Blooms of Emiliania huxleyi are sinks of atmospheric carbon dioxide: A field and mesocosm study derived simulation

Abstract

Abstract. During field measurements in a bloom of Emiliania huxleyi in the North Sea in 1993, an apparently inconsistent combination of observations was measured: (1)JCO2 was lower in the center of the bloom than in the surrounding nonbloom areas and undersaturated with respect to the atmosphere in both cases, (2) within the bloom, enhanced sedimentation of coccoliths-containing fecal pellets was observed, (3) a large atmospheric sink of 1.3 mol C m -2 was derived, and (4) in the same bloom a positive correlation between CaCO3 andfCO2 was observed, which was interpreted as an increase offCO 2 during production of CaCO3. In order to resolve the inconsistency between observations (1, 2, 3) and 4 a one-dimensional three-layer model was constructed. A positive correlation between CaCO3 andfCO2 was obtained when the model was parameterized with data obtained from field and mesocosm studies. The correlation is a feature of the decay phase of a bloom and represents a decrease offCO 2 with a decrease of CaCO3. Thus it represents the dissolution and sedimentation of CaCO3 rather than its production. Having resolved the ambiguity within the field data by adding the dimension of time in the model, blooms of E. huxleyi can be identified as sinks for atmospheric carbon dioxide. This sink is a function of the calcification to photosynthesis (C:P) ratio of the nitrate-using phytoplankton and is maximal when the C:P ratio is 0.42 (that is, E. huxleyi constitutes 97% of the nitrate-using phytoplankton). Rather than using the model for making accurate predictions about the magnitude of this sink, a sensitivity analysis was performed to give a range of magnitudes for the range of parameter values that were obtained during previous studies. Furthermore, gaps were identified in the current knowledge of carbon fluxes within blooms of E. huxleyi.

Long-term culture at elevated atmospheric CO2fails to evoke specific adaptation in seven freshwater phytoplankton species

“…Many populations of freshwater phytoplankton may thus already experience chronically elevated CO 2 . In the oceans, relative saturation varies over time and space [48], with strong local decreases caused by blooming [49,50]. The availability of CO 2 for phytoplankton is further modified by factors including pH, ionic strength and temperature [51].…”

Distribution of planktonic biogenic carbonate organisms in the Southern Ocean south of Australia: a baseline for ocean acidification impact assessment

“…On the one hand, carbonate precipitation raises the partial pressure of CO 2 reducing the uptake of carbon dioxide from the atmosphere into the surface Published by Copernicus Publications on behalf of the European Geosciences Union. 32 T. W. Trull et al: Distribution of planktonic biogenic carbonate organisms in the Southern Ocean ocean; on the other hand, the high density and slow dissolution of these minerals promotes the sinking of associated organic carbon more deeply into the ocean interior, increasing sequestration (Boyd and Trull, 2007b;Buitenhuis et al, 2001;Klaas and Archer, 2002;Ridgwell et al, 2009;Salter et al, 2014). Carbonate production is expected to be reduced by ocean acidification from the uptake of anthropogenic CO 2 , with potentially large consequences for the global carbon cycle and ocean ecosystems (Orr et al, 2005;Pörtner et al, 2005).…”

Response of coccolithophorid Emiliania huxleyi to elevated partial pressure of CO2 under nitrogen limitation

“…Third, most experiments have investigated acute responses but have not provided information on acclimation over short (daily) time scales. Fourth, the effect of this response on air-ocean CO 2 fluxes not only depends on its magnitude but also on other factors that are equally difficult to estimate, such as changes in seawater buffering capacity (Frankignoulle et al 1994), the sedimentation rate of planktonic CaCO 3 particles (Buitenhuis et al 2001), the effect of grazing by zooplankton (Harris 1994), and the response of the net photosynthetic uptake of CO 2 (Zondervan et al 2001, Leclercq et al 2002). These uncertainties hamper the prediction of the effect of marine calcification on future air-ocean CO 2 fluxes, and, not surprisingly, the 2 attempts made so far have reached conflicting conclusions.…”