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2003-2004 USAP
Field Season
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Biology & Medicine
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Dr. Polly Penhale
Program Manager
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B-272-M
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NSF/OPP
02-30513
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Station:
McMurdo Station
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RPSC POC:
Patricia Jackson
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Research Site(s):
McMurdo Station
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Dates in Antarctica:
Early to mid January (McMurdo), mid December to early January (R/V NBP)
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Iron and light effects on Phaeocystis antarctica isolates from the Ross Sea
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Photo not available.
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Deploying Team Members:
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Giacomo R. DiTullio
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Nathan S. Garcia
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Sarah F. Riseman
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Peter Sedwick
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Research Objectives:
The colonial prymnesiophyte Phaeocystis antarctica is a major bloom-forming alga in antarctic shelf waters, where, together with diatoms, it is considered a key species in regional biogeochemical cycling and ecosystem structure. Iron levels in these waters fall sharply during the mid- to late summer to concentrations that are likely to limit the growth of phytoplankton, including P. antarctica. However, in contrast to diatoms, very little work has been done to examine the effects of iron, or the combined effects of iron and irradiance, on the growth, physiology, and biochemical composition of P. antarctica. We will collect samples of P. antarctica from the southern Ross Sea and samples grown in semicontinuous batch cultures to investigate the effects of iron availability and irradiance on growth rate, cellular iron quota, buoyancy, biogenic sulfur production, pigment content, redox-protein expression, and photosynthetic efficiency.
Over time scales ranging from seasonal to interannual, P. antarctica is known to have a significant effect on regional biogeochemical cycles of carbon, nutrient elements, and sulfur in the Ross Sea. This species may also have played a central role in the inferred basin-scale changes in biogeochemical cycles linked to glacial-interglacial climatic change. Thus, it is important to develop a mechanistic understanding of the factors that control the growth, physiology, and biochemical composition of P. antarctica in order to better understand the biogeochemical ecology of the Ross Sea and the wider Southern Ocean and possible linkages with regional and global climate. The data we gather from these laboratory experiments, together with the results of recent and ongoing field and modeling studies, will substantially improve our ability to predict how the antarctic region will be affected by and modulate future climate change.
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