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| Titel |
Response of Nodularia spumigena to pCO2 – Part 1: Growth, production and nitrogen cycling |
| VerfasserIn |
N. Wannicke, S. Endres, A. Engel, H.-P. Grossart, M. Nausch, J. Unger, M. Voss |
| 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 ; 9, no. 8 ; Nr. 9, no. 8 (2012-08-06), S.2973-2988 |
| Datensatznummer |
250007230
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| Publikation (Nr.) |
 copernicus.org/bg-9-2973-2012.pdf |
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| Zusammenfassung |
| Heterocystous cyanobacteria of the genus Nodularia form extensive
blooms in the Baltic Sea and contribute substantially to the total annual
primary production. Moreover, they dispense a large fraction of new nitrogen
to the ecosystem when inorganic nitrogen concentration in summer is low.
Thus, it is of ecological importance to know how Nodularia will
react to future environmental changes, in particular to increasing carbon
dioxide (CO2) concentrations and what consequences there might arise for
cycling of organic matter in the Baltic Sea. Here, we determined carbon (C)
and dinitrogen (N2) fixation rates, growth, elemental stoichiometry of
particulate organic matter and nitrogen turnover in batch cultures of the
heterocystous cyanobacterium Nodularia spumigena under low (median
315 μatm), mid (median 353 μatm), and high (median
548 μatm) CO2 concentrations. Our results demonstrate an overall
stimulating effect of rising pCO2 on C and N2 fixation, as well as on
cell growth. An increase in pCO2 during incubation days 0 to 9 resulted
in an elevation in growth rate by 84 ± 38% (low vs. high pCO2)
and 40 ± 25% (mid vs. high pCO2), as well as in N2 fixation
by 93 ± 35% and 38 ± 1%, respectively. C uptake rates
showed high standard deviations within treatments and in between sampling
days. Nevertheless, C fixation in the high pCO2 treatment was elevated
compared to the other two treatments by 97% (high vs. low) and 44%
(high vs. mid) at day 0 and day 3, but this effect diminished afterwards.
Additionally, elevation in carbon to nitrogen and nitrogen to phosphorus
ratios of the particulate biomass formed (POC : POP and PON : POP) was
observed at high pCO2. Our findings suggest that rising pCO2
stimulates the growth of heterocystous diazotrophic cyanobacteria, in a
similar way as reported for the non-heterocystous diazotroph
Trichodesmium. Implications for biogeochemical cycling and food web
dynamics, as well as ecological and socio-economical aspects in the Baltic
Sea are discussed. |
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