Physiologic and metagenomic attributes of the rhodoliths forming the largest CaCO3 bed in the South Atlantic Ocean

Giselle S. Cavalcanti, Gustavo B. Gregoracci, Eidy O. Dos Santos, Cynthia B. Silveira, Pedro M. Meirelles, Leila Longo, Kazuyoshi Gotoh, Shota Nakamura, Tetsuya Iida, Tomoo Sawabe, Carlos E. Rezende, Ronaldo B. Francini-Filho, Rodrigo L. Moura, Gilberto M. Amado-Filho, Fabiano L. Thompson

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Rhodoliths are free-living coralline algae (Rhodophyta, Corallinales) that are ecologically important for the functioning of marine environments. They form extensive beds distributed worldwide, providing a habitat and nursery for benthic organisms and space for fisheries, and are an important source of calcium carbonate. The Abrolhos Bank, off eastern Brazil, harbors the world's largest continuous rhodolith bed (of ∼21 000 km 2) and has one of the largest marine CaCO 3 deposits (producing 25 megatons of CaCO 3 per year). Nevertheless, there is a lack of information about the microbial diversity, photosynthetic potential and ecological interactions within the rhodolith holobiont. Herein, we performed an ecophysiologic and metagenomic analysis of the Abrolhos rhodoliths to understand their microbial composition and functional components. Rhodoliths contained a specific microbiome that displayed a significant enrichment in aerobic ammonia-oxidizing betaproteobacteria and dissimilative sulfate-reducing deltaproteobacteria. We also observed a significant contribution of bacterial guilds (that is, photolithoautotrophs, anaerobic heterotrophs, sulfide oxidizers, anoxygenic phototrophs and methanogens) in the rhodolith metagenome, suggested to have important roles in biomineralization. The increased hits in aromatic compounds, fatty acid and secondary metabolism subsystems hint at an important chemically mediated interaction in which a functional job partition among eukaryal, archaeal and bacterial groups allows the rhodolith holobiont to thrive in the global ocean. High rates of photosynthesis were measured for Abrolhos rhodoliths (52.16 μmol carbon m -2 s -1), allowing the entire Abrolhos rhodolith bed to produce 5.65 × 10 5 tons C per day. This estimate illustrates the great importance of the Abrolhos rhodolith beds for dissolved carbon production in the South Atlantic Ocean.

Original languageEnglish
Pages (from-to)52-62
Number of pages11
JournalISME Journal
Volume8
Issue number1
DOIs
Publication statusPublished - Jan 1 2014
Externally publishedYes

Keywords

  • Abrolhos Bank
  • biomineralization
  • carbon cycle
  • holobionts
  • rhodoliths

ASJC Scopus subject areas

  • Microbiology
  • Ecology, Evolution, Behavior and Systematics

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    Cavalcanti, G. S., Gregoracci, G. B., Dos Santos, E. O., Silveira, C. B., Meirelles, P. M., Longo, L., Gotoh, K., Nakamura, S., Iida, T., Sawabe, T., Rezende, C. E., Francini-Filho, R. B., Moura, R. L., Amado-Filho, G. M., & Thompson, F. L. (2014). Physiologic and metagenomic attributes of the rhodoliths forming the largest CaCO3 bed in the South Atlantic Ocean. ISME Journal, 8(1), 52-62. https://doi.org/10.1038/ismej.2013.133