The FACEMUSSEL project, dedicated to investigating the causes behind the mass decline of freshwater mussels and their ability to adapt to climate change, has been awarded funding by the Swiss National Science Foundation.
It is one of only eleven Polish-led projects selected from 334 proposals submitted worldwide to the prestigious MAPS (Multilateral Academic Projects) program. In the field of life sciences, only eight projects received funding — including this initiative led by Dr. hab. Tadeusz Zając, professor at the Institute of Nature Conservation of the Polish Academy of Sciences, in collaboration with Dr. Alexandra Weber (Switzerland) and Prof. Jasna Leitner (Croatia).
Freshwater mussels are among the most endangered groups of aquatic animals globally. Although they have successfully adapted to life in rivers and lakes over millions of years, their populations are now declining at an alarming rate, even in Europe. That’s why scientists want to find out what specific biological mechanisms underlie this inconspicuous phenomenon.
“Mussels have achieved remarkable evolutionary success, and the disappearance of such an ancient and widespread group is deeply concerning — especially since it signals a broader ecological crisis in freshwater ecosystems,” says Prof. Zając.
Not long ago, mussels represented a significant portion of aquatic biomass, but today they are vanishing at a disturbing pace.
While the issue is particularly visible in North America — home to the greatest diversity of mussel species — it has also become critical in Europe.
According to Prof. Zając, climate warming is clearly the main driver of mussel decline, leading to rising water temperatures in rivers worldwide. “This change is harmful to aquatic life in general, but in the case of mussels, temperature alone may not be the direct cause. We have recorded instances where water temperatures exceeded 30°C, and mussels didn’t die off in such massive numbers solely because of that,” he explains.
Therefore, as part of the FACEMUSSEL project, he will not only observe the problem, but also try to determine what exactly happens in the body of the clams and in their environment when whole populations die.
“Just like humans have a gut and skin microbiome, mussels have their own microbial communities. As environmental conditions change, these microbiomes may shift as well. Some evidence suggests that changes in bacterial composition, along with the emergence of new pathogens, could be weakening mussels’ natural immune defenses,” says the researcher.
The project also focuses on phenotypic plasticity — a key adaptive mechanism that allows organisms to respond to environmental changes through physiological, behavioral, or morphological modifications, even if their genetic makeup remains unchanged.
The research team will integrate environmental monitoring with advanced genetic and physiological analyses. By doing so, they hope to understand how different mussel populations respond to climate-related stress and whether they have the capacity to adapt.
In addition to Polish rivers, the project will study rivers in Croatia. “Our mussels have evolved in cooler, well-oxygenated waters, while Croatian mussels are naturally exposed to warmer conditions. They may therefore show higher resilience,” he explains.
Prof. Zając emphasizes that the recent mussel die-offs demand urgent and thorough investigation. “It’s no longer enough to say that climate change is to blame — we need to understand the exact mechanisms behind it. Mussels play a vital ecological role: they filter water, enhance biodiversity, and stabilize sediments. They are also long-lived and have low reproductive turnover. If one-third of a population disappears every year without sufficient recruitment, it inevitably leads to extinction.”
The MAPS-funded project is titled “Multifaceted approach to understand freshwater mussel decline and resilience in the face of global warming – FACEMUSSEL.”
Photo by Roman gulua on Unsplash
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