Scientists have uncovered an unexpected source of food in the deep ocean that could fundamentally change how researchers understand both marine ecosystems and Earth's carbon cycle.
A new study from the University of Southern Denmark (SDU), published July 12, 2026 in the journal Science Advances, reveals that extreme deep-sea pressure squeezes valuable nutrients out of sinking organic particles — providing an immediate and previously unknown food source for deep-ocean microbes.
The Ocean's 'Giant Juicer'
Marine snow — tiny clumps of dead algae, microbes, and other organic material drifting through the ocean — has long been known to carry carbon and nutrients to the deep sea. But researchers assumed these particles largely kept their contents intact until they reached the seafloor.
The new study turns that assumption on its head. Once particles reach depths of about 2 to 6 kilometers, the enormous hydrostatic pressure begins forcing dissolved organic matter out of them.
"The pressure acts almost like a giant juicer," said Dr. Peter Stief, the study's first author and a biologist at SDU's Nordcee and Danish Center for Hadal Research. "It squeezes dissolved organic compounds out of the particles, and microbes can use them immediately."
Staggering Losses
The researchers estimate that sinking marine snow can lose as much as 50% of its original carbon and between 58% and 63% of its original nitrogen during its descent through the deep ocean. Most of the released material consists of proteins and carbohydrates that free-living deep ocean microbes can readily consume.
Laboratory experiments confirmed the effect. When the team recreated marine snow using diatoms — microscopic algae that naturally clump together — and placed them in specially designed rotating pressure tanks that simulated deep-ocean conditions, the results were dramatic. Within just two days, bacterial abundance increased 30-fold, while respiration rates rose sharply, demonstrating that the leaked nutrients provide a rapid and valuable energy source for deep-sea life.
Rewriting the Carbon Cycle
The discovery has major implications for climate science. Scientists have long assumed that much of the carbon carried by marine snow eventually becomes buried in deep ocean sediments, where it can remain locked away for millions of years. Much of the oil and natural gas extracted today formed through this long-term burial process.
But if large amounts of carbon leak out before particles reach the seafloor, less carbon may be permanently stored in sediments than previously believed. Instead, much of that dissolved carbon remains suspended in deep ocean waters, where it can stay for hundreds or even thousands of years before gradually returning to the surface and eventually the atmosphere.
"This process affects how much carbon the ocean can store and for how long," Stief said. "It's relevant for understanding climate processes and for improving future models."
Widespread and Confirmed
The researchers observed the same leakage pattern across multiple species of diatoms, suggesting that this mechanism is likely widespread throughout the world's oceans. The next phase of research will move from the laboratory to the open ocean. The team plans to search for molecular fingerprints of this pressure-driven leakage during a future expedition to the Arctic aboard the German research vessel Polarstern.
The study was supported by the Danish National Research Foundation, the European Union's Horizon 2020 program, and the Independent Research Fund Denmark.
