An extensive reef system at the Amazon River mouth

• Published in: Science Advances
• Main Authors: Moura, Rodrigo Leão de, Amado-Filho, Gilberto Menezes, Moraes, Fernando Coreixas de, Brasileiro, Poliana Silva, Salomon, Paulo Sergio, Mahiques, Michel M., Bastos, Alex Cardoso, Almeida, Marcelo G., Silva, Jomar M., Jr., Araujo, Beatriz F., Brito, Frederico P., Rangel, Thiago P., Oliveira, Braulio C. V., Bahia, Ricardo da Gama, Paranhos, Rodolfo P., Dias, Rodolfo J. S., Siegle, Eduardo, Figueiredo, Alberto G., Jr., Pereira, Renato Crespo, Leal, Camille V., Hajdu, Eduardo, Asp, Nils E., Gregoracci, Gustavo Bueno UNIFESP, Neumann-Leitao, Sigrid, Yager, Patricia L., Francini-Filho, Ronaldo Bastos, Froes, Adriana, Campeao, Mariana, Silva, Bruno S., Moreira, Ana Paula B., Oliveira, Louisi, Soares, Ana C., Araujo, Lais, Oliveira, Nara L., Teixeira, Joao B., Valle, Rogerio A. B., Thompson, Cristiane C., Rezende, Carlos E., Thompson, Fabiano Lopes
• Format: Article in Journal/Newspaper
• Language: English
• Published: Amer Assoc Advancement Science 2016
• Subjects: North Atlantic
• Online Access: https://repositorio.unifesp.br/handle/11600/56079; https://doi.org/10.1126/sciadv.1501252

Large rivers create major gaps in reef distribution along tropical shelves. The Amazon River represents 20% of the global riverine discharge to the ocean, generating up to a 1.3 x 10(6)-km(2) plume, and extensive muddy bottoms in the equatorial margin of South America. As a result, a wide area of the tropical North Atlantic is heavily affected in terms of salinity, pH, light penetration, and sedimentation. Such unfavorable conditions were thought to imprint a major gap in Western Atlantic reefs. We present an extensive carbonate system off the Amazon mouth, underneath the river plume. Significant carbonate sedimentation occurred during lowstand sea level, and still occurs in the outer shelf, resulting in complex hard-bottom topography. A permanent near-bottom wedge of ocean water, together with the seasonal nature of the plume's eastward retroflection, conditions the existence of this extensive (similar to 9500 km(2)) hard-bottom mosaic. The Amazon reefs transition from accretive to erosional structures and encompass extensive rhodolith beds. Carbonate structures function as a connectivity corridor for wide depth-ranging reef-associated species, being heavily colonized by large sponges and other structure-forming filter feeders that dwell under low light and high levels of particulates. The oxycline between the plume and subplume is associated with chemoautotrophic and anaerobic microbial metabolisms. The system described here provides several insights about the responses of tropical reefs to suboptimal and marginal reef-building conditions, which are accelerating worldwide due to global changes. Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERS) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Brasoil MCTI Brazilian Navy U.S. NSF Gordon and Betty Moore Foundation (GBMF) Univ Fed Rio de Janeiro UFRJ, Inst ...