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

Stéphanie Jacquet (1) , Dominique Lefèvre (1) , Christian Tamburini (1) , Marc Garel (1) , Frédéric A.C. Le Moigne (1) , Nagib Bhairy (1) , Sophie Guasco (1)

1 MIO - Institut méditerranéen d'océanologie

Abstract. In 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.

Domaines: Océan, Atmosphère

Stéphanie Jacquet, Dominique Lefèvre, Christian Tamburini, Marc Garel, Frédéric A.C. Le Moigne, et al.. On the barium–oxygen consumption relationship in the Mediterranean Sea: implications for mesopelagic marine snow remineralization. Biogeosciences, 2021, 18 (6), pp.2205-2212. ⟨10.5194/bg-18-2205-2021⟩. ⟨hal-03357294⟩