Latitudinal and seasonal variations in carbon dioxide and oxygen in the northeast Atlantic and the effects on Emiliania huxleyi and other phytoplankton

Abstract

Several cruise programs, such as Transient Tracers in the Ocean (TTO), the Biogeochemical Ocean Flux Study (BOFS), and the Joint Global Ocean Flux Study (JGOFS), have measured physical, chemical, and biological variables in the northeast Atlantic, with the aim of understanding the seasonal variation in oceanic components such as carbon dioxide and oxygen and the role of different factors (e.g., the marine biota) in determining these seasonal variations. For this paper, data from the different cruise programs have been collated, and then three‐dimensional (3‐D) interpolated surfaces have been plotted in order to illustrate the seasonal and latitudinal changes in these different components. These data‐generated plots are then compared with plots generated from the results of the simulation model of Taylor et al. (1991). The model‐derived and data‐derived plots are shown to be similar, and the model is subsequently used to explain the interaction of the processes underlying the observed variation in pCO2. It is argued that more data needs to be collected at the time of the spring bloom north of 50°N. The plot of carbon dioxide concentration is discussed in relation to the effects of carbon dioxide concentration on phytoplankton growth, as proposed by Riebesell et al.(1993). In addition, it is shown that the distribution of blooms of Emiliania huxleyi in the NE Atlantic (55°–63°N but not farther south) is not coincident with areas of low [CO2], contrary to the hypothesis that Emiliania huxleyi has evolved to be a successful competitor at low [C02].