Ocean oxygen shapes marine life in ways most of us never think about. This episode explores how oxygen enters the ocean (air–sea exchange and photosynthesis), how it circulates through surface waters and the deep sea, and why scientists track changes in oxygen over time. Learn what oxygen minimum zones are, how they form, and what they can mean for midwater ecosystems in the mesopelagic (“twilight”) zone.

Featuring research that uses fossil fish ear bones (otoliths) preserved in seafloor sediment, the conversation looks back thousands of years to reconstruct a past oxygen shift in the Mediterranean—and what long-term records can teach us about ocean dynamics today.

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Special thanks to the Monterey Bay Aquarium for sponsoring this episode.

Episode Guests: Dr. Sven Pallacks

Find Dr. Pallacks’ publications on Google Scholar

Read Dr. Pallacks’ article,  Ocean deoxygenation linked to ancient mesopelagic fish decline. 

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Episode Transcript  and more information on the Pine Forest Media website

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Hosted, produced, and edited by Clark Marchese 

Cover art by Jomiro Eming

Theme music by Nela Ruiz

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