| Summary: | Even though echinoderms are one of the main components of the benthic communities, especially in deep waters (Gage and Tyler, 1991), and a great number of studies on Atlantic fauna have been published, little is known about Northwest African echinoderms. The present work shows a first insight on biodiversity and distribution of Northwest African Echinodermata fauna at regional level. Specimens were collected during 10 Spanish and Norwegian multidisciplinary surveys carried out onboard R/V ‘Vizconde de Eza’ and ‘Dr. Fridtjof Nansen’ from 2004 to 2012. A total of 1298 stations were sampled between the Strait of Gibraltar (36°N) and the Sierra Leona border (9°N) from 19 to 1888 m depth. We used three different samplers: commercial and beam trawls on soft bottoms, and rock dredge on hard substrates (on the canyon borders, the coral carbonate mounds barrier and the seamount). This research was conducted within the framework of the EcoAfrik Spanish project, aimed to study the biodiversity of African benthic ecosystems. Echinoderms were collected in 1038 stations —77% of the total—, being their catch almost one and a half million of individuals and 28 tons. Excepting Crinoidea, all classes presented an occurrence higher than 50%, being Asteroidea the most frequent class, appearing in 67% of the stations where echinoderms were collected. Ophiuroidea and Holothuroidea, the two classes of which taxonomic studies are more advanced, show a high diversity with more than 50 species each. Asteroidea is expected to have a similar diversity, with about 40 to 50 species, while Echinoidea will have lower diversity —about 30 species. Crinoidea seems poorly represented in the region. The echinoderm fauna of Northwest Africa seems dominated by Holothuroidea, which accounted for 91.5% of the total biomass, showing the highest values in Mauritanian deep-waters; while the numerical abundance seems dominated by Ophiuroidea (70.4%), due to the great abundances found in Western Sahara and Mauritania. Echinoderms diversity shows an ...
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