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| Choquel, Constance; Geslin, Emmanuelle; Metzger, Edouard; Filipsson, Helena L.; Risgaard-petersen, Nils; Launeau, Patrick; Giraud, Manuel; Jauffrais, Thierry; Jesus, Bruno; Mouret, Aurélia. |
| Oxygen availability impacts the marine nitrogen cycle at a range of spatial and temporal scales. Invasive organisms have shown to sustainably affect sediment geochemistry and benthic ecology. Nonionella sp. T1 was recently described as an invasive benthic foraminifer in the North Sea region. Here, we demonstrate the impact of this denitrifying species on the foraminifera fauna and the nitrogen cycle of the Gullmar Fjord (Sweden). The foraminifera contribution to benthic denitrification was estimated by coupling living foraminifera micro-distribution, denitrification rate measurement and sedimentary nitrate 2D distribution. Nonionella sp. T1 dominated the foraminifera fauna and could denitrify up to 50–100 % of nitrate porewater in oxygenated bottom waters... |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00643/75482/76327.pdf |
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| Jauffrais, Thierry; Jesus, Bruno; Metzger, Edouard; Mouget, Jean-luc; Jorissen, Frans; Geslin, Emmanuelle. |
| 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 mot 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.... |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00457/56899/58754.pdf |
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| Jauffrais, Thierry; Lekieffre, Charlotte; Schweizer, Magali; Geslin, Emmanuelle; Metzger, Edouard; Bernhard, Joan M.; Jesus, Bruno; Filipsson, Helena L.; Maire, Olivier; Meibom, Anders. |
| The assimilation of inorganic compounds in foraminiferal metabolism compared to predation or organic matter assimilation is unknown. Here we investigate possible inorganic‐compound assimilation in Nonionellina labradorica, a common kleptoplastidic benthic foraminifer from Arctic and North Atlantic sublittoral regions. The objectives were to identify the source of the foraminiferal kleptoplasts, assess their photosynthetic functionality in light and darkness, and investigate inorganic nitrogen and sulfate assimilation. We used DNA barcoding of a ~830 bp fragment from the SSU rDNA to identify the kleptoplasts, and correlated transmission electron microscopy and nanometer‐scale secondary ion mass spectrometry (TEM‐NanoSIMS) isotopic imaging to study... |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00460/57188/59151.pdf |
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| Jauffrais, Thierry; Lekieffre, Charlotte; Schweizer, Magali; Jesus, Bruno; Metzger, Edouard; Geslin, Emmanuelle. |
| The aim of this work is to document the complex nutritional strategy developed by kleptoplastic intertidal foraminifera. We study the mixotrophic ability of a common intertidal foraminifer, E. williamsoni, by (1) investigating the phylogenetic identity of the foraminiferal kleptoplasts, (2) following their oxygenic photosynthetic capacity, and (3) observing the modification in cellular ultrastructural features in response to photoautotrophic conditions. This was achieved by coupling molecular phylogenetic analyses and TEM observations with non-destructive measurements of kleptoplast O2 production over a 15-day experimental study. Results show that the studied E. williamsoni actively selected kleptoplasts mainly from pennate diatoms and had the ability to... |
| Tipo: Text |
Palavras-chave: Foraminifera; Electron microscopy; DNA barcoding; Kleptoplasty; Lipids. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00487/59894/63074.pdf |
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| Androuin, Thibault; Polerecky, Lubos; Decottignies, Priscilla; Dubois, Stanislas; Dupuy, Christine; Hubas, Cedric; Jesus, Bruno; Le Gall, Erwan; Marzloff, Martin; Carlier, Antoine. |
| The slipper limpet Crepidula fornicata is an emblematic invasive species along the northeast Atlantic coast. This gregarious gastropod lives in stacks of several individuals and forms extended beds in shallow subtidal areas. The effects of this engineer species on the colonized habitat can be physical (e.g., presence of hard-shell substrates with uneven topography) or biological (e.g., nutrient enrichment by direct excretion or via biodeposition). We hypothesized that through biological activity, nutrient fluxes at the sediment-water interface are enhanced, leading to stimulated primary productivity by microphytobenthos (MPB) associated with Crepidula beds. To test this fertilization hypothesis, we conducted a 10-day mesocosm experiment using C. fornicata... |
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Palavras-chave: Crepidula fornicata; Engineer species; Subtidal microphytobenthos; Fertilization; Hyperspectral imaging. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00472/58338/60893.pdf |
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