Consulta: creatorFacets:"Ratmaya, Widya"
Registros recuperados: 4
Data/hora: 03/06/2024 18:08:04

Diagnostic étendu de l'eutrophisation (DIETE). Rôle des sédiments dans le cycle des nutriments et impacts sur l'eutrophisation de la baie de Vilaine (2014-2017)
Provedor de dados: 5
Autores: Souchu, Philippe; Cochennec-laureau, Nathalie; Ratmaya, Widya; Retho, Michael; Andrieux, Francoise; Le Merrer, Yoann; Barille, Laurent; Barille, Anne-laure; Goubert, Evelyne; Plus, Martin; Laverman, Anniet.
Le projet DIETE a exploré les données hydrobiologiques (paramètres physico-chimiques, nutriments, phytoplancton) acquises depuis les années 80 dans les eaux côtières au large de la Loire et de la Vilaine, parallèlement à celles des deux fleuves. L’augmentation des concentrations de nitrates dans les eaux de la Loire, appuyée par les réserves sédimentaires de phosphates et de silicate ont entraîné de profonds bouleversements dans la dynamique du phytoplancton de la baie de Vilaine ces deux dernières décennies avec 1) une augmentation substantielle de la biomasse, 2) une modification importante de l’évolution saisonnière, 3) un changement dans les proportions entre diatomées et dinoflagellés au profit des diatomées. Ces résultats ouvrent tout un champ...
Tipo: Text
Palavras-chave: Eutophisation; Azote; Phosphore; Silicium; Sédiments; Modélisation.
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00425/53695/54593.pdf

Rôle des sédiments dans le cycle des nutriments et impacts sur l’eutrophisation des écosystèmes côtiers
Provedor de dados: 5
Autores: Ratmaya, Widya.
Eutrophication was studied in the coastal waters of Vilaine Bay (VB) in relation to that in the Loire and Vilaine rivers, by analyzing long-term trends of phytoplankton biomass and nutrient concentrations during the past decades. The reduction in dissolved riverine inorganic phosphorus concentrations (DIP) during the last two decades led to the significant decrease in chlorophyll a concentrations. However, dissolved inorganic nitrogen concentrations (DIN) decreased only slightly in the Vilaine and actually increased in the Loire, especially during summer. Simultaneously, phytoplankton in VB has undergone the following changes: 1) increase in biomass, 2) change in timing of the annual peak of biomass from spring to summer, 3) modification in seasonal course...
Tipo: Text
Palavras-chave: Eutrophisation; Cycle des nutriments; Régénération benthique; Nutriment limitant; Baie de Vilaine; Eutrophication; Nutrient cycling; Benthic regeneration; Nutrient limitation; Vilaine Bay.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00476/58799/61337.pdf

Reduced phosphorus loads from the Loire and Vilaine Rivers were accompanied by increasing eutrophication in Vilaine Bay (South Brittany, France)
Provedor de dados: 5
Autores: Ratmaya, Widya; Soudant, Dominique; Salmon-monviola, Jordy; Plus, Martin; Cochennec-laureau, Nathalie; Goubert, Evelyne; Andrieux, Francoise; Barillé, Laurent; Souchu, Philippe.
The evolution of eutrophication (i.e., phytoplankton biomass) during recent decades was examined in the coastal waters of Vilaine Bay (VB, France) in relation to those in their main external nutrient sources, the Loire and Vilaine Rivers. Dynamic Linear Models, corroborated by the Mann-Kendall test, were used to study long-term trends and seasonality of dissolved inorganic nutrient and chlorophyll a concentrations (Chl a) in rivers and coastal waters between 1980 and 2013. The reduction in dissolved riverine inorganic phosphorus concentrations (DIP) from the early 1990s led to the decrease in their Chl a levels. However, dissolved inorganic nitrogen concentrations (DIN) decreased only slightly in the Vilaine and actually increased in the Loire, especially...
Tipo: Text
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00461/57244/59248.pdf

Comparing diatom and Alexandrium catenella/tamarense blooms in Thau lagoon: Importance of dissolved organic nitrogen in seasonally N-limited systems
Provedor de dados: 5
Autores: Collos, Yves; Jauzein, Cecile; Ratmaya, Widya; Souchu, Philippe; Abadie, Eric; Vaquer, André.
Diatom blooms in Thau lagoon are always related to rain events leading to inputs of inorganic nutrients such as phosphate, ammonium and nitrate through the watershed with time lags of about 1 week. In contrast, blooms of Alexandrium catenella/tamarense can occur following periods of 3 weeks without precipitation and no significant input of conventional nutrients such as nitrate and phosphate. Field results also indicate a significant drop (from 22–25 to 15–16 μM over 3 days) in dissolved organic nitrogen (DON) at the bloom peak, as well as a significant inverse relationship between A. catenella/tamarense cell density and DON concentrations that is not apparent for diatom blooms. Such dinoflagellate blooms are also associated with elevated (6–9 μM) ammonium...
Tipo: Text
Palavras-chave: Alexandrium catenella/tamarense; Non classical blooms; Organic nitrogen; Ammonium; Growth rate.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00194/30488/29758.pdf