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Contribution of several nitrogen sources to growth of Alexandrium catenella during blooms in Thau lagoon, southern France ArchiMer
Collos, Y; Vaquer, A; Laabir, M; Abadie, Eric; Laugier, Thierry; Pastoureaud, Annie; Souchu, Philippe.
A monitoring program with a weekly sampling frequency over a 15-month period indicates that urea concentrations above a certain threshold level may trigger the blooms of Alexandrium catenella in Thau lagoon. However, urea concentrations were also sometimes related to ammonium and dissolved organic nitrogen concentrations, indicating that the role of urea may not be a direct one. An original approach is used to assess the relative contribution of several nitrogen sources (nitrate, nitrite, ammonium, urea) to growth of A. catenella by comparing nitrogen uptake rates to nitrogen-based growth rates estimated from dilution experiments during four blooms over a 4-year period (2001-2004) in Thau lagoon. Nitrate and nitrite contributed 0.1-14% and 0.1-5%...
Tipo: Text Palavras-chave: Uptake kinetics; Ammonium; Urea; Growth; Nitrogen; HAB; Alexandrium catenella.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-6454.pdf
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Short-term temporal variability of ammonium and urea uptake by Alexandrium catenella (Dinophyta) in cultures ArchiMer
Jauzein, Cecile; Collos, Yves; Garces, E; Vila, M; Maso, M.
In batch cultures of four Mediterranean strains (from France, Italy, and Spain) of Alexandrium catenella (Whedon et Kof.) Balech growing on a daily light cycle, ammonium and urea uptake were estimated by the N-15 tracer technique. Ammonium uptake could be described by Michaelis-Menten kinetics along a substrate gradient of 0.1-10 mu gat N.L-1 for the four strains, while two different patterns were observed for urea uptake with Michaelis-Menten kinetics for one strain and linear kinetics for the others. In all cases, an increase in uptake rates with time was noted over the daylight period. This trend led to a net increase in the maximum uptake rate (V-max; for saturable kinetics) and in the initial slope alpha. For ammonium, V-max increased by a factor of...
Tipo: Text Palavras-chave: Urea; Uptake kinetics; Temporal variability; Ammonium release; Ammonium; Alexandrium catenella.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-6416.pdf
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Paramétrisation de la nutrition azotée et phosphorée d'Alexandrium catenella, microalgue toxique responsable d'efflorescences dans la lagune de Thau ArchiMer
Jauzein, Cecile.
In the Thau lagoon, blooms of the toxic microalgae Alexandrium catenella have induced regular losses of shellfish production since 1998 due to bioaccumulation of toxins in oysters and mussels. This thesis was conducted to enhance knowledge of toxic bloom development regulation by environmental factors, focusing on nitrogen and phosphorus nutrients influence on A. catenella growth. These works highlighted a large variety of potential nutritive sources for this species and a major part of these nutrients appeared to be potentially regenerated in the water column. Different organic sources may contribute to the growth of A. catenella from diverse nutrition processes: direct absorption through the cell membrane (for urea), enzymatic degradation in the...
Tipo: Text Palavras-chave: Alkaline phosphatases; Mixotrophy; Phosphate; Urea; Ammonium; Uptake kinetics; Alexandrium catenella; Phosphatases alcalines; Mixotrophie; Phosphate; Urée; Ammonium; Cinétiques d'absorption; Alexandrium catenella.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/these-6511.pdf
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