|
|
|
|
|
| Souchu, Philippe; Gasc, Anne; Collos, Y; Vaquer, A; Tournier, Henri; Bibent, B; Deslous-paoli, Jean-marc. |
| Physical and chemical characteristics (temperature, salinity, dissolved oxygen), nutrients [dissolved inorganic nitrogen (DIN), soluble reactive phosphorus (SRP) and silicate], dissolved organic nitrogen (DON) and phosphorus and particulate matter [particulate organic carbon (POC) and nitrogen (PON) and chlorophyll a] were measured at a station located in the deepest part of the Thau lagoon (8.5 m), France, during a 10 d period of bottom anoxia in summer 1994. The upper 8 cm of sediment were also analyzed for ammonium (NH(4)(+)) and SRP concentrations in the porewater. The study period was characterized by mean wind speed under 4 m s(-1) which induced an increase of surface temperature from 18 to 29 degrees C with the formation of a thermocline. The... |
| Tipo: Text |
Palavras-chave: Anoxia; Nitrogen; Phosphorus; Eutrophication; Thau lagoon; Mediterranean Sea. |
| Ano: 1998 |
URL: http://archimer.ifremer.fr/doc/00070/18142/15694.pdf |
| |
|
|
| 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 |
| |
|
|
| Collos, Y; Descolas Gros, C; Mornet, Francoise. |
| During parallel sampling of seawater samples in bottles and in free water (1000-2000 m(3) clay ponds), we have measured phytoplankton biomass, Ribulose biphosphate carboxylase (Rubisco), phosphoenol pyruvate carboxylase, and phosphoenol pyruvate carboxykinase activities and major nutrients (ammonium, nitrate, phosphate, silicate). This was done in two ecosystems: one with high grazing pressure due to the presence of oysters and another with low grazing pressure (no oysters). In the ecosystem subjected to high grazing pressure, anaplerotic carbon fixation by phytoplankton in free water was higher in the light period and could represent 25% of total carbon fixation. Incubating samples in bottles led to a major increase in Rubisco activity (80% in 3 h)... |
| Tipo: Text |
Palavras-chave: Grazing; Carboxylases; Carbon assimilation; Anaplerotic; Ammonium. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-6437.pdf |
| |
|
|
| Leruste, A; Guilhaumon, F; De Wit, R; Malet, Nathalie; Collos, Y; Bec, Beatrice. |
| We studied a mesotrophic and a hypertrophic Mediterranean coastal lagoon, both of which had been simultaneously subjected to a nutrient input reduction for 9 yr. We compared these 2 lagoons to an oligotrophic coastal lagoon. Using bioassays comprising 24 h incubations with added phosphorus and/or ammonium, we investigated the response of the phytoplankton communities to nutrient enrichment during summer in terms of biomass, size class structure, abundance and growth. For nitrogen and phosphorus, we identified which nutrient limited phytoplankton growth, and what strategies of nutrient exploitation the communities adopted to cope with these limitations. Ultraphytoplankton dominated the 3 communities, but it differed in composition among the lagoons. Green... |
| Tipo: Text |
Palavras-chave: Growth rate; Nutrient limitation; Dilution experiment; HPLC. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00508/61978/66084.pdf |
| |
|
| |
|
|
|
