Low-oxygen environments and deoxygenation in open and coastal marine waters
Low-oxygen environments and deoxygenation in open and coastal marine waters
Editor(s): Marilaure Grégoire, Sean A. Crowe, Véronique Garçon, Lisa Levin, Andreas Oschlies, Michael Roman, Caroline P. Slomp, and Kenneth Rose
Oxygen (O2) is considered an effective indicator of ocean health and climate change. Its level, distribution and variability from sub-seasonal to multidecadal scales provide relevant information on the physical and biogeochemical functioning of the ocean and often act to constrain life in the ocean.

Current evidence indicates that the coastal (i.e., most directly influenced by land) and open-ocean areas have been losing O2 since the middle of the last century, with consequences for living organisms and biogeochemical cycles that are not yet fully understood. In the open ocean the O2 inventory has decreased by a few percent (i.e., 0.5–3%), and oxygen minimum zones (OMZs) are expanding, which is primarily attributed to global warming, although a quantitative understanding is still lacking. The number of hypoxic coastal sites has increased, predominantly in response to worldwide eutrophication, yet trends in deoxygenation in the global coastal zone remain ill-defined.

The development and extension of low-O2 concentration areas degrade the living conditions and contract the metabolically viable habitat for a large number of pelagic, mesopelagic, and benthic organisms. The effects on individuals exposed to low O2 can result in altered foodweb structures.

Deoxygenation affects many aspects of the ecosystem services provided by the ocean and coastal waters. For example, deoxygenation effects on fisheries include low oxygen affecting populations through reduced recruitment and population abundance and also through altered spatial distributions of the harvested species causing changes in fishing activity. This can lead to changes in the profitability of the fisheries and can affect the interpretation of the monitoring data, leading to misinformed management advice.

Model simulations for this century project a decrease in oxygen under both high- and low-CO2 emission scenarios, while the projections of the coastal ocean at the land–ocean interface indicate that eutrophication will likely continue in many regions of the world. Warming is expected to further amplify deoxygenation in coastal areas influenced by eutrophication by strengthening and extending stratification.

This special issue will investigate new developments and insights related to low-oxygen environments and deoxygenation in open and coastal waters.

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21 Sep 2023
Ocean models as shallow sea oxygen deficiency assessment tools: from research to practical application
Sarah Piehl, René Friedland, Thomas Neumann, and Gerald Schernewski
Biogeosciences Discuss., https://doi.org/10.5194/bg-2023-152,https://doi.org/10.5194/bg-2023-152, 2023
Preprint under review for BG (discussion: open, 0 comments)
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23 Aug 2023
Ideas and perspectives: The fluctuating nature of oxygen shapes the ecology of aquatic habitats and their biogeochemical cycles – the aquatic oxyscape
Marco Fusi, Sylvain Rigaud, Giovanna Guadagnin, Alberto Barausse, Ramona Marasco, Daniele Daffonchio, Julie Régis, Louison Huchet, Capucine Camin, Laura Pettit, Cristina Vina-Herbon, and Folco Giomi
Biogeosciences, 20, 3509–3521, https://doi.org/10.5194/bg-20-3509-2023,https://doi.org/10.5194/bg-20-3509-2023, 2023
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23 Aug 2023
Linking northeastern North Pacific oxygen changes to upstream surface outcrop variations
Sabine Mecking and Kyla Drushka
Biogeosciences Discuss., https://doi.org/10.5194/bg-2023-132,https://doi.org/10.5194/bg-2023-132, 2023
Preprint under review for BG (discussion: open, 3 comments)
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17 Aug 2023
Benthic foraminifera and gromiids from oxygen-depleted environments – survival strategies, biogeochemistry and trophic interactions
Nicolaas Glock
Biogeosciences, 20, 3423–3447, https://doi.org/10.5194/bg-20-3423-2023,https://doi.org/10.5194/bg-20-3423-2023, 2023
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11 Jul 2023
The fate of fixed nitrogen in Santa Barbara Basin sediments during seasonal anoxia
Xuefeng Peng, David J. Yousavich, Annie Bourbonnais, Frank Wenzhoefer, Felix Janssen, Tina Treude, and David L. Valentine
EGUsphere, https://doi.org/10.5194/egusphere-2023-1498,https://doi.org/10.5194/egusphere-2023-1498, 2023
Preprint under review for BG (discussion: open, 0 comments)
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27 Jun 2023
Impact of deoxygenation and warming on global marine species in the 21st century
Anne L. Morée, Tayler M. Clarke, William W. L. Cheung, and Thomas L. Frölicher
Biogeosciences, 20, 2425–2454, https://doi.org/10.5194/bg-20-2425-2023,https://doi.org/10.5194/bg-20-2425-2023, 2023
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26 Jun 2023
Vertical mixing alleviates autumnal oxygen deficiency in the central North Sea
Charlotte Williams, Tom Hull, Matthew Palmer, Claire Mahaffey, Naomi Greenwood, Jan Kaiser, and Matthew Toberman
Biogeosciences Discuss., https://doi.org/10.5194/bg-2023-100,https://doi.org/10.5194/bg-2023-100, 2023
Revised manuscript under review for BG (discussion: final response, 4 comments)
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19 Jun 2023
Marine anoxia initiates giant sulfur-bacteria mat proliferation and associated changes in benthic nitrogen, sulfur, and iron cycling in the Santa Barbara Basin, California Borderland
David J. Yousavich, De'Marcus Robinson, Xuefeng Peng, Sebastian J. E. Krause, Frank Wenzhoefer, Felix Janßen, Na Liu, Jonathan Tarn, Frank Kinnaman, David L. Valentine, and Tina Treude
EGUsphere, https://doi.org/10.5194/egusphere-2023-1198,https://doi.org/10.5194/egusphere-2023-1198, 2023
Preprint under review for BG (discussion: final response, 2 comments)
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31 May 2023
Intra-scenario variability of trends and controls of near-bed oxygen concentration on the Northwest European Continental Shelf under climate change
Giovanni Galli, Sarah Wakelin, James Harle, Jason Holt, and Yuri Artioli
EGUsphere, https://doi.org/10.5194/egusphere-2023-1049,https://doi.org/10.5194/egusphere-2023-1049, 2023
Revised manuscript under review for BG (discussion: final response, 6 comments)
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26 May 2023
Impacts and uncertainties of climate-induced changes in watershed inputs on estuarine hypoxia
Kyle E. Hinson, Marjorie A. M. Friedrichs, Raymond G. Najjar, Maria Herrmann, Zihao Bian, Gopal Bhatt, Pierre St-Laurent, Hanqin Tian, and Gary Shenk
Biogeosciences, 20, 1937–1961, https://doi.org/10.5194/bg-20-1937-2023,https://doi.org/10.5194/bg-20-1937-2023, 2023
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25 May 2023
Unique ocean circulation pathways reshape the Indian Ocean oxygen minimum zone with warming
Sam Ditkovsky, Laure Resplandy, and Julius Busecke
EGUsphere, https://doi.org/10.5194/egusphere-2023-1082,https://doi.org/10.5194/egusphere-2023-1082, 2023
Revised manuscript under review for BG (discussion: final response, 6 comments)
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10 May 2023
Revisiting the applicability and constraints of molybdenum and uranium-based paleo redox proxies: comparing two contrasting sill fjords
K. Mareike Paul, Martijn Hermans, Sami A. Jokinen, Inda Brinkmann, Helena L. Filipsson, and Tom Jilbert
Biogeosciences Discuss., https://doi.org/10.5194/bg-2023-83,https://doi.org/10.5194/bg-2023-83, 2023
Preprint under review for BG (discussion: final response, 4 comments)
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03 May 2023
Underestimation of global O2 loss in optimally interpolated historical ocean observations
Takamitsu Ito, Hernan E. Garcia, Zhankun Wang, Shoshiro Minobe, Matthew C. Long, Just Cebrian, James Reagan, Tim Boyer, Christopher Paver, Courtney Bouchard, Yohei Takano, Seth Bushinsky, Ahron Cervania, and Curtis A. Deutsch
Biogeosciences Discuss., https://doi.org/10.5194/bg-2023-72,https://doi.org/10.5194/bg-2023-72, 2023
Preprint under review for BG (discussion: final response, 4 comments)
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26 Apr 2023
Oceanographic Processes Favoring Deoxygenation Inside Patagonian Fjords
Pamela Linford, Iván Pérez-Santos, Paulina Montero, Patricio Díaz, Claudia Aracena, Elías Pinilla, Facundo Barrera, Manuel Castillo, Aida Alvera-Azcárate, Mónica Alvarado, Gabriel Soto, Cécile Pujol, Camila Schwerter, Sara Arenas-Uribe, Pilar Navarro, Guido Mancilla-Gutiérrez, Robinson Altamirano, Javiera San Martín, and Camila Soto-Riquelme
EGUsphere, https://doi.org/10.5194/egusphere-2023-706,https://doi.org/10.5194/egusphere-2023-706, 2023
Revised manuscript under review for BG (discussion: final response, 6 comments)
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25 Apr 2023
Deoxygenation of the Gulf of Mexico thermocline linked to a decrease in the detachment frequency of Loop Current Eddies
José Gerardo Quintanilla, Juan Carlos Herguera, and Julio Sheinbaum
EGUsphere, https://doi.org/10.5194/egusphere-2023-751,https://doi.org/10.5194/egusphere-2023-751, 2023
Preprint under review for BG (discussion: final response, 5 comments)
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31 Mar 2023
Marked recent declines in boron in Baltic Sea cod otoliths – a bellwether of incipient acidification in a vast hypoxic system?
Karin E. Limburg, Yvette Heimbrand, and Karol Kuliński
EGUsphere, https://doi.org/10.5194/egusphere-2023-512,https://doi.org/10.5194/egusphere-2023-512, 2023
Revised manuscript under review for BG (discussion: final response, 4 comments)
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24 Feb 2023
Temporal and spatial evolution of bottom-water hypoxia in the St Lawrence estuarine system
Mathilde Jutras, Alfonso Mucci, Gwenaëlle Chaillou, William A. Nesbitt, and Douglas W. R. Wallace
Biogeosciences, 20, 839–849, https://doi.org/10.5194/bg-20-839-2023,https://doi.org/10.5194/bg-20-839-2023, 2023
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14 Dec 2022
Iron “Ore” Nothing: Benthic iron fluxes from the oxygen-deficient Santa Barbara Basin enhance phytoplankton productivity in surface waters
De’Marcus Robinson, Anh L. D. Pham, David J. Yousavich, Felix Janssen, Frank Wenzhöfer, Eleanor C. Arrington, Kelsey M. Gosselin, Marco Sandoval-Belmar, Matthew Mar, David L. Valentine, Daniele Bianchi, and Tina Treude
Biogeosciences Discuss., https://doi.org/10.5194/bg-2022-237,https://doi.org/10.5194/bg-2022-237, 2022
Revised manuscript under review for BG (discussion: final response, 5 comments)
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