| NSF Org: |
OPP Office of Polar Programs (OPP) |
| Recipient: |
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| Initial Amendment Date: | August 14, 2009 |
| Latest Amendment Date: | July 30, 2012 |
| Award Number: | 0909839 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Henrietta Edmonds
hedmonds@nsf.gov (703)292-7427 OPP Office of Polar Programs (OPP) GEO Directorate for Geosciences |
| Start Date: | September 1, 2009 |
| End Date: | August 31, 2012 (Estimated) |
| Total Intended Award Amount: | $0.00 |
| Total Awarded Amount to Date: | $390,827.00 |
| Funds Obligated to Date: |
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| ARRA Amount: | $390,827.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
1375 GREATE RD GLOUCESTER POINT VA US 23062-2026 (804)684-7000 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
1375 GREATE RD GLOUCESTER POINT VA US 23062-2026 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | ANS-Arctic Natural Sciences |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.078 |
ABSTRACT
This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
Bronk 0909839
Virginia Institute of Marine Science
Unds are provided to investigate the microbial controls on the productivity of a coastal Arctic ecosystem by focusing on the competition between autotrophs and heterotrophs for nitrogen (N). In the winter and summer waters near Barrow, Alaska, supplemented with complementary international research opportunities, the PIs propose to measure in situ concentrations of key microbial and biogeochemical constituents, relevant uptake activities, and expression of key N cycling genes to address two hypotheses:
H1: The balance of autotrophy and heterotrophy in the Arctic is regulated both temporally and spatially by nitrate (NO3ˉ) and light.
? Phytoplankton out-compete heterotrophic bacteria for NO3ˉ during the well-lit spring and summer conditions.
? Heterotrophic bacterial uptake of NO3ˉ will be greater during the dark winter and under sea ice than in open water or well-lit summer conditions when bacteria are replete with phytoplankton-derived DON.
? NO3 -, combined with terrestrial DOC derived from riverine and groundwater flow, may provide the means for bacterial growth and respiration during the dark winter.
H2: Microbial community structure will vary according to the seasonal light cycle and the sources of available N. The observed lag in bacterial response to phytoplankton growth is due to a community shift.
? Bacterial community composition will vary significantly between winter and summer.
? The composition and dynamics of bacterial communities will correspond to concentrations and sources of N.
? The expression of key N-cycling genes, N-uptake and regeneration, and DON uptake kinetics will vary with season and community composition.
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