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| Titel |
Microzooplankton grazing and phytoplankton growth in marine mesocosms with increased CO2 levels |
| VerfasserIn |
K. Suffrian, P. Simonelli, J. C. Nejstgaard, S. Putzeys, Y. Carotenuto, A. N. Antia |
| 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 (2008-08-18), S.1145-1156 |
| Datensatznummer |
250002684
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| Publikation (Nr.) |
 copernicus.org/bg-5-1145-2008.pdf |
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| Zusammenfassung |
| Microzooplankton grazing and algae growth responses to increasing pCO2
levels (350, 700 and 1050 μatm) were investigated in nitrate and
phosphate fertilized mesocosms during the PeECE III experiment 2005. Grazing
and growth rates were estimated by the dilution technique combined with
taxon specific HPLC pigment analysis. Microzooplankton composition was
determined by light microscopy. Despite a range of up to 3 times the present
CO2 levels, there were no clear differences in any measured parameter
between the different CO2 treatments. During days 3–9 of the experiment
the algae community standing stock, measured as chlorophyll a (Chl-a), showed
the highest instantaneous grow rates (k=0.37–0.99 d−1) and increased
from ca. 2–3 to 6–12 μg l−1, in all mesocosms. Afterwards the
phytoplankton standing stock decreased in all mesocosms until the end of the
experiment. The microzooplankton standing stock, that was mainly constituted
by dinoflagellates and ciliates, varied between 23 and 130 μg C l−1
(corresponding to 1.9 and 10.8 μmol C l−1), peaking on
day 13–15, apparently responding to the phytoplankton development.
Instantaneous Chl-a growth rates were generally higher than the grazing
rates, indicating only a limited overall effect of microzooplankton grazing
on the most dominant phytoplankton. Diatoms and prymnesiophytes were
significantly grazed (12–43% of the standing stock d−1) only in the
pre-bloom phase when they were in low numbers, and in the post-bloom phase
when they were already affected by low nutrients and/or viral lysis. The
cyanobacteria populations appeared more affected by microzooplankton grazing
which generally removed 20–65% of the standing stock per day. |
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