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| Loureiro, Sofia; Jauzein, Cecile; Garces, Esther; Collos, Yves; Camp, Jordi; Vaque, Dolors. |
| The influence of organic nutrients on the evolution of Pseudo-nitzschia delicatissima cultures was investigated in an enrichment experiment with high-molecular-weight dissolved organic matter (HMWDOM) and in an uptake assay with N-15-ammonium and N-15-urea. HMWDOM was extracted from seawater collected at a nearby shore station during the decline of a diatom bloom. Four incubations were prepared: L1/5+DOM (P. delicatissima grown in L1 growth medium with 1/5 of the nitrate concentration of standard L1), (L1-N)+DOM (L1 without nitrate, i.e. nitrogen-deficient treatment), L1-DOM (control culture without added DOM) and BV+DOM (bacterial and viral control, free of microalgae). Incubations were carried out for 10 days. Chlorophyll a concentrations differed after... |
| Tipo: Text |
Palavras-chave: Harmful Algal Blooms (HABs); Nitrogen Uptake; Urea; Dissolved Organic Matter (DOM). |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6438.pdf |
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| Jauzein, Cecile; Loureiro, Sofia; Garces, Esther; Collos, Yves. |
| Short-term experiments were carried out to investigate whether interactions between ammonium (NH4+) and urea uptake regulate the total nitrogen assimilation of the toxic dinoflagellate Alexandrium catenella. To test for strain variability, 5 strains of A. catenella from the NW Mediterranean were used: 3 strains from the Thau lagoon (southern France) and 2 strains from the Catalonia basin (Spain). For each strain, the uptake rate of 1 nutrient (NH4+ or urea) at a reference concentration (10 mu gatN l(-1)) was measured as a function of the increasing concentration of the other nutrient (0 to 10 mu gatN l(-1)). Simultaneous N uptake rates of the distinct nitrogen sources were obtained from N-15-NH4+ and N-15-urea incorporation measurements. A strong... |
| Tipo: Text |
Palavras-chave: Strain variability; Interactions; Urea; Ammonium; Alexandrium catenella. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-6432.pdf |
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