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Titel |
Photosynthesis–irradiance responses in the Ross Sea, Antarctica: a meta-analysis |
VerfasserIn |
W. O. Smith, K. Donaldson |
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 ; 12, no. 11 ; Nr. 12, no. 11 (2015-06-10), S.3567-3577 |
Datensatznummer |
250117978
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Publikation (Nr.) |
copernicus.org/bg-12-3567-2015.pdf |
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Zusammenfassung |
A meta-analysis of photosynthesis–irradiance measurements was completed
using data from the Ross Sea, Antarctica, using a total of 417 independent
measurements. PmB, the maximum, chlorophyll-specific,
irradiance-saturated rate of photosynthesis, averaged 1.1 ± 0.06 μg C
(μg Chl)−1 h−1. Light-limited,
chlorophyll-specific photosynthetic rates (αB) averaged 0.030 ± 0.023 μg C
(μg Chl)−1 h−1 (μmol quanta m−2 s−1)−1.
Significant variations in PmB and
αB were found as a function of season, with spring maximum
photosynthetic rates being 60% greater than those in summer. Similarly,
α values were 48% greater in spring. There was no detectable
effect of sampling location on the photo-synthetic parameters, and
temperature and macronutrient (NO3) concentrations also did not have an
influence. However, irradiance and carbon dioxide concentrations, when
altered under controlled conditions, exerted significant influences on
photosynthetic parameters. Specifically, reduced irradiance resulted in
significantly decreased PmB and increased αB values,
and increased CO2 concentrations resulted in significantly increased
PmB and αB values. Comparison of photosynthetic
parameters derived at stations where iron concentrations were above and
below 0.1 nM indicated that reduced iron levels were associated with
significantly increased PmB values, confirming the importance of
iron within the photosynthetic process. No significant difference was
detected between stations dominated by diatoms and those dominated by the
haptophyte Phaeocystis antarctica. The meta-analysis confirms the photosynthetic rates predicted
from global analyses that are based solely on temperature and irradiance
availability, but suggests that, for more accurate predictions of
productivity in polar systems, a more detailed model that includes temporal
effects of photosynthetic parameters will be required. |
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