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| Titel |
Combined δ11B, δ13C, and δ18O analyses of coccolithophore calcite constrains the response of coccolith vesicle carbonate chemistry to CO2-induced ocean acidification |
| VerfasserIn |
Yi-Wei Liu, Robert Tripati, Sarah Aciego, Rosaleen Gilmore, Justin Ries |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250131360
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| Publikation (Nr.) |
 EGU/EGU2016-11760.pdf |
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| Zusammenfassung |
| Coccolithophorid algae play a central role in the biological carbon pump, oceanic carbon
sequestration, and in marine food webs. It is therefore important to understand the potential
impacts of CO2-induced ocean acidification on these organisms. Differences in the regulation
of carbonate chemistry, pH, and carbon sources of the intracellular compartments where
coccolith formation occurs may underlie the diverse calcification and growth responses to
acidified seawater observed in prior experiments. Here we measured stable isotopes of boron
(δ11B), carbon (δ13C) and oxygen (δ18O) within coccolith calcite, and δ13C of algal tissue to
constrain carbonate system parameters in two strains of Pleurochrysis carterae (P. carterae).
The two strains were cultured under variable pCO2, with water temperature, salinity,
dissolved inorganic carbon (DIC), and alkalinity monitored. Notably, PIC, POC, and
PIC/POC ratio did not vary across treatments, indicating that P. carterae is able
to calcify and photosynthesize at relatively constant rates irrespective of pCO2
treatment. The δ11B data indicate that mean pH at the site of coccolith formation did
not vary significantly in response to elevated CO2. These results suggest that P.
carterae regulates calcifying vesicle pH, even amidst changes in external seawater pH.
Furthermore, δ13C and δ18O data suggest that P. carterae may utilize carbon from
a single internal DIC pool for both calcification and photosynthesis, and that a
greater proportion of dissolved CO2 relative to HCO3− enters the internal DIC pool
under acidified conditions. These results suggest that P. carterae is able to calcifyand
photosynthesize at relatively constant rates across pCO2 treatments by maintaining pH
homeostasis at their site of calcification and utilizing a greater proportion of aqueous CO2. |
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