On the barium–oxygen consumption relationship in the Mediterranean Sea: implications for mesopelagic marine snow remineralization

• Published in: Biogeosciences
• Main Authors: Jacquet, Stéphanie Hm, Lefèvre, Dominique, Tamburini, Christian, Garel, Marc, Le Moigne, Frédéric Ac, Bhairy, Nagib, Guasco, Sophie
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus GmbH 2021
• Subjects: Southern Ocean
• Online Access: https://archimer.ifremer.fr/doc/00648/76038/76959.pdf; https://archimer.ifremer.fr/doc/00648/76038/83021.pdf; https://doi.org/10.5194/bg-18-2205-2021; https://archimer.ifremer.fr/doc/00648/76038/

n the ocean, remineralization rate associated with sinking particles is a crucial variable. Since the 1990s, particulate biogenic barium (Baxs) has been used as an indicator of carbon remineralization by applying a transfer function relating Baxs to O2 consumption (Dehairs's transfer function, Southern Ocean-based). Here, we tested its validity in the Mediterranean Sea (ANTARES/EMSO-LO) for the first time by investigating connections between Baxs, prokaryotic heterotrophic production (PHP) and oxygen consumption (JO2-Opt; optodes measurement). We show that (1) higher Baxs (409 pM; 100–500 m) occurs in situations where integrated PHP (PHP100/500=0.90) is located deeper, (2) higher Baxs occurs with increasing JO2-Opt, and (3) there is similar magnitude between JO2-Opt (3.14 mmol m−2 d−1; 175–450 m) and JO2-Ba (4.59 mmol m−2 d−1; transfer function). Overall, Baxs, PHP and JO2 relationships follow trends observed earlier in the Southern Ocean. We conclude that such a transfer function could apply in the Mediterranean Sea.