Arimatéa C. Ximenes, Monica M. P. Tognella, Armando S. Reis-Neto, Moises F. Bezerra, Mário Luiz Gomes Soares, Raymond D. Ward, McGregor Sean, Ena Suarez

The “Mangroves of the Tropical Southwestern Atlantic” (TSA) is a regional ecosystem subgroup (level 4 unit of the IUCN Global Ecosystem Typology). It includes the marine ecoregions of Eastern Brazil, Northeastern Brazil, including the Fernando de Noronha Archipelago and Rocas Atoll. The TSA mangroves had a mapped extent of 1719.7 km2 in 2020, representing 1.2% of the global mangrove area. The flora is characterized by four true mangrove species: Rhizophora mangle, Avicennia schaueriana, A. germinans and Laguncularia racemosa. They provide essential biological functions such as supplying food resources to nearby settlements, including fish, crabs, mussels, and prawns, as well as timber and coastal defence. Furthermore, these environments promote ecological interactions with adjacent coral reefs. The climate ranges from humid to semi-arid along the Brazilian coast, which influences the diversity of geological environments and forest structures in the mangrove ecosystem. Despite their ecological and socio-economic importance, mangroves are at risk from conversion to aquaculture, salt panning, coastal infrastructure development, and oil pollution. Mangroves have also been significantly impacted by two recent major disasters: the 2015 collapse of the Mariana dam, which released a vast quantity of iron mining waste, and an extensive oil spill along the Brazilian northeast coast in 2019. As of today, the TSA mangrove ecosystem area has undergone a net loss of -3.7% since 1996. If this trend continues an overall change of -6.7% is projected over the next 50 years. Furthermore, under a high sea level rise scenario (IPCC RCP8.5) ≈10.5% of the TSA mangrove area would be submerged by 2060. Moreover, 2.2% of the province’s mangrove ecosystem is undergoing degradation, with the potential to increase to 6.6% within a 50-year period, based on a vegetation index decay analysis. Overall, the Tropical Southwestern Atlantic mangrove ecosystem is assessed as Least Concern (LC).