ABSTRACT
Northern subprovinces of the Brazilian Province East of the Amazon River mouth and the Baia de Marajó, along the coasts of the Pará and Maranhão States in Brazil, the oceanography of the neritic environments changes abruptly. Instead of being dominated by organic-rich mud, the sea oors along this coast are composed of carbonate sand mixed with quartz sand and typically contain large bioherms of calcareous red coralline algae. The northward-owing North Equatorial Current, which deects northward at the “nose” of Brazil near Recife, Pernambuco State, brings warm, eutropical conditions to this area and pushes the Amazonian muds away and up the coast to Amapá and French Guiana. South of the nose of Brazil, the southward-owing Brazilian Current carries warm tropical water along the coasts of Bahia and Espiritu Santo States as far south as Cabo Frio, Rio de Janeiro State and creates warm-temperate water conditions as far south as the Rio de la Plata in Argentina. These two currents essentially divide northern and central Brazil into two distinct subprovinces of the Brazilian province: the Cearaian (named for Ceará State, Brazil); and the Bahian (named for Bahia State, Brazil) (Figure 10.1). Although they have separate, distinct malacofaunas, the Cearaian and Bahian Subprovinces also share many Brazilian endemic species, producing a small amount of faunal overlap.
