The southernmost Atlantic coral reef is off the subtropical island of Queimada Grande (24°S), Brazil

The Atlantic Ocean encompasses approximately 10% of the global carbonate reef area, but the austral limits of coral reef distribution within this basin are still unclear. The lack of reef area and distribution estimates clearly hampers marine spatial planning and management in several regions, especially in the southwestern Atlantic Ocean. In this area, significant freshwater, nutrient, and terrigenous sediment inputs constrain the detection of subtidal features by remote sensing. Here, we describe the coral reef of Queimada Grande Island (QGI) (24 degrees S). The documented reef covers approximately 75,000 m(2) between depths of 7 and 12 m, forming a relatively flat-topped plateau that fringes the leeward (W) side of the island. The framework was built mainly by M. decactis colonies that were cemented in place by crustose coralline algae (CCA). This peculiar structure lays approximately 1000 km south of the Abrolhos reefs, within a tropical-subtropical transition zone, constituting the southernmost Atlantic carbonate reef built by corals already reported. Our data reveal the enormous scientific and biodiversity conservation value hidden at the coastal islands of the Brazilian Biogeographical Province. Despite the high levels of fisheries activities, we found living coral coverage similar to that of southwestern Atlantic marine protected areas.