TY - JOUR T1 - 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 A1 - Barbieux,Marie A1 - Uitz,Julia A1 - Mignot,Alexandre A1 - Roesler,Collin A1 - Claustre,Hervé A1 - Gentili,Bernard A1 - Taillandier,Vincent A1 - D'Ortenzio,Fabrizio A1 - Loisel,Hubert A1 - Poteau,Antoine A1 - Leymarie,Edouard A1 - Penkerc'h,Christophe A1 - Schmechtig,Catherine A1 - Bricaud,Annick AD - CNRS and Sorbonne Université, Laboratoire d’Océanographie de Villefranche, LOV, 06230 Villefranche-sur-Mer, France AD - Mercator Océan, 31520 Ramonville-Saint-Agne, France AD - Bowdoin College, Earth and Oceanographic Science, Brunswick, Maine 04011, USA AD - Université Littoral Côte d’Opale, Université Lille, CNRS, Laboratoire d’Océanologie et de Géosciences, 59000 Lille, France AD - OSU Ecce Terra, UMS 3455, CNRS and Sorbonne Université, Paris 6, 4 place Jussieu, 75252 Paris CEDEX 05, France UR - https://archimer.ifremer.fr/doc/00750/86247/ DO - 10.5194/bg-2021-123 N2 - 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. Y1 - 2022 PB - Copernicus GmbH JF - Biogeosciences SN - 1726-4189 VL - 19 IS - 4 SP - 1165 EP - 1194 ID - 86247 ER -