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| Titel |
Calcifying phytoplankton biomass and CO2: A striking balance |
| VerfasserIn |
Jorijntje Henderiks, Bjarte Hannisdal, Lee Hsiang Liow |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250041098
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| Zusammenfassung |
| Calcifying phytoplankton play a fundamental role in marine ecosystems and global
biogeochemical cycles. Their cell size and abundance modulate the strength of the biological
carbon and carbonate “pumps”, which represent important feedbacks in the Earth System.
Phytoplankton biomass is thus coupled to climate variability, but the behavior of this coupling
on geological time scales remains unknown. We compared fossil time series of
coccolithophore relative abundance and cell size to geochemical proxy records of global
climate change over much of the Cenozoic (~45-5 million years ago). We show that the
Cenozoic decline in atmospheric carbon dioxide levels (pCO2) caused a reduction in
calcifying phytoplankton biomass. Our results demonstrate that long-term variation in CO2
availability and concomitant shifts in ocean carbonate chemistry have been important
drivers of planktonic ecosystems beyond their association with ocean temperature
and stratification. This supports the hypothesis that large-celled coccolithophores
lacking a carbon concentrating mechanism were disadvantaged in a low-pCO2
world (Henderiks & Pagani 2008). In addition, decreasing biomass of calcifying
phytoplankton may have represented a negative feedback during global cooling by reducing
carbon drawdown and burial fluxes, potentially contributing to the stabilization
of atmospheric CO2 concentrations over the past 24 million years (Pagani et al.
2009).
References
Henderiks, J. and M. Pagani (2008), Coccolithophore cell size and the Paleogene decline
in atmospheric CO2, Earth and Planetary Science Letters, 269, 575-583.
Pagani, M., K. Caldeira, R. Berner and D. J. Beerling (2009), The role of terrestrial plants
in limiting atmospheric CO2 decline over the past 24 million years, Nature, 460, 85-88. |
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