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Bird, Clare; Lekieffre, Charlotte; Jauffrais, Thierry; Meibom, Anders; Geslin, Emmanuelle; Filipsson, Helena L.; Maire, Olivier; Russell, Ann D.; Fehrenbacher, Jennifer S.. |
Nitrogen availability often limits biological productivity in marine systems, where inorganic nitrogen, such as ammonium is assimilated into the food web by bacteria and photoautotrophic eukaryotes. Recently, ammonium assimilation was observed in kleptoplast-containing protists of the phylum foraminifera, possibly via the glutamine synthetase/glutamate synthase (GS/GOGAT) assimilation pathway imported with the kleptoplasts. However, it is not known if the ubiquitous and diverse heterotrophic protists have an innate ability for ammonium assimilation. Using stable isotope incubations (15N-ammonium and 13C-bicarbonate) and combining transmission electron microscopy (TEM) with quantitative nanoscale secondary ion mass spectrometry (NanoSIMS) imaging, we... |
Tipo: Text |
Palavras-chave: Nitrogen cycle; Heterotrophic protists; Foraminifera; Ammonium assimilation; Heterotrophy; Marine. |
Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00662/77421/79087.pdf |
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Mostajir, Behzad; Roques, Cecile; Bouvier, Corinne; Bouvier, Thierry; Fouilland, Eric; Got, Patrice; Le Floc'H, Emilie; Nouguier, Jean; Mas, Sebastien; Sempere, Richard; Sime-ngando, Telesphore; Troussellier, Marc; Vidussi, Francesca. |
The impact of fish and oysters on components of the pelagic microbial food web (MFW) was studied in a 10 d mesocosm experiment using Mediterranean coastal waters. Two mesocosms contained natural water only ('Controls'), 2 contained natural water with Crassostrea gigas ('Oyster'), and 2 contained natural water with Atherina spp. ('Fish'). Abundances and biomasses of microorganisms (viruses, bacteria, phytoplankton, heterotrophic flagellates, and ciliates) were measured to estimate their contribution to the total microbial carbon biomass. Two MFW indices, the microbial autotroph: heterotroph C biomass ratio (A:H) structural index and the gross primary production: respiration ratio (GPP:R) functional index, were defined. In the Fish mesocosms, selective... |
Tipo: Text |
Palavras-chave: Microbial food web; Virioplankton; Bacterioplankton; Phytoplankton; Protozooplankton; Crassostrea; Atherina; Autotrophy; Heterotrophy. |
Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00284/39489/73675.pdf |
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