Senior Researcher
“Bringing to light the unseen depths of our oceans”—that is the mission Miriam Brandt has fulfilled with her dissertation, which explores the incredible biodiversity of the deep ocean. A portrait of a researcher who gets to the bottom of things.
During her doctoral research, Miriam Brandt hit rock bottom—literally, all the way down to 8,000 meters below sea level. Was this just a case of the post-grad blues? Not at all; in fact, that was her goal: to collect the sediment covering the seafloor in order 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 the material that falls from the surface,” explains the young researcher, who defended her thesis in July 2020. An essential role for a distant and little-known ecosystem.
To shed some light 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 took samples from depths ranging from 330 to 8,000 meters; we lower core samplers or send robots down to retrieve 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 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 mud 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, in her final year 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 match
A conviction that isn’t always easy to translate into a course of study when it comes time to choose a major. Unable to find the right guidance, the student enrolled in a biology prep program in Marseille. A strong student, she passed her first year with flying colors, but found herself“drifting away from the sea” with a sense of sadness. To get closer to it, Miriam Brandt crossed 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 prep year, 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 passionate people, and went diving 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 homesick for the Old Continent.“It was either go back then or never go back.” Her mind was made up: she was returning to Europe. She ended up in Bremen, “Germany’s hub for marine science,” where she secured a spot in an international master’s program in ecology. She would write 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 distance herself from what she truly loved: “With my background in ecology, I felt out of step with microbiology; I was starting to lose 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, it was “total crisis mode.” Miriam Brandt turned down a thesis opportunity in Bremen and, after a brief detour to the tropics, returned to the Ardèche, where she grew up, and found herself teaching biology in a middle school. Then 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 Deep Sea? 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; this reinforced my decision to conduct my doctoral research at the University of Montpellier.”
He finds the subject all the more fascinating because this research has taken on a truly societal dimension.“People aren’t yet fully aware of it, but there’s a veritable arms race underway to exploit our deep-sea 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 didn’t 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 postdoctoral fellowship in Bergen this August, focusing on the impact of offshore oil and gas extraction on biodiversity. This is a natural next step in an already distinguished career, with the ocean as a constant theme and a commitment to protecting it as the driving force behind her work.