Microbial feedbacks optimize ocean iron availability
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4842.full.pdf
Description
Published version
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1.37 MB
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Adobe PDF
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70aaded44def12460a5d2b257cfee1ae
Author(s)
Lauderdale, Jonathan
Braakman, Rogier
Forget, Gael
Dutkiewicz, Stephanie
Follows, Michael J.
Date Issued
February 2020
Journal
Proceedings of the National Academy of Sciences of the United States of America
Publisher
Proceedings of the National Academy of Sciences
Citation
Lauderdale, Jonathan, et al., "Microbial feedbacks optimize ocean iron availability." Proceedings of the National Academy of Sciences of the United States of America 117, 9 (February 2020): p. 4842-9 doi 10.1073/pnas.1917277117 ©2020 Author(s)
Version
Final published version
Abstract
Iron is the limiting factor for biological production over a large fraction of the surface ocean because free iron is rapidly scavenged or precipitated under aerobic conditions. Standing stocks of dissolved iron are maintained by association with organic molecules (ligands) produced by biological processes. We hypothesize a positive feedback between iron cycling, microbial activity, and ligand abundance: External iron input fuels microbial production, creating organic ligands that support more iron in seawater, leading to further macronutrient consumption until other microbial requirements such as macronutrients or light become limiting, and additional iron no longer increases productivity. This feedback emerges in numerical simulations of the coupled marine cycles of macronutrients and iron that resolve the dynamic microbial production and loss of iron-chelating ligands. The model solutions resemble modern nutrient distributions only over a finite range of prescribed ligand source/sink ratios where the model ocean is driven to global-scale colimitation by micronutrients and macronutrients and global production is maximized. We hypothesize that a global-scale selection for microbial lig- and cycling may have occurred to maintain “just enough” iron in the ocean. ©2020
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
Massachusetts Institute of Technology. Center for Global Change Science
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1073/pnas.1917277117
