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| Bednarz, Vanessa N.; Grover, Renaud; Maguer, Jean-francois; Fine, Maoz; Ferrier-pages, Christine. |
| Tropical corals are associated with a diverse community of dinitrogen (N-2)-fixing prokaryotes (diazotrophs) providing the coral an additional source of bioavailable nitrogen (N) in oligotrophic waters. The overall activity of these diazotrophs changes depending on the current environmental conditions, but to what extent it affects the assimilation of diazotroph-derived N (DDN) by corals is still unknown. Here, in a series of N-15(2) tracer experiments, we directly quantified DDN assimilation by scleractinian corals from the Red Sea exposed to different environmental conditions. We show that DDN assimilation strongly varied with the corals ' metabolic status or with phosphate availability in the water. The very autotrophic shallow-water (similar to 5 m)... |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00616/72832/72319.pdf |
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| Ezzat, Leila; Maguer, Jean-francois; Grover, Renaud; Ferrier-pages, Christine. |
| During the 20th century, seawater temperatures have significantly increased, leading to profound alterations in biogeochemical cycles and ecosystem processes. Elevated temperatures have also caused massive bleaching (symbiont/pigment loss) of autotrophic symbioses, such as in coral-dinoflagellate association. As symbionts provide most nutrients to the host, their expulsion during bleaching induces host starvation. However, with the exception of carbon, the nutritional impact of bleaching on corals is still unknown, due to the poorly understood requirements in inorganic nutrients during stress. We therefore assessed the uptake rates of nitrogen and phosphate by five coral species maintained under normal and thermal stress conditions. Our results showed that... |
| Tipo: Text |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00616/72845/72920.pdf |
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| Pupier, Chloe A.; Bednarz, Vanessa N.; Grover, Renaud; Fine, Maoz; Maguer, Jean-francois; Ferrier-pages, Christine. |
| Corals are associated with dinitrogen (N-2)-fixing bacteria that potentially represent an additional nitrogen (N) source for the coral holobiont in oligotrophic reef environments. Nevertheless, the few studies investigating the assimilation of diazotrophically derived nitrogen (DDN) by tropical corals are limited to a single scleractinian species (i.e., Stylophora pistillata). The present study quantified DDN assimilation rates in four scleractinian and three soft coral species from the shallow waters of the oligotrophic Northern Red Sea using the N-15(2) tracer technique. All scleractinian species significantly stimulated N, fixation in the coral-surrounding seawater (and mucus) and assimilated DDN into their tissue. Interestingly, N-2 fixation was not... |
| Tipo: Text |
Palavras-chave: Dinitrogen fixation; Diazotrophs; Scleractinian corals; Soft corals; Red Sea. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00512/62370/66644.pdf |
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