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| Ridame, Celine; Le Moal, Marc; Guieu, Cecile; Ternon, E.; Biegala, I.c.; L'Helguen, Stéphane; Pujo-pay, M.. |
| A better understanding of the factors controlling N2 fixation is a pre-requisite for improving our knowledge on the contribution of N2 fixation process in the nitrogen cycling. Trace-metal clean nutrient/dust addition bioassays (+P, +PFe, +dust) were performed at three stations located in the western, central and eastern Mediterranean Sea, in summer 2008 as part of the BOUM cruise. The main goals were (1) to investigate the nutrient factor(s) limiting N2 fixation (uptake of 15N2) and (2) to evaluate the potential impact of a Saharan dust event on this biological process during the stratification period. Initially, surface waters at the three stations were DIP-depleted (<10 nM) while the DFe concentrations were relatively high (from 1.2 to 2.3 nM) most... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00133/24410/22403.pdf |
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| Le Moal, Marc; Collin, H.; Biegala, I.c.. |
| The Mediterranean Sea is one of the most oligotrophic marine areas on earth where nitrogen fixation has formally believed to play an important role in carbon and nitrogen fluxes. Although this view is under debate, the diazotrophs responsible for this activity have still not been investigated in the open sea. In this study, we characterised the surface distribution and species richness of unicellular and filamentous diazotrophs across the Mediterranean Sea by combining microscopic counts with size fractionated in situ hybridization (TSA-FISH), and 16S rDNA and nifH genes phylogenies. These genetic analyses were possible owing to the development of a new PCR protocol adapted to scarce microorganisms that can detect as few as 1 cell ml(-1) in cultures. Low... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00133/24392/22416.pdf |
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