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| Registros recuperados: 31 | |
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| Chardy, Pierre; Gros, Philippe; Mercier, Herle; Monbet, Yves. |
| A steady-state energy flow model is proposed for the benthic fine sand community of the Bay of Saint-Brieuc. The main objective is to assess the relative importance of benthic processes associated with the carbon cycle in an eutrophicated bay. Available data include biomass estimates of the major trophic groups and measurements of the most critical fluxes : particulate organic carbon sedimentation, community respiration, microbial production. A balanced annual carbon budget is estimated using an inverse method, particularly appropriate in food web research where the number of unknowns is far higher than the number of independent observations. The method offers the possibility of taking dynamical constraints into account, by introducing global flow... |
| Tipo: Text |
Palavras-chave: CARBON CYCLE; BENTHIC COMMUNITY; FINE SANDS; SUBTIDAL AREA; INVERSE METHOD. |
| Ano: 1993 |
URL: http://archimer.ifremer.fr/doc/00100/21131/18751.pdf |
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| Guarini, Jean-marc; Blanchard, Gf; Gros, Philippe; Gouleau, Dominique; Bacher, Cedric. |
| In the present paper, we list and document the relevant behavioral and physiological processes controlling primary productivity of epipelic microalgae on intertidal mudflats in order to develop a simplified model. We first propose, in an attempt to characterize the 'photosynthetically active biomass' of the epipelic community, a new approach to describe the photic environment at the sediment surface, by substituting a discrete a-layer model in place of continuous vertical light distribution. This concept thus allows us to build a functional representation of the distribution of the photosynthetically active biomass in the sediment and, by then integrating the light and temperature forcing of the latter biomass, to predict the dynamics of the whole epipelic... |
| Tipo: Text |
Palavras-chave: Microphytobenthos; Intertidal mudflat; Primary production; Dynamic model; Migratory rhythm; Ecophysiological response. |
| Ano: 2000 |
URL: http://archimer.ifremer.fr/doc/00000/10540/7601.pdf |
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| Guarini, Jean-marc; Blanchard, Gerard; Bacher, Cedric; Gros, Philippe; Riera, Pascal; Richard, Pierre; Gouleau, Dominique; Galois, Robert; Prou, Jean; Sauriau, Pierre-guy. |
| Microphytobenthos plays an important role as primary producer in shallow embayments subject to a tidal regime. The present paper aims to characterize the spatial patterns of sedimentary chlorophyll a (chl a) biomass in 2 seasons in the wide intertidal mudflats of the Marennes-Oleron Bay (France); furthermore, it provides estimates of total microphytobenthic biomass. Accordingly, a systematic sampling scheme was performed in June 1995 and in January 1996. On average, biomass was higher in June (ca 120 mg chl a m-2) than in January (ca 85 mg chl a m-2). Moreover, the geostatistical analysis revealed that spatial similarities were propagated over larger distances in June (6 km) than in January (2.2 km). In order to account for this result , we suggest that... |
| Tipo: Text |
Palavras-chave: Marennes Oleron; Intertidal mudflat; Geostatistics; Spatial distribution; Chrlorophyll a; Microphytobenthos. |
| Ano: 1998 |
URL: https://archimer.ifremer.fr/doc/1998/publication-3820.pdf |
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| Guarini, Jean-marc; Blanchard, Fabian; Bacher, Cedric; Gros, Philippe; Riera, P; Richard, P; Gouleau, D; Galois, R; Prou, Jean; Sauriau, Pg. |
| Microphytobenthos plays an important role as primary producer in shallow embayments subject to a tidal regime. The present paper aims to characterize the spatial patterns of sedimentary chlorophyll a (chl a) biomass in 2 seasons in the wide intertidal mudflats of the Marennes-Oleron Bay (France); furthermore, it provides estimates of total microphytobenthic biomass. Accordingly, a systematic sampling scheme was performed in June 1995 and in January 1996. On average, biomass was higher in June (ca 120 mg chi a m(-2)) than in January (ca 85 mg chi a m(-2)). Moreover, the geostatistical analysis revealed that spatial similarities were propagated over larger distances in June (6 km) than in January (2.2 km). In order to account or this result, we suggest that... |
| Tipo: Text |
Palavras-chave: Microphytobenthos; Chlorophyll a; Spatial distribution; Geostatistics; Intertidal mudflat. |
| Ano: 1998 |
URL: http://archimer.ifremer.fr/doc/00447/55852/58117.pdf |
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| Gros, Philippe. |
| Gros, Ph. (2011). Marine Ecosystems, Chapter 5 in: Current knowledge of impacts of climate change on biodiversity from Metropolitan France – A literature review. Coord. N. Massu & G. Landmann (Ecofor), MEDDTL, 179 pp. This chapter aims at providing an overview of the current knowledge of impacts of climate change on biodiversity in the marine eco-regions from Metropolitan France (i.e. in the North Sea, English Channel, Celtic Sea, Bay of Biscay and north-western Mediterranean Sea). The major physical (heat budget, circulation) and chemical (acidification) changes in waters of the north-eastern Atlantic and of the western Mediterranean Sea are summarized. Based on results from multidecadal time series analysis and from ongoing research work, examples... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00043/15394/12749.pdf |
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| Gros, Philippe; Hamon, Dominique. |
| The aim of this report is to provide total biomass estimates of the blue mussel (Mytilus edulis, M. galloprovincialis) livestock harvested on mussel beds, and of the cockle Cerastoderma edule in the Bay of Saint-Brieuc. The sampling scheme for reared mussels combines stratification and three-stage sampling. The biomass of mussels, estimated twice in a year, remains close to 3 500 metric tons of wet weight (coefficient of variation : 10 to 14 %). A nonrandom, systematic sampling was performed to estimate the total biomass of cockles, the data being processed according to the geostatistical methods the biomass of the stock exhibits seasonal variability : 4 800 tons (CV : 15 %) at the end of summer, vs. 3 700 tons (CV: 17 %) at the beginning of spring. The... |
| Tipo: Text |
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| Ano: 1989 |
URL: http://archimer.ifremer.fr/doc/00040/15152/12489.pdf |
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| Blanchard, Michel; Gros, Philippe. |
| Three main intertidal macrofauna communities are identified in Saint-Brieuc Bay: a Macoma balthica community, a Tellina tenuis community; and a third community with Cerastroderma and Tellina tenuis. Physiological parameters such as filtration, respiration and excretion are examined, for the filter-feeding molluscs with the highest biomass (the cockle Cerastoderma edule, the tellinid Tellina tenuis, and the blue mussel Mytilus edulis), either through laboratory experiments, or through previous literature. These results are used together to build up an annual energy budget for the complete soft bottom community, and to observe trophic relations. Results show that the mussel population has a negative influence on the cockle beds that lie just above. |
| Tipo: Text |
Palavras-chave: ENERGY BUDGET; FLUXES; CERASTODERMA-EDULE; TELLINA-TENUIS; SAINT-BRIEUC BAY. |
| Ano: 1993 |
URL: http://archimer.ifremer.fr/doc/00100/21132/18752.pdf |
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| Gros, Philippe; Laurec, A.; Dupouy, Herve. |
| This paper is devoted to statistical problems associated to the estimation of the parameters of a Von Bertalanffy growth curve. A first part corresponds to theoretical considerations, first within the classical regression point of view, corresponding to residuals normaly and independently distributed, then to resampling techniques (Jackknife/Bootstrap). The possibility of using not only the arithmetic mean of observed lengths for a given age, but also medians and modes is discussed. A software has been written in Fortran, which makes it possible to fit by (Weighted) least squares either mean, median or modal length at age, and provides estimates of variances/covariances using the classical approximation within regression theory or resampling techniques. An... |
| Tipo: Text |
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| Ano: 1987 |
URL: http://archimer.ifremer.fr/doc/00394/50575/51267.pdf |
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| Gros, Philippe. |
| The objective of this report is to characterize the evolution of the pelagie coastal ecosystem (studied by sampling hydrobiological parameters, phytoplankton and zooplankton) off the Gravelines' nuclear power plant (french coast of the North Sea). The sampling program (contractually defined by the Centre National pour l'Exploitation des Océans and Electricité de France) is composed of several successive phases. The results obtained for the first three of them (september 1974 - december 1975 ; august 1976 - july 1977 ; january 1978- june 1979) are presented in this report, with special emphasis on the third one realized just before the power plant's activity started (march 1980). It is shown that, from 1974 to 1979, some subsets of the ecosystem (such as... |
| Tipo: Text |
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| Ano: 1981 |
URL: http://archimer.ifremer.fr/doc/00101/21213/18828.pdf |
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| Bertrand, Arnaud; Josse, Erwan; Bach, Pascal; Gros, Philippe; Dagorn, Laurent. |
| We studied relationships between tropical tunas (albacore (Thunnus alalunga), bigeye (Thunnus obesus), and yellowfin (Thunnus albacares)) and their biotic and abiotic environments through simultaneous acoustic observations of tunas and their prey, experimental longline catch, and oceanographic data in French Polynesia. Vertical habitat limits were estimated based on temperature and dissolved oxygen at capture data. We then studied tuna-micronekton relationships to better understand how tuna occupy the pelagic space, At a regional scale, tunas were more abundant in areas rich in prey with favourable hydrological conditions. Inside such areas, at the scale of a longline set, however, the longline catches were maximal only when prey were not distributed in... |
| Tipo: Text |
Palavras-chave: Hydrological; Acoustic observations; Tunas. |
| Ano: 2002 |
URL: http://archimer.ifremer.fr/doc/2002/publication-733.pdf |
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| Gros, Philippe. |
| Fisheries and aquaculture provide at least 15% of their animal protein diet to 4.3 billion persons. The rise of aquaculture dates back to the end of the 1980s, when fisheries’ production rate was beginning to decline, sounding the end of its post World War II growth phase. The volume of official landings culminated 25 years ago, without outlook for any further increase. About 60% of fish stocks are currently exploited at the maximum sustainable yield (MSY) level, most of the other ones being overexploited because of the chronic overcapacity of the fleets and of poorly regulated access to fishing. The ecosystem approach to fisheries (EAF) emerged as paradigm shift in the 1990s, underpinning the renewal of management objectives and governance along with... |
| Tipo: Text |
Palavras-chave: Common fishery policy; Ecological footprint; Ecosystem approach to fisheries; Fisheries; Global change; Good ecological status. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00183/29414/27775.pdf |
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| Gros, Philippe. |
| First analytic approaches in population dynamics modelling did not really begin until the 1920s and 1930s. By the 1950s, models that described how fish populations respond to fishing were developed, and provided useful tools in the management of living resources. These early studies, as well as the bulk of existing theoretical ecology, are usually in spatially homogeneous settings: they deal with temporal processes, and ask specifically about steady-state solutions to nonspatial systems. However, several lines of inquiry have stressed the critical role of spatial complexity when thinking about populations and communities as dynamical systems varying in response to natural or human-created disturbance. The introduction of this report is designed to... |
| Tipo: Text |
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| Ano: 2001 |
URL: http://archimer.ifremer.fr/doc/00013/12409/9196.pdf |
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| Gros, Philippe; Santarelli, Leonardo. |
| The experimental design of the capture field area of baited whelk-pots involves, as a controlled factor, four different spacings between pots (6, 12, 24 and 36m), randomly distributed along a ground line. This spectrum of values is sufficiently broad to preclude overlap of capturing fields of sorne pots. Taking account of the patterns of the M2 tidal currents in the area studied, an ellipse was chosen as a geometrical model of the shape of the capture field. Semimajor and semiminor axes were estimated by least squares, the expected catch per pot being defined as a decreasing function of the area of overlap with adjacent capture fields. · Experimental fishing of Buccinum undatum L. was carried out in the Channel Isles region (Western Channel), and provided... |
| Tipo: Text |
Palavras-chave: Échantillonnage quantitatif; Estimation de densité; Casier appâté; Gestion de stocks; Buccin; Quantitative sampling; Density estimate; Baited pot; Stock assessment; Whelk. |
| Ano: 1986 |
URL: http://archimer.ifremer.fr/doc/00112/22279/19954.pdf |
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| Santarelli, L; Gros, Philippe. |
| The totality of French landings of whelk (Buccinum undatum L.) is assignable to the fisheries of the Normand-Breton Gulf, western Channel. The aim of this paper is to forecast economic rent of the potters of the harbour of Granville, as a function of the two main variates open to supervision: the size of the fishing fleet, and the number of whelk-pots per ship. In order to assess the biological and financial consequences of a prospective development, a deterministic model of the fleet-resource system is proposed. Results of simulations emphasize the sharpness of the rent-dissipation problem under existing tendencies. Therefore some recommendations are put forward to derive a fishery policy that would enable the system to be maintained near optimal... |
| Tipo: Text |
Palavras-chave: Gastropoda; Marine mollusks; Fishery management; Economic models; Fishery economics. |
| Ano: 1984 |
URL: http://archimer.ifremer.fr/doc/1984/publication-1786.pdf |
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| Registros recuperados: 31 | |
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