Unveiling the mesophotic South Atlantic reef system (SARS): Mapping, evolution, and implications for Marine Spatial Planning (MSP) in the Western South Atlantic

Abstract

Despite the global efforts to recognize the seabed, large-scale mesophotic bioconstructions, the western South Atlantic remains outdated. Utilizing the Geographic Information System (GIS) for reprocessing existing datasets, it was possible to bridge this gap and enable the improvement of Marine Spatial Planning (MSP) in poorly mapped areas. This study presents an unprecedented reanalysis of multidisciplinary public datasets, encompassing information on seabed samples, seabed video inspections, interpretations of the collected data, and dating efforts using GIS and statistical approaches. Results revealed a direct correlation between high carbonate content and gravel, and the visual inspection highlighted the presence of mesophotic reefs, confirming the existence of the mesophotic South Atlantic Reef System (SARS). The most prominent bioengineers were crustose calcareous algae (CCA), rhodoliths (coalescent and free-living form), sponges, corals, and Halimeda. There is a direct relationship between reef age, depth and distance to the coast and an inverse relationship between age and latitude. Countries bordering the SARS should incorporate this unique and fragile seabed feature into their MSP governance, helping strike a balance between conservation and economic growth.