N₂ fixation by subsurface populations of Trichodesmium : an important source of new nitrogen to the North Atlantic Ocean
Thesis (S.M.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Biology; and the Woods Hole Oceanographic Institution), 2011. Cataloged from PDF version of thesis. "February 2011." Includes bibliographical references (leav...
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ftmit:oai:dspace.mit.edu:1721.1/62790 2023-06-11T04:14:19+02:00 N₂ fixation by subsurface populations of Trichodesmium : an important source of new nitrogen to the North Atlantic Ocean Nitrogen gas fixation by subsurface populations of Trichodesmium : an important source of new nitrogen to the North Atlantic Ocean Heithoff, Abigail Sonya T. Dyhrman. Woods Hole Oceanographic Institution. Joint Program in Oceanography/Applied Ocean Science and Engineering Massachusetts Institute of Technology Woods Hole Oceanographic Institution Massachusetts Institute of Technology. Department of Biology 2011 48 leaves application/pdf http://hdl.handle.net/1721.1/62790 eng eng Massachusetts Institute of Technology http://hdl.handle.net/1721.1/62790 709777221 M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Joint Program in Oceanography/Applied Ocean Science and Engineering Woods Hole Oceanographic Institution Cyanobacteria North Atlantic Ocean Marine productivity North Atlantic Ocean Thesis 2011 ftmit 2023-05-29T08:52:32Z Thesis (S.M.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Biology; and the Woods Hole Oceanographic Institution), 2011. Cataloged from PDF version of thesis. "February 2011." Includes bibliographical references (leaves 44-48). Trichodesmium, a genus of diazotrophic cyanobacteria, is an important contributor to the marine nitrogen (N) and carbon (C) cycles. The extent to which Trichodesmium dinitrogen (N2) fixation contributes to the marine N cycle has been modeled based on abundance data and rate estimates from surface populations. However, recent data show that Trichodesmium populations have a broad vertical distribution. The presence of previously unaccounted for subsurface populations suggests that past estimates of the contribution of new N by Trichodesmium to the North Atlantic may be artificially low. Herein, culture and field studies were combined to examine trends in N2 fixation in discrete surface and subsurface Trichodesmium populations in the western North Atlantic. Surface populations were dominated by the raft colony morphology of Trichodesmium and surface N2 fixation rates ranged from (33 to 156 μmol h-1 mol C-1). Subsurface populations were dominated by the puff colony morphology. Subsurface N2 fixation was typically detectable, but consistently lower than surface population rates (9 to 88 μmol h-1 mol C-1). In an analysis of the entire field dataset, N2 fixation rates varied non-linearly as a function of in situ irradiance. This trend in N2 fixation versus in situ irradiance is consistent with field and culture observations in the literature (Bell et al., 2005; Capone et al., 2005), however other models that predict N2 fixation based on light predict higher subsurface N2 fixation than what was detected in this study. In culture, N2 fixation in Trichodesmium was proportional to light level over the range of irradiances tested (10 to 70 μmol quanta m-2 s-1) and over long and short time scales, suggesting subtle changes ... Thesis North Atlantic DSpace@MIT (Massachusetts Institute of Technology) |
institution |
Open Polar |
collection |
DSpace@MIT (Massachusetts Institute of Technology) |
op_collection_id |
ftmit |
language |
English |
topic |
Joint Program in Oceanography/Applied Ocean Science and Engineering Woods Hole Oceanographic Institution Cyanobacteria North Atlantic Ocean Marine productivity North Atlantic Ocean |
spellingShingle |
Joint Program in Oceanography/Applied Ocean Science and Engineering Woods Hole Oceanographic Institution Cyanobacteria North Atlantic Ocean Marine productivity North Atlantic Ocean Heithoff, Abigail N₂ fixation by subsurface populations of Trichodesmium : an important source of new nitrogen to the North Atlantic Ocean |
topic_facet |
Joint Program in Oceanography/Applied Ocean Science and Engineering Woods Hole Oceanographic Institution Cyanobacteria North Atlantic Ocean Marine productivity North Atlantic Ocean |
description |
Thesis (S.M.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Biology; and the Woods Hole Oceanographic Institution), 2011. Cataloged from PDF version of thesis. "February 2011." Includes bibliographical references (leaves 44-48). Trichodesmium, a genus of diazotrophic cyanobacteria, is an important contributor to the marine nitrogen (N) and carbon (C) cycles. The extent to which Trichodesmium dinitrogen (N2) fixation contributes to the marine N cycle has been modeled based on abundance data and rate estimates from surface populations. However, recent data show that Trichodesmium populations have a broad vertical distribution. The presence of previously unaccounted for subsurface populations suggests that past estimates of the contribution of new N by Trichodesmium to the North Atlantic may be artificially low. Herein, culture and field studies were combined to examine trends in N2 fixation in discrete surface and subsurface Trichodesmium populations in the western North Atlantic. Surface populations were dominated by the raft colony morphology of Trichodesmium and surface N2 fixation rates ranged from (33 to 156 μmol h-1 mol C-1). Subsurface populations were dominated by the puff colony morphology. Subsurface N2 fixation was typically detectable, but consistently lower than surface population rates (9 to 88 μmol h-1 mol C-1). In an analysis of the entire field dataset, N2 fixation rates varied non-linearly as a function of in situ irradiance. This trend in N2 fixation versus in situ irradiance is consistent with field and culture observations in the literature (Bell et al., 2005; Capone et al., 2005), however other models that predict N2 fixation based on light predict higher subsurface N2 fixation than what was detected in this study. In culture, N2 fixation in Trichodesmium was proportional to light level over the range of irradiances tested (10 to 70 μmol quanta m-2 s-1) and over long and short time scales, suggesting subtle changes ... |
author2 |
Sonya T. Dyhrman. Woods Hole Oceanographic Institution. Joint Program in Oceanography/Applied Ocean Science and Engineering Massachusetts Institute of Technology Woods Hole Oceanographic Institution Massachusetts Institute of Technology. Department of Biology |
format |
Thesis |
author |
Heithoff, Abigail |
author_facet |
Heithoff, Abigail |
author_sort |
Heithoff, Abigail |
title |
N₂ fixation by subsurface populations of Trichodesmium : an important source of new nitrogen to the North Atlantic Ocean |
title_short |
N₂ fixation by subsurface populations of Trichodesmium : an important source of new nitrogen to the North Atlantic Ocean |
title_full |
N₂ fixation by subsurface populations of Trichodesmium : an important source of new nitrogen to the North Atlantic Ocean |
title_fullStr |
N₂ fixation by subsurface populations of Trichodesmium : an important source of new nitrogen to the North Atlantic Ocean |
title_full_unstemmed |
N₂ fixation by subsurface populations of Trichodesmium : an important source of new nitrogen to the North Atlantic Ocean |
title_sort |
n₂ fixation by subsurface populations of trichodesmium : an important source of new nitrogen to the north atlantic ocean |
publisher |
Massachusetts Institute of Technology |
publishDate |
2011 |
url |
http://hdl.handle.net/1721.1/62790 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
http://hdl.handle.net/1721.1/62790 709777221 |
op_rights |
M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 |
_version_ |
1768392262861979648 |