Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 13, issue 9
Biogeosciences, 13, 2715–2726, 2016
https://doi.org/10.5194/bg-13-2715-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 13, 2715–2726, 2016
https://doi.org/10.5194/bg-13-2715-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 10 May 2016

Research article | 10 May 2016

Effect of light on photosynthetic efficiency of sequestered chloroplasts in intertidal benthic foraminifera (Haynesina germanica and Ammonia tepida)

Thierry Jauffrais1,*, Bruno Jesus2,3,*, Edouard Metzger1, Jean-Luc Mouget4, Frans Jorissen1, and Emmanuelle Geslin1 Thierry Jauffrais et al.
  • 1UMR CNRS 6112 LPG-BIAF, Bio-Indicateurs Actuels et Fossiles, Université d'Angers, 2 Boulevard Lavoisier, 49045 Angers CEDEX 1, France
  • 2EA2160, Laboratoire Mer Molécules Santé, 2 rue de la Houssinière, Université de Nantes, 44322 Nantes CEDEX 3, France
  • 3BioISI – Biosystems & Integrative Sciences Institute, Campo Grande University of Lisboa, Faculty of Sciences, 1749-016 Lisboa, Portugal
  • 4EA2160, Laboratoire Mer Molécules Santé, Université du Maine, Ave O. Messiaen, 72085 Le Mans CEDEX 9, France
  • *These authors contributed equally to this work.

Abstract. Some benthic foraminifera have the ability to incorporate functional chloroplasts from diatoms (kleptoplasty). Our objective was to investigate chloroplast functionality of two benthic foraminifera (Haynesina germanica and Ammonia tepida) exposed to different irradiance levels (0, 25, 70 µmol photon m−2 s−1) using spectral reflectance, epifluorescence observations, oxygen evolution and pulse amplitude modulated (PAM) fluorometry (maximum photosystem II quantum efficiency (Fv/Fm) and rapid light curves (RLC)). Our results clearly showed that H. germanica was capable of using its kleptoplasts for more than 1 week while A. tepida showed very limited kleptoplastic ability with maximum photosystem II quantum efficiency (Fv/Fm  =  0.4), much lower than H. germanica and decreasing to zero in only 1 day. Only H. germanica showed net oxygen production with a compensation point at 24 µmol photon m−2 s−1 and a production up to 1000 pmol O2 cell−1 day−1 at 300 µmol photon m−2 s−1. Haynesina germanica Fv/Fm slowly decreased from 0.65 to 0.55 in 7 days when kept in darkness; however, it quickly decreased to 0.2 under high light. Kleptoplast functional time was thus estimated between 11 and 21 days in darkness and between 7 and 8 days at high light. These results emphasize that studies about foraminifera kleptoplasty must take into account light history. Additionally, this study showed that the kleptoplasts are unlikely to be completely functional, thus requiring continuous chloroplast resupply from foraminifera food source. The advantages of keeping functional chloroplasts are discussed but more information is needed to better understand foraminifera feeding strategies.

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Some benthic foraminifera can incorporate chloroplasts from microalgae. We investigated chloroplast functionality of two benthic foraminifera (Haynesina germanica & Ammonia tepida) exposed to different light levels. Only H. germanica was capable of using the kleptoplasts, showing net oxygen production. Chloroplast functionality time was longer in darkness (2 weeks) than at high light (1 week). Kleptoplasts are unlikely to be completely functional, thus requiring continuous chloroplast resupply.
Some benthic foraminifera can incorporate chloroplasts from microalgae. We investigated...
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