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| Registros recuperados: 47 | |
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| Merceron, Michel; Antoine, Virginie; Auby, Isabelle; Morand, P. |
| Ulva spp., the algae most responsible for green tides in Brittany (France), are found on the foreshore and in the most beachward wave area (MBWA) of many bays during green tide phenomena. These algae have recently been seen drifting at greater depths (reaching -20 m). In view of the significant quantities of algae found at these depths, and the less favorable conditions for algal growth than in the intertidal zone, we attempted to determine if they could grow there. For that, during their maximum growth period (from May to July), algae were picked up at three stations located on the foreshore, in the MBWA and in the subtidal (deep) zones of the Bay of Douarnenez, and their nitrogen, carbon and chlorophyll a+b contents were determined, and their... |
| Tipo: Text |
Palavras-chave: Nutrients; Irradiance; Photosynthesis; Ulva sp.; Algal blooms; Eutrophication. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-3527.pdf |
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| Merceron, Michel. |
| At the end of July 1982, a massive number of fish and benthic invertebrates died in Vilaine Bay. The mass of fish concerned has been estimated at several tens of tonnes. The analysis of the event's conditions indicates that it was asphyxiation caused by a very pronounced depletion of dissolved oxygen in the bay's bottom waters. The appearance of toxic phytoplankton in the years that followed (Dinophysis) is aseparate topic of research by IFREMER. The most likely mechanism of that anoxia is a succession of events: (1) a first flood of Vilaine River inducing a vertical stratification of waters in Vilaine Bay, (2) an intense and superficial bloom of marine phytoplankton, (3) a stormy weather breaking up the stratification and mixing superficial... |
| Tipo: Text |
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| Ano: 1989 |
URL: http://archimer.ifremer.fr/doc/1989/publication-2833.pdf |
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| Merceron, Michel; Jegou, Anne-marie; Couteaux, Bertrand; Piriou, Jean-yves. |
| Producing the Inventory of Potential Sites for Aquaculture along the Finistère Shoreline was decided by the Département's Regional Council with the goal of integrating aquafarming in the best way possible into the variety of businesses that are based along the coastal zone. Aquafarming, in order for it to exist tomorrow, needs to be taken into account today as far as preservation of sites, and this must be done with two aspects in mind: - land, on shore; - water quality (which implies maritime and land constraints). In this context, the Regional Council has entrusted the Centre National pour l'Exploitation des Océans with a study that will make it possible to define the aquafarming potential of the Finistère shoreline. It was decided to split this study... |
| Tipo: Text |
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| Ano: 1978 |
URL: http://archimer.ifremer.fr/doc/1978/rapport-2655.pdf |
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| Piriou, Jean-yves; Coic, Daniel; Merceron, Michel. |
| The coastal marsh of Kervigen is located near by the bay of Douarnenez and its 22 hectares are almost entirely covered by reeds. An experiment was there carried out to assess the nitrogen flux depletion of a small stream, the Kerharo. That one has a 45 km 2 mostly agricultural drainage basin. Due to its nitrate loadings to the next sandy beach, it feeds a green algae (Ulva) proliferation. In order to control its nitrogen fluxes, the stream was partly diverted through a part of the marsh (9 ha), before it was allowed to go back to the main bed. Thus a collapsible weir was set up during several springs and summers, i.e. the growing period of Ulva. The nitrate stripping off the going through flux is within a 30 to 90 % range,that is important (175 kg N03... |
| Tipo: Text |
Palavras-chave: Algae; Nitrogen; Ulva; Nitrate depletion; Costal marsh; Algue; Azote; Ulva; Abattement de nitrate; Marais côtier. |
| Ano: 1999 |
URL: http://archimer.ifremer.fr/doc/1999/rapport-64.pdf |
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| Merceron, Michel. |
| On tens of sandy beaches of Brittany, a green seaweed (Ulva) blooms during spring and summer. In the sites where the proliferation is the most important, the total biomass amounted to 20 000 t of wet weight in 1997, at the time of maximum. These "green tides" occur every year in nearly the same locations. They have a very harmful impact on local tourism. In many communes, beached and rotting algae are collected and dumped (43 000 m 3 as a whole in 1997). The main development of biomass takes place between the surf zone and the bare sand.The outbreak requires three coexisting conditions : 1) a sandy beach gently sloping, 2) a weak residual current (i.e. once the tidal back and forth movement has been filtered), 3) a nitrogen loading, even moderate (ammonium... |
| Tipo: Text |
Palavras-chave: Brittany; Eutrophication; Proliferation; Ulva; Marine algae; Bretagne; Eutrophisation; Prolifération; Ulves; Algues marines. |
| Ano: 1999 |
URL: http://archimer.ifremer.fr/doc/1999/acte-46.pdf |
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| Merceron, Michel; Jegou, Anne-marie; Couteaux, B; Piriou, Jean-yves. |
| This report is the first stage of the Inventory of Potential Sites for Aquafarming along the Finistère shoreline. This type of inventory was conducted previously in Seine-Maritime, in Basse-Normandie, and along the central part of the Atlantic coast. This kind of study is generally motivated by two findings: -the growing use of the shoreline area for various activities, -the need to set aside suitable sites along the shoreline for the development of aquafarming. In order to make consistent growth choices, it is important to know as well as possible the aquafarming potential that we have available, their size, their nature, their geographic distribution, as well as the degree of maturity of the techniques to be implemented. In Brittany itself, a quick... |
| Tipo: Text |
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| Ano: 1978 |
URL: http://archimer.ifremer.fr/doc/1978/rapport-2661.pdf |
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| Kempf, Marc; Cadour, Gwenael; Jeanneret, Hélène; Mear, Yan; Miramand, Pierre; Merceron, Michel. |
| This document is a result of an environmental impact study carried out between 1993 and 1995 on the site of a marine trout culture located in the Harbour of Cherbourg, France. It deals with the solid waste of the farm and concems deposition rate, sediment analysis and chemistry (fine fraction < 63 ~m, organic matter, carbon, nitrogen, copper and zinc), bottom living organisms and underwater video monitoring. The impact observed is very moderate and localised. This is mainly due to the strong d)'TIamics and flushing rate of the site. A seperate volume of the same study deals with dissolved waste and concems the water mass (volume 1 : water and pelagos). (Not controlled OCR) |
| Tipo: Text |
Palavras-chave: Rade de Cherbourg; Étude biosédimentaire; Impact; Salmoniculture marine; France; Cherbourg; Benthos; Sediment; Environmental impact; Trout; Marine fish farming. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/1997/rapport-3349.pdf |
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| Merceron, Michel. |
| The Frêt Pond at Crozon (Finistère) occupies the southwest part of Frêt's cove in Brest's harbour (fig. 1). This 18-hectare pond was isolated from the harbour by the natural accumulation of a mound of pebbles, which was reinforced by rocks so that it could support the D 155 road. At the free end of this mound, a tide mill had been built in the past, and it is through its release channel that water exchanges currently take place between the Frêt pond and Brest's harbour. The pond's catchment area occupies a surface area of 2.70 km2, of which 1.8 km2 are being farmed and 0.5 are forest area (fig. 1). The average flow over the year is estimated at 58 l/s based on a specific flow of 21.4 l/s/km2. It is therefore about 1.8 million cubic metres of fresh water... |
| Tipo: Text |
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| Ano: 1985 |
URL: http://archimer.ifremer.fr/doc/1985/rapport-2649.pdf |
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| Merceron, Michel; Le Bozec, Gildas. |
| As for its physical layout, Brittany is characterised by a very dense water system, catchment areas that are mostly of small size (a few dozen square kilometres) and a very significant line of coasts with regard to its surface area. These environments, very close and interdependent, are rich with life, and yet have been affected for many years by dramatic incidents of contamination: the proliferation of marine green algae and the degradation of the quality of the surface fresh waters are the most visible manifestation of this. Among the incidents of contamination that affect these environmentsmany of them are brought mainly and crucially by continental watersare those originating from agriculture. Over the last 30 years, Brittany has experienced very... |
| Tipo: Text |
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| Ano: 1999 |
URL: http://archimer.ifremer.fr/doc/1999/acte-2840.pdf |
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| Couteaux, B; Jegou, Anne-marie; Merceron, Michel; Piriou, Jean-yves. |
| This report is the first stage of the Inventory of Potential Sites for Aquafarming along the Côtes-du-Nord shoreline. This type of inventory was conducted previously in Seine-Maritime, in Basse-Normandie, in Finistère, and along the central part of the Atlantic coast. This kind of study is generally motivated by two findings: -the growing use of the shoreline area for various activities -the need to set aside suitable sites for the development of aquafarming. In order to make consistent development choices, it is important to know as well as possible the aquafarming potential sites that we have available, their size, their nature, their geographic distribution, as well as the state of the techniques to be implemented. In Brittany itself, a quick... |
| Tipo: Text |
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| Ano: 1979 |
URL: http://archimer.ifremer.fr/doc/1979/rapport-2660.pdf |
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| Merceron, Michel. |
| (Not controlled OCR) Every summer, since 1983, important mortalities of Atlantic salmon smolts occur in net pen farmings in Brittany (France) (Harache and Gaignon, 1986). These mortalities, ranging from 30 to 87 % of stock, are in the way of the economic development of this activity. They take place between mid-June and the end of July. Most of the smolts are sluggish and without appetite. Looking for a viral or bacterial aetiology by the veterinary services was often unfruitful. In order to investigate a possible role of environment, a set of parameters was monitored and compared in two farming sites displaying very different mortality rates. |
| Tipo: Text |
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| Ano: 1991 |
URL: http://archimer.ifremer.fr/doc/1991/acte-2648.pdf |
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| Merceron, Michel. |
| The 1998 survey of green tides on the Brittany coast was performed in the same way as that of 1997 in order to allow comparison. 11 includes an inventory ofail the concerned sites, and a precise assessment ofthirteen ofthem, the most loaded. On these ones, nitrogen fluxes were surveyed during the critical period, and the green seaweed stock on the beach and in the first waves was quantified. The climatic conditions were opposite between the two years, very dry in spring and summer 1997, and wet in 1998. The irradiance contrast was inverse, and less pronounced. The nitrate contents and mostly the flows were more important in 1998. They generated nitrogen fluxes about 3.3 times those of 1997. The total number of sites concerned in 1998 is clearly higher than... |
| Tipo: Text |
Palavras-chave: Bretagne; Nitrate; Prolifération; Ulve; Eutrophisation; Brittany; Nitrate; Proliferation; Ulva; Eutrophication. |
| Ano: 1999 |
URL: http://archimer.ifremer.fr/doc/1999/rapport-2665.pdf |
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| Bordenave, Paul; Merceron, Michel. |
| The transmission of several contaminants from agricultural land to the shoreline has been studied within the scope of this programme, both by general research and by field investigations. The field investigations took place in two test catchment areas (fig. 1). One of them, Coët-Dan, has been fitted out with various measuring devices since the year 1971 and has been monitored since that date. The other one, Kerharo, has never been studied until now. The research topics were distributed between these two catchment areas in the following way. At Coët-Dan, what was handled were the transfer of pesticides and bacteria of sanitary interest, the nitrogen and phosphorus supplied to the fields by farms, the transfer of these nutrients into the surface horizons and... |
| Tipo: Text |
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| Ano: 1999 |
URL: http://archimer.ifremer.fr/doc/1999/acte-2841.pdf |
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| Morand, Philippe; Merceron, Michel. |
| Algal blooms, often associated with eutrophication, are common in temperate regions in coastal lagoons and estuarine areas as well as in open seas. However, because of recent changes in water flows and sediment and nutrient loads in most rivers, eutrophication phenomena are now occurring in areas previously non affected. One of its most widespread and easily recognized effects in a coastal marine ecosystem is the excessive growths and drifts of macroalgae, to such a degree that the biomass becomes a significant problem. The nutrients, notably from anthropogenic origin, constitute a significant factor in the appearance of the blooms in coastal waters. Besides a background originating from natural areas and precipitations, nutrients come from agriculture,... |
| Tipo: Text |
Palavras-chave: Green tides; Macroalgae; Eutrophication; Nutrients; Black Sea. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-2131.pdf |
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| Merceron, Michel. |
| En agriculture, le passage de l'élevage traditionnel à l'élevage dit industriel a été rendu possible, entre autres éléments, par la disponibilité régulière d'un aliment de qualité suffisante et bon marché. Pour son développement, l'aquaculture des animaux carnivores requérira également la disponibilité d'un aliment présentant les mêmes avantages. Il ne servirait de rien de produire de fortes quantités de stades juveniles en écloserie si nous n'étions pas aptes à assurer leur croissance ultérieure dans des conditions économiquement satisfaisantes. Il n'est donc pas prématuré de se pencher sur ce qui pourra être le ou les aliments qui répondront à cette exigence. Nous limiterons évidemment cette étude au cadre des régions tempérées et nous laisserons de... |
| Tipo: Text |
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| Ano: 1974 |
URL: http://archimer.ifremer.fr/doc/00151/26193/24212.pdf |
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| Registros recuperados: 47 | |
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