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Etude de l'impact de l'algue envahissante Caulerpa taxifolia sur les peuplements de poissons. Etude approfondie sur une espèce « modèle » : Symphodus ocellatus (Labridae)

Abstract : We studied the impact of the invasive Caulerpa taxifolia (Vahl) C. Agardh, on fish in the Mediterranean and particularly on a fish "model" species: Symphodus ocellatus (Forsskål). A fish monitoring and experiments have been led in sites located in the Alpes-Maritimes region, on sites colonized by C. taxifolia and on uncolonized sites. C. taxifolia forms a very dense and high meadow from the end of summer to the beginning of winter, altering microhabitats and presenting a physical barrier to benthic prey access. In situ surveys of two artificial reefs showed that the silting and obstruction of holes by C. taxifolia decreases the accessibility of the substratum to shelter fish. This decrease in shelter leads to an increase in young fish predation. Gut and body fatty acid analyses of S. ocellatus showed a diet switch on C. taxifolia-colonized sites, i.e. increase in plankton- and decrease in benthic- foraging. These analyses were further supported by correlating an increase in C. taxifolia frond density with a decrease in benthic prey accessibility in the aquarium. In situ observations also corroborated our findings at C. taxifolia sites (i.e. decrease of prey accessibility) for the red mullet (Mullus surmuletus). At colonized sites, the body lipid content in young S. ocellatus was 21% less and the liver storage lipid content was 59% less in reproductive females. In addition, liver and ovary weights were also diminished in females from the C. taxifolia meadow. However, analyses of eggs yielded no discernible differences, and in situ C. taxifolia toxins have no observable influence on embryogenesis.
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https://tel.archives-ouvertes.fr/tel-00006063
Contributor : Flora Levi <>
Submitted on : Wednesday, May 12, 2004 - 10:09:14 AM
Last modification on : Monday, October 12, 2020 - 10:27:46 AM
Long-term archiving on: : Friday, April 2, 2010 - 8:21:59 PM

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  • HAL Id : tel-00006063, version 1

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Flora Levi. Etude de l'impact de l'algue envahissante Caulerpa taxifolia sur les peuplements de poissons. Etude approfondie sur une espèce « modèle » : Symphodus ocellatus (Labridae). Interactions entre organismes. Université Nice Sophia Antipolis, 2004. Français. ⟨tel-00006063⟩

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