3D preliminary image obtained with multibeam

A 3D seismic survey, carried out in 1999-2000 by Woodside Energy Ltd during the exploration of offshore hydrocarbon deposits, revealed the presence of deep-water carbonate mound systems off Mauritania. The system, described by Colman et al. (2005), covers a linear extent of at least 190 km at 450-550 m depth on the continental slope, and could be one of the largest carbonate mounds so far discovered.
During the Spanish-Mauritanian survey ‘Maurit-0811’, carried out in November-December 2008 on board of R/V Vizconde de Eza, some strange structures, surprisingly as reef-like, were identified with a multibeam system in the continental slope along almost the entire Mauritanian coast .

The structure, almost two km wide and 100 meters high over the seabed, runs parallel to the shelf break, always at 450-550 m depth, between two channels 50 meters deep which runs east and west of the main formation.
In spite of the presence of deep canyons in the Mauritanian continental margin, which clearly cut these structures, the reef is continuous, stretching from the Senegal river to Cap Timiris for 405 km! Further North the reef seems to disappear and can only be weakly followed among the canyons.

Rough extension of coral-reef from Mauritanian Continental margin (Author: Javier Rey)

Living exemplaires of deep-water coral together with sessil epifauna at southern reef boundary, near Senegal (Photo: Ana Ramos)

Samples study suggests that the reef is mostly constituted by death coral (mainly Lophelia pertusa), soaked in an abundant fine and compacted mud; moreover the coral surface was almost devoid of sessile epifauna. Except for its southern part, where some fragments of living L. pertusa were collected (400 gr wet weight!!), the coral seems more eroded and “older” towards the north, being almost fossilized at some places.
The next multidisciplinary survey, which will be carried out in November 2010, within the framework of ECOAFRIK IEO-Project, will try to complete the coral-reef research, using other geophysical and imaging techniques.
Discussion about the biggest reef in the world is now opened to experts on cold-water corals!!