1. Caroline De Bodt, Quentin d’Hoop, Jérôme Harlay and Lei Chou
Calcification and transparent exopolymer particles (TEP) production in batch cultures of Emiliania huxleyi exposed to different pCO2
Core theme IV Biogeochemical feedbacks on the oceanic carbon sinks
2nd annual CarboOcean meeting
Caroline De Bodt, Quentin d’Hoop, Jérôme Harlay
and Lei Chou

2. Outline of the presentation
Introduction
Description of the experiment
Results of chl a, calcification and TEP for the 3 cultures
Calcification in relation to the Ωcalcite
Correlation between TEP, particulate organic and inorganic carbon
Conclusions

3. Outline of the presentation
Introduction
Description of the experiment
Results of chl a, calcification and TEP for the 3 cultures
Calcification in relation to the Ωcalcite
Correlation between TEP, particulate organic and inorganic carbon
Conclusions

4. Outline of the presentation
Introduction
Description of the experiment
Results of chl a, calcification and TEP for the 3 cultures
Calcification in relation to the Ωcalcite
Correlation between TEP, particulate organic and inorganic carbon
Conclusions

5. Outline of the presentation
Introduction
Description of the experiment
Results of chl a, calcification and TEP for the 3 cultures
Calcification in relation to the Ωcalcite
Correlation between TEP, particulate organic and inorganic carbon
Conclusions

6. Outline of the presentation
Introduction
Description of the experiment
Results of chl a, calcification and TEP for the 3 cultures
Calcification in relation to the Ωcalcite
Correlation between TEP, particulate organic and inorganic carbon
Conclusions

7. Outline of the presentation
Introduction
Description of the experiment
Results of chl a, calcification and TEP for the 3 cultures
Calcification in relation to the Ωcalcite
Correlation between TEP, particulate organic and inorganic carbon
Conclusions

8. The coccolithophore E.huxleyi
- Photosynthesis: sink for CO2
106CO2 ↓ + 16NO3- + H2PO H H2O
↔ (CH2O)106(NH3)16H3PO O2
- Calcification: source of CO2
Ca2+ + 2HCO3- ↔ CaCO3 + CO2↑ + H2O
- Extracellular release (Transparent exopolymer particles, TEP)
(Engel et al., 2004a)

9. Description of the Experiment
Cultures were grown in filtered seawater enriched with NO3 and PO4
Irradiance : 150 µmol m-2 s-1
Temperature : 13°C
Light/Dark cycle : 14h/10h
Culture 1
Culture 2
Culture 3
Vol. batch reactor (L) 2 8
Initial pCO2 (µatm)
490
630
930

10. Measured parameters pH Total alkalinity pCO2, Ωcalcite
Nutrient concentrations
(NO3 and PO4)
Chlorophyll a
TEP
POC
pCO2, Ωcalcite

11. Evolution of the pCO2

12. Results
490 µatm
630 µatm
930 µatm

13. Results
490 µatm
630 µatm
930 µatm

14. Results
490 µatm
630 µatm
930 µatm

15. Results
490 µatm
630 µatm
930 µatm

16. Results
490 µatm
630 µatm
930 µatm

17. Link between calcification and Ωcalcite
Ca2+ (aq) + CO32- (aq) ↔ CaCO3 (s)
- Saturation state with respect to calcite:
> 1 precipitation
< 1 dissolution

18. Link between calcification and Ωcalcite
Ca2+ (aq) + CO32- (aq) ↔ CaCO3 (s)
- Saturation state with respect to calcite:
> 1 precipitation
< 1 dissolution

19. Link between calcification and Ωcalcite
Culture Culture Culture 3
Key value : Ωcalcite = 3

20. Correlation between TEP and POC
During the exponential growth phase, POC concentration increases linearly with chlorophyll a.
After nutrient exhaustion, TEP continue to be produced and contribute to POC increase by 61%.

21. Correlation between TEP and CaCO3
TEP production is strongly correlated with CaCO3 concentrations. → Calcification may be considered as a source of TEP.

22. Conclusions
E. huxleyi is sensitive to pCO2

23. Conclusions E. huxleyi is sensitive to pCO2
TEP concentrations continue to increase after the decline in E. huxleyi growth

24. Conclusions E. huxleyi is sensitive to pCO2
TEP concentrations continue to increase after the decline in E. huxleyi growth
Very good correlation between TEP and calcite production

25. Conclusions E. huxleyi is sensitive to pCO2
TEP concentrations continue to increase after the decline in E. huxleyi growth
Very good correlation between TEP and calcite production
key value of 3 for the Ωcalcite

26. Thank you for your attention This study was partially supported by the PEACE project, funded the Belgian Science Policy Office.