Diversity, distribution and spatial structure of the cold-water coral fauna of the Azores (NE Atlantic)

[摘要] Cold-water corals are widely considered as important structural componentsof benthic habitats, potentially enhancing local abundance in a variety offish and invertebrate species. Yet, current knowledge of the taxonomicdiversity and distribution patterns of these vulnerable, slow-growingorganisms is scarce and fragmented, limiting the effectiveness of spatialmanagement and conservation measures. We have conducted an exhaustivecompilation of records of alcyonaceans, antipatharians, scleractinians andstylasterids available through present day to assess the diversity,distribution and spatial structure of coral assemblages in the Azoresexclusive economic zone (EEZ). The resulting database comprises 2501 entriesconcerning historical oceanographic expeditions and other published sources,as well as unpublished data from bottom longline by-catch. Our taxonomicinventory appears to be fairly complete for the explored habitats,accounting for 164 species (79 alcyonaceans, 58 scleractinians, 18antipatharians and 9 stylasterids), nine of which were documented for the first time. The Azores EEZ harbours a mixed coral fauna with severalzoogeographic origins, showing the closest affinity with theLusitanian–Mediterranean region. Very few apparent endemics were found (14%), and only in part supported by consistent sampling. Coral diversity isparticularly high between 300 and 900 m depths, in areas recognized astraditional fishing grounds or exploitable fish habitat within the 100-milelimit of the EEZ. The composition of coral assemblages shows significantgeographical structure among longitudinal sections of the study area atcomparable depths (100–1500 m). There is no evidence of a possible role ofthe Mid-Atlantic Ridge or latitudinal effects underlying this pattern, whichsuggests that it may instead reflect assemblage variability among features.Stronger changes in species composition were found along the bathymetricgradient. Notwithstanding the mix of partially overlapping steno- andeurybathic species that characterize the vertical distribution of corals,there is a distinct transition from shallow (100–600 m) to intermediate(600–1000 m) depths. The analysis presented here constitutes a valuablecontribution for efficient conservation policies of coral-associatedvulnerable marine ecosystems and their sustainable use as fishing areas.

[学科分类] 地球化学与岩石