Proceedings of the 11 th International Coral Reef Symposium, Ft. Lauderdale, Florida, 7-11 July 2008 Session number 26 Coral assemblages of Cabo Verde: preliminary assessment and description J. Monteiro 1,2 , C. Almeida 3 , R. Freitas 3 , A. Delgado 3 , F. Porteiro 1,2 ,R. S. Santos 1,2 1) Dep. Oceanografia e Pescas – Universidade dos Açores, Cais de Sta. Cruz, 9901-862 Horta, Portugal 2) Centro do IMAR da Universidade dos Açores, Cais de Sta Cruz 9901-862 Horta, Portugal 3) DPTRA/ISECMAR, Ribeira de Julião, S. Vicente, Republic of Cabo Verde CP163 Abstract. A preliminary ecological assessment of coral communities was conducted in Cabo Verde (North Atlantic). Two fieldtrips recorded underwater transects with DAFOR semi-quantitative scale to estimate relative abundance of coral species. This effort, together with a review of historical records, allowed a preliminary identification and description of three major coral biotopes: i) antipatharian facies in vertical walls; ii) Siderastrea radians pavements over shallow bedrock; and iii) diverse coral coverage over rocky reef with sand patches. Coral species diversity in these biotopes is lower than in other tropical reef ecosystems. Sal Island, where a more extensive survey was possible, revealed greater living coverage and biodiversity on the leeward side when compared with the windward side of the island. Depth and hard substratum orientation (vertical/horizontal) appear to act as major environmental factors structuring communities in these biotopes. The importance of other factors affecting their distribution, structure and diversity, such as water temperature, West African upwelling influence and dust deposition from Sahara desert, by prevailing and Harmattan winds, are briefly discussed. Key words: Ecological assessment, coral diversity, biotopes Introduction Sited at 15.02N, 23.34W, the Cabo Verde archipelago comprises ten islands and five islets located about 300 nautical miles WNW off the coast of Dakar, Senegal (Fig. 1). Volcanic in origin, the islands rise from the deep abyssal plain beyond the African continental shelf. Figure 1: Geographical location of Cabo Verde Islands.©ImagDOP These islands are considered to be an important hotspot of tropical reef biodiversity and one of the top ten priority locations worldwide for the conservation of reef habitats (Roberts et al. 2002). Despite the absence of major coral reef structures and of the relatively low richness of coral species and reef-associated fauna, these islands’ coral communities constitute unique habitats as many species display a small distributional range (Laborel 1974; Moses et al. 2003; Roberts et al. 2002). These coral communities are of major importance for coastal ecosystems (providing habitat and supporting other fauna and flora) and play a key role on the sustainability of local fishing and economy (Wells 1988; Wilkinson 2004). Recent efforts to characterize coral communities and associated fauna and flora have been conducted in specific locations of São Vicente Island (Delgado 2006) and Sal Island (Henriquez et al. 2006). Although providing valuable information and extensive lists of coral species and associated fauna and flora, studies are site restricted and lack a uniform approach that relates species composition and its variance to environmental conditions. The goal of the present work was a preliminary ecological assessment of coral communities in Cape Verde Islands, setting the basis for the experimental design of a more detailed characterization of these coral communities. Determining the species composition and its variance within and between locations, related to physical and environmental parameters and gradients, such as depth and substratum nature and orientation, allows one to determine areas of uniform environmental conditions providing a living place for a specific 1416