There are 3 regions of a cold-water coral reef that function as habitats (Fig.6c), which are coral rubble at the base, blocks of dead corals further up the reef slope and smaller areas of live coral at the top of the reef (Buhl-Mortensen et al., 2010). These areas of the reef increase habitat heterogenity through the availiability of microhabitats, such as space between coral branches (Fig.6b), within the coral cavities, in the tissue of live corals or on top of dead corals (Buhl-Mortensen et al., 2010). This array of microhabitats in turn attracts a plethora of encrusting and mobile invertebrate and vertebrate fauna. For example, high densities of xanthid and galatheid crabs live amongst dead Oculina varicosa (Reed et al., 1982) (Fig.7b) and antheid fish (Hemanthias vivanus) use the areas between the corals as refuges and foraging areas. The tube dwelling species, Eunice norvegica cements a tube onto the surface of live Lophelia pertusa and makes use of this location for feeding (Mortensen, 2001;Buhl-Mortensen et al., 2010) (Fig.6a). Due to the provision of habitats, areas on reefs have a much higher diversity and evenness of species, especially suspension and filter feeders versus off-reef areas, as demonstrated by comparison of corals mounds in the Porcupine Seabight (Henry and Roberts, 2007).