Wednesday, January 23, 2019

Ocean Acidification Impact on Phytoplankton Studied

Researchers from three universities are collaborating on a $954,000-plus National Science Foundation grant to determine the effect of ocean acidification on iron availability to phytoplankton in the eastern North Pacific.

Ocean acidification is caused by increasing atmospheric carbon dioxide from fossil fuel burning. The carbon dioxide dissolves from the atmosphere into the ocean surface and reacts with seawater to form acid, which lowers the seawater pH. The increased ocean acidification results in changes in availability of iron to marine phytoplankton that support the marine food web and accounts for more than half the biomass of the oceans.

Phytoplankton, like people, require iron to grow, but a lot of the iron dissolved in seawater is bound with organic molecules in ways that limit the ability of phytoplankton to access it.

Scientific teams from the University of Maine, University of Washington and University of South Florida are planning a major research cruise in 2020. They will be joined by researchers from the University of Nagasaki. They plan to collect samples of surface waters, adjust the seawater pH to levels predicted for the end of the century, and measure how phytoplankton respond at a high and low light levels, a factor that changes the iron demand of phytoplankton.

The goal is to develop proxies for quantifying iron availability under present and future ocean acidification conditions and learn more about how ocean acidification-induced changes in iron chemistry affect phytoplankton production and the composition of the phytoplankton community.

“Understanding the effect of ocean acidification on the iron cycle is a critical unknown in global biogeochemical models, and their projections of climate change effects on the ocean system over the next century,” the researchers said.

The information on the research was published online by the Ocean Acidification International Coordination Center. To read the full article visit

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