Biodiversity hotspots and threatened species under human influence in the Amazon continental shelf.

The Amazon Continental Shelf (ACS) stretches for more than 2500 km along the coast of northern Brazil, where it is influenced directly by the discharge of the Amazon River, which deposits enormous quantities of organic matter at its mouth. Despite the extraordinary importance of this region, it is still among the least-studied sectors of the Brazilian coast. The present study, which is based on the data generated by the continuous monitoring conducted by the National Center for Research and Conservation of the Marine Biodiversity of Northern Brazil (CEPNOR/ICMBio) and the systematic review of the databases of reference collections, provides the most comprehensive inventory of the marine biodiversity of the ACS compiled up to now. A total of 3286 species were identified, 1247 more than previous studies, including primarily bony fish (28%) microorganisms (15%) and molluscs (14%). Considering the conservation status of the species, 67 of which are threatened at some level according to the list of endangered species in Brazil, mainly cartilaginous fish (40%), bony fish (31%) and seabirds (11%). The results of the present study reveal hotspots of biodiversity, especially near offshore oilfields and fishing grounds, raising concerns about the potential impact of human activity in the region. These findings emphasize the need for systematic ecosystem management combined with continuous monitoring, to mitigate these threats to the biodiversity of the ACS, while also reinforcing the importance of integrating scientific and conservation efforts to protect this unique, but vulnerable biome.