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| Titel |
Calcite production by coccolithophores in the south east Pacific Ocean |
| VerfasserIn |
L. Beaufort, M. Couapel, N. Buchet, H. Claustre, C. Goyet |
| 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 ; 5, no. 4 ; Nr. 5, no. 4 (2008-08-04), S.1101-1117 |
| Datensatznummer |
250002681
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| Publikation (Nr.) |
 copernicus.org/bg-5-1101-2008.pdf |
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| Zusammenfassung |
| BIOSOPE cruise covered an oceanographic transect through the centre of the
South Pacific Gyre (SPG) from the Marquesas archipelago to the Peru-Chile
upwelling (PCU). Water samples from 6 depths in the euphotic zone were
collected at 20 stations. The concentrations of suspended calcite particles,
coccolithophores cells and detached coccoliths were estimated together with
size and weight using an automatic polarizing microscope, a digital camera,
and a collection of softwares performing morphometry and pattern
recognition. Some of these softwares are new and described here for the
first time. The coccolithophores standing stocks were usually low and
reached maxima west of the PCU. The coccoliths of Emiliania huxleyi, Gephyrocapsa spp. and Crenalithus spp. (Order
Isochrysidales) represented more than 30% of all the suspended calcite
particles detected in the size range 0.1–46 μm (22% of PIC in term
of calcite weight). These species grew preferentially in the Chlorophyll
maximum zone. In the SPG their maximum cell concentrations were recorded
between depth of 150 and 200 m, which is unusually deep for these taxa. The
weight of coccoliths and coccospheres were correlated to their size. Large
and heavy coccoliths and coccospheres were found in regions with relatively
high fertility in the Marquises Island and in the PCU. Small and light
coccoliths and coccospheres were found west of the PCU. This distribution is
strongly related to ocean chemistry in particular to alkalinity and to
carbonate ions concentration. The biotic (coccolithophores production)
influence on calcification is mainly driven at the local scale (depth)
whereas the abiotic (carbonate chemistry) plays its most important role at
the regional (horizontal) level. Here 94% of the variability of coccolith
and coccosphere weight can be explained by a change in 7 environmental
variables. |
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