Importance relative des facteurs hydroclimatiques et des traits d'histoire de vie sur la dispersion larvaire et la connectivité à différentes échelles spatiales (Manche, Golfe Gascogne).

Abstract : By ensuring the dispersal, the larval phase plays a fundamental role in the population dynamics of benthic invertebrates with a complex life cycle and determines the connectivity within marine metapopulations. Hence, the connectivity influences directly the dynamics of metapopulations and the persistence of local populations, the expansion abilities of species in response to changes in environmental conditions or biogeographic range limits. In this context, the aim of the present work was to better understand the relative roles played by hydrodynamics and hydroclimatic processes and life history traits of coastal invertebrates on the larval dispersal and the connectivity in the Bay of Biscay and in the western English Channel. To answer this question, a coupled approach was used, joining in situ observation and bio-physical modelling at two spatial scales, a regional one and a local one. In the northern Bay of Biscay, the description of larval distribution of three coastal species of polychaetes (Pectinaria koreni, Owenia fusiformis, and Sabellaria alveolata) highlighted the major role of the spatial organization of the mesoscale hydrological structures (i.e., river plumes) in the the variability of larval abundance distributions. At the regional scale of the Bay of Biscay and the western English Channel, the Lagrangian simulation of the larval dispersal under realistic hydroclimatic forcing underlined the importance of the seasonal variability of the hydroclimatic conditions and the life history traits (spawning month, planktonic larval duration, larval swimming behaviour) in the larval transport and connectivity between populations. These results suggested possible larval exchanges from the Bay of Biscay to the western English Channel, i.e. through a biogeographic transition zone. They allowed to test several hypothesis about the potential consequences of climate change on the dispersal and connectivity of marine populations, i.e. through an earlier spawning period and a shortened planktonic larval duration. At the local scale of the Gulf of Saint-Malo, western English Channel, an Eulerian dispersal model permitted to estimate the connectivity between the biogenic reefs built by Sabellaria alveolata, a species with a high patrimonial value. This model allowed to determine the relative influences of the intra- and inter-annual variability of the hydroclimatic conditions on connectivity, in a context of management and conservation of natural heritage.
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Contributor : Sakina-Dorothée Ayata <>
Submitted on : Monday, September 13, 2010 - 2:59:44 PM
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Sakina-Dorothée Ayata. Importance relative des facteurs hydroclimatiques et des traits d'histoire de vie sur la dispersion larvaire et la connectivité à différentes échelles spatiales (Manche, Golfe Gascogne).. Ecologie, Environnement. Université Pierre et Marie Curie - Paris VI, 2010. Français. ⟨tel-00517082⟩

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