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| Titel |
Disparities between in situ and optically derived carbon biomass and growth rates of the prymnesiophyte Phaeocystis globosa |
| VerfasserIn |
L. Peperzak, H. J. van der Woerd, K. R. Timmermans |
| 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. 6 ; Nr. 12, no. 6 (2015-03-16), S.1659-1670 |
| Datensatznummer |
250117860
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| Publikation (Nr.) |
 copernicus.org/bg-12-1659-2015.pdf |
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| Zusammenfassung |
| The oceans play a pivotal role in the global carbon cycle. It is not
practical to measure the global daily production of organic carbon, the
product of phytoplankton standing stock and its growth rate using discrete
oceanographic methods. Instead, optical proxies from Earth-orbiting
satellites must be used. To test the accuracy of optically derived proxies
of phytoplankton physiology and growth rate, hyperspectral reflectance data
from the wax and wane of a Phaeocystis bloom in laboratory mesocosms were compared with
standard ex situ data. Chlorophyll biomass could be estimated accurately
from reflectance using specific chlorophyll absorption algorithms. However,
the conversion of chlorophyll (Chl) to carbon (C) was obscured by the
non-linear increase in C : Chl under nutrient-limited growth. Although C : Chl
was inversely correlated (r2 = 0.88) with the in situ fluorometric
growth rate indicator Fv / Fm (Photosystem II quantum efficiency), none of
them was linearly correlated to growth rate, constraining the accurate
calculation of Phaeocystis growth or production rates. Unfortunately, the optical proxy
ϕph (quantum efficiency of fluorescence: the ratio of the
number of fluoresced photons to the number of photons absorbed by the
phytoplankton) did not show any correlation with Phaeocystis growth rate, and
therefore it is concluded that ϕph cannot be applied in the
remotely sensed measurement of this species' carbon production rate. |
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