Carbon-13 labelling shows no effect of ocean acidification on carbon transfer in Mediterranean plankton communities

• Published in: Estuarine, Coastal and Shelf Science
• Main Authors: Maugendre, Laure, Gattuso, Jean-Pierre, de Kluijver, A., Soetaert, K., van Oevelen, D., Middelburg, J.J., 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), Institute for sustainable development and international relations, Sciences Po (Sciences Po), Deltares The Netherlands, Royal Netherlands Institute for Sea Research (NIOZ), Faculty of Geosciences Utrecht, Universiteit Utrecht / Utrecht University Utrecht
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2017
• Subjects: Ocean acidification; plankton communities; carbon transfer; 13 C and biomarkers; mesocosm experiments; Mediterranean Sea; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography
• Online Access: https://hal.sorbonne-universite.fr/hal-01252022; https://hal.sorbonne-universite.fr/hal-01252022/document; https://hal.sorbonne-universite.fr/hal-01252022/file/Maugendre_Carbon-13_labelling.pdf; https://doi.org/10.1016/j.ecss.2015.12.018

International audience Despite an increasing number of experiments, no consensus has emerged on the effect of ocean acidification on plankton communities and carbon flow. During two experiments, performed in the Bay of Calvi (France, Corsica; summer 2012) and the Bay of Villefranche (France; winter 2013), nine off-shore mesocosms (∼50 m3) were deployed among which three served as controls and six were enriched with CO2 to reach partial pressure of CO2 (pCO2) levels from 450 to 1350 μatm and 350–1250 μatm in the Bay of Calvi and the Bay of Villefranche, respectively. In each mesocosm, inorganic 13C was added in order to follow carbon transfer from inorganic via bulk particulate organic carbon and phytoplankton to bacteria by means of biomarkers as well as to zooplankton and settling particles. Despite very low plankton biomasses, labelled carbon was clearly transferred through plankton communities. Incorporation rates in the various plankton compartments suggested a slow-growing community based on regenerated production in the Bay of Calvi while in the Bay of Villefranche, fast-growing species were clearly dominating community production at the start with a shift toward slow-growing species during the experiment due to nutrient limitation. Both bulk and group-specific productions rates did not respond to increasing pCO2 levels. These experiments were the first conducted in the Mediterranean Sea under low nutrient concentrations and phytoplankton biomasses and suggest that ocean acidification may not significantly impact plankton carbon flows in low nutrient low chlorophyll (LNLC) areas.