Coccolithophore surface distributions in the North Atlantic and their modulation of the air-sea flux of CO 2 from 10 years of satellite Earth observation data
Coccolithophores are the primary oceanic phytoplankton responsible for the production of calcium carbonate (CaCO 3 ). These climatically important plankton play a key role in the oceanic carbon cycle as a major contributor of carbon to the open ocean carbonate pump (~50%) and their calcification can...
Published in: | Biogeosciences |
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Main Authors: | , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Copernicus Publications
2013
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Subjects: | |
Online Access: | https://doi.org/10.5194/bg-10-2699-2013 https://doaj.org/article/07c20d31996c4b77bd8f79b689dbdc9a |
Summary: | Coccolithophores are the primary oceanic phytoplankton responsible for the production of calcium carbonate (CaCO 3 ). These climatically important plankton play a key role in the oceanic carbon cycle as a major contributor of carbon to the open ocean carbonate pump (~50%) and their calcification can affect the atmosphere-to-ocean (air-sea) uptake of carbon dioxide (CO 2 ) through increasing the seawater partial pressure of CO 2 ( p CO 2 ). Here we document variations in the areal extent of surface blooms of the globally important coccolithophore, Emiliania huxleyi, in the North Atlantic over a 10-year period (1998–2007), using Earth observation data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS). We calculate the annual mean sea surface areal coverage of E. huxleyi in the North Atlantic to be 474 000 ± 104 000 km 2 , which results in a net CaCO 3 carbon (CaCO 3 -C) production of 0.14–1.71 Tg CaCO 3 -C per year. However, this surface coverage (and, thus, net production) can fluctuate inter-annually by −54/+8% about the mean value and is strongly correlated with the El Niño/Southern Oscillation (ENSO) climate oscillation index ( r =0.75, p <0.02). Our analysis evaluates the spatial extent over which the E. huxleyi blooms in the North Atlantic can increase the p CO 2 and, thus, decrease the localised air-sea flux of atmospheric CO 2 . In regions where the blooms are prevalent, the average reduction in the monthly air-sea CO 2 flux can reach 55%. The maximum reduction of the monthly air-sea CO 2 flux in the time series is 155%. This work suggests that the high variability, frequency and distribution of these calcifying plankton and their impact on p CO 2 should be considered if we are to fully understand the variability of the North Atlantic air-to-sea flux of CO 2 . We estimate that these blooms can reduce the annual N. Atlantic net sink atmospheric CO 2 by between 3–28%. |
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