Title:
Contribution of Nitrogen Fixation to Planktonic Food Webs North of Australia

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dc.contributor.advisor Montoya, Joseph P.
dc.contributor.author Drexel, Jan Peter en_US
dc.contributor.committeeMember Kim Cobb
dc.contributor.committeeMember Snell, Terry
dc.contributor.department Biology en_US
dc.date.accessioned 2008-02-07T18:13:57Z
dc.date.available 2008-02-07T18:13:57Z
dc.date.issued 2007-11-16 en_US
dc.description.abstract Nitrogen fixation is no longer considered to be a minor factor of the nitrogen cycle in oceanic ecosystems. Recent geochemical and biological efforts have led to a significant increase in the estimated input of nitrogen to marine ecosystems by biological fixation, while molecular studies have increased our knowledge of the number and diversity of nitrogen fixers known to be active in the ocean. Although Trichodesmium spp. have long been viewed as the primary marine nitrogen fixers, recent efforts have shown that various members of the picoplankton community are also actively involved in nitrogen fixation. The relative abundance of different nitrogen fixers is an important ecosystem parameter since nitrogen fixers may differ significantly in their physiology, life history and ecology. Here we combine rate measurements and stable isotope natural abundance measurements to constrain the impact of N2 fixation in the waters north of Australia. Samples were collected in the Coral, Arafura, and East Timor Seas, thus spanning three distinct hydrographic regions. Our data show that Trichodesmium has a significant influence on the stable nitrogen isotope ratios of particulate and zooplankton biomass and suggest that Trichodesmium is a significant source of nitrogen for the pelagic ecosystem. Based on stable carbon isotope ratios, it is also likely that the pathways are indirect and nitrogen fixed by Trichodesmium enters the higher trophic levels via decomposition as dissolved organic and inorganic nitrogen. Picocyanobacteria showed high diazotrophic activity at some stations, but unlike Trichodesmium, their N2 fixation rate was not reflected in the stable N isotope ratios of particulate and zooplankton biomass. Our results suggest an important N contribution to biomass by diazotrophs in the Coral Sea, Arafura Sea and East Timor Sea. en_US
dc.description.degree M.S. en_US
dc.identifier.uri http://hdl.handle.net/1853/19733
dc.publisher Georgia Institute of Technology en_US
dc.subject Nitrogen fixation en_US
dc.subject Diazotrophy en_US
dc.subject Trichodesmium en_US
dc.subject New nitrogen en_US
dc.subject Food web en_US
dc.subject D15N en_US
dc.subject D13C en_US
dc.subject.lcsh Nitrogen--Fixation
dc.subject.lcsh Ecosystem management
dc.subject.lcsh Australia
dc.title Contribution of Nitrogen Fixation to Planktonic Food Webs North of Australia en_US
dc.type Text
dc.type.genre Thesis
dspace.entity.type Publication
local.contributor.advisor Montoya, Joseph P.
local.contributor.corporatename College of Sciences
local.contributor.corporatename School of Biological Sciences
relation.isAdvisorOfPublication 0000b67d-bef5-4edf-b2d6-3577c297f4c3
relation.isOrgUnitOfPublication 85042be6-2d68-4e07-b384-e1f908fae48a
relation.isOrgUnitOfPublication c8b3bd08-9989-40d3-afe3-e0ad8d5c72b5
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