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| Registros recuperados: 63 | |
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| Dussauze, Morgan; Menesguen, Alain; Dumas, Franck. |
| Two techniques of tracking are compared for delineating the marine area impacted by a river plume. The first one uses a simple conservative tracer released in the river during a several year long period: the probability density function of the tracer concentration in each mesh of the model is used to map 3 characteristic descriptors of the freshwater influence (10%, 50% and 90% percentiles). The second one uses a signature of the river attached to a state variable of a biogeochemical model (e.g. the Dissolved Inorganic Nitrogen components), which can be followed in space and time in the various nitrogenous state variables. Departure between the two methods increases when tracking of nitrogen is considered in biogeochemical forms more and more distant from... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00068/17892/15423.pdf |
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| Plus, Martin; Chapelle, Annie; Menesguen, Alain; Deslous-paoli, Jean-marc; Auby, Isabelle. |
| A numerical deterministic model for a seagrass ecosystem (Zostera noltii meadows) has been developed for the Thau lagoon. It involves both above- and belowground seagrass biomasses, nitrogen quotas and epiphytes. Driving variables are light intensity, wind speed, rain data and water temperature. This seagrass model has been coupled to another biological model in order to simulate the relative contributions of each primary producer to: (i) the total ecosystem production, (ii) the impact on inorganic nitrogen and (iii) the fluxes towards the detritus compartment. As a first step in the modelling of seagrass beds in the Thau lagoon, the model has a vertical structure based on four boxes (a water box on top of, three sediment boxes) and the horizontal... |
| Tipo: Text |
Palavras-chave: Thau lagoon; Nitrogen cycle; Oxygen cycle; Box model; Seagrass ecosystem. |
| Ano: 2003 |
URL: https://archimer.ifremer.fr/doc/2003/publication-461.pdf |
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| Menesguen, Alain; Hachet, Alois; Gregoris, Thomas. |
| The anthropogenic introduction in U.K. waters of the north-American marine gastropod Crepidula fornicata (Linné, 1758), commonly called slipper limpet, and its consecutive spreading has led in less than a century to the invasion of a part of benthic grounds along the North-European coasts. Competition for space has hampered the maintenance of the native scallop Pecten maximus, whereas dredge clogging has drastically limited scallop fishing, especially in the Western English Channel. In order to assess the possible future distribution and abundance of both species (Crepidula and Pecten), an original model of slipper limpet chains joined to a simple year-class model of the scallop (Ménesguen and Grégoris, 2017) has been coupled to a connectivity matrix... |
| Tipo: Text |
Palavras-chave: Slipper limpet; Invasive species; Colony model; Connectivity matrix eigenvectors; Scallop; Competition for space. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00431/54231/57333.pdf |
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| Le Moal, Morgane; Gascuel-odoux, Chantal; Menesguen, Alain; Souchon, Yves; Etrillard, Claire; Levain, Alix; Moatar, Florentina; Pannard, Alexandrine; Souchu, Philippe; Lefebvre, Alain; Pinay, Gilles. |
| Eutrophication is one of the most common causes of water quality impairment of inland and marine waters. Its best-known manifestations are toxic cyanobacteria blooms in lakes and waterways and proliferations of green macro algae in coastal areas. The term eutrophication is used by both the scientific community and public policy-makers, and therefore has a myriad of definitions. The introduction by the public authorities of regulations to limit eutrophication is a source of tension and debate on the activities identified as contributing or having contributed decisively to these phenomena. Debates on the identification of the driving factors and risk levels of eutrophication, seeking to guide public policies, have led the ministries in charge of the... |
| Tipo: Text |
Palavras-chave: Eutrophication; Nitrogen; Phosphorus; Algae bloom; Land-sea continuum; Diffuse pollution. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00456/56734/58551.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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| Chapelle, Annie; Menesguen, Alain; Deslous-paoli, Jean-marc; Souchu, Philippe; Mazouni, Nabila; Vaquer, André; Millet, Bertrand. |
| An ecosystem model based on nitrogen cycling and oxygen has been developed for the Thau lagoon. It takes into account the specific features of this Mediterranean lagoon, a semi-confined system with watershed inputs and oyster farming. The ecosystem model uses currents calculated by a two-dimensional hydrodynamic model and integrated into a box model. This model is compared with a year survey data and used to estimate nitrogen and oxygen fluxes between the different ecosystem compartments. The yearly simulation shows that the ecosystem behavior is driven by meteorological forcing, especially rain which causes watershed inputs. These inputs trigger microphytoplankton growth, which is responsible for new primary production. During dry periods, nitrogen is... |
| Tipo: Text |
Palavras-chave: Oxygen; Nitrogen; Oysters; Primary production; Box model; Lagoon ecosystem. |
| Ano: 2000 |
URL: http://archimer.ifremer.fr/doc/2000/publication-725.pdf |
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| Menesguen, Alain; Le Foll, Francois. |
| "Par courrier en date du 22 avril dernier, vous avez sollicité les observations de l'Ifremer sur les zones d'extraction et de stockage de crépidules en Rade de Brest prévues par le programme CREPIRADE initié par le Comité Local des Pêches du Nord Finistère. Sur la zone d'extraction, l'Ifremer n'a pas d'observations particulières à formuler ; sur les conséquences possibles du stockage dans la zone dite « de remblai », vous trouverez ci-joint les conclusions de notre département d'Ecologie Côtière." |
| Tipo: Text |
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| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/2003/rapport-6323.pdf |
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| Perrot, Thierry; Menesguen, Alain; Dumas, Franck. |
| Every spring and summer, and for two decades, mass-blooms produced by a green alga of the genus Ulva, have been polluting some localities along the Brittany coasts. The main aspect of the nuisance lies in the stranding and further decomposition of large amounts of algae along recreational zones inducing visual and odoriferous pollution. Sites which are favourable to Ulva mass-blooms are shallow areas where water exchange with the open sea is slow (weak residual drift of water masses and long residence time). Drifting algae and nutrients are both trapped in these zones thus allowing Ulva thalli to be kept in good cultivation conditions. In collaboration with Ifremer, the so-called “MARS-ulve” ecological model (coupling the biochemical model ELISE with the... |
| Tipo: Text |
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| Ano: 2007 |
URL: https://archimer.ifremer.fr/doc/00480/59150/61779.pdf |
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| Heral, Maurice; Bacher, Cedric; Razet, Daniel; Prou, Jean; Deslous-paoli, Jean-marc; De Pontual, Helene; Raillard, Olivier; Maestrini, Serge; Mornet, Francoise; Menesguen, Alain; Sautour, Benoit; Robert, Jean-michel. |
| Les termes du contrat passé entre le Fond de la Recherche et de la Technologie et l'IFREMER précisent qu ele programmer a pour objectif une gestion rationnelle du milieu conchylicole avec notamment une mise au point de modèles (voir notification de l'aide en annexe). Un premier modèle appelé modèle global par analogie avec les modèles de pêche met en évidence la limite de la capacité trophique du bassin de Marennes-Oléron pour les huîtres cultivées. Un modèle analytique avec un modèle physique simple permet dans un premier temps de développer un modèle de croissance des huîtres en fonction de la nourriture disponible et d'effectuer des simulations qui confirment l'influence du stock sur les performances de croissance des bivalves. Un troisième approche... |
| Tipo: Text |
Palavras-chave: Modèle production; Biomasse; Huître creuse; Crassostrea gigas; Modèle énergétique; Croissance; Modèle multiboîte; Marennes Oléron; Modèle trophique; Marennes Oléron. |
| Ano: 1986 |
URL: http://archimer.ifremer.fr/doc/00048/15908/13337.pdf |
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| Lecornu, Fabrice; Pineau-guillou, Lucia; Dumas, Franck; Le Traon, Pierre-yves; Gohin, Francis; Menesguen, Alain. |
| Our coastal zones are subject to increasing anthropogenic pressure. Monitoring systems are required to protect them, prevent or mitigate risks and to ensure a sustainable management of their resources. PREVIMER is a partnership between Ifremer (French Research Institute for Exploitation of the Sea), SHOM (French Hydrographic Office) and several major French institutions (www.previmer.org). It provides coastal observations, analyses and 4 days forecasts for the French coasts of the English Channel, Atlantic Ocean and Mediterranean Sea: currents, water levels, waves, temperature, salinity, turbidity, nutrients and plankton concentrations. The service includes information based on in situ, satellite observations and numerical simulations. PREVIMER products... |
| Tipo: Text |
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| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00189/30039/28525.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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| Menesguen, Alain; Desmit, Xavier; Duliere, Valerie; Lacroix, Genevieve; Thouvenin, Benedicte; Thieu, Vincent; Dussauze, Morgan. |
| Since 1950, increase in nitrogen (N) and phosphorus (P) river loadings in the North-East Atlantic (NEA) continental seas has induced a deep change in the marine coastal ecosystems, leading to eutrophication symptoms in some areas. In order to recover a Good Ecological Status (GES) in the NEA, as required by European Water Framework Directive (WFD) and Marine Strategy Framework Directive (MSFD), reductions in N- and P-river loadings are necessary but they need to be minimal due to their economic impact on the farming industry. In the frame of the “EMoSEM” European project, we used two marine 3D ecological models (ECO-MARS3D, MIRO&CO) covering the Bay of Biscay, the English Channel and the southern North Sea to estimate the contributions of various... |
| Tipo: Text |
Palavras-chave: Marine eutrophication; Ecosystem modelling; Nutrient reduction scenario; Linear optimization; Good ecological status; EU policies. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00426/53774/54661.pdf |
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| Registros recuperados: 63 | |
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