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| Registros recuperados: 148 | |
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| Prou, Jean; Barille, Laurent; Heral, Maurice; Ratiskol, Gilles; Soletchnik, Patrick; Bougrier, Serge; Razet, Daniel; Geairon, Philippe. |
| During a fortnightly tidal cycle, a Mytilus edulis population was submitted to natural food conditions in the bay of Marennes-Oléron. During 4 tidal cycles, in vivo continuous measurements of turbidity and fluorescence were recorded to study the evolution of Total Particulate Matter (TPM), phaeopigments and chlorophyll-a concentrations. Turbidity in the water column is clearly influenced by resuspension of sediment. Degradated cells of phytoplankton were associated with sediments, involving strong correlation between phaeopigments and turbidity. High values of chlorophyll-a were encountered during neap tides when turbidity was low. No relation with resuspension processes were observed. No effect of fortnightly variability on retention was observed by... |
| Tipo: Text |
Palavras-chave: Ancova; Utilisation du matériel particulaire; Mytilus edulis; Moules. |
| Ano: 1994 |
URL: http://archimer.ifremer.fr/doc/1994/publication-3079.pdf |
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| Heral, Maurice. |
| The different methods for the estimation of the carrying capacity of cultivated area by oyster or mussel farming are presented gradually by order of complexity. The yield of production permit to follow if the adequation between the importance of the cultivated biomass and disponibility of food is realised. In another way, the study of the cultivated biomass and the annual production could be used for the building of global dynamic models showing the maximum of annual production that a bay can support. These approaches take for main hypothesis that the environment is constant. The study of the trophic relations for simulation of the growth rate of molluscs can be presented in function (i) of the level of complexity of the coupling between physical and... |
| Tipo: Text |
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| Ano: 1989 |
URL: http://archimer.ifremer.fr/doc/1989/acte-2392.pdf |
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| Rotschild, B. J.; Ault, J. S.; Goulletquer, Philippe; Jensen, W. P.; Heral, Maurice. |
| The oyster population in the Maryland portion of the Chesapeake Bay has declined b y more than 38-fold since the early part of the century. Although the effects of fishing have been implicated, the decline has been attributed primarily to water quality and recently oyster disease. The decline has also been thought to have affected the biota and chemistry of the Bay. Our analysis provides a quantitative demonstration that the long-term declines are largely the result of habitat loss related to over fishing early in the century, stock over fishing, early in the century' through the recent times. Furthermore, the major ecological effects on Chesapeake Bay occurred well-before World War 1/, before industrialization and the prevalence of disease |
| Tipo: Text |
Palavras-chave: USA; Chesapeake Bay; Prevalence of disease; Industrialization; Diseases; Crassostrea virginica; Oysters. |
| Ano: 1991 |
URL: http://archimer.ifremer.fr/doc/1991/acte-3058.pdf |
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| Goulletquer, Philippe; Heral, Maurice. |
| Le développement de la mytiliculture dans un bassin conchylicole peut aboutir à la surexploitation du site avec des conséquences néfastes pour les populations en cours d'exploitation. Pour cette raison, il est particulièrement important de développer un plan d'aménagement de bassins tels que le Pertuis Breton considérant l'ensemble des utilisateurs de cet espace. A moyen terme, le développement d'un modèle mathématique est l'outil plus approprié pour tester et valider les différents schémas d'aménagement, permettant ainsi de limiter l'impact sur l'existant. Pour un tel modèle, une parfaite connaissance des caractéristiques biologiques et physico- chimiques du milieu est nécessaire. Au délà de la biomasse en élevage, sa répartition spatiale, ses besoins... |
| Tipo: Text |
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| Ano: 1996 |
URL: http://archimer.ifremer.fr/doc/00406/51771/52369.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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| 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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| Gruet, Yves; Heral, Maurice; Robert, Jean-marie. |
| The intentional establishment of the Japanese oyster Crassostrea gigas (Thunberg) in replacement of the Portuguese oyster caused numerous biological problems. The possible introduction of some Turbellariae, oyster predators, was at the origin of the regulation concerning the "stay in freshwater" of the spat. The implantation of other microorganisms drew our attention. Our results, though fragmentary, show that some Japanese species live on our coasts (Bay of Bourgneuf and Traiet du Croisic) a year after the immersion of the original collectors: Annelida Hydroides ezoensis, Cnidarian Aiptasia pulchella, Mollusc Anomia chinensis, Cirripedes Balanus amphitrite amphitrite and Balanus albicostatus. The survival chances seem to vary according to the oyster... |
| Tipo: Text |
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| Ano: 1976 |
URL: http://archimer.ifremer.fr/doc/1976/publication-4927.PDF |
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| Raillard, Olivier; Soletchnik, Patrick; Heral, Maurice; Prou, Jean; Bougrier, Serge; Razet, Daniel; Geairon, Philippe; Barille, Laurent; Guezennec, Loïc. |
| Les expérimentations on continu sur le site du Chapus au centre du bassin de Marennes-Oléron pendant le mois de mai 1991 et d'octobre 1991 ont permis de préciser la filtration des huîtres en fonction de la variabilité de la charge particulaire. Ces nouveaux résultats permettent d'affiner les modèles de croissance des huîtres. Un nouveau modèle de croissance phytoplanctonique permet de démontrer la sensibilité du bassin de Marennes-Oléron aux apports de nitrates provenant de la Charente, et leur impact sur la croissance des huîtres. L'étude des caractéristiques mécaniques des vases et des biodépôts ainsi que l'étude de l'agitation (houle et clapots, permet de modifier et de préciser les formulations d'un nouveau modèle de transport particulaire représentant... |
| Tipo: Text |
Palavras-chave: Séries en continu; Filtration; Crassostrea gigas; Modèle phytoplanctonique; Sédiment; Modèle de transport particulaire; Bassin de Marennes Oléron. |
| Ano: 1992 |
URL: http://archimer.ifremer.fr/doc/00048/15907/13335.pdf |
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| Heral, Maurice. |
| In areas where oyster or mussel culture is very intensive, declines of growth rate and decreases of survival rate have occurred. For these reasons, plans have been proposed to regulate the cultivated biomasses in order to fit the carrying capacity of the different ecosystems (Heral et al 1990; Heral, 1991). In areas where new aquaculture of molluscs is beginning, oyster or mussel farmers need to know how large the extension of the culture could be and what the maximal densities should be in order to obtain the maximum economic benefit. Furthermore, as mollusc cultures are developed in coastal areas, they are very susceptible to changes in environmental conditions that can modify trophic relationships, or directly reduce growth rate, physiological... |
| Tipo: Text |
Palavras-chave: Oyster model; Analytical model; Bivalve molluscs culture; Models. |
| Ano: 1993 |
URL: http://archimer.ifremer.fr/doc/1993/publication-6104.PDF |
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| Heral, Maurice; Bacher, Cedric; Razet, Daniel; Prou, Jean; Deslous-paoli, Jean-marc. |
| Le bassin conchylicole de Marennes-Oléron assure 40 % des 100 000 tonnes d ' huîtres commercialisées annuellement en moyenne en France (20 000 emplois, 1 milliard de chiffre d'affaire) . La modélisation des équilibres qui s'établissent entre l es stocks mis en culture , et la production annuelle , réalisée par la station IFREMER de La Tremblade , a mis en évidence les résultats suivants : Lorsque la biomasse augmente : a) La production plafonne vers 40 000 tonnes pour une biomasse de l'ordre de 80 000 tonnes avec l'huître japonaise, ce qui correspond à une biomasse équivalente de 130 000 tonnes d'huîtres portugaises. b) La durée du cycle de production d'une huître de 70 g passe de 2 ans à 4 ans. c) Les mortalités courantes passent simultanément de 20 % à... |
| Tipo: Text |
Palavras-chave: Production; Ostréiculture; Biomasse; Modélisation; Marennes Oléron. |
| Ano: 1986 |
URL: http://archimer.ifremer.fr/doc/00048/15909/13338.pdf |
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| Registros recuperados: 148 | |
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