Comment on egusphere-2025-4234

Abstract

Abstract. Pelagic calcifying plankton play an important role in the marine carbon cycle. However, field studies quantifying the contributions of multiple calcifying plankton groups to particulate inorganic carbon (PIC) stocks and export into the ocean interior are scarce. Most studies target one specific plankton group and adjust their sampling strategy accordingly, hampering comparisons. Furthermore, the literature is strongly biased towards foraminifera and coccolithophores, so aragonite contributions (e.g., gastropods) remain virtually unconstrained. A holistic view is required for future projections of marine carbon cycle changes. Here, we present the contributions of three main calcifying plankton groups – coccolithophores, foraminifera and planktonic gastropods (comprising heteropods and pteropods) – to PIC stocks and fluxes throughout the water column during a sampling campaign in the South Atlantic Ocean. Coccolithophore calcite dominated the depth-integrated PIC standing stock (~80 %), followed by aragonite from planktonic gastropods (~17 %) and calcite from foraminifera (~3 %). The estimated production and export of the calcifying plankton largely depend on assumed turnover times and sinking speeds, which both have large uncertainties. Coccolithophores contributed 92 % of the produced PIC and from 52 to 99 % of the exported PIC, depending on their mode of sinking. Both the production and export of planktonic gastropods was significantly larger than that of foraminifera. Similarity between our results and those from different ocean basins suggests that these patterns are global in nature, implying that not only coccolithophores but also gastropods may be more important PIC producers than foraminifera, challenging a longstanding paradigm.

Authors 13

1. Anne Kruijt corresponding

   Utrecht University

   Affiliation as printed

   Department of Earth Sciences, Faculty of Geosciences, Utrecht University, The Netherlands

2. Olivier Sulpis

   Centre National de la Recherche Scientifique · Aix-Marseille Université · Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement · Centre de Recherche et d’Enseignement de Géosciences de l’Environnement · Institut de Recherche pour le Développement

   Affiliation as printed

   Aix-Marseille Université, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France

3. Luc Beaufort

   Centre National de la Recherche Scientifique · Aix-Marseille Université · Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement · Centre de Recherche et d’Enseignement de Géosciences de l’Environnement · Institut de Recherche pour le Développement

   Affiliation as printed

   Aix-Marseille Université, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France

4. Guillaume Lassus

   Centre National de la Recherche Scientifique · Aix-Marseille Université · Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement · Centre de Recherche et d’Enseignement de Géosciences de l’Environnement · Institut de Recherche pour le Développement

   Affiliation as printed

   Aix-Marseille Université, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France

5. Geert-Jan Brummer

   Royal Netherlands Institute for Sea Research

   Affiliation as printed

   Department of Ocean Systems, NIOZ Royal Netherlands Institute for Sea Research, PO Box 59, 1790 AB Den Burg (Texel), the Netherlands

6. A. Daniëlle van der Burg Aachen Marine Evolution and Ecology Naturalis Biodiversity Center now at: Department of Environmental Biology Institute of Environmental Sciences (CML)

   Leiden University · Naturalis Biodiversity Center

   Affiliation as printed

   Marine Evolution and Ecology, Naturalis Biodiversity Center, Leiden, the Netherlands

   now at: Department of Environmental Biology, Institute of Environmental Sciences, Leiden University, Leiden, the Netherlands

7. Ben A. Cala

   Utrecht University · Royal Netherlands Institute for Sea Research

   Affiliation as printed

   Department of Earth Sciences, Faculty of Geosciences, Utrecht University, The Netherlands

   Department of Ocean Systems, NIOZ Royal Netherlands Institute for Sea Research, PO Box 59, 1790 AB Den Burg (Texel), the Netherlands

8. Yasmina Ourradi

   Royal Netherlands Institute for Sea Research

   Affiliation as printed

   Department of Ocean Systems, NIOZ Royal Netherlands Institute for Sea Research, PO Box 59, 1790 AB Den Burg (Texel), the Netherlands

9. Katja T. C. A. Peijnenburg Aachen Marine Evolution and Ecology Naturalis Biodiversity Center

   Naturalis Biodiversity Center · University of Amsterdam

   Affiliation as printed

   Freshwater and Marine Ecology, Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, Amsterdam, the Netherlands

   Marine Evolution and Ecology, Naturalis Biodiversity Center, Leiden, the Netherlands

10. Matthew Paul Humphreys

    Royal Netherlands Institute for Sea Research

    Affiliation as printed

    Department of Ocean Systems, NIOZ Royal Netherlands Institute for Sea Research, PO Box 59, 1790 AB Den Burg (Texel), the Netherlands

11. Sonia Chaabane

    Centre National de la Recherche Scientifique · Aix-Marseille Université · Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement · Centre de Recherche et d’Enseignement de Géosciences de l’Environnement · Institut de Recherche pour le Développement

    Affiliation as printed

    Aix-Marseille Université, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France

12. Appy Sluijs

    Utrecht University

    Affiliation as printed

    Department of Earth Sciences, Faculty of Geosciences, Utrecht University, The Netherlands

13. Jack J. Middelburg

    Utrecht University

    Affiliation as printed

    Department of Earth Sciences, Faculty of Geosciences, Utrecht University, The Netherlands