The availability of the micronutrient iron governs phytoplankton growth across much of the ocean, but the global iron cycle is changing rapidly due to accelerating acidification, stratification, warming and deoxygenation. These mechanisms of global change will cumulatively affect the aqueous chemistry, sources and sinks, recycling, particle dynamics and bioavailability of iron. Biological iron demand will vary as acclimation to environmental change modifies cellular requirements for photosynthesis and nitrogen acquisition and as adaptive evolution or community shifts occur. Warming, acidification and nutrient co-limitation interactions with iron biogeochemistry will all strongly influence phytoplankton dynamics. Predicting the shape of the future iron cycle will require understanding the responses of each component of the unique biogeochemistry of this trace element to many concurrent and interacting environmental changes.
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The authors thank F. Fu and S. Sanudo-Wilhelmy for help with obtaining unpublished Fe quota data, and J. Brown and the University of Southern California Wrigley Institute of Environmental Sciences for their generous assistance with graphics. Support was provided by US National Science Foundation grants OCE 1260490 and OCE 1538525 to D.A.H., Australian Research Council Australian Laureate Fellowship project FL160100131 and Antarctic Climate and Ecosystems Cooperative Research Centre funding to P.W.B. and the Australian Research Council's Special Research Initiative for Antarctic Gateway Partnership Project ID SR140300001 to both authors.
The authors declare no competing financial interests.
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Hutchins, D., Boyd, P. Marine phytoplankton and the changing ocean iron cycle. Nature Clim Change 6, 1072–1079 (2016). https://doi.org/10.1038/nclimate3147