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| Benavides, Mar; Houlbreque, Fanny; Camps, Mercedes; Lorrain, Anne; Grosso, Olivier; Bonnet, Sophie. |
| Corals aremixotrophs: they are able to fix inorganic carbon through the activity of their symbiotic dinoflagellates and to gain nitrogen from predation on plankton and uptake of dissolved organic and inorganic nutrients. They also live in close association with diverse diazotrophic communities, inhabiting their skeleton, tissue and mucus layer, which are able to fix dinitrogen (N-2). The quantity of fixed N-2 transferred to the corals and its distribution within coral compartments as well as the quantity of nitrogen assimilated through the ingestion of planktonic diazotrophs are still unknown. Here, we quantified nitrogen assimilation via (i) N-2 fixation by symbiont diazotrophs, (ii) ingestion of cultured unicellular diazotrophs and (iii) ingestion of... |
| Tipo: Text |
Palavras-chave: Scleractinian corals; Heterotrophic nutrition; Cyanothece; N-2 fixation; New Caledonia. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00356/46678/72967.pdf |
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| Saulia, Emmrick; Benavides, Mar; Henke, Britt; Turk-kubo, Kendra; Cooperguard, Haley; Grosso, Olivier; Desnues, Anne; Rodier, Martine; Dupouy, Cécile; Riemann, Lasse; Bonnet, Sophie. |
| Coastal and open ocean regions of the Western Tropical South Pacific ocean have been identified as a hotspot of N2 fixation. However, the environmental factors driving the temporal variability of abundance, composition, and activity of diazotrophs are still poorly understood, especially during the winter season. To address this, we quantified N2 fixation rates and the abundance of seven diazotroph phylotypes (UCYN-A1 symbiosis, UCYN-B, UCYN-C, Trichodesmium, Het-1, Het-2, and Het-3) on a monthly basis during two full years (2012 to 2014) at four stations along a coast to open ocean transect in the New Caledonian lagoon. The total nifH gene concentration (sum of all nifH gene copies) clearly decreased from the barrier reef to the shore. Apart from UCYN-B,... |
| Tipo: Text |
Palavras-chave: N-2 fixation; Diazotrophs; NifH; Abundance; New Caledonia. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00658/77027/78307.pdf |
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| Tang, Weiyi; Li, Zuchuan; Cassar, Nicolas. |
| Marine nitrogen (N2) fixation supplies “new” nitrogen to the global ocean, supporting uptake and sequestration of carbon. Despite its central role, marine N2 fixation and its controlling factors remain elusive. In this study, we compile over 1,100 published observations to identify the dominant predictors of marine N2 fixation and derive global estimates based on the machine learning algorithms of random forest (RF) and support vector regression (SVR). We find that no single environmental property predicts N2 fixation at global scales. Our RF and SVR algorithms, trained with sampling coordinates and month, solar radiation, wind speed, sea surface temperature, sea surface salinity, surface nitrate, surface phosphate, surface excess phosphorus, minimum... |
| Tipo: Text |
Palavras-chave: N-2 fixation; Machine-learning; Ocean. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00483/59501/62371.pdf |
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