News summary produced by Claude AI
Researchers at the University of Southern Denmark have identified a previously unknown mechanism that sustains deep-ocean microbial life. Marine snow—clumps of dead algae and organic material sinking through the water column—releases dissolved carbon and nitrogen when exposed to the extreme pressures found at depths of 2 to 6 kilometers below the surface. This leakage provides an immediate nutrient source for microorganisms living in the surrounding seawater.
The study, published in Science Advances, found that the hydrostatic pressure acts similarly to a juicing mechanism, extracting dissolved organic compounds from the sinking particles. Laboratory experiments using diatoms revealed that particles can lose approximately 50 percent of their original carbon content and between 58 and 63 percent of their nitrogen during descent. The released material consists primarily of proteins and carbohydrates, which deep-ocean microbes can readily consume.
These findings have significant implications for understanding Earth’s carbon cycle. Scientists previously assumed that most carbon transported by marine snow would eventually become permanently buried in deep-sea sediments. However, if substantial quantities of carbon leak out during descent, the amount of carbon permanently stored in ocean floor sediments may be considerably lower than earlier estimates suggested. Carbon that escapes into deep waters can remain in circulation for centuries or millennia before returning to the surface.
The research team conducted controlled experiments in specially designed rotating pressure tanks that simulated deep-ocean conditions while keeping particles suspended. Within two days of exposure to the released nutrients, bacterial populations increased 30-fold, demonstrating that the leaked organic matter provides a rapid and significant energy source. The leakage pattern was consistent across multiple diatom species, suggesting the mechanism operates broadly throughout ocean ecosystems worldwide.
Future research will involve field investigations in the Arctic Ocean aboard the research vessel Polarstern, where scientists will search for molecular signatures of this pressure-driven leakage process in natural ocean waters to validate laboratory observations.