Skip to main content

Mesophotic ecosystems of the unique South Atlantic atoll are composed by rhodolith beds and scattered consolidated reefs


Rocas Atoll is the only atoll in the South Atlantic and one of the smallest atolls in the world, and is mainly built by coralline algae. Even being unique in the world, reefs from its mesophotic zone (i.e., >30 m depth) have never been described. For the first time, we surveyed the bottom features of Rocas Atoll mesophotic zone by using side scan sonar, a remotely operated vehicle and TRIMIX diving. Rhodolith beds were the main habitat observed, composed mainly by crustose coralline algae, and presenting different patterns of bed structure. In deeper areas (60–80 m), most rhodoliths were coalesced in patches of ∼1 m2, while in the shallow areas (20–50 m), the more typical pattern of free-living rhodoliths predominated. Depths between 50 and 65 m were marked as transitional zones in which a step-shaped carbonate reefs were discovered. In addition to describing the rhodolith beds and the formation of carbonate reefs by the coalescence of rhodoliths, we highlight the importance of oceanic areas such as the one investigated here. They are excellent models for testing and understanding the influence of rhodolith beds in supporting the marine biodiversity and in promoting demographic connectivity between shallow and mesophotic reefs.

This is a preview of subscription content, access via your institution.

Fig. 1


  • Amado-Filho GM, Moura RL, Bastos AC, Salgado LT, Sumida PYG et al (2012) Rhodolith beds are major CaCO3 bio-factories in the Tropical South West Atlantic. PLoS ONE 7(4):e35171

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  • Foster M, Amado-Filho GM, Steller D, Riosmena-Rodriguez R and Kamenos N (2013) Rhodoliths and rhodoliths beds. In: Lang MA, Martinelli RL, Roberts SJ, Taylor PR (eds) Research and discoveries: the revolution of science through scuba. Smithsonian Contribution to the marine sciences, Smithsonian Institution 39, pp 143-156

  • Gherardi DFM (1996) Recent carbonate sedimentation on the coralline-algal Atol das Rocas, equatorial South Atlantic, Brazil. PhD thesis, Royal Holloway University of London

  • Gherardi DFM, Bosence DWJ (2001) Composition and community structure of the coralline algal reefs from Atol das Rocas, South Atlantic, Brazil. Coral Reefs 19:205–219

    Article  Google Scholar 

  • Kikuchi RKP and Leão ZMAN (1997) Rocas (southwestern equatorial Atlantic, Brazil): an atoll built primarily by coralline algae. Proc 8th Int Coral Reef Symp 1:731-736

  • Ordines F, Bauzá M, Sbert M, Roca P, Gianotti M, Massutí E (2015) Red algal beds increase the condition of nekto-benthic fish. J Sea Res 95:115–123

    Article  Google Scholar 

  • Pereira-Filho GH, Francini-Filho RB, Pierozzi I Jr, Pinheiro HT, Bastos AC, Moura RL, Moraes FC, Matheus Z, Bahia RG, Amado-Filho GM (2015) Sponges and fish facilitate succession from rhodolith beds to reefs. Bull Mar Sci 91(1):45–46

    Article  Google Scholar 

  • Pinheiro HT, Joyeux JC, Moura RL (2014) Reef oases in a seamount chain in the southwestern Atlantic. Coral Reefs. doi:10.1007/s00338-014-1211-9

    Google Scholar 

  • Richards ZT, O’Leary MJ (2015) The coralline algal cascades of Tallon Island (Jalan) friging reef, NW Australia. Coral Reefs 34:595

    Article  Google Scholar 

  • Riding R (2002) Structure and composition of organic reefs and carbonate mud mounds: concepts and categories. Earth Sci Rev 58:63–231

    Article  Google Scholar 

Download references


We thank to the ICMBIO Atol das Rocas Marine Biological Reserve team and the “Borandá” crew for supporting the 2011 expedition. This work was financially supported by grants of the Brazilian Science Agencies CNPq, CAPES, FAPERJ and FAPES.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Gilberto M. Amado-Filho.

Additional information

Communicated by P. Martinez Arbizu

Electronic supplementary material

Below is the link to the electronic supplementary material.

(MP4 30606 kb)

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Amado-Filho, G.M., Moura, R.L., Bastos, A.C. et al. Mesophotic ecosystems of the unique South Atlantic atoll are composed by rhodolith beds and scattered consolidated reefs. Mar Biodiv 46, 933–936 (2016).

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:


  • Rocas Atoll
  • Crustose coralline algae
  • Step-shaped reefs
  • Connectivity