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| Registros recuperados: 148 | |
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| Goulletquer, Philippe; Heral, Maurice; Prou, Jean. |
| Oyster landings in the Maryland portion of the Chesapeake Bay have declined by more than 50fold since the early part of the century, despite intensive management efforts. The annual shell repletion program is the most critical programmatic element to effect recovery of the ailing Eastern oyster Crassotrea virginica stock and fishery. The overall efficacy of shell repletion management depends primarily on the success of spat settlement on the planted shell, and furthermore on their survival rate. The Operations Research techniques and mathematical programming developed by Rothschild et al. (1991) attempt to maximize spat recruitment to the oyster stock subject to a series of operational constraints. Allocation and timing of shell deployment are the most... |
| Tipo: Text |
Palavras-chave: Larval; Settlement; USA; Chesapeake Bay; Crassotrea virginica; Oysters. |
| Ano: 1994 |
URL: http://archimer.ifremer.fr/doc/1994/publication-3074.pdf |
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| Heral, Maurice; Razet, Daniel; Maestrini, Serge; Garnier, Jacqueline. |
| A twice monthly study shows that the major amount of organic material is from detrtic origin, and is brought in winter, when valeus of mineral seston are very high. In the sping time, phytoplancton blooms, do not make up for lack of detritic material where as in the summer, oceanic phytoplancton is composed of important amounts of carbohydrates. Available food is defined as sum of protids, lipids and carbohydrates and mesured in energetic therms. This allows to foretell the amount of food that molluscs ar likely to assimilate. |
| Tipo: Text |
Palavras-chave: Marennes Oléron; Nutrition; Matière organique; Crassostrea gigas; Huîtres. |
| Ano: 1980 |
URL: http://archimer.ifremer.fr/doc/1980/acte-3003.pdf |
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| Heral, Maurice; Robert, Jean-michel; Truquet, Isabelle; Barbaroux, Olivier; Garnier, Jacqueline; Razet, Daniel. |
| Values of nitrogen nutrients (ammonia, nitrite and nitrate) are compared with values of total organic nitrogen and urea. In summer, the consumation by micro and macrophytes is added to less important telluric input of nineral nitroge. However, an important provision of organic nitrogen remains. On the contrary, in winter, organic nitrogen does not represent more than 10% of total nitrogen. The autors postulate that populations of oysters are at the starting point of the organic nitrogen production cycle. |
| Tipo: Text |
Palavras-chave: Crassostrea gigas; Biochimical composition; Oysters; Crassostrea gigas; Composition biochimique; Huîtres. |
| Ano: 1981 |
URL: http://archimer.ifremer.fr/doc/1981/acte-2940.pdf |
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| Delmas, Daniel; Herbland, Alain; Maestrini, Serge; Mornet, Francoise; Morand, Philippe; Spano, Anna-maria; Burgeot, Thierry; Margat, Sylvie; Charpentier, Gabriel; Fillon, Alain; Leguay, Didier; Thomas, Gerard; Bacher, Cedric; Heral, Maurice; Prou, Jean. |
| Environmental and species features which lead to increases in cell density of the D.S.P. Dinoflagellate Dinophysis in inshore and offshore waters of the île de Ré - île d'Oléron area, France (cruises "Dinopertuis89"). Four weekly sampling series have been carried out, within 10 May – 31 May 1989, at 24 stations located from inshore to offshore waters of the "île de Ré" - "île d’Oléron" area, with the aim to investigate (i) whether Dinophysis increases in cell density occur first in offshore waters and then, eventually, are pushed to the coast, or develop simultaneously in the whole area, and (ii) whether there are some environmental conditions which are related to Dinophysis blooms. Depths of sampling have been stated on the bas is of STD profiles. All... |
| Tipo: Text |
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| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/00174/28532/26916.pdf |
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| Chevalier, Claude; Heral, Maurice; Razet, Daniel. |
| Dans le contexte de développement agricole très actif des trente dernières années les marais atlantiques littoraux qui couvrent, pour leur partie endiguée environ 300.000 ha. ont été et continuent d'être soumis à des transformations importantes qui influent sur la circulation et la qualité des eaux de surface. Ce développement, visant à une amélioration de la productivité et à une meilleure intégration de l' activité agricole dans les grands processus économiques, s'est appuyé, là comme ailleurs, sur les intensifications fourragère et surtout céréalière. L'adaptation de ce modèle général aux caractéristiques écologiques du milieu nécessitait de limiter les effets des excès d'eau hivernaux sur la mise en culture ainsi que ceux de la sécheresse estivale sur... |
| Tipo: Text |
Palavras-chave: Marais atlantique; Littoral; Agriculture; Conchyliculture; Impact; Compatibilité; Charente Maritime Dep.. |
| Ano: 1989 |
URL: http://archimer.ifremer.fr/doc/00071/18235/15795.pdf |
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| Heral, Maurice; Rothschild, Brian J .; Goulletquer, Philippe. |
| The historical landings of the oyster production are described for the Maryland part of the Chesapeake Bay. The different trends are analysed concurently with the main events and management strategies which occured on the bay. Three main periods are identified : - the greatest fishery from 1840 to 1890 with a large overfishing and the destruction of the oyster habitat caused by the oyster gears, - the decrease and stable landings from 1900 to 1980 due to the failure of the reseeding plan connected to the heavy sedimentation and the anoxic summer conditions, - the large decrease of the production (1981-1988) caused by high mortalities related to diseases (MSX and Perkinsus marinus) prédation and management practices. Alternative strategies for restoration... |
| Tipo: Text |
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| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/1990/acte-2393.pdf |
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| Rothschild, Bj; Ault, Js; Goulletquer, Philippe; Heral, Maurice. |
| The oyster population in the Maryland portion ot Chesapeake Bay, USA, has declined by more than 50-Iold since the early part of this century. The paper presents evidence that the mechanical destruction of habitat and stock over fishing have been important factors in the decline, even thouqh it is commonly thought that 'water quality' and, more recently, oyster diseases are critical. Quantitative analyses show that the long-term decline 01 oysters largely resuIts from habitat loss associated with intense fishing pressure early in this century and stock over fishing from early in the century throuqh recent limes. Furthermore, the major ecological effects on Chesapeake Bay occurred weIl betore World War II, before industrialization and the reported prevalence... |
| Tipo: Text |
Palavras-chave: OYSTERS; POPULATION DYNAMICS; OVERFISHING. |
| Ano: 1994 |
URL: http://archimer.ifremer.fr/doc/1994/publication-3080.pdf |
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| Heral, Maurice; Goulletquer, Philippe; Razet, Daniel; Prou, Jean; Ravail, Brigitte; Maestrini, Serge. |
| Different sampling strategies have been tested for estimation of phytoplanktonic biomasses in a bay submitted to estuarine conditions and high velocity of currents. Daily variations showed that for a precision of 5% of the daily mean, it is necessary to sample with a 1 hour and a half time scale. Systematic sampling appears to be more preceise than the random sampling. A sampling during 35 days at low tide and at high tide, during the phytoplanktonic bloom, showed the large variability between the days. A precision of 30% of the mean biomass of the month is obtained with a 8 days time scale. Comparison between tidal cycle sampling (10% of precision) with a punctual sample in the middle of the day did not show large differences. As the main variability is... |
| Tipo: Text |
Palavras-chave: Marennes Oleron; Phytoplanktonic biomasses; Estimation. |
| Ano: 1988 |
URL: http://archimer.ifremer.fr/doc/1988/acte-2877.pdf |
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| Goulletquer, Philippe; Prou, Jean; Heral, Maurice. |
| Following the development of net protection techniques (1980), Japanese clam Ruditapes philippinarum farms develop in the ponds of Charente-Maritime. The county production for 1984 is about 100 tonnes, for a turnover of 4.5 Million Francs. To this day, farmers cultivating clams in ponds over a full cycle get better growth results during the first year. The size of 24 mm is obtained with a density of 200 individuals per square metre. However, due to the type of water input in ponds and to the limited primary production developing in the latter, it appears that biomasses in farms during the second year should not be greater than 0.5 to 1 kg per m² (30 to 50 clams per m²). Thus, the development of clam culture in marsh areas comes to a halt, as farmers are... |
| Tipo: Text |
Palavras-chave: Marennes Oléron; Mortalité; Biomasse; Croissance pondérale; Croissance linéaire; Biométrie; Elevage; Ruditapes philippinarum; Palourdes. |
| Ano: 1985 |
URL: http://archimer.ifremer.fr/doc/1985/rapport-3840.PDF |
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| Delmas, François; Heral, Maurice; Laplana, Ramon; Loubersac, Lionel; Prou, Jean. |
| Parmi les régions Ouest Européennes, la région Poitou Charentes se caractérise dans sa dimension économique par la présence d'activités où les cultures marines, l'agriculture et le tourisme occupent une place prédominante. Cette identité, partagée par d' autres régions, notamment atlantiques, s'appuie sur l'exploitation de la ressource hydrique et implique de plus en plus des critères de haute qualité tant vis à vis des produits finis agricoles, conchylicoles, touristiques que vis à vis de l'environnement, des paysages et des eaux. Sur cet ensemble de points la Région est dotée d'atouts indiscutables. Cependant les contraintes liées à la disponibilité de la ressource hydrique continentale comme marine et à son maintien à un bon niveau de qualité, font... |
| Tipo: Text |
Palavras-chave: Conchyliculture; Agriculture; Charente; Marennes Oléron; Transfert eau; Modèle trophique; Gestion eau. |
| Ano: 1996 |
URL: http://archimer.ifremer.fr/doc/00018/12933/9898.pdf |
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| Heral, Maurice; Deslous-paoli, Jean-marc; Prou, Jean. |
| The evolution of the production of cupped oysters is estimated on a century (1885-1985) with three different sources of data. The total biomass in culture is calculated from productions by knowing regularly the growing rate and the mortality rate of the populations of oysters. It appears that the efficiencies of the culture (P/B) decrease when the stock increase. The production reaches a plateau maximum of 40 000 tons whereas the stock goes on to growth up to 200 000 tons. This plateau correspond to the maximal capacity of production of the ecosystem limited by the trophic capacities of the bay. This work shows that without management of the cultivated oysters, the stocks tend to exceed the minimal biomass which is necessary to reach the maximal potential... |
| Tipo: Text |
Palavras-chave: Biomasse; Marennes Oléron; Huîtres; Crassostrea angulata; Crassostrea gigas. |
| Ano: 1986 |
URL: http://archimer.ifremer.fr/doc/1986/acte-2965.pdf |
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| Barille, Laurent; Heral, Maurice; Barilleboyer, Al. |
| An ecophysiological deterministic model of growth, reproduction and interactions between the bivalve and its estuarine environ ment was established for the Japanese oyster Crassostrea gigas. The environmental variables used in the model are: total particulate matter, particulate organic matter, particulate inorganic matter, chlorophyll, phaeopigments, proteins, lipids and carbohydrates. Rates of clearance, filtration, ingestion, absorption and respiration along with efficiencies of retention, selection and absorption are modelled with endogenous (dry weight of the animal, energy allocation between growth and reproduction) and exogenous variables (temperature, food quality and quantity). The model simulate the temporal evolution of two compartments: somatic... |
| Tipo: Text |
Palavras-chave: Crassoslrea gigas; Croissance; Écophysiologie; Modélisation; Turbidité; Crassostrea gigas; Ecophysiology; Growth; Modelling; Turbidity. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00038/14892/12219.pdf |
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| Pouvreau, Stephane; Bacher, Cedric; Heral, Maurice. |
| A model of bioenergetics of the black pearl oyster (Pinctada margaritifera) was built to simulate growth, reproduction and spawning in suspended culture at field sites in Takapoto lagoon (French Polynesia). This model was based on allometric scaling of physiological functions and scope for growth (SFG) calculations. The input functions were clearance rate (CR, 1 day(-1)), retention efficiency (RE, %) for each kind of particle encountered in suspended matter, pseudofaeces and faeces productions (PF and F, mg C day(-1)), excretion and respiration rate (U and R, mg C day(-1)). The assimilated carbon (i.e., SFG, mg C day(-1)) was partitioned to the three internal state variables (somatic tissue, shell and gonad) according to the asymptotic increase of the... |
| Tipo: Text |
Palavras-chave: Pearl farming; Food depletion; Scope for growth; Carrying capacity; Suspension feeding; Tropical lagoon. |
| Ano: 2000 |
URL: http://archimer.ifremer.fr/doc/2000/publication-380.pdf |
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| Alzieu, Claude; Heral, Maurice. |
| The toxic effect of trialkyltin compounds is used in antifouling paints to protect vessels against biofouling organisrns. Tributyltin oxide (TBTO) or fluoride (TBTS) leaches by diffusion from the paint layer into the seawater. Trialkyltin compounds in aqueous solutions are resistant to hydrolysis and biodegradation, but are rapidly converted into diakyl, monoalkyl and inorganic tin by UV irradiation. As inhibiting agents of the oxidative phosphorylation, organotin compounds are extremely dangerous for aquatic organisms such as molluscs. The following estimated toxicity levels for Crassostrea gigas oyster larvae have been put forward : at 100 µg.l(1) the fecondation is inhibited, at 10 µg.l1 the already of 20 % of the eggs is affected larval development... |
| Tipo: Text |
Palavras-chave: Toxicity; Fluoride; Tribultyltin oxide; Toxic effect; Oysters; Crassostrea gigas. |
| Ano: 1984 |
URL: http://archimer.ifremer.fr/doc/1984/publication-2931.pdf |
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| Registros recuperados: 148 | |
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