Net community production in the northwestern Mediterranean Sea from glider and buoy measurements

Hemming, Michael P., Kaiser, Jan ORCID: https://orcid.org/0000-0002-1553-4043, Boutin, Jacqueline, Merlivat, Liliane, Heywood, Karen J. ORCID: https://orcid.org/0000-0001-9859-0026, Bakker, Dorothee C. E. ORCID: https://orcid.org/0000-0001-9234-5337, Lee, Gareth A. ORCID: https://orcid.org/0000-0003-4640-5487, Cobas García, Marcos, Antoine, David and Shitashima, Kiminori (2022) Net community production in the northwestern Mediterranean Sea from glider and buoy measurements. Ocean Science, 18 (4). pp. 1245-1262. ISSN 1812-0784

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Abstract

The Mediterranean Sea comprises just 0.8 % of the global oceanic surface, yet considering its size, it is regarded as a disproportionately large sink for anthropogenic carbon due to its physical and biogeochemical characteristics. An underwater glider mission was carried out in March–April 2016 close to the BOUSSOLE and DyFAMed time series moorings in the northwestern Mediterranean Sea. The glider deployment served as a test of a prototype ion-sensitive field-effect transistor pH sensor. Dissolved oxygen (O2) concentrations and optical backscatter were also observed by the glider and increased between 19 March and 1 April, along with pH. These changes indicated the start of a phytoplankton spring bloom, following a period of intense mixing. Concurrent measurements of CO2 fugacity and O2 concentrations at the BOUSSOLE mooring buoy showed fluctuations, in qualitative agreement with the pattern of glider measurements. Mean net community production rates (N) were estimated from glider and buoy measurements of dissolved O2 and inorganic carbon (DIC) concentrations, based on their mass budgets. Glider and buoy DIC concentrations were derived from a salinity-based total alkalinity parameterisation, glider pH and buoy CO2 fugacity. The spatial coverage of glider data allowed the calculation of advective O2 and DIC fluxes. Mean N estimates for the euphotic zone between 10 March and 3 April were (-17±36) for glider O2, (44±94) for glider DIC, (17±37) for buoy O2 and (49±86)  mmolm-2d-1 for buoy DIC, all indicating net metabolic balance over these 25 d. However, these 25 d were actually split into a period of net DIC increase and O2 decrease between 10 and 19 March and a period of net DIC decrease and O2 increase between 19 March and 3 April. The latter period is interpreted as the onset of the spring bloom. The regression coefficients between O2 and DIC-based N estimates were 0.25 ± 0.08 for the glider data and 0.54 ± 0.06 for the buoy, significantly lower than the canonical metabolic quotient of 1.45±0.15. This study shows the added value of co-locating a profiling glider with moored time series buoys, but also demonstrates the difficulty in estimating N, and the limitations in achievable precision.

Item Type: Article
Additional Information: Data availability: BOUSSOLE buoy data can be found at http://www.obs-vlfr.fr/Boussole/ (Antoine et al., 2022). Meteorological buoy data are archived in the database “SErvice de DOnnées de l'OMP (SEDOO) Mistrals” (http://mistrals.sedoo.fr/Data-Download, Bouin and Emzivat, 2022). All glider data are archived at the British Oceanographic Data Centre (BODC, https://doi.org/10.5285/e686816f-8bdd-4782-e053-6c86abc07adc, Kaiser and Hemming, 2022). Financial support: This work was partially funded by the UK National Environment Research Council (NERC; grant nos, NE/K002473/1, NE/N018699/1). BOUSSOLE is funded by the European Space Agency (ESA/ESRIN contracts 4000102992/11/I-NB and 4000111801/14/I-NB) and the Centre National d’Etudes Spatiales (CNES), and this particular study is funded through a grant from the Agence Nationale de la Recherche (ANR, Paris) to the Bio-optics and Carbon Experiment (BIOCAREX).
Uncontrolled Keywords: oceanography,palaeontology ,/dk/atira/pure/subjectarea/asjc/1900/1910
Faculty \ School: Faculty of Science
Faculty of Science > School of Environmental Sciences
Related URLs:
Depositing User: LivePure Connector
Date Deposited: 03 Sep 2022 00:22
Last Modified: 28 Sep 2022 08:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/87691
DOI: 10.5194/os-18-1245-2022

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