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| Registros recuperados: 148 | |
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| Deslous-paoli, Jean-marc; Heral, Maurice; Berthome, Jean-paul; Razet, Daniel; Garnier, Jacqueline. |
| In summer 1979, the natural reproduction of oysters Crassostrea gigas Thunberg, in Marennes-Oleron basin, produced a large number of juveniles which was not the case in summer 1981. If one compares the evolution of the main constituents of the flesh, one can see that, at the beginning of August, before spawning the male oysters in 1981 contained 6,3% less proteins, 34,2% less lipids and 61,2% less glucids than those in 1979 and respectively 12,3%, 21,3% and 69,8% less as far as females are concerned. The energetic value of ash-free dry flesh of female oysters is nearly the same for the two years whereas for male oysters the value is slightly lower in 1981 than in 1979. The total energetic values of male and female oysters show a slight difference between... |
| Tipo: Text |
Palavras-chave: Crassostrea gigas; Seasonal variations; Food availability; Water temperature; Saccharides; Proteins; Lipids; Biochemical composition; Gametogenesis; Spawning; Sexual reproduction. |
| Ano: 1981 |
URL: http://archimer.ifremer.fr/doc/1981/publication-1891.pdf |
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| Heral, Maurice; Bacher, Cedric; Razet, Daniel; Prou, Jean; Galgani, Francois; Renault, Tristan; Bodoy, Alain; Garnier, Jacqueline; Geairon, Philippe; Chagot, Dominique; Grizel, Henri; Comps, Michel; Masson, Daniel; Noinin, Michel. |
| Dès le 4 JUIN 1992, un ostréiculteur digne de confiance avait signalé aux services d'IFREMER, une situation anormale sur le banc de Ronce les Bains. Un premier prélèvement a été effectué le jour même. En effet, ce secteur avait déjà été le lieu de mortalités d'huitres estimées à 7 000 tonnes, au printemps 1988, et s'est révélé par le passé comme étant un endroit sensible. Pour information, figure en annexe le rapport établi en 1988, à destination du Préfet de la Charente Maritime. Ces mortalités ayant rapidement pris de l'ampleur, un dépôt de plainte contre X a été effectué par la Section Régionale de la Conchyliculture. A la suite de quoi, les services d'IFREMER ont été requis par la Gendarmerie Nationale (Brigade de Marennes) le 10 juin 1992, pour... |
| Tipo: Text |
Palavras-chave: Ostréiculture; Huîtres creuses; Crassostrea gigas; Mortalité; Banc de Ronce Les Bains; Bassin de Marennes Oléron. |
| Ano: 1992 |
URL: http://archimer.ifremer.fr/doc/00048/15899/13327.pdf |
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| Heral, Maurice; Deslous-paoli, Jean-marc; Prou, Jean; Razet, Daniel. |
| The study of the trophic relations needs to collect data which can best represent the variability of the populations of molluscan and the parameters of the water. For the water, the main parameters which play a role on the production of molluscan in an estuarine area are the temperature, the seston, and the phytoplanctonic biomass. For the temperature is proposed to sample only twice a month. At the contrary for seston variations which are very large on a tidal cycle and correlated with the currents and the waves, it is necessary to take in count this variability. For the phytoplancton, the annual cycle is well characterized, but the variability at a station is depending on the caracteristic of each water masses. The authors suggest that a sampling... |
| Tipo: Text |
Palavras-chave: Estuarine ecosystem; Trophic relationships; Time variations; Sampling strategies; Ecosystème estuarien; Relations trophiques; Variabilité temporelle; Stratégie d'échantillonnage. |
| Ano: 1987 |
URL: http://archimer.ifremer.fr/doc/1987/publication-2868.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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| Ravail, Brigitte; Heral, Maurice; Razet, Daniel; Robert, Jean-michel. |
| Le suivi bi-mensuel des caractéristiques des eaux de l'estuaire de la Charente met en évidence les fortes teneurs en sels nutritifs transportés par ce fleuve. Les apports de fin d'hiver en nitrates sont supérieurs à 240 µ atg N 1(1). Le phosphore a un comportement particulier puisqu'en période de crue, il s'adsorbe sur les particules et le sédiment, jouant un effet régulateur, ainsi les aports ne dépassent guère 2 µ atg P 1(1) en hiver mais aussi en été. Les biomasses phytoplanctoniques vivantes ou dégénérescentes sont fortes avec deux périodes defflorescence bien marquées, mai-juin et octobre. Les teneurs en chlorophylle a atteignent è µg de chla pour la surface et 23 µgde chla pour le fond. Par ailleurs, les teneurs en phéopigments dépassent 31 µg de... |
| Tipo: Text |
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| Ano: 1986 |
URL: http://archimer.ifremer.fr/doc/00390/50177/50798.pdf |
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| Heral, Maurice. |
| The different methods of estimating the trophic capacity of ecosystems cultivated by oyster farming and mussel farming are introduced by ascending order of complexity. Thus, production yields make it possible to monitor whether the size of the farmed stock is being successfully matched with the availability of food. Moreover, the study of annual production farmed stocks has made it possible to create comprehensive dynamic models that show the maximum annual production that a given ecosystem can support. These last two approaches assume the environment to be constant. The study of trophic links that can simulate growth performance of molluscs can be classified according to two criteria, (i) their level of complexity in combining biology and physics, (ii)... |
| Tipo: Text |
Palavras-chave: Ecosystèmes conchylicoles; Conchyliculture; Capacité trophique. |
| Ano: 1991 |
URL: http://archimer.ifremer.fr/doc/1991/publication-3052.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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| Heral, Maurice; Bayne, B.. |
| The Workshop was held in Plymouth (6-10 October 1996) in the Royal Plymouth Corinthian Yacht club organised by the Plymouth Marine Laboratory under the joint charmanships of B. Bayne et M. Héral. 36 scientists were participated to this meeting from 11 countries, 8 belonging to ICES (Annex 1) 30 communications have been presented. This meeting was supported by an European Union contrat from DG14 with a concerted action AIR3 CT 942219 on Trophic capacity of coastal zone of oysters, mussels and cockles cultivation. This contract has paid the travel cost of all the participants. |
| Tipo: Text |
Palavras-chave: Coastal systems; Carrying capacity; Physiological results; Oyster; Shefflish bivalve. |
| Ano: 1996 |
URL: http://archimer.ifremer.fr/doc/1996/acte-7350.pdf |
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| Heral, Maurice; Deslous-paoli, Jean-marc. |
| Three species of oysters have been or are cultivated in Europe: Crassostrea angulata, C. gigas, and Ostrea edulis. If we follow the taxonomic critera of Grassé, the European oysters belong to the group of Mollusca, class of Lamellibranchia or Bivalves, order of Filibranchia, family Ostreidae with two genera: C. angulata (Lamarck), Portuguese, cupped oyster; C. gigas, (Thunberg), Japanese or Pacific, cupped oyster; Ostrea edulis (Linné), fiat European oyster. Some authors think that C. gigas and C. angulata belong to the same species. lndeed, Ranson stated that the characteristics of the larvae are the same, and Menzel obtained viable hybrids (F2) between these two oysters. AIso, Buroker et al. in studying the genetic variations of proteins and enzymes of... |
| Tipo: Text |
Palavras-chave: European countries; Pathology; Methods of culture; Recruitment; Fishery; Salinity and temperature tolerances; Larval development; Growh; Biology; Oyster culture. |
| Ano: 1991 |
URL: http://archimer.ifremer.fr/doc/1991/publication-3038.pdf |
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| Heral, Maurice; Bacher, Cedric; Razet, Daniel; Prou, Jean; Deslous-paoli, Jean-marc; De Pontual, Helene; Raillard, Olivier; Maestrini, Serge; Mornet, Francoise; Menesguen, Alain; Sautour, Benoit; Robert, Jean-michel. |
| Les termes du contrat passé entre le Fond de la Recherche et de la Technologie et l'IFREMER précisent qu ele programmer a pour objectif une gestion rationnelle du milieu conchylicole avec notamment une mise au point de modèles (voir notification de l'aide en annexe). Un premier modèle appelé modèle global par analogie avec les modèles de pêche met en évidence la limite de la capacité trophique du bassin de Marennes-Oléron pour les huîtres cultivées. Un modèle analytique avec un modèle physique simple permet dans un premier temps de développer un modèle de croissance des huîtres en fonction de la nourriture disponible et d'effectuer des simulations qui confirment l'influence du stock sur les performances de croissance des bivalves. Un troisième approche... |
| Tipo: Text |
Palavras-chave: Modèle production; Biomasse; Huître creuse; Crassostrea gigas; Modèle énergétique; Croissance; Modèle multiboîte; Marennes Oléron; Modèle trophique; Marennes Oléron. |
| Ano: 1986 |
URL: http://archimer.ifremer.fr/doc/00048/15908/13337.pdf |
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| 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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| Goulletquer, Philippe; Razet, Daniel; Prou, Jean; Garnier, Jacqueline; Taillade, Sylvie; Heral, Maurice; Peyre, R; Faivre, C. |
| Etant donné que la production de mollusques (palourdes ou huîtres) est limitée à 0,8 kg à 1 kg au m2 soit 40 à 50 palourdes adultes de 20 g au m2, il est intéressant d'essayer de forcer cette production en augmentant la production primaire qui est le facteur limitant de la production de palourdes. Cette production primaire dépend des apports en sels nutritifs en effet les travaux antérieurs de Zanette (1979), de Zanette et Garnier (1980), de Robert (1984) ont mis en évidence que les biomasses phytoplanctoniques ne peuvent dépasser un certain seuil à cause de l'épuisement progressif en sels nutritifs. Robert et al. (1984) ont mis en évidence, dans les claires de la Baie de Bourgneuf que l'azote est le premier facteur limitant de la croissance... |
| Tipo: Text |
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| Ano: 1985 |
URL: http://archimer.ifremer.fr/doc/00389/50053/50641.pdf |
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| Registros recuperados: 148 | |
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