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Provedor de dados:  ArchiMer
País:  France
Título:  Contribution of several nitrogen sources to growth of Alexandrium catenella during blooms in Thau lagoon, southern France
Autores:  Collos, Y
Vaquer, A
Laabir, M
Abadie, Eric
Laugier, Thierry
Pastoureaud, Annie
Souchu, Philippe
Data:  2007-11
Ano:  2007
Palavras-chave:  Uptake kinetics
Alexandrium catenella
Resumo:  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% respectively of growth requirements. Ammonium and urea were the main N sources fueling growth of A. catenella (30-100% and 2-59%, respectively). Indirect estimates indicated that an unidentified N source could also contribute significantly to growth at specific times. Concerning ammonium and urea uptake kinetics, half-saturation constants varied between 0.2 and 20 mu gat NL-1 for ammonium and between 0.1 and 44 mu gat N L-1 over the 4-year period, indicating that A. catenella can have a competitive advantage over other members of the phytoplankton even under low concentrations of ammonium and urea. However, the observed large changes in ammonium and urea uptake kinetics on a short time scale (days) during blooms preclude more precise estimates of those contributions to growth and require further investigation. (C) 2007 Elsevier B.V. All rights reserved.
Tipo:  Text
Idioma:  Inglês

Editor:  Elsevier
Formato:  application/pdf
Fonte:  Harmful Algae (1568-9883) (Elsevier), 2007-11 , Vol. 6 , N. 6 , P. 781-789
Direitos:  2007 Elsevier B.V. All rights reserved.

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