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| Titel |
Global variability of phytoplankton functional types from space: assessment via the particle size distribution |
| VerfasserIn |
T. S. Kostadinov, D. A. Siegel, S. Maritorena |
| 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 ; 7, no. 10 ; Nr. 7, no. 10 (2010-10-20), S.3239-3257 |
| Datensatznummer |
250005021
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| Publikation (Nr.) |
 copernicus.org/bg-7-3239-2010.pdf |
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| Zusammenfassung |
| A new method of retrieving the parameters of a power-law particle size
distribution (PSD) from ocean color remote sensing data was used to assess
the global distribution and dynamics of phytoplankton functional types
(PFT's). The method retrieves the power-law slope, ξ, and the
abundance at a reference diameter, N0, based upon the shape and
magnitude of the particulate backscattering coefficient spectrum. Relating
the PSD to PFT's on global scales assumes that the open ocean particulate
assemblage is biogenic. The retrieved PSD's can be integrated to define
three size-based PFT's by the percent volume concentration contribution of
three phytoplankton size classes – picoplankton (0.5–2 μm in
equivalent spherical diameter), nanoplankton (2–20 μm) and
microplankton (20–50 μm). Validation with in-situ HPLC diagnostic
pigments resulted in better match-ups for the pico- and micro-phytoplankton
size classes as compared to nanoplankton. Global decadal averages derived
from SeaWiFS monthly data reveal PFT and particle abundance spatial patterns
that are consistent with current understanding. Oligotrophic gyres are
characterized by lower particle abundance and higher contribution by
picoplankton-sized particles than transitional or eutrophic regions.
Seasonal succession patterns for size-based PFT's reveal good correspondence
between increasing chlorophyll concentration and percent contribution by microplankton, as well as
increasing particle abundance. Long-term trends in particle abundances are
generally well correlated with the MEI index indicating increased
oligotrophy (i.e. lower particle abundance and increased contribution of
picoplankton-sized particles) during the warm phase of an El Niño event.
This work demonstrates the utility and future potential of assessing
phytoplankton functional types using remote characterization of the particle
size distribution. |
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