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Etude du processus invasif de Crassostrea gigas en Bretagne: Etat des lieux, dynamique et conséquences écologiques

Abstract : The Pacific oyster, Crassostrea gigas, was introduced in France at the end of the sixties to replace the Portuguese oyster, Crassostrea angulata, decimated by disease. But only since the nineties that wild populations established on Brittany's shores. The first part of this study shows all Brittany coasts now to be colonized by C. gigas. Stocks of wild oysters are estimated at 10 000 and 6 420 tons in the Bay of Brest, and the Morbihan Bay, respectively. The second part of this study concerns factors determining C. gigas invasive process dynamics. The responsibility of climate change in the establishment of C. gigas in Brittany is confirmed. Results also highlight that C. gigas does not recruit in the subtidal zone, which refutes accusations of European oyster, Ostrea edulis, exclusion. Finally, monitoring of the summer 2008 massive mortalities reveals that wild populations were little impacted. Analysis of ecological consequences of C. gigas invasion on Brittany shores is done in the last part of this study. Impacts on communities become marked when colonization intensifies with the creation of oyster reefs, which increase macrofaunal abundance and diversity. Studies on respiration and calcification processes show that total annual carbon production of rocky intertidal communities is increased twenty fold, reaching 761,77 g C m-2 year-1 when high density populations of C.gigas establish (nearly 700 ind. m-2).
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Contributor : Morgane Lejart <>
Submitted on : Wednesday, January 6, 2010 - 11:47:11 AM
Last modification on : Friday, October 23, 2020 - 4:47:59 PM
Long-term archiving on: : Thursday, June 17, 2010 - 10:22:45 PM


  • HAL Id : tel-00444262, version 1



Morgane Lejart. Etude du processus invasif de Crassostrea gigas en Bretagne: Etat des lieux, dynamique et conséquences écologiques. Ecologie, Environnement. Université de Bretagne occidentale - Brest, 2009. Français. ⟨tel-00444262⟩



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