Understanding the connectivity between mangrove and terrestrial ecosystems in semi-arid areas of both sides of the Atlantic

The thesis collectively examines how mangrove–salt flat–terrestrial ecosystem interfaces function as a dynamic continuum, particularly in the semi-arid regions of Brazil and Senegal. The research focuses on three core questions: how terrestrial inputs and mangrove inputs influence salt flats, and whether fauna mediate nutrient exchange between these ecosystems. Study sites were selected in Jaguaripe and Tamandaré (Brazil) and Sine-Saloum (Senegal), with transects established perpendicularly to tidal reach. Measurements of mangrove structure, sediment properties, and porewater confirm that salinity, tidal flooding, and freshwater availability shape how mangroves, salt flats, and the hinterland connect. Using pyrolysis-GC/MS, one chapter reveals distinct metabolic profiles in plants, sediments, and fecal samples: salt flats often show mixed signatures, while animal-digested litter (e.g., lignin, tannins) underscores cross-boundary nutrient flows. Another chapter details an experiment using metabarcoding of sediment microbes, finding that salinity largely determines bacterial communities. A further chapter places these findings within complex adaptive systems (CAS) theory, advocating adaptive, multiscale governance - rooted in precaution and stakeholder engagement - over static, top-down management. Finally, the dissertation concludes by highlighting spatial subsidies (organic matter, fauna mobility) and urging more holistic Marine Spatial Planning (MSP) and Integrated Coastal Zone Management (ICZM). In essence, the thesis illustrates a continuum shaped by salinity gradients, tidal forces, and ecological interactions, calling for flexible, resilience-focused management to sustain both biodiversity and human needs.