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| Titel |
High nitrate to phosphorus regime attenuates negative effects of rising pCO2 on total population carbon accumulation |
| VerfasserIn |
B. Matthiessen, S. L. Eggers, S. A. Krug |
| 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. 3 ; Nr. 9, no. 3 (2012-03-28), S.1195-1203 |
| Datensatznummer |
250006854
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| Publikation (Nr.) |
 copernicus.org/bg-9-1195-2012.pdf |
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| Zusammenfassung |
| The ongoing rise in atmospheric pCO2 and consequent increase in ocean
acidification have direct effects on marine calcifying phytoplankton, which
potentially alters carbon export. To date it remains unclear, firstly, how
nutrient regime, in particular by coccolithophores preferred phosphate
limitation, interacts with pCO2 on particulate carbon
accumulation; secondly, how direct physiological responses on the
cellular level translate into total population response. In this study,
cultures of Emiliania huxleyi were full-factorially exposed to two different N:P regimes and
three different pCO2 levels. Cellular biovolume and PIC and POC content
significantly declined in response to pCO2 in both nutrient regimes.
Cellular PON content significantly increased in the Redfield treatment and
decreased in the high N:P regime. Cell abundance significantly declined in
the Redfield and remained constant in the high N:P regime. We hypothesise
that in the high N:P regime severe phosphorous limitation could be
compensated either by reduced inorganic phosphorous demand and/or by
enzymatic uptake of organic phosphorous. In the Redfield regime we suggest
that enzymatic phosphorous uptake to supplement enhanced phosphorous demand
with pCO2 was not possible and thus cell abundance declined. These
hypothesised different physiological responses of E. huxleyi among the
nutrient regimes significantly altered population carrying capacities
along the pCO2 gradient. This ultimately led to the attenuated total population
response in POC and PIC content and biovolume to increased pCO2 in the high N:P regime. Our
results point to the fact that the physiological (i.e. cellular) PIC and POC
response to ocean acidification cannot be linearly extrapolated to total
population response and thus carbon export. It is therefore necessary to
consider both effects of nutrient limitation on cell physiology and their
consequences for population size when predicting the influence of
coccolithophores on atmospheric pCO2 feedback and their function in
carbon export mechanisms. |
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