Diversity of Antarctic echinoids and ecoregions of the Southern Ocean.
Abstract
Significant environmental changes have already been documented in the Southern Ocean (e.g. sea
water temperature increase and salinity drop) but its marine life is still incompletely known given the heterogeneous
nature of biogeographic data. However, to establish sustainable conservation areas, understanding
species and communities distribution patterns is critical. For this purpose, the ecoregionalization approach
can prove useful by identifying spatially explicit and well-delimited regions of common species composition
and environmental settings. Such regions are expected to have similar biotic responses to environmental
changes and can be used to define priorities for the designation of Marine Protected Areas. In the present
work, a benthic ecoregionalization of the Southern Ocean is proposed based on echinoids distribution data
and abiotic environmental parameters. Echinoids are widely distributed in the Southern Ocean, they are taxonomically
and 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 procedure
was 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 ecoregions
at the scale of the entire Southern Ocean.