Climate-driven challenges to the survival of restored coralligenous reefs: a pilot study on Cladocora caespitosa and Eunicella cavolini in the central Tyrrhenian Sea

Marine ecosystems are increasingly exposed to anthropogenic and climate-related pressures that impair biodiversity and ecosystem functioning, with thermal anomalies playing a particularly significant role in affecting habitat-forming benthic organisms. In this context, the development and assessment of ecological restoration interventions represent key tools for the conservation and sustainable use of oceans and marine resources, in line with Sustainable Development Goal 14 of the 2030 Agenda.

Within the framework of the RENOVATE project (Ecosystem Approach to the Evaluation and Experimentation of Compensation and Mitigation Actions in the Marine Environment: the case of the Civitavecchia Port Hub), we conducted a pilot coral restoration intervention at the Mano Aperta site (Santa Marinella, northern Latium, Tyrrhenian Sea), focusing on two key Mediterranean benthic habitat-forming species, Cladocora caespitosaand Eunicella cavolini. A total of 120 and 60 fragments, respectively, were sourced from bycatch of small-scale local fisheries, maintained under controlled conditions to allow recovery, and subsequently transplanted at the restoration site. Survival represents the primary indicator for evaluating the effectiveness of ecological restoration activities, particularly in benthic habitats dominated by ecosystem-engineering organisms such as corals. Monitoring activities included the assessment of key health descriptors, such as necrosis, bleaching, tissue loss, and colour changes. In parallel, continuous temperature was recorded at the restoration site to support the interpretation of biological responses under variable thermal conditions.

Here, the performance dynamics of the two corals in relation to the observed thermal anomalies is presented. These results contribute to improving our understanding of environmental thresholds influencing restoration outcomes in Mediterranean coralligenous communities under ongoing climate stress and provide practical insights to inform and refine future restoration protocols.