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| Titel |
Effects of CO2 on particle size distribution and phytoplankton abundance during a mesocosm bloom experiment (PeECE II) |
| VerfasserIn |
A. Engel, K. G. Schulz, U. Riebesell, R. Bellerby, B. Delille, M. Schartau |
| 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. 2 ; Nr. 5, no. 2 (2008-04-08), S.509-521 |
| Datensatznummer |
250002382
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| Publikation (Nr.) |
 copernicus.org/bg-5-509-2008.pdf |
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| Zusammenfassung |
| The influence of seawater carbon dioxide (CO2) concentration on the
size distribution of suspended particles (2–60 μm) and on phytoplankton
abundance was investigated during a mesocosm experiment at the large scale
facility (LFS) in Bergen, Norway, in the frame of the Pelagic Ecosystem
CO2 Enrichment study (PeECE II). In nine outdoor enclosures the partial
pressure of CO2 in seawater was modified by an aeration system to
simulate past (~190 μatm CO2), present (~370 μatm
CO2) and future (~700 μatm CO2) CO2 conditions in
triplicates. Due to the initial addition of inorganic nutrients,
phytoplankton blooms developed in all mesocosms and were monitored over a
period of 19 days. Seawater samples were collected daily for analysing the
abundance of suspended particles and phytoplankton with the Coulter Counter
and with Flow Cytometry, respectively. During the bloom period, the
abundance of small particles (<4 μm) significantly increased at past,
and decreased at future CO2 levels. At that time, a direct relationship
between the total-surface-to-total-volume ratio of suspended particles and
DIC concentration was determined for all mesocosms. Significant changes with
respect to the CO2 treatment were also observed in the phytoplankton
community structure. While some populations such as diatoms seemed to be
insensitive to the CO2 treatment, others like Micromonas spp. increased with
CO2, or showed maximum abundance at present day CO2 (i.e. Emiliania huxleyi).
The strongest response to CO2 was observed in the abundance of small
autotrophic nano-plankton that strongly increased during the bloom in the
past CO2 mesocosms. Together, changes in particle size distribution and
phytoplankton community indicate a complex interplay between the ability of
the cells to physiologically respond to changes in CO2 and size
selection. Size of cells is of general importance for a variety of processes
in marine systems such as diffusion-limited uptake of substrates, resource
allocation, predator-prey interaction, and gravitational settling. The
observed changes in particle size distribution are therefore discussed with
respect to biogeochemical cycling and ecosystem functioning. |
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