Consulta: creatorFacets:"Menesguen, Alain"
Registros recuperados: 63
Data/hora: 03/06/2024 07:52:45

Use of passive and active tracers in the biogeochemical-3D hydrodynamical ECO-MARS3D model to assess the role of river inputs on coastal zone of France, British Channel and southern North Sea
Provedor de dados: 5
Autores: 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
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00068/17892/15423.pdf

Modelling seasonal dynamics of biomasses and nitrogen contents in a seagrass meadow (Zostera noltii Hornem.): application to the Thau lagoon (French Mediterranean coast)
Provedor de dados: 5
Autores: 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

A deterministic population dynamics model to study the distribution of a benthic bivalve with planktonic larvae (Paphia rhomboides) in the English Channel (NW Europe)
Provedor de dados: 5
Autores: Savina, Marie; Menesguen, Alain.
This paper describes the development of a modelling framework to study the distribution in the English Channel of a benthic bivalve with planktonic larvae, Paphia rhomboides. Age-structured population dynamics and growth models are linked together to a compartmental transport and NPZ (Nutrients-Phytoplankton-Zooplankton) model. Used in a spin-up mode, i.e. with identical environmental forcing from a year to the next, this deterministic model converges to the same steady state whatever the initial conditions, after 15-30 years of simulation. Important features of the P. rhomboides distribution are reproduced, particularly its high abundance in the GNB (Golfe Normand-Breton) and its almost complete absence in the Western Channel. The results are discussed in...
Tipo: Text
Palavras-chave: Spatial distribution; Meroplanktonic invertebrates; Growth model; Population dynamics model; Paphia rhomboides; English Channel.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-3718.pdf

Modélisation de l'écosystème du bassin de Marennes-Oléron
Provedor de dados: 5
Autores: Bacher, Cedric; Menesguen, Alain; Raillard, Olivier; Heral, Maurice; Deslous-paoli, Jean-marc; Razet, Daniel.
Une approche analytique permet de coupler un modèle physique avec un modèle biologique qui prédit la croissance des huîtres en fonction de la quantité, de la qualité de la nourriture particulaire et de la température. Ce modèle montre clairement l'effet de surcharge du bassin induisant un ralentissement des performances de croissance avec un gradient marqué du nord au sud. Un modèle phytoplanctonique basé sur les apports respectifs en nitrates de la Charente et de l'océan permet de prédire la production primaire en fonction de la température et de la transparence de l'eau. Une simulation supprimant les apports de la Charente permet de préciser la quantité de phytoplancton dépendant de ces apports. Un troisième modè le s'applique à représenter dans une...
Tipo: Text
Palavras-chave: Modèle de croissance huîtres; Modèle phytoplanctonique; Remise en suspension; Marennes-Oléron.
Ano: 1990
URL: http://archimer.ifremer.fr/doc/00439/55045/56481.pdf

Modelling benthic invasion by the colonial gastropod Crepidula fornicata and its competition with the bivalve Pecten maximus . 2. Coupling the 0D model of colony-forming species to a connectivity matrix for a realistic distributed simulation of benthic invasion
Provedor de dados: 5
Autores: 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

Eutrophication: A new wine in an old bottle?
Provedor de dados: 5
Autores: 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

Modelling green macroalgal blooms on the coasts of Brittany, France to enhance water quality management
Provedor de dados: 5
Autores: 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

Modelling nitrogen, primary production and oxygen in a Mediterranean lagoon. Impact of oysters farming and inputs from the watershed
Provedor de dados: 5
Autores: 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

L'utilisation de modèles écologiques dans la lutte contre l'eutrophisation des eaux côtières françaises
Provedor de dados: 5
Autores: Menesguen, Alain.
Increasing anthropogenic nitrogen and phosphorus loadings in some coastal areas have induced during the last twenty years excessive production of algal material, either phytoplanktonic or macrophytic. This so-called eutrophication phenomenon alters the usual structure of ecosystem and can lead to massive kills caused by anoxia in some extreme cases, when almost all the dissolved oxygen in bottom waters has been consumed by organic matter decomposition. Just behind the semi-enclosed lagoons, the most sensible areas are the dilution plumes of main rivers. In the case of French coasts, mediterranean lagoons have been eutrophicated for a long time, whereas the coastal areas of the Bay of Biscay and English Channel have been partially preserved by the strong...
Tipo: Text
Palavras-chave: Ecological models; Hydrodynamical models; Residence time; Limiting factor; Phytoplankton blooms; Green tides; Coastal eutrophication; Modèles écologiques; Modèles hydrodynamiques; Temps de résidence; Elément limitant; Eau colorée; Marée verte; Eutrophisation côtière.
Ano: 1999
URL: http://archimer.ifremer.fr/doc/1999/rapport-144.pdf

Modelling benthic invasion by the colonial gastropod Crepidula fornicata and its competition with the bivalve Pecten maximus . 1. A new 0D model for population dynamics of colony-forming species
Provedor de dados: 5
Autores: Menesguen, Alain; Gregoris, Thomas.
The north-American marine gastropod Crepidula fornicata (Linné 1758), commonly called slipper limpet, has been introduced accidentally in Great Britain, along with American oysters (Crassostrea virginica) at the end of the 19th century. Its spreading, enhanced by oyster transport and international shipping, turned into invasion of a lot of benthic grounds along the North-European coasts. When local conditions are favorable to larval confinement and adult growth, the invasion by very dense populations may deeply change initially sandy or muddy benthic communities into similar “slipper limpet communities”. Competition for space eliminates several species of native infauna, and hampers the survival of some epibenthic bivalves such as the scallop Pecten...
Tipo: Text
Palavras-chave: Crepidula fornicata; Invasive species; Benthic gastropod; Colony model; Matching matrix; Pecten maximus; Competition; Population dynamics; Limit cycle.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00415/52601/53491.pdf

Analyse statistique de l'évolution temporelle de paramètres hydrobiologiques dans les bassins du port du Havre
Provedor de dados: 5
Autores: Menesguen, Alain; Laurec, Alain.
The study of the spatial structure and temporal evolution of several hydrobiological parameters in a flooding docks system provided a good illustration for the analytical power of a methodology dealing with the statistical processing of multivariate timeseries. This technique can be characterized by prior extraction of the trends, treated separately as ordinary multivariate data, and by a consequent multi-spectral analysis of the residual signais. This procedure offers the advantage of clarifying the analysis of the major features of the phenomenon (i.e. the trends) and unmasking the subtle spatio-temporal structure through the residual signais. The application on Le Havre harbour showed a strong enrichment in nutrients and also a plausible but partial...
Tipo: Text
Palavras-chave: Analyse spectrale; Désaisonnalisation; Séries temporelles multivariées; Eutrophisation; Spectral analysis; Deseasonalisation; Multivariate time-series; Nutrient enrichment.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/00113/22466/20147.pdf

Observations de l'Ifremer sur les zones d'extraction et de stockage de crépidules prévues en rade de Brest par le programme Crepirade du CLPM du Nord-Finistère
Provedor de dados: 5
Autores: 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
Ano: 2003
URL: http://archimer.ifremer.fr/doc/2003/rapport-6323.pdf

Simulation de l'effet sur l’eutrophisation côtière bretonne de 3 scénarios de réduction des teneurs en nitrate et phosphate de chaque bassin versant breton et de la Loire
Provedor de dados: 5
Autores: Dussauze, Morgan; Menesguen, Alain.
This study commissioned by the Région Bretagne and the Agence de l'Eau Loire Bretagne aimed at assessing on a mathematical modelling basis the marine influence of most of watersheds in Brittany, and the impact of 4 scenarios of reduction of the loadings of each of these watersheds on the phytoplanctonic biomass and ulva mass proliferation. The ecological 3D model ECOMARS3D has been applied to a domain containing Brittany (which is also used in an operational mode for putting everyday the 2dayforecasts on the website: http://www.previmer.org/previsions/production_primaire/modele_eco_mars3d_bretagne) and to 6 zooms which enabled a finer representation of coastal waters. This study highlighted the fact that: •a nitrate reduction for any river has no effect on...
Tipo: Text
Palavras-chave: Bretagne; Bassins versants; Eaux côtières; Nitrate; Phosphate; Marée verte; Ulve; Diatomée; Dinoflagellé; Modèle mathématique; Brittany; Watersheds; Coastal waters; Nitrate; Phosphate; Green tide; Ulva; Diatom; Dinoflagellate; Mathematical model.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/00097/20804/18429.pdf

On the interest of using field primary production data to calibrate phytoplankton rate processes in ecosystem models
Provedor de dados: 5
Autores: Grangere, Karine; Lefebvre, Sebastien; Menesguen, Alain; Jouenne, Fabien.
In many ecosystem models based on empirical formulations, parameters generally are calibrated in order to achieve the best fit between measured and simulated chlorophyll a standing stocks. An accurate calibration of rate processes as primary production rarely is taken into account. In this paper, we test the usefulness of calibration of phytoplankton photosynthetic processes in an ecosystem model using field primary production data. We used 18 months of photosynthetic process data from the Baie des Veys ecosystem (Normandy, France). Five empirical formulations of photosynthesis-irradiance curve models amongst the most widely used were tested. In each formulation, the variability of photosynthetic parameters (i.e. the light-saturated rate of photosynthesis...
Tipo: Text
Palavras-chave: Baie des Veys; Normandy; France; Diatoms; Chlorophyll a to carbon ratio; Parameter optimisation; Mechanistic formulations; Empirical formulations; Photosynthesis irradiance curve.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6810.pdf

Modélisation écologique de la marée verte sur les côtes bretonnes
Provedor de dados: 5
Autores: 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
Ano: 2007
URL: https://archimer.ifremer.fr/doc/00480/59150/61779.pdf

Programme Charente-Marennes-Oléron Volet Maritime
Provedor de dados: 5
Autores: 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

PREVIMER: A coastal operational oceanography system coupled to the Copernicus Marine Service
Provedor de dados: 5
Autores: 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
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00189/30039/28525.pdf

L'eutrophisation des eaux marines et saumâtres en Europe, en particulier en France
Provedor de dados: 5
Autores: 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

How to avoid eutrophication in coastal seas? A new approach to derive river-specific combined nitrate and phosphate maximum concentrations
Provedor de dados: 5
Autores: 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&amp;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

Communautés du phytoplancton. Sous-région marine Manche - Mer du Nord. Evaluation initiale DCSMM.
Provedor de dados: 5
Autores: Belin, Catherine; Haberkorn, Hansy; Menesguen, Alain.
Tipo: Text
Palavras-chave: Manche; Mer du Nord; Communautés du phytoplancton; Biocénoses; Modélisation écologique; Synthèse bibliographique.
Ano: 2012
URL: https://archimer.ifremer.fr/doc/00327/43832/43406.pdf

Bulletin d'information PREVIMER - Informations et analyses des eaux côtières. Janvier Février 2010 - n°12
Provedor de dados: 5
Autores: Lazure, Pascal; Huret, Martin; Gohin, Francis; Menesguen, Alain; Lecornu, Fabrice; Le Traon, Pierre-yves; Thomin, Pascale; Jegou, P.; Baraer, F.; Corre, Gilles; Louazel, Stephanie; Equipe projet PREVIMER.
Sommaire * Météo et débits des fleuves.....2 * Caractéristiques des masses d’eau côtières..............5 * Production biologique............11 * Rappel des objectifs du bulletin PREVIMER..................13 * Les moyens d’observations et de prévisions de l’état des mers côtières...........................13 * Glossaire..................................15
Tipo: Text
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00242/35367/33866.pdf

EMOSEM Final Report - Ecosystem Models as Support to Eutrophication Management In the North Atlantic Ocean
Provedor de dados: 5
Autores: Desmit, Xavier; Lacroix, Geneviève; Thieu, Vincent; Menesguen, Alain; Dulière, Valerie; Campuzano, Francisco; Billen, Gilles; Neves, Ramiro; Lancelot, Christiane; Gypens, Nathalie; Dussauze, Morgan; Garnier, Josette; Silvestre, Marie; Passy, Paul; Lassaletta, Luis; Guittard, Gabriel; Théry, Sylvain; Thouvenin, Benedicte; Garcia, Carla; Pinto, Ligia; Sobrinho, Joao; Mateus, Marco; Ascione Kenov, Isabella.
One of the leading challenges in marine science and governance is to improve scientific guidance of management measures to mitigate eutrophication nuisances in the EU seas. Too few approaches integrate the eutrophication process in space (continuum river-ocean) and in time (past, present and future status). A strong need remains for (i) knowledge/identification of all the processes that control eutrophication and its consequences, (ii) consistent and harmonized reference levels assigned to each eutrophication-related indicator, (iii) identification of the main rivers directly or indirectly responsible for eutrophication nuisances in specific areas, (iv) an integrated transboundary approach and (v) realistic short term and long term nutrient reduction...
Tipo: Text
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00292/40301/38750.pdf

La modélisation des " marées vertes " littorales et ses applications
Provedor de dados: 5
Autores: Menesguen, Alain.
Excessive proliferation of UIva sp. (Chlorophyta) during spring and summer was responsible for increasing injuries to recreational use of several beaches of Britanny (France) during the last decade. These worldwide mass blooms are well known in eutrophicated lagoons (Venice, Tunis... ), but look paradoxical along open beaches with large tidal range and weak terrestrial nutrients inputs. Numerical modelling of the coupled physical and biological aspects clearly explains the Ulva mass blooms by the dynamical trapping of water masses in bays where tidal residual drift vanishes, and shows the main responsability of the increase of nitrogen inputs (of agricultural sources) in triggering the recent magnification of a natural phenomenon.
Tipo: Text
Ano: 1990
URL: https://archimer.ifremer.fr/doc/00480/59125/61753.pdf

Modelling the Karenia mikimotoi bloom that occurred in the western English Channel during summer 2003
Provedor de dados: 5
Autores: Vanhoutte Brunier, Alice; Fernand, L; Menesguen, Alain; Lyons, S; Gohin, Francis; Cugier, Philippe.
Observations from space and in situ from the R.V Corystes 8/03 Cruise show that a massive Karenia mikimotoi bloom occured during summer 2003 in the western English Channel. Due to exceptional climatoligical conditions that occured in June 2003, the installation of a very strong thermocline enhanced the development of a massive bloom over 1 million cells 1(-1) in the Central English Channel. This paper presents the application of a mathematical model of this species, previously developed in for the Bay of Biscay, into a general 3D model of the primary production of the English Channel and southern Bight of the North Sea. Allelopathic interactions exerted by K. mikimotoi on other phytoplankton species and the role of agitation in the mortality of this...
Tipo: Text
Palavras-chave: Western English Channel; SeaWiFS; Primary production; Karenia mikimotoi; 3D modelling; Coupled physical biogeochemical.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-3717.pdf

Simulations de rejet en rade de Brest d'ulves draguées dans l'anse du Moulin Blanc
Provedor de dados: 5
Autores: 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
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/rapport-6326.pdf

A steady-state model of PCB accumulation in dab food web
Provedor de dados: 5
Autores: Loizeau, Veronique; Menesguen, Alain.
A five-compartment steady-state food web model is proposed for the benthic food web leading to the dab. Three exposure pathways are considered in the description of accumulation by benthic animals: ingestion of particulate contaminants associated with either sediment or phytoplankton, and respiratory uptake of free dissolved contaminant in overlaying water. Application of the model to a simple food web in the Bay of Seine (Eastern Channel) indicates that : a) feeding is the principal route of contamination, especially for PCB which have more than four chlorine atoms in the molecule ; b) excretion and growth rates, phytoplankton lipid fraction and organic carbon content of sediment are the parameters which mostly determine the chemical bioaccumulation in...
Tipo: Text
Palavras-chave: MODEL; PCB; FOOD WEB; BENTHIC INVERTEBRATES; DAB.
Ano: 1993
URL: http://archimer.ifremer.fr/doc/00100/21127/18747.pdf

Seasonal evolution of the nutrient pattern on Biscay Bay continental shelf over the years 1999-2000
Provedor de dados: 5
Autores: Loyer, Sophie; Lampert, Luis; Menesguen, Alain; Cann, Philippe; Labasque, Thierry.
The French Atlantic shelf is Subjected to strong anthropic influences (urban, industrial and agricultural discharges) of two main rivers (Loire and Gironde). The extension and consequences of these continental loadings for the nutrient and chlorophyll distribution have never been studied before oil the Bay of Biscay continental shelf as a whole. We present the first synoptic view of the nutrient distribution and evolution oil the French Atlantic shelf. Nutrient concentrations of the surface layer were Studied during four cruises in April, June, September 1999 and March 2000. Until June, the freshwater inputs induce a nitrate gradient from river months to offshore waters in the vicinity of the 100 m isobath. The Redfield's ratio Study highlights the nitrate...
Tipo: Text
Palavras-chave: Nutrients; River inputs; Coastal water; Bay of Biscay.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-3956.pdf

Modélisation de la production primaire dans le bassin conchylicole de Marennes-Oléron (France)
Provedor de dados: 5
Autores: 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
Ano: 1989
URL: http://archimer.ifremer.fr/doc/00390/50179/50800.pdf

Les problèmes d'eutrophisation littorale et leur modélisation
Provedor de dados: 5
Autores: Menesguen, Alain.
Following lakes and rivers, a lot of estuaries (during the last twenty years) and shallow coastal zones (during the last decade) have been severely eutrophicated because of the too much increasing loads of nitrogen and phsophorus. In situ stutdy and numerical modelling of two french case studies bring some explanation to the facts that, in some sites, enrichment turns into green macroalgal proliferation whereas, in others, mass blooms of phytoplankton are induced. Whatever the case may be, the prominent role of the residence time of water in the enriched zone has been proven. In open coastal ecosystems, the difficulty in determining this residence time as well as the limiting factor (nitrogen, or phosphorus, or light) lowers considerably the reliability of...
Tipo: Text
Palavras-chave: Eutrophisation côtière; Elément limitant; Temps de résidence; Modèles hydrodynamiques; Modèles écologiques; Coastal eutrophication; Limiting factor; Residence time; Hydrodynamical models; Ecological models.
Ano: 1992
URL: http://archimer.ifremer.fr/doc/00423/53416/54295.pdf

Two- or three-layered box-models versus fine 3D models for coastal ecological modelling? A comparative study in the English Channel (Western Europe)
Provedor de dados: 5
Autores: 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

Modélisation sur vingt ans (1976-1995) de la production phytoplanctonique en baie de Seine
Provedor de dados: 5
Autores: Guillaud, Jean-francois; Menesguen, Alain.
This paper presents an ecological modelling of the Bay of Seine (Eastern Channel) over the last twenty years, chosen as a typical case of eutrophication in a river plume. In the physical sub-model, the Bay is divided into 42 boxes and water fluxes between them are calculated automatically using Ifremer's "Elise" software. A two-layer, vertical thermohaline model is then linked with the horizontal circulation scheme in order to take vertical stratification into account. The biological submodel deals with two chemical elements, nitrogen and silicon, and splits phytoplankton into diatoms and flagellates. Results from this ecological model point out the spatial concordance of highest phytoplanktonic concentrations with the river plume spreading in the bay....
Tipo: Text
Palavras-chave: Eutrophication; Flagellate; Diatom; Bay of Seine; Two layer model; Eutrophisation; Diatomée; Diatomée; Baie de Seine; Modèle bicouche.
Ano: 1998
URL: https://archimer.ifremer.fr/doc/1998/publication-842.pdf

Utilisation de l'analyse mathématique de la croissance dans la comparaison de diverses techniques d'élevage de la Palourde
Provedor de dados: 5
Autores: Menesguen, Alain; Flassch, Jean-pierre; Nedelec, J.
In order to determine the best strategy for manilla clam rearing, twenty seven batches of the species Rudilapes philippinarum (Adams, Reeve, 1850) were reared under various technical conditions, over periods of up to two and-a-half years. The numerous data conceming the length growth (sampling was donc every one-and-a-half months) allowed us to quantify, by means of the parameters appearing in a seasonaly modulated von Bertalanffy growth curve, several aspects of the growth process in each balch. Subsequently, on the basis of a stepwise multilinear regression technique, we searched for an ernpirical relation between the technical characteristics of the various rearing procedures (independent variables) and the previous growth pararneters (dependent...
Tipo: Text
Ano: 1984
URL: http://archimer.ifremer.fr/doc/00018/12952/9927.pdf

Flux de nutriments dans le continuum Homme-Terr-Mer : évaluation de scénarios agricoles et impacts du changement climatique
Provedor de dados: 5
Autores: Garnier, Josette; Raimonet, Mélanie; Billen, Gilles; Thieu, Vincent; Menesguen, Alain; Le Gendre, Romain; Silvestre, Marie; Thery, Sylvain; Riou, Philippe.
Tipo: Text
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00618/73054/72169.pdf

L’eutrophisation : manifestations, causes, conséquences et prédictibilité. Synthèse de l’Expertise scientifique collective CNRS - Ifremer - INRA - Irstea
Provedor de dados: 5
Autores: Pinay, Gilles; Gascuel, Chantal; Menesguen, Alain; Souchon, Yves; Le Moal, Morgane; Levain, Alix; Moatar, Florentina; Pannard, Alexandrine; Souchu, Philippe.
L'eutrophisation génère des perturbations majeures pour les écosystèmes aquatiques et a des impacts sur les biens et les services associés, sur la santé humaine et sur les activités économiques. Ses manifestations les plus connues sont les efflorescences de cyanobactéries toxiques dans les lacs et cours d'eau et les proliférations de macroalgues vertes dans les zones côtières. Ces proliférations représentent de fortes biomasses dont la décomposition par des bactéries induit un appauvrissement ou un épuisement en oxygène du milieu, voire l'émission de gaz toxiques. Les débats sur l'identification des facteurs et des niveaux de risque d'eutrophisation ont conduit à la réalisation d'une expertise scientifique collective. Elle vise à fournir aux pouvoirs...
Tipo: Text
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00408/51903/52526.pdf

Simulation de l'effet de 3 scénarios de réduction des teneurs de l'Elorn en nitrate sur l'eutrophisation de la rade de Brest
Provedor de dados: 5
Autores: Menesguen, Alain.
This study commissioned by the Syndicat de l'Elorn et de la Rivière de Daoulas aimed at assessing on a mathemical modelling basis the impact of 3 scenarios of reduction of the loadings of Elorn river (imposed concentrations : 20, 15 et 10 mg/L NO3) on the status of ulva mass proliferation in the Moulin Blanc cowe (Bay of Brest). An ecological 3D model of N, P and Si cycling in the bay of Brest has been applied to a "reference situation": 2004 meteorological forcing combined to recent loadings of the new sewage plant. This model showed that: · the 3 reduction scenarios did not reduce significantly the early summer biomass of ulvae, but allowed to slightly reduce the subsequent summer and autumn levels of biomass (up to 20% reduction for 10 mg/L NO3). The...
Tipo: Text
Palavras-chave: Mathematical model; Dinoflagellate; Diatom; Ulva; Green tide; Nitrate; Moulin Blanc cowe; Elorn river; Bay of Brest; Modèle mathématique; Dinoflagellé; Diatomée; Ulve; Marée verte; Nitrate; Anse du Moulin Blanc; Elorn; Rade de Brest.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/rapport-6327.pdf

Modèlisation des transferts de nutriments dans le continuum "Seine, Seine Aval, Baie de Seine"
Provedor de dados: 5
Autores: Billen, Gilles; Cugier, Philippe; Garnier, Josette; Menesguen, Alain; Guillaud, Jean-francois; Durand, I.
Le processus d'eutrophisation des milieux marins côtiers, et le développement épisodiques de dinoflagellés qui en est une des manifestations, dépend de manière complexe de l'équilibre des flux d'azote, de phosphore et de silice en provenance des milieux terrestres du bassin versant. Ceux ci sont déterminés par la manière dont les activités humaines sur le bassin versant interagissent avec les processus naturels. La possibilité de prévoir l'effet sur l'eutrophisation marine des mesures prises pour l'amélioration de la qualité des eaux continentales dépend donc à la fois de notre connaissance du fonctionnement des milieux marins et de celui des bassins versants. En vue de développer les outils de modélisation nécessaire pour prévoir l'Etat de la Baie de...
Tipo: Text
Ano: 2003
URL: http://archimer.ifremer.fr/doc/00106/21695/19274.pdf

Modélisation de la production de l'huître Crassostrea gigas du bassin de Marennes-Oléron (France). Etude de l'influence des apports de nitrates du fleuve Charente sur la production primaire et ostréicole
Provedor de dados: 5
Autores: 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

Modeling the nitrogen cycle in the channel : a first approach
Provedor de dados: 5
Autores: 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

Modelling the biogeochemical cycles of elements limiting primary production in the English channel .2. Sensitivity analyses
Provedor de dados: 5
Autores: Hoch, T; Menesguen, Alain.
A general framework for an ecological model of the English Channel was described in the first of this pair of papers. In this study, it was used to investigate the sensitivity of the model to various factors: model structure, parameter values, boundary conditions and forcing variables. These sensitivity analyses show how important quota formulation for phytoplankton growth is, particularly for growth of dinoflagellates. They also stress the major influence of variables and parameters related to nitrogen. The role played by rivers and particularly the river Seine was investigated. Their influence on global English Channel phytoplanktonic production seems to be relatively low, even though nutrient inputs determine the intensity of blooms in the Bay of Seine....
Tipo: Text
Palavras-chave: English Channel; Sensitivity analyses; Ecological model.
Ano: 1997
URL: http://archimer.ifremer.fr/doc/00337/44791/44478.pdf

Les risques conchylicoles en Baie de Quiberon. Troisième partie : le risque d’hypoxie pour l’huître creuse Crassostrea gigas. Rapport final du projet Risco 2010-2013
Provedor de dados: 5
Autores: 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

Surveillance Ecologique. Site de Flamanville Année 1984
Provedor de dados: 5
Autores: Gentien, Patrick; Erard-le Denn, Evelyne; Quintin, Jean-yves; Dreves, Luc; Guillaumont, Brigitte; Loarer, Ronan; Menesguen, Alain; Piriou, Jean-yves.
The Flamanville site has been the focus of a number of hydrobiological and biological measurement cycles in the years 1976-1978 and 1983-1984. The first project studies resulted in a reference ecological assessment based on 41 missions (229 stations). The monitoring studies conducted in 1983 and 1984 consisted of 16 campaigns (32 stations). The lowering of the number of samplings between both cycles is explained by the programs coherence; the monitoring indeed focuses on a number of parameters considered as the most significant or sensitive according to the most efficient strategy.
Tipo: Text
Ano: 1986
URL: http://archimer.ifremer.fr/doc/1986/rapport-6466.pdf

A coastal operational oceanography system coupled to the GMES marine service
Provedor de dados: 5
Autores: Lecornu, Fabrice; Dumas, Franck; Gohin, Francis; Le Traon, Pierre-yves; Menesguen, Alain; Pineau-guillou, Lucia.
Tipo: Text
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00243/35380/33883.pdf

Modelling the biogeochemical cycles of elements limiting primary production in the English channel .1. Role of thermohaline stratification
Provedor de dados: 5
Autores: Menesguen, Alain; Hoch, Thierry.
This paper presents the general framework of an ecological model of the English Channel. The model is a result of combining a physical sub-model with a biological one. in the physical submodel, the Channel is divided into 71 boxes and water fluxes between them are calculated automatically. A 2-layer, vertical thermohaline model was then linked with the horizontal circulation scheme. This physical sub-model exhibits thermal stratification in the western Channel during spring and summer and haline stratification in the Bay of Seine due to high flow rates from the river. The biological sub-model takes 2 elements, nitrogen and silicon, into account and divides phytoplankton into diatoms and dinoflagellates. Results from this ecological model emphasize the...
Tipo: Text
Palavras-chave: Ecological box-model; Thermohaline stratification; English Channel; Primary production.
Ano: 1997
URL: http://archimer.ifremer.fr/doc/00337/44790/44479.pdf

Modelling the spatial heterogeneity of ecological processes in an intertidal estuarine bay: dynamic interactions between bivalves and phytoplankton
Provedor de dados: 5
Autores: Grangere, Karine; Lefebvre, Sebastien; Bacher, Cedric; Cugier, Philippe; Menesguen, Alain.
Spatial patterns in ecological communities result from a combination of physical and biological factors. In an estuarine intertidal bay, spatial differences have been found in the structure of phytoplanktonic communities and in the biological performance of cultivated oysters. It has been hypothesised that trophic heterogeneity exists, although the mechanisms controlling it remain undefined. Spatial and temporal interactions in the structure of phytoplanktonic biomass and in the biological performance of cultivated oysters were highlighted in this estuarine intertidal bay using a 2-dimensional hydrodynamic model coupled to a nutrient-phytoplankton-zooplankton bivalve food web model. The coupled models allowed a reproduction in space and time of variations...
Tipo: Text
Palavras-chave: Spatial heterogeneity; Hydrodynamics; Ecosystem model; Food supply; Bivalves; Dynamic energy budget model; Physiological status; Baie des Veys.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00017/12854/9819.pdf

Observation and modelling of natural retention structures in the English Channel
Provedor de dados: 5
Autores: Menesguen, Alain; Gohin, Francis.
Accumulation of heat, or dissolved substances (nutrients, pollutants, etc.), or fine suspended particles in a water body is a key process in the functioning of aquatic ecosystems and their resistance to perturbations. In complex and wide open environments such as marine ecosystems, net accumulation is not only linked to the local renewal capacity of the water body, but also to the partial recirculation of water due to convective cells of various sizes. The English Channel, which can be considered as mainly dominated by tidal movements, exhibits such a complex quasi-permanent long-term circulation, made of a central "river" bordered with a lot of nested gyres. Here, we show that structures visible on satellite images of SST (Sea Surface Temperature),...
Tipo: Text
Palavras-chave: Remote sensing; Suspended Particulate Matter; Chlorophyll; SST; Retention structures; Tidal residual circulation; Steady state model; English Channel.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-2181.pdf

Designing optimal scenarios of nutrient loading reduction in a WFD/MSFD perspective by using passive tracers in a biogeochemical-3D model of the English Channel/Bay of Biscay area
Provedor de dados: 5
Autores: Menesguen, Alain; Dussauze, Morgan; Dumas, Franck.
In most cases, eutrophication of a coastal zone is a multi-source phenomenon. The questions often raised by authorities about these different sources are: what are their marine area of influence and their respective role in the eutrophication process? A first answer to these questions is proposed for the bay of Biscay-English Channel French coasts, using a hydrodynamical model alone with a passive tracer for each of the main 45 French watersheds of the domain. The statistical marine receiving area of each river is then defined over a whole decade (2000–2010) by using different percentiles (respectively the 10th, 50th, 90th ones) of the distribution of tracer values in each mesh of the grid: this enables to map the dilution areas of each river plume...
Tipo: Text
Palavras-chave: 3D modelling; Regions of freshwater influence; Nutrient loading reduction; Good ecological status; Simplex method.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00445/55626/57302.pdf

Ecological model of the Bay of Biscay and English Channel shelf for Environmental Status assessment Part 1: Nutrients, phytoplankton and oxygen
Provedor de dados: 5
Autores: Menesguen, Alain; Dussauze, Morgan; Dumas, Franck; Thouvenin, Benedicte; Garnier, Valerie; Lecornu, Fabrice; Repecaud, Michel.
European directives (Water Framework Directive - WFD and Marine Strategy Framework Directive - MSFD) require a regular survey of several descriptors of the Environmental Status of coastal waters of the North-east Atlantic Ocean. Especially for the MSFD, which may concern large continental shelf areas where measurements are scarce, realistic ecological models can help assessing the Environmental Status. The ECO-MARS3D model of the pelagic ecosystem of the Bay of Biscay and English Channel continental shelf (NE Atlantic) has been developed for these applied purposes and validated against various types of historic data. This first paper deals with the basic biogeochemical version, which contains inorganic nutrients (NH4, NO3, PO4, Si(OH)4), three...
Tipo: Text
Palavras-chave: Ecological 3D model; Continental shelf; Bay of Biscay and English Channel; Surface chlorophyll; Dissolved oxygen; MSFD.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00469/58098/60510.pdf

Modélisation des écosystèmes conchylicoles : bassin de Marennes-Oléron - Rapport de fin de Contrat
Provedor de dados: 5
Autores: Heral, Maurice; Bacher, Cedric; Razet, Daniel; Prou, Jean; Deslous-paoli, Jean-marc; De Pontual, Helene; Raillard, Olivier; Ravail, Brigitte; 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: Modélisation; Production; Biomasse; Huîtres creuses; Crassostrea gigas; Capacité biotique; Bassin de Marennes Oléron.
Ano: 1989
URL: http://archimer.ifremer.fr/doc/00048/15904/13332.pdf

Operational modelling of nutrients and phytoplancton in the bay of biscay and english channel
Provedor de dados: 5
Autores: Menesguen, Alain; Dussauze, Morgan; Lecornu, Fabrice; Dumas, Franck; Thouvenin, Benedicte.
Nitrate loadings to the French coastal waters of the Bay of Biscay and the English Channel have increased from 5 to 10 times during the four last decades, due to runoff on intensively fertilized agricultural watersheds. Eutrophication of this coastal zone is now a recurrent problem, with wellknown direct impacts (Ulva “green tides” on beaches, excessive phytoplanktonic blooms responsible for “coloured waters” and bottom hypoxia events offshore), but also indirect enhancement of the toxicity of some phytoplankton species, caused for instance by increased N:Si ratio in the coastal sea. In order to better guide the decision makers about nutrient loading reduction, Ifremer uses the so-called ECO-MARS3D biogeochemicalhydrodynamical model to simulate the present...
Tipo: Text
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00197/30797/29166.pdf

Reducing marine eutrophication may require a paradigmatic change
Provedor de dados: 5
Autores: 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&amp;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

Biogeochemical modelling in the Bay of Seine (France): an improvement by introducing phosphorus in nutrient cycles
Provedor de dados: 5
Autores: Guillaud, Jean-francois; Andrieux-loyer, Francoise; Menesguen, Alain.
As part of the French National Programme for Coastal Oceanography, this paper focuses on improvement of biogeochemical modelling in the: Bay of Seine (Eastern Channel), by introducing phosphorus in nutrient cycles. The Bay of Seine receives the Seine river, which exhibits very high nutrient concentrations, and this coastal zone constitutes a typical case of eutrophication in a river plume area. In terms of analyses, sequential extraction and analysis of sedimentary phosphorus were used in order, to measure various forms of particulate phosphorus in suspended matter and sediment (calcium-bound phosphate, Fe/Al-bound phosphate, exchangeable phosphate and organic phosphorus). In the modelling approach, the Bay is divided into 42 boxes and a two-layer,...
Tipo: Text
Palavras-chave: Bay of Seine; Phytoplankton; Phosphorus; River plume; Biological two layer box model.
Ano: 2000
URL: http://archimer.ifremer.fr/doc/2000/publication-462.pdf

Impacts of high-nitrate freshwater inputs on macrotidal ecosystems. I. Seasonal evolution of nutrient limitation for the diatom-dominated phytoplankton of the Bay of Brest (France)
Provedor de dados: 5
Autores: 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 &gt;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

Overview of eutrophication indicators to assess environmental status within the European Marine Strategy Framework Directive
Provedor de dados: 5
Autores: Ferreira, Joao G.; Andersen, Jesper H.; Borja, Angel; Bricker, Suzanne B.; Camp, Jordi; Da Silva, Margarida Cardoso; Garces, Esther; Heiskanen, Anna-stiina; Humborg, Christoph; Ignatiades, Lydia; Lancelot, Christiane; Menesguen, Alain; Tett, Paul; Hoepffner, Nicolas; Claussen, Ulrich.
In 2009, following approval of the European Marine Strategy Framework Directive (MSFD, 2008/56/EC), the European Commission (EC) created task groups to develop guidance for eleven quality descriptors that form the basis for evaluating ecosystem function. The objective was to provide European countries with practical guidelines for implementing the MSFD, and to produce a Commission Decision that encapsulated key points of the work in a legal framework. This paper presents a review of work carried out by the eutrophication task group, and reports our main findings to the scientific community. On the basis of an operational, management-oriented definition, we discuss the main methodologies that could be used for coastal and marine eutrophication assessment....
Tipo: Text
Palavras-chave: Eutrophication; Chlorophyll; Dissolved oxygen; Harmful algae; Marine; Coastal; Assessment methods; Europe; Marine Strategy Framework Directive; Water Framework Directive.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00039/15055/12609.pdf

Sea-temperature anomalies and population dynamics variations : effects on growth and density of three bivalves
Provedor de dados: 5
Autores: Menesguen, Alain; Dreves, Luc.
The demographic structure of stable populations is usually modelled by a simple exponential decay mode. For 3 mollusc species, this model has been improved by taking inlo account monthly sea-temperature anomalies calculated on a 20 yr daily temperature chronicle. For the 3 species examined, Tapes rhomboïdes, Glycymeris glycymeris and Spisula ovalis, from the southern part of the Western English Channel, only temperature anomalies during the 2 mo following the major spawning period were positively eorrelated with density anomalies, probably in eonneetion with larval stage sensitivity. Comparison of temperature anomalies and mean annual growth va riability suggests an apparent positive effeet of temperature during autumn or winter months, significant for T....
Tipo: Text
Ano: 1987
URL: http://archimer.ifremer.fr/doc/00155/26639/24880.pdf

Modelling the influence of environmental factors on the physiological status of the Pacific oyster Crassostrea gigas in an estuarine embayment; The Baie des Veys (France)
Provedor de dados: 5
Autores: Grangere, Karine; Menesguen, Alain; Lefebvre, Sébastien; Bacher, Cedric; Pouvreau, Stephane.
It is well known that temporal changes in bivalve body mass are strongly correlated with temporal variations in water temperature and food supply. In order to study the influence of the year-to-year variability of environmental factors on oyster growth, we coupled a biogeochemical sub-model, which simulates trophic resources of oysters (i.e. phytoplankton biomass via chlorophyll a), and an ecophysiological sub-model, which simulates growth and reproduction (i.e. gametogenesis and spawning), using mechanistic bases. The biogeochemical sub-model successfully simulated phytoplankton dynamics using river nutrient inputs and meteorological factors as forcing functions. Adequate simulation of oyster growth dynamics requires a relevant food quantifier compatible...
Tipo: Text
Palavras-chave: Baie des Veys; Normandy; France; Physiological Status; Phytoplankton Carbon Concentration; Food Supply; Temperature; Dynamic Energy Budget model; Biogeochemical Model.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6809.pdf

Détermination des "bassins récepteurs" marins des principaux fleuves français de la façade Manche-Atlantique, et de leurs rôles respectifs dans l'eutrophisation phyto-planctonique des masses d'eau DCE et des sous-régions DCSMM. Phase 1 (2013) : Calcul de scénarios optimaux à partir des " bassins récepteurs". Phase 2 (2014) : Simulation de scénarios imposés et des scénarios optimaux
Provedor de dados: 5
Autores: Menesguen, Alain; Dussauze, Morgan.
- This study (granted up to 50% by the French Office for Water and Aquatic Environments ONEMA) aimed at determining by modelling (hydrodynamical/biogeochemical ECOMARS3D model) the marine "receiving basins" of the main tributaries to the French waters of the English Channel and the Bay of Biscay. Knowing the respective part of each of these marine "receiving basins" in winter nutrient distribution, some optimal scenarios of nutrient loading reduction can be computed for nitrate or phosphate in order to bring back any marine water to the Good Ecological Status regarding eutrophication, at the best efficiency/cost ratio. - The study encompasses 45 watersheds (or clusters of neighboring watersheds) which have been retained because of their sizes and flow...
Tipo: Text
Palavras-chave: Zone Manche-Atlantique; Modélisation 3D; Bassins versants; Bassins récepteurs marins; Nitrate; Phosphate; Réduction d'apports; Situation "pristine"; Production primaire; Oxygène dissous; Classement DCE; Bon Etat Ecologique; Optimisation linéaire; Simplexe; Optimisation quadratique; Méthode de Beale.; English Channel; Bay of Biscay; 3D modelling; Watersheds; Receiving basins; Nitrate; Phosphate; Nutrient loading reduction; Pristine situation; Primary production; Dissolved oxygen; WFD classification; Good Ecological Status; Linear optimisation; Simplexe method; Quadratic optimisation; Beale's method.
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00333/44422/44083.pdf

La Crépidule : identifier les mécanismes de sa prolifération et caractériser ses effets sur le milieu pour envisager sa gestion (Chantier : Baie de Saint-Brieuc)
Provedor de dados: 5
Autores: Hamon, Dominique; Blanchard, Michel; Houlgatte, Eric; Blanchet, Aline; Gaffet, Jean-dominique; Cugier, Philippe; Menesguen, Alain; Bassoullet, Philippe; Cann, Philippe; Domalain, David; Haubois, Anne-gaelle.
La crépidule (Crepidula fornicata), mollusque gastéropode de la famille des Calyptraeidés, originaire de la côte atlantique d'Amérique du nord, a été introduite accidentellement sur le littoral français en plusieurs étapes (Blanchard, 1995, 1997). La plus importante d'entre elles, au début des années 70, est liée à l'importation massive de l'huître japonaise (Crassostrea gigas), en remplacement de l'huître portugaise (Crassostrea angulata) décimée par une épizootie. Cette espèce opportuniste a notamment proliféré au voisinage des principaux bassins ostréicoles de la Manche et de l'Atlantique. C'est en particulier le cas des zones conchylicoles infralittorales du golfe normano-breton où des évaluations de stocks font état de plusieurs centaines de milliers...
Tipo: Text
Ano: 2002
URL: http://archimer.ifremer.fr/doc/00032/14295/11574.pdf

The growth of the banded carpet shell (Paphia rhomboides) in a contrasted region, the English Channel (Western Europe): A modelling study
Provedor de dados: 5
Autores: 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

PREVIMER: A contribution to in situ coastal observing systems
Provedor de dados: 5
Autores: Charria, Guillaume; Repecaud, Michel; Quemener, Loic; Menesguen, Alain; Rimmelin-maury, Peggy; L'Helguen, Stephane; Beaumont, Laurence; Jolivet, Aurelie; Morin, Pascal; Mace, E; Lazure, Pascal; Le Gendre, Romain; Jacqueline, Franck; Verney, Romaric; Marie, Louis; Jegou, Paul; Le Reste, Serge; Andre, Xavier; Dutreuil, Vincent; Regnault, Jean-pierre; Jestin, Herve; Lintanf, Herve; Pichavant, Pascal; Retho, Michael; Allenou, Jean-pierre; Stanisiere, Jean-yves; Bonnat, Armel; Nonnotte, Lidwine; Duros, Wenceslas; Tarot, Stephane; Carval, Thierry; Le Hir, Pierre; Dumas, Franck; Vandermeirsch, Frederic; Lecornu, Fabrice.
To design a prototype for an Integrated Ocean Observing System (IOOS), at least three components are mandatory: a modeling platform, an in situ observing system and a structure to collect and to disseminate the information (e.g. database, website). The PREVIMER project followed this approach and in order to sustain model applications, PREVIMER has developed, funded and organized part of in situ observing networks in the Bay of Biscay and the Channel. For a comprehensive system, focus was addressed on fi xed platforms (MAREL MOLIT, MAREL Iroise, Island network and D4 for sediment dynamics), ships of opportunity (RECOPESCA program and FerryBoxes), and coastal profi lers (ARVOR-C/Cm). Each system is briefl y described and examples of scientifi c results...
Tipo: Text
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00197/30785/29143.pdf

Les "marées vertes" en Bretagne, la responsabilité du nitrate
Provedor de dados: 5
Autores: 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

Predicting the consequences of nutrient reduction on the eutrophication status of the North Sea
Provedor de dados: 5
Autores: Lenhart, Hermann-j.; Mills, David K.; Baretta-bekker, Hanneke; Van Leeuwen, Sonja M.; Van Der Molen, Johan; Baretta, Job W.; Blaas, Meinte; Desmit, Xavier; Kuehn, Wilfried; Lacroix, Genevieve; Los, Hans J.; Menesguen, Alain; Neves, Ramiro; Proctor, Roger; Ruardij, Piet; Skogen, Morten D.; Vanhoutte Brunier, Alice; Villars, Monique T.; Wakelin, Sarah L.
In this paper the results from a workshop of the OSPAR Intersessional Correspondence Group on Eutrophication Modelling (ICG-EMO) held in Lowestoft in 2007 are presented. The aim of the workshop was to compare the results of a number of North Sea ecosystem models under different reduction scenarios. In order to achieve comparability of model results the participants were requested to use a minimum spin-up time, common boundary conditions which were derived from a wider-domain model, and a set of common forcing data, with special emphasis on a complete coverage of river nutrient loads. Based on the OSPAR requirements river loads were derived, taking into account the reductions already achieved between 1985 and 2002 for each country. First, for the year 2002,...
Tipo: Text
Palavras-chave: Eutrophication; Ecosystem modeling; OSPAR Comprehensive Procedure; Eutrophication assessment; North Sea; River nutrient loads; Reduction scenarios.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00003/11391/8054.pdf

Modélisation des blooms de Gymnodinium mikimotoï le long de la façade atlantique française : répartition spatiale
Provedor de dados: 5
Autores: Loyer, Sophie; Lazure, Pascal; Gentien, Patrick; Menesguen, Alain.
In order to study the occurrence of Gymnodinium mikimotoï bloom on the French Atlantic coast, a three-dimensional model of primary production was set up. The biological model was coupled to a hydrodynamic model previously developed at Ifremer, by the intermediary of transport, diffusion and heat fluxes. The cycles of three limiting elements for the phytoplankton growth were modelised: nitrogen, phosphorus and silicon. The second phase of the study aimed at reproducing the summer dinoflagellate blooms. In this new approach a model of the species Gymnodinium mikimotoï was coupled with the previous biomass model which provides the physical and chemical environments. The study focuses on the results obtained by this specific sub-model. The parametrisation was...
Tipo: Text
Palavras-chave: Turbulence; Dinoflagellés; Gymnodinium mikimotoï; Modèle; Nutriments; Turbulence; Dinoflagellate; Gymnodinium mikimotoï; Model; Nutrients.
Ano: 2001
URL: https://archimer.ifremer.fr/doc/00479/59100/61738.pdf

Modelling the marine eutrophication: A review
Provedor de dados: 5
Autores: Menesguen, Alain; Lacroix, Genevieve.
In the frame of a national, joint scientific appraisal, 45 scientific French-speaking experts have been mandated in 2015–2016 by the French ministries of Environment and Agriculture to perform a global review of scientific literature dealing with the eutrophication phenomenon, in freshwater as well as in marine waters. This paper summarizes the main results of this review restricted to a sub-domain, the modelling approach of the marine eutrophication. After recalling the different aims pursued, an overview is given on the historical time course of this modelling effort, its world distribution and the various tools used. Then, the main results obtained are examined, highlighting the specific strengths and weaknesses of the present models. Needs for future...
Tipo: Text
Palavras-chave: Marine eutrophication; Biogeochemical models; Deterministic versus statistical; Nutrient reduction scenarios; Land-sea coupling; Climate change.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00439/55066/56546.pdf