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Impact de la fonte de la glace sur le phytoplancton et le CO2 de l'Océan Arctique

Abstract : The most abrupt changes in response to climate change are observed in the Arctic Ocean. The high sensitivity of this polar environment was revealed by the exceptional sea ice reduction in recent summers. What is in turn the impact of ice melting on phytoplankton and atmospheric CO2 uptake? To address this question data were acquired during two oceanographic cruises carried out in the Western Arctic, during two summers 2008 and 2010 of extensive ice melting. Several parameters were used to characterize the physical environment (temperature, salinity, sea ice cover) and conditions for phytoplankton growth (light, nutrients). Primary production, pigments and taxonomy data were generated to describe and quantify the phytoplankton communities. Carbonate chemistry, hydrology and phytoplankton observations were combined to estimate the impact of ice melting on atmospheric CO2 uptake. Sub-regions were distinguished based on their sea ice cover, namely the ice edge, the ice-free deep basins and shelves and ice-covered areas where phytoplankton communities and carbonate chemistry differ. The role of freshening resulting from sea ice melting is evaluated from the biomass and phytoplankton community structure. We further investigated the impact of dilution and desalinization due to freshening on the CO2 uptake and acidification of the Arctic waters. Comparison to historical data documenting heavy ice years suggests that biomass, primary production, phytoplankton species and sewater CO2 are greatly modified in an Arctic Ocean affected by accelerated melting of ice.
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Submitted on : Friday, November 2, 2012 - 3:14:51 PM
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  • HAL Id : tel-00747878, version 1

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Pierre Coupel. Impact de la fonte de la glace sur le phytoplancton et le CO2 de l'Océan Arctique. Milieux et Changements globaux. Université Pierre et Marie Curie - Paris VI, 2012. Français. ⟨tel-00747878⟩

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