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| Titel |
An alternative method for correcting fluorescence quenching |
| VerfasserIn |
L. Biermann, C. Guinet, M. Bester, A. Brierley, L. Boehme |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1812-0784
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| Digitales Dokument |
URL |
| Erschienen |
In: Ocean Science ; 11, no. 1 ; Nr. 11, no. 1 (2015-01-13), S.83-91 |
| Datensatznummer |
250117127
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| Publikation (Nr.) |
 copernicus.org/os-11-83-2015.pdf |
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| Zusammenfassung |
| Under high light intensity, phytoplankton protect their photosystems from
bleaching through non-photochemical quenching processes. The consequence of
this is suppression of fluorescence emission, which must be corrected when
measuring in situ yield with fluorometers. We present data from the Southern Ocean,
collected over five austral summers by 19 southern elephant seals
tagged with fluorometers. Conventionally, fluorescence data collected during
the day (quenched) were corrected using the limit of the mixed layer, assuming
that phytoplankton are uniformly mixed from the surface to this depth.
However, distinct deep fluorescence maxima were measured in approximately
30% of the night (unquenched) data. To account for the evidence that
chlorophyll is not uniformly mixed in the upper layer, we propose correcting
from the limit of the euphotic zone, defined as the depth at which
photosynthetically available radiation is ~ 1% of the
surface value. Mixed layer depth exceeded euphotic depth over 80% of the
time. Under these conditions, quenching was corrected from the depth of the
remotely derived euphotic zone Zeu, and compared with fluorescence
corrected from the depth of the density-derived mixed layer. Deep
fluorescence maxima were evident in only 10% of the day data when
correcting from mixed layer depth. This was doubled to 21% when
correcting from Zeu, more closely matching the unquenched (night) data.
Furthermore, correcting from Zeu served to conserve non-uniform
chlorophyll
features found between the 1% light level and mixed layer depth. |
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