Respiration Patterns in the Dark Ocean
Sulpis, Olivier; Trossman, David s.; Holzer, Mark; Jeansson, Emil; Lauvset, Siv k.; Middelburg, Jack J.
(2023) Global Biogeochemical Cycles, volume 37, issue 8
(Article)
Abstract
In the dark ocean, respiring organisms are the main sink for dissolved oxygen. The respiration rate in a given seawater volume can be quantified through dissolved oxygen drawdown or organic matter consumption as a function of time. Estimates of dissolved oxygen utilization rates (OUR) abound in the literature, but are
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typically obtained using proxies of questionable accuracy, often with low vertical resolution, and neglecting key regions such as the Southern and Indian oceans. Respiration rates based on particulate (POC) or dissolved (DOC) organic carbon are also sparsely observed and for DOC are unavailable in many regions. Consequently, the relative contributions of POC or DOC as a respiration substrate in the dark ocean are unknown. Here, we use recent datasets of true oxygen utilization, seawater age, and DOC to derive OUR and DOC consumption-rate profiles in 10 oceanic regions. We demonstrate that although DOC and POC consumption rates are globally consistent with OUR, they underestimate OUR in the deep, suggesting strong oxygen utilization at the seafloor. In the abyss, we find a negative correlation of the DOC consumption rate with seawater age, suggesting that DOC reactivity decreases along the deep branch of the conveyor circulation. Our results highlight that benthic organisms are sensitive to perturbations in the surface production of organic matter and to large-scale circulation changes that affect its supply to the abyss.
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Keywords: ocean, oxygen, utilization, organic, carbon, respiration
ISSN: 0886-6236
Publisher: American Geophysical Union
Note: Funding Information: This manuscript has benefited from discussions with many colleagues, in particular, members of the SCOR working group 161 ReMO (Respiration in Mesopelagic Ocean). We thank all of those who contributed to the creation of GLODAPv2 (Key et al., 2015 ; Lauvset et al., 2016 ; Olsen et al., 2016 ), the dissolved organic matter data set (Hansell et al., 2021 ), the particulate flux data set (Mouw et al., 2016 ), as well as the TTD age (Jeansson et al., 2021 ) and C age (Gebbie & Huybers, 2012 ) products. This study has been conducted using E.U. Copernicus Marine Service Information. This research was supported by the Netherlands Organisation for Scientific Research (NWO‐VENI Grant VI.Veni.212.086 to O.S.) and the Netherlands Earth System Science Center. D.S.T. was supported by the Cooperative Institute for Climate, Ocean, & Ecosystem Studies (CISESS) at the University of Maryland/ESSIC. M. H. acknowledges funding from Australian Research Council (ARC) Grant DP210101650. S.K.L. funding from the European Union's Horizon 2020 research and innovation programme under the project OceanICU (grant agreement No 101083922). E.J. acknowledges funding from the Bjerknes Centre for Climate Research strategic project DYNASOR. 14 Funding Information: This manuscript has benefited from discussions with many colleagues, in particular, members of the SCOR working group 161 ReMO (Respiration in Mesopelagic Ocean). We thank all of those who contributed to the creation of GLODAPv2 (Key et al., 2015; Lauvset et al., 2016; Olsen et al., 2016), the dissolved organic matter data set (Hansell et al., 2021), the particulate flux data set (Mouw et al., 2016), as well as the TTD age (Jeansson et al., 2021) and 14C age (Gebbie & Huybers, 2012) products. This study has been conducted using E.U. Copernicus Marine Service Information. This research was supported by the Netherlands Organisation for Scientific Research (NWO-VENI Grant VI.Veni.212.086 to O.S.) and the Netherlands Earth System Science Center. D.S.T. was supported by the Cooperative Institute for Climate, Ocean, & Ecosystem Studies (CISESS) at the University of Maryland/ESSIC. M. H. acknowledges funding from Australian Research Council (ARC) Grant DP210101650. S.K.L. funding from the European Union's Horizon 2020 research and innovation programme under the project OceanICU (grant agreement No 101083922). E.J. acknowledges funding from the Bjerknes Centre for Climate Research strategic project DYNASOR. Publisher Copyright: © 2023. The Authors.
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