Mesophotic coral ecosystems occur offshore and north of the Amazon River

Since the 1960s, it has been accepted that the distribution of reef-building corals off Brazil has its northernmost limit at the Manuel Luis Marine State Park (approximately 0°46´S, 44°15´W), about 530 km south of the Amazon River mouth. In the present study, we challenge this view and report a geographic extension of coral distribution of over 550 km to the north (to 02°13′48′′N and 48°10′12′′W). The Amazon River is believed to be the greatest barrier to the distribution of marine species between Brazilian and Caribbean waters. After examining specimens deposited in museums and documented in scientific literature, we recorded 38 coral species offshore of the Amazon River mouth, including 27 octocorals, 9 scleractinians, 1 hydrocoral, and 1 black coral. Corals were found at depths between 18 and 125 m, providing evidence of mesophotic coral ecosystems adjacent to the mouth of Amazon River, which raises important questions about the origin and connectivity between populations of reef organisms off Brazil and those in the Caribbean region.