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

• Published in: Biogeosciences
• Main Authors: S. H. M. Jacquet, D. Lefèvre, C. Tamburini, M. Garel, F. A. C. Le Moigne, N. Bhairy, S. Guasco
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2021
• Subjects: Ecology; QH540-549.5; Life; QH501-531; Geology; QE1-996.5; Southern Ocean
• Online Access: https://doi.org/10.5194/bg-18-2205-2021; https://doaj.org/article/9c0e30fbaf554e6894e2a74b9b333c98

In the ocean, remineralization rate associated with sinking particles is a crucial variable. Since the 1990s, particulate biogenic barium ( Ba xs ) has been used as an indicator of carbon remineralization by applying a transfer function relating Ba xs to O 2 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 Ba xs , prokaryotic heterotrophic production (PHP) and oxygen consumption ( JO 2 -Opt; optodes measurement). We show that (1) higher Ba xs (409 pM; 100–500 m) occurs in situations where integrated PHP (PHP <math xmlns="http://www.w3.org/1998/Math/MathML" id="M7" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">100</mn><mo>/</mo><mn mathvariant="normal">500</mn><mo>=</mo><mn mathvariant="normal">0.90</mn></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="78pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="bd671fe71f08f2d46c69f771869d5436"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-18-2205-2021-ie00001.svg" width="78pt" height="14pt" src="bg-18-2205-2021-ie00001.png"/></svg:svg> ) is located deeper, (2) higher Ba xs occurs with increasing JO 2 -Opt, and (3) there is similar magnitude between JO 2 -Opt (3.14 mmol m −2 d −1 175–450 m) and JO 2 -Ba (4.59 mmol m −2 d −1 transfer function). Overall, Ba xs , PHP and JO 2 relationships follow trends observed earlier in the Southern Ocean. We conclude that such a transfer function could apply in the Mediterranean Sea.