An extensive reef system at the Amazon River mouth
| Autor: | Poliana S. Brasileiro, Rodolfo Paranhos, Gilberto M. Amado-Filho, Rogerio Valle, Carlos Eduardo de Rezende, Thiago Pessanha Rangel, Renato Crespo Pereira, Braulio Cherene Vaz de Oliveira, Jomar M. Silva, Ronaldo B. Francini-Filho, Cristiane C. Thompson, Lais Silva Araujo, Fernando C. Moraes, Alberto G. Figueiredo, Nara L. Oliveira, F. P. Brito, Nils E. Asp, Eduardo Hajdu, Eduardo Siegle, Alex Cardoso Bastos, Ricardo G. Bahia, Ana Paula B. Moreira, Gustavo B. Gregoracci, Rodolfo Jasão Soares Dias, Rodrigo L. Moura, Sigrid Neumann-Leitão, Beatriz Ferreira Araújo, Fabiano L. Thompson, Marcelo Gomes de Almeida, Ana Carolina Soares, João Batista Teixeira, Patricia L. Yager, Paulo S. Salomon, Bruno S. Silva, Michel Michaelovitch de Mahiques, Adriana M. Fróes, Louisi de Oliveira, Camille V. Leal, Mariana E. Campeão |
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| Rok vydání: | 2016 |
| Předmět: |
0106 biological sciences
Geologic Sediments 010504 meteorology & atmospheric sciences Rhodolith 01 natural sciences chemistry.chemical_compound Marine biogeography stepping stones Rivers River mouth Animals mineralization 14. Life underwater Reef Sea level Research Articles Ecosystem 0105 earth and related environmental sciences geography Marine Ecosystems Multidisciplinary geography.geographical_feature_category biology Amazon rainforest Coral Reefs 010604 marine biology & hydrobiology SciAdv r-articles Coral reef 15. Life on land South America biology.organism_classification Anthozoa Plume Porifera Oceanography chemistry 13. Climate action phase shifts Carbonate Geology Research Article OCEANOGRAFIA |
| Zdroj: | Repositório Institucional da USP (Biblioteca Digital da Produção Intelectual) Universidade de São Paulo (USP) instacron:USP Science Advances Repositório Institucional da UNIFESP Universidade Federal de São Paulo (UNIFESP) instacron:UNIFESP |
| Popis: | A novel Amazonian reef biome was discovered, encompassing large rhodolith and sponge beds under low light, low oxygen, and high POC. 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 × 106–km2 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 (~9500 km2) 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. |
| Databáze: | OpenAIRE |
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