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    Ecoregionalisation of the Kerguelen and Crozet islands oceanic zone. Part I: Introduction and Kerguelen oceanic zone

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    P. Koubbi, C. Guinet, N. Alloncle, N. Ameziane, C.S. Azam, A. Baudena, C.A. Bost, R. Causse, C. Chazeau, G. Coste,C. Cotté, F. D'Ovidio, K. Delord, G. Duhamel, A. Forget, N. Gasco, M. Hautecœur, P. Lehodey, C. Lo Monaco, C. Marteau, A. Martin, C. Mignard, P. Pruvost, T. Saucède, R. Sinegre, T. Thellier, A.G. Verdier and H. Weimerskirch
    Submitted By:
    Professor Philippe Koubbi (France)
    Approved By:
    Professor Philippe Koubbi (France)

    A workshop was held in Paris from June 6 to 9th 2016. It was convened by Philippe Koubbi and Christophe Guinet. The main aim was to determine ecoregions in the Kerguelen oceanic zones to give orientations for extending the actual coastal natural reserve managed by the Terres Australes and Antarctiques Françaises. The workshop listed general conservation objectives to evaluate boundaries of ecoregions based on abiotic (geography, geomorphology and oceanography) and biotic features such as pelagic, benthic (including demersal ichthyofauna) and top predators species or assemblages. As biodiversity is not only species diversity, the workshop also considered the functional diversity (trophic web, essential habitats, life history traits,…).

    This report is a summary of the conclusions based on expert knowledge. It is divided into three parts:

    -          A summary of the ecological characteristics of the Kerguelen oceanic zone;

    -          The ecoregionalisation of the pelagic realm, the benthic realm and the top predators;

    -          A final ecoregionalisation and recommendations for future works.

    The workshop determined 12 main pelagic ecoregions based on oceanographic processes, pelagic assemblages and on keystone species distribution such as mesopelagic fish. Four Important areas for top predators were defined and 8 benthic ecoregions were drawn from the coast to the limit of the Kerguelen EEZ.

    The experts found relevant to combine the pelagic and benthic ecoregions to obtain a global ecoregional map of 18 ecoregions based mainly on:

    -      Habitat characteristics (bathymetry, oceanography, primary production, biogeochemical parameters, …),

    -          Types of species assemblages with consideration of endemicity and conservation status,

    -      Functionality (essential habitats such as spawning grounds, nursery grounds or foraging habitats, areas of high primary and secondary production or, structure of the habitat by benthic species,…).

    In this process, the workshop verified the superposition of the ecoregional synthetic map with specific habitats of species (birds and mammals distribution, essential fish habitats,...). It corrected some of the boundaries of ecoregions with these ecological parameters so that some essential species habitats are mainly within one region. For each of the final ecoregions, the workshop summarized the essential characteristics that support the creation of the ecoregion and estimated its ecological importance.

    To conclude, the workshop indicated the need to continue research and monitoring over this vast area and to identify special research zones such as observatories to:

    -          Study the impacts of global change,

    -          Minimize knowledge gaps in ecology and environment,

    -          Consider natural variability,

    -          Study the resistance and resilience towards potential human impacts.