Factors affecting the distribution of ahermatypic corals on the Mediterranean seafloor: a probabilistic study

Abstract Over 300 dredge samples from the Mediterranean Sea have been examined from a probabilistic viewpoint for the presence of ahermatypic corals. The frequency of finding the organisms decreases with increasing depth, indicating either that the density of coral specimens decreases or that colonizable substrates become scarcer upon going deeper, and the frequency depends on the type of substrates. Particulate seafloors are more poorly colonized than rocky ones. The former have practically no corals below 400 m depth, whilst the latter appear to be colonized with the same intensity regardless of the depth. The settlement of Mediterranean deep-sea corals is favoured by the absence of sedimented fine materials; this factor is in turn controlled by the physiography and hydrodynamic energy of the environment.