Deep-Sea Oxygen Levels Echo Ancient Shift, Raising Concerns for Modern Ocean Life
SEATTLE, WA – August 25, 2025 – A new study published today reveals a critical link between oxygen levels in the deep ocean and the evolution of animal life, with implications for the health of modern marine ecosystems. researchers have found that the rise of oxygen in the deep ocean roughly 400 million years ago enabled animals to thrive in those environments, and that current trends of oxygen depletion pose a meaningful threat to this delicate balance.
The research, led by Kunmanee Bubphamanee at the University of Washington and Michael Kipp at Duke University, analyzed ancient marine sediments to reconstruct oxygen levels in the ocean over millions of years. They discovered that a major increase in oxygen coincided with the diversification of animal life in the deep sea during the devonian period. This oxygenation wasn’t simply a result of atmospheric oxygen increases; it was driven by changes in ocean circulation and the burial of organic matter.
“We found that the burial of organic matter in sediments essentially ‘sucked up’ oxygen when they decay, causing levels to plummet,” Kipp said. “This work shows very clearly the link between oxygen and animal life in the ocean. This was a balance struck about 400 million years ago, and it would be a shame to disrupt it today in a matter of decades.”
The study highlights that the deep ocean, onc largely devoid of oxygen, became habitable for animals as oxygen levels rose. Though,modern human activities – including pollution and climate change – are reversing this process,creating “dead zones” where oxygen is too low to support most marine life. Increased temperatures reduce oxygen solubility, while nutrient runoff from agriculture and sewage fuels algal blooms. When these blooms die and decompose, the process consumes vast amounts of oxygen.
The research team included Roger Buick, a professor in Earth and space science and astrobiology at the University of Washington; Jana Meixnerová, a UW graduate student in Earth and space science; Eva E. Stüeken, a reader in Earth and environmental sciences at the University of st. Andrews; linda C. Ivany, a professor in Earth and environmental science at Syracuse University; Alexander J. Bartholomew,an associate professor of geology at SUNY New Paltz; Thomas J. Algeo, a professor of geology at the University of Cincinnati; Jochen J.Brocks, a professor in the Research School of Earth Sciences at Australian National University; Tais W. Dahl, an associate professor of geobiology at the University of Copenhagen; Jordan Kinsley, a postdoctoral candidate at Australian National University; and François L. H. Tissot, a professor of geochemistry at CalTech.
The research was funded by the National Science Foundation, the Agouron Institute and the NASA Astrobiology Institute Virtual Planetary Laboratory.
For more details, contact Bubphamanee at kubu7847@uw.edu or Kipp at michael.kipp@duke.edu.
Adapted from a release from Duke University.
tag(s): college of the Environment • Department of Earth and Space Sciences • evolution • Kunmanee Bubphamanee
