For decades, the deep ocean was widely regarded as an environment characterized by extreme nutrient scarcity, where microbial life eked out a fragile existence on scant resources. However, groundbreaking new research conducted by a team of marine biologists at the University of Southern Denmark (SDU) is revolutionizing this long-held perspective. Their findings reveal that the deep sea harbors a previously unrecognized wellspring of dissolved organic nutrients, challenging assumptions about carbon and nitrogen dynamics in one of Earth’s most remote ecosystems.
Central to this discovery is the phenomenon of “marine snow” — the continuous shower of organic particles descending from ocean surface waters. These aggregates consist of detritus such as dead algae, microbial cells, and other biogenic debris. Previous models treated these sinking particles chiefly as vehicles transporting carbon and nitrogen to the seafloor for burial, effectively removing organic matter from the active oceanic cycle for millennia. The SDU study introduces a paradigm shift by showing that intense hydrostatic pressures experienced between depths of 2 and 6 kilometers force these particles to leak substantial fractions of their organic content into the surrounding seawater, thus supplying microbes with an accessible and valuable nutrient source.
According to Peter Stief, Associate Professor and lead author, the immense pressure at these depths operates much like a colossal “juicer.” It mechanically compresses marine snow aggregates, extracting dissolved organic compounds such as proteins and carbohydrates. These leaked molecules represent a readily utilizable form of dissolved organic matter (DOM), which heterotrophic bacteria and other microbes in the deep ocean can immediately metabolize. This process effectively energizes deep-sea microbial communities that were previously thought to subsist on limiting resources.
Demonstrating this novel mechanism demanded meticulous laboratory recreation of pressure conditions approximating the deep ocean’s physical environment. The researchers cultivated synthetic marine snow from diatoms — microscopic, photosynthetic algae known to naturally coalesce in surface waters. These particles were then subjected to specially-designed, rotating pressure tanks capable of simulating the extreme hydrostatic pressures encountered thousands of meters below sea level. The rotation ensured particles remained suspended, accurately mimicking their natural descent through the water column without settling. Measurements revealed that up to 50% of the initial carbon and up to 63% of nitrogen content within these particles were released into surrounding waters as dissolved organic matter.
The chemical signature of these leakages confirmed a dominance of nitrogenous proteins and carbohydrates — compounds that fuel microbial metabolism efficiently. Correspondingly, incubation experiments demonstrated a rapid proliferation of bacterial abundance, soaring thirtyfold within just two days under pressurized conditions. Notably, bacterial respiration rates peaked simultaneously, signifying an energized microbial community swiftly capitalizing on this newly available carbon and nitrogen pool.
Beyond advancing microbiological understanding, this discovery has profound implications for global biogeochemical cycles. The conventional view holds that a major portion of sinking organic matter is sequestered in deep-sea sediments, where carbon is fossilized over millions of years and contributes to long-term climate regulation. The revelation that marine snow particles lose significant organic content midway through their descent implies that less carbon ultimately reaches the sediment floor. Instead, more dissolved carbon remains suspended within the deep ocean waters, exposed to complex circulation patterns that can retain it for centuries or millennia before eventual return to surface layers and the atmosphere.
This nuanced carbon leakage mechanism thus reshapes estimates of the ocean’s capacity to store carbon over different timescales, with critical consequences for predictive climate models. The longevity of dissolved organic carbon in abyssal waters alters feedback mechanisms between oceans and atmosphere, influencing how carbon fluxes respond to natural variability and anthropogenic pressures. Furthermore, since hydrocarbon deposits like oil and gas originated from ancient sedimented organic matter, understanding the efficiency of marine snow carbon burial enhances our knowledge of Earth’s fossil fuel genesis.
Intriguingly, the pressure-induced leakage of dissolved organic matter was consistent across multiple species of diatoms tested, suggesting this process is widespread rather than species-specific. Such ubiquity highlights a potentially universal role of hydrostatic pressure in modulating nutrient fluxes and microbial energetics throughout the global ocean. This challenges entrenched scientific dogmas and opens new avenues for research into deep-sea ecology and elemental cycling.
Next steps for the research team involve validating their laboratory findings in situ during an upcoming Arctic expedition aboard the German research vessel Polarstern. By collecting water samples spanning surface to abyssal depths, they aim to identify molecular fingerprints characteristic of leaked dissolved organic matter, verifying that this pressure-driven process occurs naturally in oceanic environments. Given the Arctic’s unique stratification and vulnerability to climate change, these observations could prove pivotal in understanding regional and global carbon budgets.
More broadly, the Danish Center for Hadal Research at SDU is committed to exploring life and biogeochemical dynamics in the ocean’s deepest trenches and hadal zones, where extreme pressures and unique ecological niches prevail. These investigations are crucial to integrate the deep ocean’s contributions into the Earth system perspective, ensuring comprehensive assessments of carbon cycling and climatic feedbacks in an era of rapid change.
This study represents a transformative stride in marine science, illuminating the hidden interplay between physical forces and biological processes shaping nutrient availability and carbon sequestration in the deep ocean. By unveiling how hydrostatic pressure effectively “juices” organic aggregates, it reshapes concepts of deep-sea microbial ecology and carbon fate, underscoring the ocean’s complexity and its central role in Earth’s climate system.
Subject of Research: Not applicable
Article Title: Hydrostatic pressure induces strong leakage of dissolved organic matter from ‘marine snow’ particles
News Publication Date: 4-Feb-2026
Web References: http://dx.doi.org/10.1126/sciadv.aef3182
References: Peter Stief, Jutta Niggemann, Margot Bligh, Hagen Buck-Wiese, Urban Wünsch, Michael Steinke, Jan-Hendrik Hehemann, Ronnie N. Glud. “Hydrostatic pressure induces strong leakage of dissolved organic matter from ‘marine snow’ particles.” Science Advances.
Keywords: Marine biology, Oceanography, Carbon cycle, Deep-sea microbiology, Hydrostatic pressure, Marine snow, Dissolved organic matter
