we have little emotional connection, so it’s harder to raise awareness about this cause,”laments Miriam Brandt, who has found a fundamental cause to fight for.
She will soon continue this work from Norway, where she will begin a postdoc in Bergen in August, focusing on the impact of offshore oil and gas extraction on biodiversity. This is a logical next step in an already rich career, with the ocean as a constant theme and a desire to protect it as the underlying motivation.