The combined effect of global warming and ocean acidification on the coccolithophore Gephyrocapsa oceanica
Increasing atmospheric CO2 concentrations are expected to impact pelagic ecosystem functioning in the near future by driving ocean acidification and increasing global average temperatures. We examined the effects of these two processes on the growth rate and carbon production of the calcifying cocco...
| Main Authors: | , , , |
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| Format: | Conference Object |
| Language: | unknown |
| Published: |
2011
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| Subjects: | |
| Online Access: | https://oceanrep.geomar.de/id/eprint/12325/ |
| Summary: | Increasing atmospheric CO2 concentrations are expected to impact pelagic ecosystem functioning in the near future by driving ocean acidification and increasing global average temperatures. We examined the effects of these two processes on the growth rate and carbon production of the calcifying coccolithophore Gephyrocapsa oceanica. 12 pCO2treatment levels (20-2500 atm) at three temperatures (15, 20 and 25°C) were established in artificial seawater by combined additions of Na2CO3 and HCl (total alkalinity constant in all treatments). Specific growth rate, particulate inorganic carbon (PIC) and particulate organic carbon (POC) production rates showed an optimum curve response to increasing pCO2 at all temperatures. Optima were found between pCO2 levels of 250-650 atm with a tendency to higher pCO2 levels at higher temperatures. Carbon production rates increased with temperature but sensitivity to increasing pCO2 remained similar at all temperatures. The PIC:POC ratio was temperature-independent and linearly decreased with increasing pCO2. The results obtained here contribute to a better understanding of the responses of coccolithophores to changing environmental conditions and may help to parameterize synergistic effects of ocean warming and acidification in marine biogeochemical models. |
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