Impact of ice melting on phytoplankton and CO2 in the Arctic Ocean

• Main Author: Coupel, Pierre
• Other Authors: Takuvik Joint International Laboratory ULAVAL-CNRS, Université Laval Québec (ULaval)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris VI, Dr. Marie-Alexandrine SICRE et Dr. Diana RUIZ-PINO,([e-mail], [e-mail]), Arctic Tipping Point (ATP-Projet Européen)
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2012
• Subjects: ARCTIC OCEAN; ICE MELTING; MARINE BIOGEOCHEMISTRY; PHYTOPLANKTON; OCEAN ARCTIQUE; FONTE DE LA GLACE; BIOGEOCHIMIE MARINE; PHYTOPLANCTON; CO2; [SDE.MCG]Environmental Sciences/Global Changes; Arctic; Arctic Ocean; Arctique*; banquise; Climate change; Phytoplankton; Sea ice; ice covered areas
• Online Access: https://theses.hal.science/tel-00747878; https://theses.hal.science/tel-00747878/document; https://theses.hal.science/tel-00747878/file/THESE_COUPEL_2_juil_2012.pdf

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. Les impacts les plus rapides et intenses du changement climatique sont observés actuellement dans l'Océan Arctique. La grande sensibilité de cet environnement polaire a été révélée par la réduction exceptionnelle de la banquise ces derniers étés. Quels est l'impact de la fonte de la glace sur le phytoplancton et la prise de CO2 atmosphèrique ? La réponse à cette question s'appuie sur des observations obtenues durant deux campagnes océanographiques, réalisées en ...