A large non-parasitic population of Savalia savaglia (Bertoloni, 1819) in the Boka Kotorska Bay (Montenegro)

The golden coral Savalia savaglia is a long living ecosystem engineer of the Mediterranean circalittoral assemblages, able to induce necrosis of gorgonians and black corals coenenchyme and grow on their cleaned organic skeleton. Despite its rarity, in Boka Kotorska Bay (Montenegro) a shallow population of more than 1000 colonies was recorded close to underwater freshwater springs, which create very peculiar environmental conditions. In this context, the species was extremely abundant in two sites, while gorgonians were rare. The abundance and size of S. savaglia colonies and the diversity of the entire benthic assemblage were investigated by photographic sampling in a depth range of 0–35 m. Several living fragments of S. savaglia spread on the sea floor and small settled colonies (< 5 cm height) suggested a high incidence of asexual reproduction and a non-parasitic behaviour of this population. This was confirmed by studying thin sections of the basal portion of the trunk lacking the central core due to the remains of the gorgonian host skeleton. The S. savaglia population of Boka Kotorska Bay forms the unique Mediterranean animal forest of the species. Recent important mitigation measures of anthropogenic impact are now temporary and minimal. Therefore, establishing an MPA is strongly recommended.