PhD student: Sylvain Blouet,Thesis directors : Katell Guizien (LECOB) and Anne Chenuil (IMBE)
Thesis defended the 6th of july 2023
Marine spatial planning is a future issue for the conservation of marine resources, but our understanding of the spatial arrangement of conservation zones and management zones to promote the persistence of populations is not so clear. The study of spatial scales structuring the distribution of species and processes influencing the dynamics and persistence of marine populations is therefore essential for a spatialized approach to the organization of marine spaces. This thesis work is therefore organized around two objectives: (i) to understand the local and regional scales structuring the spatial distribution of sessile invertebrates in natural and artificial habitats (part 2 and part 3) and (ii) to evaluate how the he integration of functional connectivity associated with larval dispersal in a hybrid network of natural habitats and artificial habitats influences the spatialized prospective schemes of conservation extension in the Gulf of Lion. The chosen approaches combine modelling tools and high-resolution inventories of common sessile invertebrates on natural habitats and on artificial reefs. Part 2 examines the regional spatial distribution of 5 gorgonian species using an ecological niche model, based on hydrological and geomorphological predictors (bottom currents, surface temperature, turbidity, depth, slope, roughness, wall orientation). The spatial structuring of 4 of the 5 species of gorgonians can be explained by these factors. In part 3, the effects of local (shape, depth and duration of immersion) and regional (geographical area) factors were evaluated by examining the assemblages of five species with contrasting life history traits. Geographical positioning prevailed over local factors in AR colonization. The multi-specific approach carried out in parts 2 and 3 showed different importance of the role of dispersal and abiotic factors on the spatial structuring (local and regional) of species. In Part 4, a prospective conservation extension design was simulated to assess the integration of functional connectivity within the natural hard bottom and with the addition of the artificial reef network. The network of marine protected areas is strongly modified when the functional connectivity within the fragmented rocky natural habitat is taken into account. The network of artificial reefs, adding stepping stone in the network of natural habitats, modifies the prospective design. These results highlight the importance of integrating functional connectivity into marine spatial planning and the potential impact of installing or dismantling artificial reefs
Towards a spatialized approach to marine spatial planning : case study for sessile invertebrate populations in the Gulf of Lion
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