The Tropical Atlantic is bounded on the north and south by temperate ocean realms. The Temperate Northern Atlantic realm lies to the north on both the North American and African-European shores of the Atlantic. To the south, the ocean realms conform to the continental margins, not the ocean basins; the Temperate South America realm lies to the south along the South American coast, and the Temperate Southern Africa realm lies to the south along the African coast.
Spalding, Mark D., Helen E. Fox, Gerald R. Allen, Nick Davidson et al. "Marine Ecoregions of the World: A Bioregionalization of Coastal and Shelf Areas". Bioscience Vol. 57 No. 7, July/August 2007, pp. 573–583. [1]