Hard-bottom coral gardens
In locations where currents are strong and the sea bed is hard, sea fans and other non-reefal coral species may provide a habitat for fish, brittle stars and small crustaceans. The most common sea fans constituting hard-bottom coral gardens in the North Atlantic are Paragorgia arborea, Primnoa resedaeformis, Paramuricea placomus and Swiftia spp. Although the biodiversity in these habitats is lower than in coral reefs, they nevertheless sustain many individuals and a large number of host-specific species that are not found in other habitats.
Bubblegum coral Paragorgia arborea and red tree coral Primnoa resedaeformis are the most common sea fans in hard-bottom coral forests in Norwegian waters. Image: MAREANO/IMR.
Primnoa resedaeformis are common coral trees in slope areas like the south shelf break of Iceland. Image: MFRI.