Diversity of Antarctic echinoids and ecoregions of the Southern Ocean.

16 pagesInternational audienceSignificant environmental changes have already been documented in the Southern Ocean (e.g. seawater temperature increase and salinity drop) but its marine life is still incompletely known given the heterogeneousnature of biogeographic data. However, to establish sustainable conservation areas, understandingspecies and communities distribution patterns is critical. For this purpose, the ecoregionalization approachcan prove useful by identifying spatially explicit and well-delimited regions of common species compositionand environmental settings. Such regions are expected to have similar biotic responses to environmentalchanges and can be used to define priorities for the designation of Marine Protected Areas. In the presentwork, a benthic ecoregionalization of the Southern Ocean is proposed based on echinoids distribution dataand abiotic environmental parameters. Echinoids are widely distributed in the Southern Ocean, they are taxonomicallyand ecologically well diversified and documented. Given the heterogeneity of the sampling effort,predictive spatial models were produced to fill the gaps in between species distribution data. A first procedurewas developed using Gaussian Mixture Models (GMM) to combine individual species models into ecoregions.A second, integrative procedure was implemented using the Generalized Dissimilarity Models (GDM)to model and assemble species distributions. Both procedures were compared to propose benthic ecoregionsat the scale of the entire Southern Ocean