Atmospheric CO2 and its role in iron deficiency among photosynthetic plankton
Photosynthetic plankton (phytoplankton) require iron for the synthesis of chlorophyll and several photosynthetic electron transport proteins as well as for the reduction of CO2 and other ions during the photosynthetic production of organic compounds. The acidification of the ocean caused by increasing atmospheric levels of CO2 and subsequent higher levels of carbonic acid in the waters can lower the availability of iron to living organisms that need it. The transfer of CO2 into organic carbon by phytoplankton contributes to CO2 sequestration and the reduction of atmospheric CO2. The EU-funded Phycosphere Fe project is investigating iron in the phycosphere, a microscopic layer around the phytoplankton cell and analogous to the plant rhizosphere, to get a better handle on the interplay between CO2 levels, warming, iron bioavailability and phytoplankton growth in the face of anthropogenic increases in CO2 and ocean warming.