Ocean Iron Fuels Oxygen and Life, Study Shows

A new Rutgers University study highlights the crucial role of iron in sustaining ocean life and global oxygen production.

The research shows that iron, delivered to the oceans by desert dust, glacial meltwater and other sources, is a key nutrient for marine phytoplankton, the microscopic algae that produce much of the world’s oxygen.

“Every other breath you take includes oxygen from the ocean, released from phytoplankton,” said Paul G. Falkowski, co-author of the study and Bennett L. Smith Chair in Business and Natural Resources at Rutgers–New Brunswick. “Our research shows that iron limits phytoplankton’s ability to make oxygen across vast regions of the ocean.”

The study, published in the Proceedings of the National Academy of Sciences, also shows that reduced iron levels can affect marine ecosystems. Phytoplankton feed krill, which are the main food source for penguins, seals, walruses and whales in the Southern Ocean. Lower iron levels reduce phytoplankton growth and could lead to fewer krill and fewer larger marine animals.

Graduate researcher Heshani Pupulewatte spent 37 days aboard a British research vessel in 2023 and 2024, collecting water samples along a route from South Africa to the Weddell Gyre in the Southern Ocean. She measured photosynthesis efficiency using fluorometers and tested how adding nutrients, including iron, affected phytoplankton in natural ocean conditions.

The results showed that iron limitation can cause up to 25 percent of the algae’s light-harvesting proteins to become uncoupled, reducing photosynthesis. When iron was added, the algae reconnected their energy systems and photosynthetic efficiency increased.

The study provides the first direct evidence of how iron affects photosynthesis in the open ocean. Researchers say the findings could help predict future ocean productivity and the global carbon cycle.