Nitrogen fixation rates diagnosed from diurnal changes in elemental stoichiometry
Limnology and Oceanography published by Wiley Periodicals, Inc. on behalf of Association for the Sciences of Limnology and Oceanography The carbon, nitrogen, and phosphorus (C, N, and P, respectively) composition and elemental ratios were measured in the 20–200 μm size fraction during July 2015 in t...
| Main Authors: | , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | English |
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Wiley
2020
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| Online Access: | https://hdl.handle.net/1721.1/125271 |
| _version_ | 1811073960332230656 |
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| author | Follett, Christopher L White, Angelicque E. Wilson, Samuel T. Follows, Michael J |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Follett, Christopher L White, Angelicque E. Wilson, Samuel T. Follows, Michael J |
| author_sort | Follett, Christopher L |
| collection | MIT |
| description | Limnology and Oceanography published by Wiley Periodicals, Inc. on behalf of Association for the Sciences of Limnology and Oceanography The carbon, nitrogen, and phosphorus (C, N, and P, respectively) composition and elemental ratios were measured in the 20–200 μm size fraction during July 2015 in the surface waters of an anticyclonic eddy encountered north of Hawaii in the oligotrophic North Pacific Subtropical Gyre. The observed particulate N : P ratio fluctuated by approximately a factor of two over the diel cycle. We present a simple mathematical argument connecting this change to a rate of biological nitrogen fixation, and calculate the nitrogen fixation rate to be ≥ 13 nmol L−1 d−1 for this size class. This value is higher than simultaneous bottle-incubation based rates measured with isotopic tracers, yet is consistent with historic rate measurements from the region. As confirmation of our methods, diurnal changes in C : N : P of laboratory cultures of the diazotrophic genus Trichodesmium were measured. In the laboratory, we show that estimates of nitrogen fixation from stoichiometric time series are equivalent to those derived directly from mass balance. The disparity between nitrogen fixation rates derived from tracer measurements and particulate stoichiometry in the field suggests that large diazotrophs may be underestimated in small volume (∼ 4 L) bottle incubations as a result of either spatial heterogeneity or vertical migration of large cells. Otherwise, processes other than diazotrophy must cause the observed changes in stoichiometry. This approach represents a novel and scalable means of quantifying in situ nitrogen fixation rates from diurnal changes in size-fractionated stoichiometry. We also infer carbon fixation, growth rates, and phosphorus uptake in the 20–200 μm size class. |
| first_indexed | 2024-09-23T09:40:52Z |
| format | Article |
| id | mit-1721.1/125271 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T09:40:52Z |
| publishDate | 2020 |
| publisher | Wiley |
| record_format | dspace |
| spelling | mit-1721.1/1252712022-09-26T13:04:23Z Nitrogen fixation rates diagnosed from diurnal changes in elemental stoichiometry Follett, Christopher L White, Angelicque E. Wilson, Samuel T. Follows, Michael J Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Limnology and Oceanography published by Wiley Periodicals, Inc. on behalf of Association for the Sciences of Limnology and Oceanography The carbon, nitrogen, and phosphorus (C, N, and P, respectively) composition and elemental ratios were measured in the 20–200 μm size fraction during July 2015 in the surface waters of an anticyclonic eddy encountered north of Hawaii in the oligotrophic North Pacific Subtropical Gyre. The observed particulate N : P ratio fluctuated by approximately a factor of two over the diel cycle. We present a simple mathematical argument connecting this change to a rate of biological nitrogen fixation, and calculate the nitrogen fixation rate to be ≥ 13 nmol L−1 d−1 for this size class. This value is higher than simultaneous bottle-incubation based rates measured with isotopic tracers, yet is consistent with historic rate measurements from the region. As confirmation of our methods, diurnal changes in C : N : P of laboratory cultures of the diazotrophic genus Trichodesmium were measured. In the laboratory, we show that estimates of nitrogen fixation from stoichiometric time series are equivalent to those derived directly from mass balance. The disparity between nitrogen fixation rates derived from tracer measurements and particulate stoichiometry in the field suggests that large diazotrophs may be underestimated in small volume (∼ 4 L) bottle incubations as a result of either spatial heterogeneity or vertical migration of large cells. Otherwise, processes other than diazotrophy must cause the observed changes in stoichiometry. This approach represents a novel and scalable means of quantifying in situ nitrogen fixation rates from diurnal changes in size-fractionated stoichiometry. We also infer carbon fixation, growth rates, and phosphorus uptake in the 20–200 μm size class. Simons Foundation (Grant 329108) Simons Foundation (Grant 553242) Gordon and Betty Moore Foundation (Grant 3778) 2020-05-15T16:25:26Z 2020-05-15T16:25:26Z 2018-04 2018-02 2020-04-17T17:13:02Z Article http://purl.org/eprint/type/JournalArticle 0024-3590 1939-5590 https://hdl.handle.net/1721.1/125271 Follett, Christopher L. et al. "Nitrogen fixation rates diagnosed from diurnal changes in elemental stoichiometry." Limnology and Oceanography (April 2018): 1911-1923 © 2018 The Authors en http://dx.doi.org/10.1002/lno.10815 Limnology and Oceanography Creative Commons Attribution NonCommercial License 4.0 https://creativecommons.org/licenses/by-nc/4.0/ application/pdf Wiley Association for the Sciences of Limnology and Oceanography |
| spellingShingle | Follett, Christopher L White, Angelicque E. Wilson, Samuel T. Follows, Michael J Nitrogen fixation rates diagnosed from diurnal changes in elemental stoichiometry |
| title | Nitrogen fixation rates diagnosed from diurnal changes in elemental stoichiometry |
| title_full | Nitrogen fixation rates diagnosed from diurnal changes in elemental stoichiometry |
| title_fullStr | Nitrogen fixation rates diagnosed from diurnal changes in elemental stoichiometry |
| title_full_unstemmed | Nitrogen fixation rates diagnosed from diurnal changes in elemental stoichiometry |
| title_short | Nitrogen fixation rates diagnosed from diurnal changes in elemental stoichiometry |
| title_sort | nitrogen fixation rates diagnosed from diurnal changes in elemental stoichiometry |
| url | https://hdl.handle.net/1721.1/125271 |
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