Biological production in two contrasted regions of the Mediterranean Sea during the oligotrophic period: An estimate based on the diel cycle of optical properties measured by BGC-Argo profiling floats

Type Article
Date 2022
Language English
Author(s) Barbieux Marie1, Uitz JuliaORCID1, Mignot Alexandre2, Roesler Collin3, Claustre HervéORCID1, Gentili Bernard1, Taillandier Vincent1, D'Ortenzio Fabrizio1, Loisel Hubert4, Poteau AntoineORCID1, Leymarie Edouard1, Penkerc'h Christophe1, Schmechtig CatherineORCID5, Bricaud Annick1
Affiliation(s) 1 : CNRS and Sorbonne Université, Laboratoire d’Océanographie de Villefranche, LOV, 06230 Villefranche-sur-Mer, France
2 : Mercator Océan, 31520 Ramonville-Saint-Agne, France
3 : Bowdoin College, Earth and Oceanographic Science, Brunswick, Maine 04011, USA
4 : Université Littoral Côte d’Opale, Université Lille, CNRS, Laboratoire d’Océanologie et de Géosciences, 59000 Lille, France
5 : OSU Ecce Terra, UMS 3455, CNRS and Sorbonne Université, Paris 6, 4 place Jussieu, 75252 Paris CEDEX 05, France
Source Biogeosciences (1726-4189) (Copernicus GmbH), 2022 , Vol. 19 , N. 4 , P. 1165-1194
DOI 10.5194/bg-2021-123
Note Special issue : Atmospheric deposition in the low-nutrient-low-chlorophyll (LNLC) ocean: effects on marine life today and in the future (BG/ACP inter-journal SI) Editor(s): Christine Klaas, Cecile Guieu, Karine Desboeufs, Jan-Berend Stuut, Mark Moore, Paraskevi Pitta, Silvia Becagli, and Chiara Santinelli Special issue jointly organized between Biogeosciences and Atmospheric Chemistry and Physics

This study assesses marine biological production of organic carbon based on the diel variability of bio-optical properties monitored by two BioGeoChemical-Argo (BGC-Argo) floats. Experiments were conducted in two distinct Mediterranean systems, the Northwestern Ligurian Sea and the Central Ionian Sea during summer months. We derived particulate organic carbon (POC) stock and gross community production integrated within the surface, euphotic and subsurface chlorophyll maximum (SCM) layers, using an existing approach applied to diel cycle measurements of the particulate beam attenuation (cp) and backscattering (bbp) coefficients. The diel cycle of cp provided a robust proxy for quantifying biological production in both systems; that of bbp was comparatively less robust. Derived primary production estimates vary by a factor of 2 depending upon the choice of the bio-optical relationship that converts the measured optical coefficient to POC, which is thus a critical step to constrain. Our results indicate a substantial, yet variable, contribution to the water column production of the SCM layer (16–42%). In the Ligurian Sea, the SCM is a seasonal feature that behaves as a subsurface biomass maximum (SBM) with the ability to respond to episodic abiotic forcing by increasing production. In contrast, in the Ionian Sea, the SCM is permanent, induced by phytoplankton photoacclimation and contributes moderately to water column production. These results emphasize the strong potential for transmissometers deployed on BGC-Argo profiling floats to quantify non-intrusively in situ biological production of organic carbon in the water column of stratified oligotrophic systems with recurring or permanent SCMs, which are widespread features in the global ocean.

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Barbieux Marie, Uitz Julia, Mignot Alexandre, Roesler Collin, Claustre Hervé, Gentili Bernard, Taillandier Vincent, D'Ortenzio Fabrizio, Loisel Hubert, Poteau Antoine, Leymarie Edouard, Penkerc'h Christophe, Schmechtig Catherine, Bricaud Annick (2022). Biological production in two contrasted regions of the Mediterranean Sea during the oligotrophic period: An estimate based on the diel cycle of optical properties measured by BGC-Argo profiling floats. Biogeosciences, 19(4), 1165-1194. Publisher's official version : , Open Access version :