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| Registros recuperados: 63 | |
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| Savina, Marie; Menesguen, Alain. |
| Paphia rhombofdes is an infaunal filter-feeding bivalve, particularly widespread and abundant in the English Channel. In order to investigate the influence of the growth-related post-settlement processes on its distribution, a spatial growth model was developed and linked to an existing ecological model of the English Channel. This model was partially parameterized on the basis of a specific ecophysiological experimental study, and calibrated with growth data collected in the "Golfe Normand-Breton" (GNB), a region of the English Channel. Compared to the actual distribution of P. rhomboides, the results suggest a strong influence of the growth-related processes on the distribution of the species: particularly, the extremely low growth obtained with the... |
| Tipo: Text |
Palavras-chave: Distribution; Meroplanktonic invertebrates; Ecophysiology; Growth model; English channel; Paphia rhomboides. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-3115.pdf |
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| Menesguen, Alain. |
| This document deals with the 3D ecological model, tailor-made in 2001 (Leblond et al., 2001) to answer a contractual demand from the CUB on the origin of the nitrogen involved in the green tide on the Moulin Blanc beach. This mathematical model of the roadsted of Brest was especially designed for a precise study of the Elorn rivermouth (area where the mesh is square, 150 m long on each side), and enables not only a hydrodynamic study, but also a study on the fate of the nitrogen and phosphorus rejects in this area. Concerning the hydrodynamic part, this model, based on the IFREMER SiAM3D code, recreates a tide propagation validated by measures, in spring tide and slack tide, in terms of surface elevation and speed ranges, as well as the freshening plume of... |
| Tipo: Text |
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| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/rapport-6326.pdf |
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| Menesguen, Alain; Cugier, Philippe; Loyer, Sophie; Vanhoutte Brunier, Alice; Hoch, Thierry; Guillaud, Jean-francois; Gohin, Francis. |
| The general trend in ecosystem modelling is to improve the spatial resolution by shifting from rough box-models to fine 3D models. Despite the continuous speeding-up of computing, 3D models involving numerous state variables may remain intractable, especially for parameter calibration, when processes with long half-life periods (i.e, from years to decades) are introduced, such as the behaviour of organic matter in sediment and population dynamics of benthic species. In these cases, a first approach can be provided by fast-running box-models, if they take into account the most crucial hydrodynamic properties of the system. In a macrotidal shelf sea such as the English Channel, the long-term horizontal transport can be summarized by the tidal residual... |
| Tipo: Text |
Palavras-chave: English Channel; Stratification; Diatom/dinoflagellate succession; 3D model; Layered box model. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2315.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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| Hoch, Thierry; Menesguen, Alain; Bentley, D. |
| A simple model of the nitrogen cycle in the Channel is proposed. Based on the long-term circulation, this box-model permits the description of the spring phytoplankton bloom in the whole Channel. Spring western thermal stratification has not been taken into account; consequently, the earliest phytoplanktonic development is observed in the eastern Channel, followed by the western, deeper part. This model also shows the influence of nutrient supply from the rivers on the Channel ecosystem, and particularly the influence of the river Seine on the chlorophyll concentrations along the eastern French coast. Comparison of calculated data with measurements shows a fairly good agreement in the eastern Channel but discrepancies are encountered for the western part.... |
| Tipo: Text |
Palavras-chave: CHANNEL; BOX-MODEL; NITROGEN; PHYTOPLANKTON. |
| Ano: 1993 |
URL: http://archimer.ifremer.fr/doc/00100/21128/18748.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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| Desmit, X.; Thieu, V.; Billen, G.; Campuzano, F.; Duliere, V.; Garnier, J.; Lassaletta, L.; Menesguen, Alain; Neves, R.; Pinto, L.; Silvestre, M.; Sobrinho, J. L.; Lacroix, G.. |
| Marine eutrophication in the North-East Atlantic (NEA) strongly relies on nutrient enrichment at the river outlets, which is linked to human activities and land use in the watersheds. The question is whether human society can reduce its nutrient emissions by changing land use without compromising food security. A new version of Riverstrahler model (pyNuts-Riverstrahler) was designed to estimate the point and diffuse nutrient emissions (N, P, Si) to the rivers depending on land use in the watersheds across a large domain (Western Europe agro-food systems, waste water treatment). The loads from the river model have been used as inputs to three marine ecological models (PCOMS, ECO-MARS3D, MIRO&CO) covering together a large part of the NEA from the Iberian... |
| Tipo: Text |
Palavras-chave: North-East Atlantic; Eutrophication; Model scenarios; Land-sea continuum; Land use; Pristine; Management support. |
| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00438/55007/56426.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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| Del Amo, Yolanda; Le Pape, Olivier; Treguer, Paul; Queguiner, Bernard; Menesguen, Alain; Aminot, Alain. |
| The chemical factors (inorganic nitrogen, phosphate, silicic acid) that potentially or actually control primary production were determined for the Bay of Brest, France, a macrotidal ecosystem submitted to high-nitrate-loaded freshwater inputs (winter nitrate freshwater concentrations >700 mu M, Si:N molar ratio as low as 0.2, i.e. among the lowest ever published). Intensive data collection and observations were carried out from February 1993 to March 1994 to determine the variations of physical [salinity, temperature, photosynthetically active radiation (PAR), freshwater discharges] and chemical (oxygen and nutrients) parameters and their impacts on the phytoplankton cycle (fluorescence, pigments, primary production). With insufficient PAR the winter... |
| Tipo: Text |
Palavras-chave: Coastal ecosystem; Phytoplankton dynamics; Macrotidal; Nutrient limitation; Silicon; Eutrophication. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00337/44782/44588.pdf |
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| Stanisiere, Jean-yves; Mazurie, Joseph; Bouget, Jean-francois; Langlade, Aime; Gabellec, Raoul; Retho, Michael; Quinsat, Kevin; Leclerc, Emilie; Cugier, Philippe; Dussauze, Morgan; Menesguen, Alain; Dumas, Franck; Gohin, Francis; Augustin, Jean-marie; Ehrhold, Axel; Sinquin, Jean-marc; Goubert, Evelyne; Dreano, Alain. |
| The project “Risco”, supported by the “Pôle Mer” and funded by the Regional Council of Brittany, deals with specific risks of mortality of oysters, Crassostrea gigas, cultivated on the bottom, in a subtidal bay of South Brittany : the bay of Quiberon (56, France). Massive mortalities of oysters were reported in summer 2006 in this bay, exclusively located in the deep muddy area with a positive gradient eastward. A validated biogeochemical model was applied in order to simulate the dissolved oxygen over 2000-2006 : it revealed several episodes of hypoxia, more or less intense according to years, but with the same spatial distribution. This approach proved 2006 to be the most hypoxic year since 2000. The hypoxia was due to a rare conjunction of 3 factors :... |
| Tipo: Text |
Palavras-chave: Baie Quiberon; Crassostrea gigas; Huître; Mortalité; Croissance; Hypoxie; Oxygène; Modèle; Upwelling; Loire; Vilaine; Quiberon; Crassostrea gigas; Oyster; Mortality; Growth; Hypoxia; Oxygen; Model; DEB; Upwelling; Loire; Vilaine. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00180/29131/27535.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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| Raillard, Olivier; Menesguen, Alain. |
| Oyster production of the Marennes-Oléron Basin is simulated using a model integrating phytoplankton growth, oyster growth and horizontal transport of suspended matter. Firstly the simulations are compared to the measurements. At season scale, the phytoplankton and nitrates evolution are well predicted by the model. In compensation, the model does not simulated well the spring/neap tidal variability of the phytoplankton. Secondly, the phytoplancton and oyster productions are calculated as a function of the nitrates river inputs. Biotic capacity of the basin appears to be particulary influenced by these nutrients during summer. On the other hand, spatial variability of the impact of the nitrates variation is clearly shown, the primary productions of the... |
| Tipo: Text |
Palavras-chave: Croissance; Production; Marennes Oléron; Crassostrea gigas; Huîtres; Modélisation. |
| Ano: 1991 |
URL: http://archimer.ifremer.fr/doc/1991/acte-3042.pdf |
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| Menesguen, Alain. |
| De nombreuses études in situ ainsi qu'un modèle numérique de la croissance des huîtres dans le basin de Marennes-Oléron ont montré le rôle primordial du flux de matière phytoplanctonique dans le rendement de croissance du stock conchylicole. Une part de cette nourriture planctonique est produite dans le bassin grâce aux apports de sels nutritifs du panache de dilution de la Charente. Un modèle simple du cycle de l'azote sans compartiment huître a été couplé à un modèle d'advection-dispersion en boîtes. Les premiers résultats montrent que la stimulation de la production primaire serait relativement faible dans le panache lui-même, en raison de la forte turbidité et du court temps de résidence. Par contre, au cours de leur dérive ultérieure, les masses d'eau... |
| Tipo: Text |
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| Ano: 1989 |
URL: http://archimer.ifremer.fr/doc/00390/50179/50800.pdf |
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| Registros recuperados: 63 | |
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