The macrofauna assemblages of a XVIIth century shipwreck off southern Portugal were studied and compared with those of nearby natural reefs and sandy bottoms, by underwater visual census. A total of 11 173 specimens of 224 different fauna taxa and 12 phyla were recorded. Natural reefs had the highest density of specimens (35 122 / 1000 m²) followed by the shipwreck (21 392 / 1000 m²) and the sandy bottoms (3771...