Bernhard, Joan M., Geslin, Emmanuelle, Schweizer, Magali, Schmidt, Christiane ORCID: https://orcid.org/0000-0001-8461-3485, LeKieffre, Charlotte and Panieri, Giuliana (2025) Chloroplast sequestration by benthic foraminifers in deep-shelf sediments of the high Arctic. Journal of Foraminiferal Research, 55 (4). pp. 397-412. DOI https://doi.org/10.61551/gsjfr.55.4.397.

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Abstract

While foraminiferan protists (single-celled eukaryotes) inhabit a wide variety of habitats and have been doing so for hundreds of millions of years, we still do not fully understand their physiological capabilities. One rather unusual attribute is the ability of certain benthic foraminifera to sequester chloroplasts, which are the photosynthetic organelle of (other) eukaryotes. Such “kleptoplasty” has been documented in approximately 20 foraminifera species, mostly from shallow-water habitats such as mudflats where sunlight is readily available. Kleptoplasty in deeper-water benthic foraminifers is less commonly documented. Sediment cores collected via ROV in 2018 from a ∼380-m deep area off southern Svalbard were sourced for living benthic foraminifera. Foraminifera were identified using DNA barcoding. Using Transmission Electron Microscopy (TEM) and subsequent cellular ultrastructural analysis, we established specimen viability and the presence of sequestered chloroplasts. Eukaryotic microbiomes of these four taxa were also sequenced to investigate the identity of the putative kleptoplast donors. The common benthic foraminifera Buccella sp., Elphidium clavatum (Phylotype Elphidium S4), Nonionellina labradorica, and Robertina arctica contained abundant structurally intact chloroplasts that appear to be of diatom origin based on morphology. While it is known that N. labradorica and some Elphidium species are kleptoplastidic, this is the first report of kleptoplasty for Buccella and Robertina, primary documentation of kleptoplastidic Elphidium living at >375-m water depth, and the first time kleptoplastidic N. labradorica has been noted in a microbial mat of a deep-water hydrocarbon seep. We believe R. arctica represents an unprecedented case of kleptoplasty in an aragonitic benthic foraminifera.

Document Type:	Article
Programme Area:	PA4
Research affiliation:	Biogeochemistry and Geology > Geoecology & Carbonate Sedimentology
Refereed:	Yes
Open Access Journal?:	Yes
DOI:	https://doi.org/10.61551/gsjfr.55.4.397
ISSN:	1943-264X
Date Deposited:	19 Nov 2025 15:22
Last Modified:	19 Nov 2025 15:22
URI:	https://cris.leibniz-zmt.de/id/eprint/6016

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