Restoration protocols for the Mediterranean coralligenous habitat

The temperate coralligenous bioconcretions harbour approximately 10% of marine Mediterranean species (about 1600 species), including long-lived algae and invertebrates. Enhanced by climate change, several pressures affect coralligenous assemblages, leading to recurrent mass mortalities and dramatic loss of habitat complexity and biodiversity. The EU- funded project MERCES is developing innovative methodologies to restore macroinvertebrate habitat-forming species from three key taxonomic groups: Cnidaria/Anthozoa, Porifera/Demospongiae and Bryozoa. Restoration protocols combined transplants from donor organisms using different techniques and recruitment-enhancing devices designed for habitat-forming species. Considering the life- history traits, population dynamics and population genetics of the selected species, restoration actions should be mainly based on transplants of small to medium size collected from donor specimens. Bearing in mind that survival of transplants is higher in species with slow growth rates such as those dwelling in the coralligenous than in more dynamic species, transplantation efforts in the coralligenous will require low initial effort but a long period will be required to fully recover habitat complexity, i.e. decades. We identified survival and growth of transplants and recruitment as the most suitable short-term indicators of the success of the restoration actions. Collaboration with volunteers (divers and diving operators) in several phases of field activities are being explored to cost- effective scaling up the restoration actions and to increase the sense of stewardship in a major users’ segment.