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| Sarazin, Gérard; Jezequel, Didier; Leboulanger, Christophe; Fouilland, Eric; Le Floc'H, Emilie; Bouvy, Marc; Gerard, Emmanuelle; Agogué, Hélène; Bernard, Cédric; Hugoni, Mylène; Grossi, Vincent; Trousselier, Marc; Ader, Magali. |
| Dziani Dzaha is a maar the age of which is close to 4000 years. While its water is thought to have originated from seawater it is now considered as an extreme environment due to its hypersaline and alkaline characteristics. Those extreme features have led to the simplification of the trophic network. Cyanobacteria account for up to 95% of the photosynthetic biomass. The main biogeochemical processes, i.e. photosynthesis, bacterial sulfate reduction and methanogenesis could explain the current water composition. As far as we know, this ecosystem could be unique on Earth, extending the nature and chemical limits of aquatic inland ecosystems |
| Tipo: Text |
Palavras-chave: Thalassohaline lake; Endorheic ecosystem; Cyanobacteria; Methane emission; Biogeochemistry; Mayotte. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00667/77948/80128.pdf |
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| Gerard, Emmanuelle; De Goeyse, Siham; Hugoni, Mylene; Agogue, Helene; Richard, Laurent; Milesi, Vincent; Guyot, Francois; Lecourt, Lena; Borensztajn, Stephan; Joseph, Marie-beatrice; Leclerc, Thomas; Sarazin, Gerard; Jezequel, Didier; Leboulanger, Christophe; Ader, Magali. |
| Lake Dziani Dzaha is a thalassohaline tropical crater lake located on the "Petite Terre" Island of Mayotte (Comoros archipelago, Western Indian Ocean). Stromatolites are actively growing in the shallow waters of the lake shores. These stromatolites are mainly composed of aragonite with lesser proportions of hydromagnesite, calcite, dolomite, and phyllosilicates. They are morphologically and texturally diverse ranging from tabular covered by a cauliflower-like crust to columnar ones with a smooth surface. High-throughput sequencing of bacterial and archaeal 16S rRNA genes combined with confocal laser scanning microscopy (CLSM) analysis revealed that the microbial composition of the mats associated with the stromatolites was clearly distinct from that of the... |
| Tipo: Text |
Palavras-chave: Stromatolites; Alkaline lake; Pleurocapsales; Mg-silicate; Alphaproteobacteria; Anoxygenic phototrophic bacteria; Aragonite; Hydromagnesite. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00443/55451/56970.pdf |
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| Postec, Anne; Quemeneur, Marianne; Bes, Meline; Mei, Nan; Benaissa, Fatma; Payri, Claude; Pelletier, Bernard; Monnin, Christophe; Guentas-dombrowsky, Linda; Ollivier, Bernard; Gerard, Emmanuelle; Pisapia, Celine; Gerard, Martine; Menez, Benedicte; Erauso, Gael. |
| Active carbonate chimneys from the shallow marine serpentinizing Prony Hydrothermal Field were sampled 3 times over a 6 years period at site ST09. Archaeal and bacterial communities composition was investigated using PCR-based methods (clone libraries, Denaturating Gel Gradient Electrophoresis, quantitative PCR) targeting 16S rRNA genes, methyl coenzyme M reductase A and dissimilatory sulfite reductase subunit B genes. Methanosarcinales (Euryarchaeota) and Thaumarchaea were the main archaeal members. The Methanosarcinales, also observed by epifluorescent microscopy and FISH, consisted of two phylotypes that were previously solely detected in two other serpentinitzing ecosystems (The Cedars and Lost City Hydrothermal Field). Surprisingly, members of the... |
| Tipo: Text |
Palavras-chave: Hydrothermal; Serpentinization; Alkaline; Prony; Microbial communities. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00467/57916/60307.pdf |
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| Pisapia, Celine; Gerard, Emmanuelle; Gerard, Martine; Lecourt, Lena; Lang, Susan Q.; Pelletier, Bernard; Payri, Claude E.; Monnin, Christophe; Guentas, Linda; Postec, Anne; Quemeneur, Marianne; Erauso, Gael; Menez, Benedicte. |
| Despite their potential importance as analogs of primitive microbial metabolisms, the knowledge of the structure and functioning of the deep ecosystems associated with serpentinizing environments is hampered by the lack of accessibility to relevant systems. These hyperalkaline environments are depleted in dissolved inorganic carbon (DIC), making the carbon sources and assimilation pathways in the associated ecosystems highly enigmatic. The Prony Bay Hydrothermal Field (PHF) is an active serpentinization site where, similar to Lost City (Mid-Atlantic Ridge), high-pH fluids rich in H-2 and CH4 are discharged from carbonate chimneys at the seafloor, but in a shallower lagoonal environment. This study aimed to characterize the subsurface microbial ecology of... |
| Tipo: Text |
Palavras-chave: Serpentinization; Alkaline hydrothermalism; Deep life; Firmicutes; Acetothermia; Omnitrophica; Organic carbon. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00467/57909/60314.pdf |
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