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MINI REVIEW article

Front. Mar. Sci.
Sec. Marine Biogeochemistry
Volume 11 - 2024 | doi: 10.3389/fmars.2024.1425250

Monitoring low-oxygen-adapted subsurface phytoplankton distribution in a changing ocean

Provisionally accepted
Isabelle Cox Isabelle Cox 1*Bob Brewin Bob Brewin 1Katy Sheen Katy Sheen 1Giorgio Dall'Olmo Giorgio Dall'Olmo 2Osvaldo Ulloa Osvaldo Ulloa 3,4
  • 1 Centre for Geography and Environmental Science, Department of Earth and Environmental Science, University of Exeter, Penryn, United Kingdom
  • 2 National Institute of Oceanography and Applied Geophysics – OGS, Sgonico, Italy
  • 3 Department of Oceanography, Faculty of Natural and Oceanographic Sciences, University of Concepción, Concepción, VIII Biobío Region, Chile
  • 4 Millennium Institute of Oceanography, University of Concepción, Concepción, VIII Biobío Region, Chile

The final, formatted version of the article will be published soon.

    Recent decadal trends of deoxygenation in the global ocean interior have resulted in the expansion and shoaling of oxygen minimum zones (OMZs). When the OMZs upper bound nears the euphotic zone a unique community of phytoplankton, residing in extremely low light (~0.04% surface irradiance; Cox et al., 2023) and dissolved oxygen concentrations (<5 μmol kg^(-1)), can appear. In this mini-review paper we synthesize our current understanding of the phytoplankton community that resides in an OMZ chlorophyll maximum (OMZ-CM), below the depths of the deep chlorophyll maximum found in permanently and seasonally stratified regions, and its role in OMZ biogeochemical cycles. Uncultivated basal lineages of the cyanobacterium Prochlorococcus dominate this community, forming an OMZ-CM that can contribute to integrated stocks of chlorophyll a, in some cases with a similar magnitude to the deep chlorophyll maximum. Photosynthesis by Prochlorococcus in the OMZ-CM provides a significant source of oxygen, that fuels the aerobic oxidation of nitrite and organic matter, impacting elemental biogeochemical cycling, including that of carbon and nitrogen. Yet, on a global scale, there is a lack of understanding and quantification of the spatial distribution of these OMZ-CM, their stocks of phytoplankton, their influence on fluxes of carbon and nitrogen, and how these may respond to climate change. Monitoring the dynamics of the OMZ-CM and biogeochemical cycles in OMZs is challenging, and requires a multidisciplinary approach, combining ship-based observations with autonomous platforms, satellite data, and conceptual models. Only then can the implications of enhanced deoxygenation on the future marine ecosystem be understood.

    Keywords: Phytoplankton, Oxygen, Monitoring, Climate Change, Cyanobacteria

    Received: 29 Apr 2024; Accepted: 03 Sep 2024.

    Copyright: © 2024 Cox, Brewin, Sheen, Dall'Olmo and Ulloa. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Isabelle Cox, Centre for Geography and Environmental Science, Department of Earth and Environmental Science, University of Exeter, Penryn, United Kingdom

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.