Researchers from UC San Diego’s Scripps Institution of Oceanography have released findings indicating that dissolved oxygen concentrations are dropping significantly across aquatic systems worldwide. The phenomenon, known as aquatic deoxygenation, affects oceans, coastal areas, rivers, lakes and streams alike. Lead author Erica Ferrer and colleagues assessed how this process interacts with major environmental systems tracked under the Planetary Boundaries framework, a system developed to identify critical environmental thresholds for planetary stability.
The primary drivers behind oxygen loss in aquatic systems are human-induced climate change, nutrient pollution from agricultural and industrial sources, and shifts in water circulation patterns that affect how deep waters are oxygenated. As dissolved oxygen levels decline, the biological and chemical processes that regulate Earth’s climate can be disrupted. The consequences extend across aquatic food chains, from microorganisms to large predators, threatening organisms at all trophic levels. Marine mammals that depend on these ecosystems face indirect impacts through prey reduction, habitat damage and food web alterations.
Ferrer and senior researcher Lisa Levin propose that aquatic deoxygenation should be formally recognized as a tenth planetary boundary, alongside nine existing ones including climate change, ocean acidification and biodiversity loss. The researchers contend that treating oxygen depletion as an isolated issue rather than an interconnected component of broader planetary challenges prevents effective assessment of Earth’s overall stability. Recognition of deoxygenation as a planetary boundary could help policymakers and scientists better understand how oxygen loss compounds other environmental pressures and inform integrated mitigation strategies.
The research was supported by multiple funding sources including the National Science Foundation’s Graduate Research Fellowship Program and UC institutions. The study was published June 30, 2026, in Limnology and Oceanography, with contributions from multiple institutional researchers across oceanography and climate science disciplines.