Nitrogen and carbon fixation rates from bulk water samples from RV/Atlantic cruise AT39-05, Feb-Mar 2018

Website: https://www.bco-dmo.org/dataset/766334
Data Type: Cruise Results, experimental
Version: 1
Version Date: 2019-05-02

Project
» Collaborative Research: Iron and phosphorus balanced limitation of nitrogen fixation in the oligotrophic ocean (TriCoLim)
ContributorsAffiliationRole
Hutchins, David A.University of Southern California (USC)Principal Investigator
Webb, Eric A.University of Southern California (USC)Co-Principal Investigator
Copley, NancyWoods Hole Oceanographic Institution (WHOI BCO-DMO)BCO-DMO Data Manager

Abstract
Nitrogen and carbon fixation rates from bulk water samples from RV/Atlantic cruise AT39-05, Feb-Mar 2018.


Coverage

Spatial Extent: N:13.6776 E:-21.998 S:-7.9989 W:-55.8123
Temporal Extent: 2018-02-11 - 2018-03-14

Dataset Description

These data reports nitrogen and carbon fixation rates from bulk water samples collected on RV/Atlantic cruise AT39-05, Feb-Mar 2018.


Methods & Sampling

Shipboard incubation experiments were carried out at 15 stations in the tropical Atlantic with trace metal clean-collected bulk water to examine iron (Fe) and phosphorus (P) co-limitation of dinitrogen (N2) fixation (see TriCoLim Station coordinates metadata). Treatments were: Co-limited control (no additions, “Colimit”), + 2nM Fe (“Fe”), + 50 nM P (“P”) and Replete (+Fe+P, “Rep”). All incubations were carried out at ambient (“Lo”) temperature and ambient temperature +3C (“Hi”) for 2-4 days on deck before measuring 15N2 and 13CO2 fixation rates and particulate organic carbon (POC) and nitrogen (PON). See related datasets.

Nitrogen and carbon fixation rates - Trichodesmium Nitrogen and carbon fixation rates from Trichodesmium colonies from RV/Atlantic cruise AT39-05, Feb-Mar 2018
POC and PON - bulk seawater POC and PON from bulk seawater samples from RV/Atlantic cruise AT39-05, Feb-Mar 2018
POC and PON - Trichodesmium POC and PON from Trichodesmium colonies from RV/Atlantic cruise AT39-05, Feb-Mar 2018

Data Processing Description

BCO-DMO Processing Notes:
added conventional header with dataset name, PI name, version date
- modified parameter names to conform with BCO-DMO naming conventions
- reduced lat and lon precision from 14 to 3 places to better reflect sampling precision


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Data Files

File
NCfix_bulkH2O.csv
(Comma Separated Values (.csv), 16.14 KB)
MD5:a05e8b98f25e8675c1c7a5205e41d511
Primary data file for dataset ID 766334

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Parameters

ParameterDescriptionUnits
Stationstation identifier unitless
Experiment_IDexperiment_id identifier unitless
Latitudelatitude; north is positive decimal degrees
Longitudelongitude; east is positive decimal degrees
Sample_Dsample identifier unitless
Treatmenttreatment: Lo temp = ambient temperature Hi temp = ambient temperature plus 3 degrees C. Colimit = Co-limited control (no additions) Fe = 2nM Fe P = 50 nM P Rep =  Replete (+Fe+P) unitless
N2_fixnitrogen fixation rate measured as 15N2 micromol/liter/hour (umol/l/h)
C_fixcarbon fixation rate measured as 13CO2 micromol/liter/hour (umol/l/h)


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Instruments

Dataset-specific Instrument Name
Generic Instrument Name
Trace Metal Bottle
Dataset-specific Description
Used to collect clean seawater.
Generic Instrument Description
Trace metal (TM) clean rosette bottle used for collecting trace metal clean seawater samples.


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Deployments

AT39-05

Website
Platform
R/V Atlantis
Start Date
2018-02-11
End Date
2018-03-14
Description
For study of iron and phosphorus balanced limitation of nitrogen fixation in the oligotrophic ocean.


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Project Information

Collaborative Research: Iron and phosphorus balanced limitation of nitrogen fixation in the oligotrophic ocean (TriCoLim)

Coverage: Tropical Atlantic


NSF abstract:

Marine cyanobacteria are able to use or "fix" atmospheric nitrogen gas, and so supply much of the essential nutrient nitrogen that supports open ocean food chains. Oceanographers have usually thought that the growth of these nitrogen-fixing cyanobacteria is limited at any particular time and place by the supply of either iron, or of phosphorus. Preliminary experiments have shown, though, that these nitrogen fixers instead grow best when both iron and phosphorus are scarce at the same time. In this project, the researchers will use cellular indicators that are specific for iron and phosphorus limitation to determine how important this type of "balanced limitation" of nitrogen-fixing cyanobacteria is in controlling the productivity of ocean food chains in the tropical Atlantic Ocean. Two graduate students will be trained at the University of Southern California (USC) and Woods Hole Oceanographic Institution, as well as a postdoctoral researcher at USC. Educational outreach efforts will take place at a Los Angeles inner city high school with a student body that is over 98% Hispanic and African-American, and with underrepresented undergraduates in the USC Global Environmental Microbiology course. In addition, two Research Experiences for Undergraduates students will be supervised for summer research projects to help them learn about science career options.

The researchers will investigate the biological and biogeochemical consequences of this unique balanced iron/phosphorus-limited phenotype, using both laboratory and fieldwork approaches. During the first year of this project, the nitrogen-fixing cyanobacteria will be cultured under iron and/or phosphorus limitation, followed by application of proteomics and transcriptomics to identify genes that are potential diagnostic biomarkers for iron/phosphorus balanced limitation. Preliminary work has already identified one promising candidate biomarker in one cyanobacterium, an EzrA protein domain that appears to be associated with the cell size decreases seen specifically under balanced limitation, and the researchers have identified numerous other potential candidates for similar biomarkers. During the second year, these new co-limitation biomarkers and others previously validated for iron limitation (IsiB) and phosphorus limitation (SphX) will be used to investigate balanced limitation during a research cruise transecting from relatively high-iron, low-phosphorus North Atlantic waters, to the relatively high-phosphorus, low-iron South Atlantic. This fieldwork component will survey nitrogen fixing cyanobacteria populations across this natural iron/phosphorus gradient for genetic, proteomic, and physiological indicators of balanced limitation, as well as testing their responses to iron and phosphorus manipulations in shipboard incubation experiments. The third year will be devoted to sample analysis, and publications exploring the responses of oceanic nitrogen fixers to simultaneous limitation by both iron and phosphorus.



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Funding

Funding SourceAward
NSF Division of Ocean Sciences (NSF OCE)

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