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Maintien des populations de coraux Scléractiniaires en milieu insulaire fragmenté (archipel de la Société, Polynésie française) : influence du recrutement et de la mortalité post-fixation

Abstract : To improve our understanding of maintenance processes of Scleractinian coral assemblages in an insular fragmented system, the influence of recruitment fluctuations and post-settlement mortality on spatial patterns of juvenile and adult assemblages was investigated. Spatio-temporal variability of recruitment was characterized at an insular scale around Moorea over five years and at a regional scale in the Society archipelago (French Polynesia) over one year. This technique enabled a muti-scale spatio-temporal analysis of the data. Benthic mortality of recruits and juveniles was also quantified around Moorea and the major factors causing mortality were identified. Our results emphasize the importance of post-recruitment events, particularly those occurring during the first weeks after settlement, in structuring and maintaining adult assemblages, regardless of the spatio-temporal scales considered. However, for some taxa, spatial patterns of adult populations around Moorea are mainly driven by spatial variability of recruitment during previous years. These results illustrate the importance of life history traits in mechanisms of population maintenance. Around Moorea, recruit mortality is particularly high (50 % in 7 days), and is notably linked with predation by Scaridae and Balistidae fishes (especially Scarus psittacus, Chlorurus sordidus, and Melichthys vidua), and competition by encrusting organisms. Moreover, at two of the three sites studied, spatial variability of early post-settlement mortality convincingly explains differences observed between recruit and juvenile spatial patterns. Juvenile mortality is less intense (40 % in 14 months), but also shows strong spatial variability, linked with the abundance spatial variability of Chaetodontid fishes (especially Chaetodon pelewensis) and with living coral cover. This research highlights the preponderance of post-recruitment events in structuring adult populations and assemblages, and the importance of events occurring during the first weeks of benthic life (recruit stage), particularly mortality due to biotic interactions (predation and competition).
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Submitted on : Friday, October 19, 2012 - 3:47:45 PM
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  • HAL Id : tel-00743644, version 1

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Lucie Penin. Maintien des populations de coraux Scléractiniaires en milieu insulaire fragmenté (archipel de la Société, Polynésie française) : influence du recrutement et de la mortalité post-fixation. Biodiversité et Ecologie. Université Pierre et Marie Curie - Paris VI, 2007. Français. ⟨tel-00743644⟩

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