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| Titel |
Nutrient regimes control phytoplankton ecophysiology in the South Atlantic |
| VerfasserIn |
T. J. Browning, H. A. Bouman, C. M. Moore, C. Schlosser, G. A. Tarran, E. M. S. Woodward, G. M. Henderson |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 2 ; Nr. 11, no. 2 (2014-01-30), S.463-479 |
| Datensatznummer |
250117154
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| Publikation (Nr.) |
 copernicus.org/bg-11-463-2014.pdf |
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| Zusammenfassung |
| Fast Repetition Rate fluorometry (FRRf) measurements of phytoplankton
photophysiology from an across-basin South Atlantic cruise (as part of the
GEOTRACES programme) characterised two dominant ecophysiological regimes
which were interpreted on the basis of nutrient limitation. South of the
South Subtropical Convergence (SSTC) in the northern sub-Antarctic sector of
the Antarctic Circumpolar Current (ACC) in the Eastern Atlantic Basin, waters
are characterised by elevated chlorophyll concentrations, a dominance by
larger phytoplankton cells, and low apparent photochemical efficiency
(Fv / Fm). Shipboard 24 h iron (Fe) addition
incubation experiments confirmed that Fe stress was primarily responsible for
the low Fv / Fm, with Fe addition to these waters,
either within the artificial bottle additions or naturally occurring
downstream enrichment from Gough Island, significantly increasing
Fv / Fm values. To the north of the SSTC at the
southern boundary of the South Atlantic Gyre, phytoplankton are characterised
by high values of Fv / Fm which, coupled with the
low macronutrient concentrations and increased presence of picocyanobacteria,
are interpreted as conditions of Fe replete, balanced macronutrient-limited
growth. Spatial correlation was found between
Fv / Fm and Fe:nitrate ratios, supporting the
suggestion that the relative supply ratios of these two nutrients can control
patterns of limitation and consequently the ecophysiology of phytoplankton in
subtropical gyre and ACC regimes. |
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