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| Registros recuperados: 12 | |
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| Piriou, Jean-yves; Coic, Daniel; Merceron, Michel. |
| The coastal marsh of Kervigen is located near by the bay of Douarnenez and its 22 hectares are almost entirely covered by reeds. An experiment was there carried out to assess the nitrogen flux depletion of a small stream, the Kerharo. That one has a 45 km 2 mostly agricultural drainage basin. Due to its nitrate loadings to the next sandy beach, it feeds a green algae (Ulva) proliferation. In order to control its nitrogen fluxes, the stream was partly diverted through a part of the marsh (9 ha), before it was allowed to go back to the main bed. Thus a collapsible weir was set up during several springs and summers, i.e. the growing period of Ulva. The nitrate stripping off the going through flux is within a 30 to 90 % range,that is important (175 kg N03... |
| Tipo: Text |
Palavras-chave: Algae; Nitrogen; Ulva; Nitrate depletion; Costal marsh; Algue; Azote; Ulva; Abattement de nitrate; Marais côtier. |
| Ano: 1999 |
URL: http://archimer.ifremer.fr/doc/1999/rapport-64.pdf |
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| Pádua,Márcia de; Fontoura,Paulo Sérgio Growoski; Mathias,Alvaro Luiz. |
| Chemical composition of three species of Chlorophyta, Ulva lactuca, Ulva fasciata and Ulvaria oxysperma, was determined. Ulvaria oxysperma showed humidity (16-20%), ash (17-31% dry-base), proteins (6-10%db), lipids (0.5-3.2%db), fibers (3-12%db) and carbohydrates (46-72%db) which corresponded to 192-270 kcal.100g-1 (wet-base). U lactuca (15-18%db) and U fasciata (13-16%db) revealed grades slightly higher for proteins, but with similar energetic contents (250-272 and 225-239 kcal.100g-1), respectively. Natural blades of U lactuca and of U fasciata were more rigid than blades of U oxysperma. Other native algae showed higher protein levels. Ulvaria sp could be cultivated on the cotton-nylon net without having significance competition from other algae or... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Chemical composition; Algae; Ulvaria; Ulva; Guaraqueçaba; Ilha do Mel. |
| Ano: 2004 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132004000100007 |
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| Brisset, Maele; Van Wynsberge, Simon; Andréfouët, Serge; Payri, Claude; Soulard, Benoit; Bourassin, Emmanuel; Le Gendre, Romain; Coutures, Emmanuel. |
| Despite the necessary trade-offs between spatial and temporal resolution, remote sensing is an effective approach to monitor macroalgae blooms, understand their origins and anticipate their developments. Monitoring of small tropical lagoons is challenging because they require high resolutions. Since 2017, the Sentinel-2 satellites has provided new perspectives, and the feasibility of monitoring green algae blooms was investigated in this study. In the Poé-Gouaro-Déva lagoon, New Caledonia, recent Ulva blooms are the cause of significant nuisances when beaching. Spectral indices using the blue and green spectral bands were confronted with field observations of algal abundances using images concurrent with fieldwork. Depending on seabed compositions and... |
| Tipo: Text |
Palavras-chave: Ulva; Sentinel-2; Satellite; Remote sensing; Algal bloom; Coral reefs; Pacific lagoons. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00668/77968/80184.pdf |
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| Merceron, Michel. |
| The yearly study of Ulva in Brittany aims at building a time series of its proliferations and corresponding nutrient loadings. The goal is to detect results of wilful loading reductions, and to distinguish them from natural variations. This first actually quantified study is the starting bench-mark of the process. Forty-five concerned sites were listed in 1997. They are nearly the same as in 1988, 1991 and 1994 (previous rough census). The Côtes d'Armor and then the Finistère are the most affected departments. The Morbihan is less and file et Vilaine not at all. Ulva biomass was precisely quantified in about fifteen locations during the growing season, along with nitrogen loadings of local streams (mostly nitrate). The fluxes of nitrogen - the limiting... |
| Tipo: Text |
Palavras-chave: Bretagne; Nitrate; Prolifération; Ulve; Eutrophisation; Brittany; Nitrate; Proliferation; Ulva; Eutrophication. |
| Ano: 1998 |
URL: http://archimer.ifremer.fr/doc/1998/rapport-1580.pdf |
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| Merceron, Michel. |
| The 1998 survey of green tides on the Brittany coast was performed in the same way as that of 1997 in order to allow comparison. 11 includes an inventory ofail the concerned sites, and a precise assessment ofthirteen ofthem, the most loaded. On these ones, nitrogen fluxes were surveyed during the critical period, and the green seaweed stock on the beach and in the first waves was quantified. The climatic conditions were opposite between the two years, very dry in spring and summer 1997, and wet in 1998. The irradiance contrast was inverse, and less pronounced. The nitrate contents and mostly the flows were more important in 1998. They generated nitrogen fluxes about 3.3 times those of 1997. The total number of sites concerned in 1998 is clearly higher than... |
| Tipo: Text |
Palavras-chave: Bretagne; Nitrate; Prolifération; Ulve; Eutrophisation; Brittany; Nitrate; Proliferation; Ulva; Eutrophication. |
| Ano: 1999 |
URL: http://archimer.ifremer.fr/doc/1999/rapport-2665.pdf |
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| Menesguen, Alain. |
| Since 25 years, an increasing number of beaches and coves along the Britanny coast are invaded from spring until autumn by proliferating green macroalgae (free ulvae, fixed enteromorphae). This typical case of eutrophication, which has been well studied in the bays of Saint-Brieuc, Lannion, Douarnenez and Brest, could be explained by the conjunction of a natural containment of shallow water masses with a recent enrichment of them by nitrate river loadings. In the naturally confined sites, field measurements of summer biomass showed a good correlation with the spring nitrate river loadings ; furthermore, the summer rarefaction of these loadings explains the fall of the nitrogen content of the ulvae, which induces the summer stop of the algal growth. The... |
| Tipo: Text |
Palavras-chave: Intensive farming; Biogeochemical models; Coastal eutrophication; Nitrate; Ulva; Green tide; Agriculture intensive; Modèles biogéochimiques; Eutrophisation côtière; Nitrate; Ulve; Marée verte. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/2003/rapport-143.pdf |
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| Menesguen, Alain; Aminot, Alain; Belin, Catherine; Chapelle, Annie; Guillaud, Jean-francois; Joanny, Michel; Lefebvre, Alain; Merceron, Michel; Piriou, Jean-yves; Souchu, Philippe. |
| In order to be able to count the cases of coastal eutrophication and to propose methods to monitor as well as to reduce these phenomena, first of all it is necessary to precisely define the word eutrophication itself. Instead of the strict etymological definition, that is to say a progression of the enrichment of a medium, we will rather retain the concept of a state enriched at a point such as it causes harmful effects on the ecosystem, and nuisances to man's activities. Based on the average chemical equations of the organic matter synthesis/degradation in the sea, this operational definition thus puts forwards the harmful consequences of enrichment, i.e. the production of an excessive algal biomass, sometimes unbalanced from the point of view of... |
| Tipo: Text |
Palavras-chave: Alexandrium; Phaeocystis; Monostroma; Ulva; Dilution plume; Water trapping; Anoxia; Nitrogen and phosphorus loadings; Red tides; Phytoplankton blooms; Green tides; Eutrophication; Alexandrium; Phaeocystis; Monostroma; Ulva; Panache de dilution; Confinement; Anoxie; Phosphate; Nitrate; Apports terrigènes; Eaux colorées; Blooms phytoplanctoniques; Marées vertes; Eutrophisation. |
| Ano: 2001 |
URL: http://archimer.ifremer.fr/doc/2001/rapport-22.pdf |
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| Merceron, Michel. |
| On tens of sandy beaches of Brittany, a green seaweed (Ulva) blooms during spring and summer. In the sites where the proliferation is the most important, the total biomass amounted to 20 000 t of wet weight in 1997, at the time of maximum. These "green tides" occur every year in nearly the same locations. They have a very harmful impact on local tourism. In many communes, beached and rotting algae are collected and dumped (43 000 m 3 as a whole in 1997). The main development of biomass takes place between the surf zone and the bare sand.The outbreak requires three coexisting conditions : 1) a sandy beach gently sloping, 2) a weak residual current (i.e. once the tidal back and forth movement has been filtered), 3) a nitrogen loading, even moderate (ammonium... |
| Tipo: Text |
Palavras-chave: Brittany; Eutrophication; Proliferation; Ulva; Marine algae; Bretagne; Eutrophisation; Prolifération; Ulves; Algues marines. |
| Ano: 1999 |
URL: http://archimer.ifremer.fr/doc/1999/acte-46.pdf |
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| Perrot, Thierry; Rossi, Nadege; Menesguen, Alain; Dumas, Franck. |
| First recorded in the 1970s, massive green macroalgal blooms have since become an annual recurrence in Brittany, France. Eutrophication (in particular to anthropogenic nitrogen input) has been identified as the main factor controlling Ulva ‘green tide’ events. In this study, we modelled Ulva proliferation using a two-dimensional model by coupling hydrodynamic and biological models (coined ‘MARS-Ulves’) for five sites along the Brittany coastline (La Fresnaye Bay, Saint-Brieuc Bay, Lannion Bay, Guissény Bay and Douarnenez Bay). Calibration of the biological model was mainly based on the seasonal variation of the maximum nitrogen uptake rate (VmaxN) and the half-saturation constant for nitrogen (KN) to reproduce the internal nutrient quotas measured in situ... |
| Tipo: Text |
Palavras-chave: 2D model; Ulva; Eutrophication; Brittany coastal waters; Tracers; Nutrient reductions. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00171/28268/26517.pdf |
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| Registros recuperados: 12 | |
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