CRUSTOSE CORALLINE ALGAE CONSERVATION AND RESTORATION IN THE CLIMATE CHANGE SCENARIO

Crustose coralline algae (CCA) play a key ecological role in marine ecosystems, especially in coralligenous reefs by contributing to habitat complexity and carbonate accretion, but they are increasingly threatened by climate change and anthropogenic disturbances, with potential cascading effects on associated benthic communities. This thesis addresses CCA conservation and restoration topics in a global change scenario, focusing on Lithophyllum stictiforme, a foundation species of the Mediterranean coralligenous assemblages. The first objective was to identify optimal laboratory conditions for enhancing survival and promoting growth of the early post-settlement stages of L. stictiforme, with the aim of improving ex-situ cultivation protocols to apply in restoration efforts. The second aim of the thesis was to identify the best substrates and field conditions for successful CCA recruitment, providing useful insights for in-situ interventions. In the third chapter, a field experiment was conducted to assess the growth response of CCA early recruits to variations in seawater temperature and irradiance, two key environmental drivers under climate change. Meanwhile, an independent study was carried out to help habitat compensation actions in response to the port enlargement in Civitavecchia (western central Italy) with the aim to identify suitable transplant sites along the coast, based on spatial variability and ecological quality of coralligenous habitats and to quantify the amount of bycatch organisms, in order to guide their potential relocation. Overall, this PhD research offers a multidisciplinary framework for advancing CCA restoration studies and contributes to the development of evidence-based approaches for the conservation of vulnerable Mediterranean marine ecosystems under increasing environmental pressure.