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The golden coral Savalia savaglia is a long-living ecosystem engineer of 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 at 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 high) 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 where the central core, generally represented by the remains of the gorgonian host skeleton, was lacking. The S. savaglia population of Boka Kotorska Bay forms the unique Mediterranean assemblage of the species deserving the definition of animal forest. Recently, temporary mitigation measures for anthropogenic impact were issued by the Government of Montenegro. Nevertheless, due to the importance of the sites the establishment of a permanent Marine Protected Area is strongly recommended., (© 2024. The Author(s).)

Coral reefs throughout the tropics have experienced large declines in the abundance of scleractinian corals over the last few decades, and some reefs are becoming functionally dominated by animal taxa other than scleractinians. This phenomenon is striking on many shallow reefs in the tropical western Atlantic, where arborescent octocorals now are numerically and functionally dominant. Octocorals are one of several taxa that have been overlooked for decades in analyses of coral reef community dynamics, and our understanding of why octocorals are favoured (whereas scleractinians are not) on some modern reefs, and how they will affect the function of future reef communities, is not commensurate with the task of scientifically responding to the coral reef crisis. We summarize the biological and ecological features predisposing octocorals for success under contemporary conditions, and focus on those features that could have generated resistance and resilience of octocoral populations to environmental change on modern reefs. There is a rich set of opportunities for rapid advancement in understanding the factors driving the success of octocorals on modern reefs, but we underscore three lines of inquiry: (1) the functional implications of strongly mixotrophic, polytrophic, and plastic nutrition, (2) the capacity to recruit at high densities and maintain rapid initial rates of vertical growth, and (3) the emergent properties associated with dense animal forests at high colony densities., (© 2020 Published by Elsevier Ltd. All rights reserved. Peter Edmunds retains copyrights for images.)