Astrid Tomczak-Plewka
“I have never eaten fish. I’ve regarded them as my friends.” As she says this, Ewa Merz is sitting at a desk in one of the most famous institutes for marine research, the Scripps Institution of Oceanography, in San Diego, California. It is the fulfilment of a childhood dream to have the sea that she dreamt of as a girl on her doorstep. Once per week she dives under, literally, to maintain instruments beneath Scripps Pier. For her thesis at the Swiss Federal Institute of Aquatic Science and Technology (Eawag), Ewa was still conducting research into lakes, albeit 10 different ones. She investigated how temperature changes and nutrient fluctuations affect communities of plankton.
Plankton are harmed by higher temperatures
Plankton, microscopically small animals and plants in bodies of water, are not just important as the base of the food chain for larger organisms, but also for biochemical processes such as photosynthesis. If the plankton are weakened, the effect is global. There has already been extensive research into how man directly influences these microorganisms. “But we still don’t know much about how plankton types interact,” explains the environmental scientist. This was precisely the focus of Merz’s thesis. “The greater the interaction between the different types of plankton, the more stable the microorganisms,” she says.
She investigated data sets on nutrients and temperature from recent decades and related her findings to plankton. The extent to which lakes are warming is striking – between 2010 and 2022 the water temperature rose by 0.4 to 1.7 degrees compared to previous years, with the result that interaction between the species decreases with increased temperatures, and they are weakened. This affects the plankton eaters, who depend more on the available sources of nutrients. Small plankton eaters and cyanobacteria prove to be particularly sensitive indicators of these changes. “It was an eye-opener for me that the species interact,” says Ewa Merz. “And it clearly shows that any environmental changes affect our ecosystem.”
Ewa Merz has now been awarded the Prix Schläfli in Biology for her work. “I had to take a deep breath when I heard about it,” she says. “The prize tells me that my curiosity and my questions are going in the right direction.”
“Nature presents so many surprises”
Ewa Merz was the oldest of four siblings growing up in Fribourg. As a lawyer, her mother worked for many years at the Swiss Federal Department of Foreign Affairs (EDA), then for the Federal Office of the Environment and now works for the International Union for Conservation of Nature (IUCN) which, alongside other states, advises on dealing with plastic. “She probably inspired me a little to study natural sciences,” says Ewa. Her father was a secondary school teacher and spent a lot of time with his children. “That was mega,” says Ewa. Her childhood featured plants and cows more than it did sea creatures. But “I always drew the sea and fish.”
The first time she encountered the sea was during a master’s degree placement, studying invasive corals in Brazil. And she also went to California for her master’s, although there she researched plants and ants. It is perhaps chance that she finally ended up studying plankton. As a child she saw herself as an archaeologist or vet. But water had her in its clutches. “And I became completely fascinated with plankton during my doctorate,” she says. “Nature offers up so many surprises.”
Her postdoc at Scripps is ongoing until February 2026. And afterwards? Completely undecided, particularly in view of the political environment in the USA. “I love working with datasets,” she says. She can think for hours about how to solve a problem and the best and simplest way to present the solution. “Of course my dream job would be in Switzerland. The universities there are super, and of course there is research funding. I can imagine myself working for an NGO, or the government.” And the skiing is also better in her home than in the endless southern Californian sunshine. But for the time being, the 33-year-old is living her childhood dream. Her drawings have come to life. And in the midst of them is Ewa Merz, perhaps during a dive, or on a surf board.
