Differential Sensitivity of a Symbiont-Bearing Foraminifer to Seawater Carbonate Chemistry in a Decoupled DIC-pH Experiment

Shai Oron, David Evans, Sigal Abramovich, Ahuva Almogi-Labin, Jonathan Erez

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7 Scopus citations

Abstract

Larger benthic foraminifera (LBF) are unicellular eukaryotic calcifying organisms and an important component of tropical and subtropical modern and ancient oceanic ecosystems. They are major calcium carbonate producers and important contributors to primary production due to the photosynthetic activity of their symbiotic algae. Studies investigating the response of LBF to seawater carbonate chemistry changes are therefore essential for understanding the impact of climate changes and ocean acidification (OA) on shallow marine ecosystems. In this study, calcification, respiration, and photosynthesis of the widespread diatom-bearing LBF Operculina ammonoides were measured in laboratory experiments that included manipulation of carbonate chemistry parameters. pH was altered while keeping dissolved inorganic carbon (DIC) constant, and DIC was altered while keeping pH constant. The results show clear vulnerability of O. ammonoides to low pH and CO32− under constant DIC conditions, and no increased photosynthesis or calcification under high DIC concentrations. Our results call into question previous hypotheses, suggesting that mechanisms such as the degree of cellular control on calcification site pH/DIC and/or enhanced symbiont photosynthesis in response to OA may render the hyaline (perforate and calcitic-radial) LBF to be less responsive to OA than porcelaneous LBF. In addition, manipulating DIC did not affect calcification when pH was close to present seawater levels in a model encompassing the total population size range. In contrast, larger individuals (>1,200 μm, >1 mg) were sensitive to changes in DIC, a phenomenon we attribute to their physiological requirement to concentrate large quantities of DIC for their calcification process.

Original languageEnglish
Article numbere2020JG005726
JournalJournal of Geophysical Research: Biogeosciences
Volume125
Issue number9
DOIs
StatePublished - 1 Sep 2020
Externally publishedYes

Bibliographical note

Publisher Copyright:
©2020. American Geophysical Union. All Rights Reserved.

Funding

We wish to express our gratitude to the staff and students of the Institute of Earth Sciences at the Hebrew University of Jerusalem, and the Interuniversity Institute for Marine Sciences in Eilat. We also wish to thank two anonymous reviewers for their very constructive comments. This work was supported by the Israel Science Foundation (ISF) Grant No. 941/17 to S. A., Ben Gurion University of the Negev, and ISF Grant No. 551/10 to J. E., Hebrew University of Jerusalem. We wish to express our gratitude to the staff and students of the Institute of Earth Sciences at the Hebrew University of Jerusalem, and the Interuniversity Institute for Marine Sciences in Eilat. We also wish to thank two anonymous reviewers for their very constructive comments. This work was supported by the Israel Science Foundation (ISF) Grant No. 941/17 to S. A., Ben Gurion University of the Negev, and ISF Grant No. 551/10 to J. E., Hebrew University of Jerusalem.

FundersFunder number
Interuniversity Institute for Marine Sciences in Eilat
Israel Science Foundation941/17
Ben-Gurion University of the Negev551/10
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    Keywords

    • Operculina ammonoides
    • benthic foraminifera
    • calcification
    • climate change
    • ocean acidification

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