Structure, fonctionnement, évolution des communautés benthiques des fonds meubles exploités du plateau continental Nord Gascogne

Abstract : In the double context of the conservation of ecosystems exposed to exploitation and in the sustainable use of a fishery, this integrated benthic ecology study concerns the structure, functioning and evolution of the benthic communities of the north Bay of Biscay continental shelf. Two distinct communities were separated: the first one in the central part of the Grande Vasière and the second one offshore, on the external margin. The structural divergences within these communities reflect a different functioning of these two ecosystems forced by different trophic inputs, biotic relationships and disturbance sources. Remarkable differences, mainly on the epifauna, were detected in relation to the disturbances generated by the bottom-trawling gears. The comparison of the benthic communities separated by 35 years revealed a long term evolution of the biosedimentary units. The interactions within the trophic webs have been specified, in terms of trophic levels and food sources. The trophic inputs from the pelagic sedimentation were quantified. At the different spatio-temporal scales considered, they showed a strong variability highlighting the major role of the physical forcing. The data collected in this study was used to develop a steady state trophic web model of the benthic-demersal ecosystem of the central part of the Grande Vasière. At the annual scale, this model reveals that the major part of the particle sedimentation imports is not consumed, the predation pressure exerted on the benthic primary consumers is important and that the consequences of the fishing discards in the trophic webs are weak. The definition of fisheries management strategy in term of preservation of the exploited ecosystems and sustainable use of these activities must take into account the amplitude width and rates of these modifications.
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Ecology, environment. Université de Bretagne occidentale - Brest, 2004. French


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Submitted on : Wednesday, June 1, 2005 - 9:01:00 AM
Last modification on : Wednesday, June 1, 2005 - 9:01:00 AM

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François Le Loc'H. Structure, fonctionnement, évolution des communautés benthiques des fonds meubles exploités du plateau continental Nord Gascogne. Ecology, environment. Université de Bretagne occidentale - Brest, 2004. French. <tel-00009359>

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