Presence and diversity of key habitats as criteria for zoning enhanced protection areas: the Mediterranean case of habitats acting as nurseries for juvenile fish

In coastal marine environments, the renewal of necto-benthic Teleost populations depends on the availability of various essential habitats at key stages in the species' life cycle, notably spawning and nursery habitats. The creation of strong protection zones (“no-take zones”) is effective in protecting adult breeding populations; however, nursery habitats require a different type of protection, to protect them from a transformation of their characteristics, essential to their nursery role; moreover, different species use different habitats within the coastal habitat mosaic, or use them successively during ontogenic migration. Knowing the typology of these habitats, their location (mapping) and their availability (relative surface areas) is therefore key information for guiding the zoning of management measures. In the Mediterranean, several habitats and ecotones are known for their nursery role. Our Medhab program, as part of the PAMM (2018-2022), has enabled us to complete their mapping, particularly for one of the little-documented nursery habitat types that do not fall within the scope of standardized biocenosis mapping, i.e. specific facies (in this case shallow heterogeneous rocky bottoms). On the basis of our mapping work locating and quantifying the availability of this nursery habitat along the 2700 km of French Mediterranean coastline, in addition to existing mapping (e.g. Posidonia meadows), we have set out recommendations for the zoning of management measures, notably the designation of reinforced protection areas.