No detectable effect of ocean acidification on plankton metabolism in the NW oligotrophic Mediterranean Sea: results from two mesocosm studies

• Published in: Estuarine, Coastal and Shelf Science
• Main Authors: Maugendre, Laure, Gattuso, Jean-Pierre, Poulton, A. J., Dellisanti, W, Gaubert, M, Guieu, Cecile, Gazeau, Frédéric
• Other Authors: Laboratoire d'océanographie de Villefranche (LOV), Observatoire océanologique de Villefranche-sur-mer (OOVM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), National Oceanography Centre (NOC)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2017
• Subjects: mesocosm experiments; mediterranean Sea; metabolic rates; plankton community; ocean acidification; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Ocean acidification
• Online Access: https://hal.sorbonne-universite.fr/hal-01132907; https://hal.sorbonne-universite.fr/hal-01132907/document; https://hal.sorbonne-universite.fr/hal-01132907/file/Maugendre_No_detectable.pdf; https://doi.org/10.1016/j.ecss.2015.03.009

International audience Oligotrophic areas account for about 30% of oceanic primary production and are projected to expand in a warm, high-CO2 world. Changes in primary production in these areas could have important impacts on future global carbon cycling. To assess the response of primary production and respiration of plankton communities to increasing partial pressure of CO2 (pCO2) levels in Low Nutrient Low Chorophyll areas, two mesocosm experiments were conducted in the Bay of Calvi (Corsica, France) and in the Bay of Villefranche (France) in June–July 2012 and February–March 2013 under different trophic state, temperature and irradiance conditions. Nine mesocosms of 50 m3 were deployed for 20 and 12 days, respectively, and were subjected to seven pCO2 levels (3 control and 6 elevated levels). The metabolism of the community was studied using several methods based on in situ incubations (oxygen light–dark, 18O and 14C uptake). Increasing pCO2 had no significant effect on gross primary production, net community production, particulate and dissolved carbon production, as well as on community respiration. These two mesocosm experiments, the first performed under maintained low nutrient and low chlorophyll, suggest that in large areas of the ocean, increasing pCO2 levels may not lead to a significant change in plankton metabolic rates and sea surface biological carbon fixation.