Macroalgal forests restoration in Italy: from the biomolecular monitoring to the mining of bioactive compounds

Mediterranean marine forests formed by canopy-forming brown macroalgae are increasingly threatened by climate change and anthropogenic pressures. Among these species, Ericaria amentacea is an endemic Mediterranean macroalga that plays a key ecological role in coastal ecosystems but has experienced significant population declines and limited natural recovery due to its restricted dispersal capacity. Improving the knowledge of its physiological responses, genetic diversity, and potential applications is therefore essential to support effective conservation and restoration strategies. This thesis adopts a multidisciplinary approach to investigate three main aspects of E. amentacea biology and ecology. First, the seasonal physiological and biochemical dynamics of wild populations were analyzed to establish a baseline framework for future restoration monitoring. Multiple biomarkers were evaluated, including photosynthetic pigments, proteins, lipids, phenolic compounds, antioxidant enzyme activities, lipid peroxidation, and phytohormones. The results revealed clear seasonal patterns that reflect the species’ acclimation to fluctuating environmental conditions, particularly during summer when enhanced antioxidant responses and photoprotective mechanisms were observed. In addition, high-quality RNA was successfully extracted from field samples, enabling future transcriptomic investigations. Second, the thesis explored the valorization of restoration by-products through the extraction and characterization of sodium alginate from apices derived from ex situ cultivation. Spectroscopic analyses confirmed the structural characteristics of the extracted polysaccharide, which showed significant antioxidant and anti-inflammatory activity in macrophage models by modulating the expression of key inflammatory mediators and inhibiting nitric oxide production. These findings highlight the potential of E. amentacea polysaccharides for future biomedical and biotechnological applications. Finally, the genetic diversity and phylogeographic structure of E. amentacea populations along Italian coasts were investigated using mitochondrial COI gene sequences. The results revealed high haplotype diversity but low nucleotide diversity, suggesting a historical bottleneck followed by demographic expansion. Strong population structuring and clear differentiation between continental and insular populations were observed, emphasizing the role of limited dispersal and geographic isolation in shaping genetic diversity. Overall, this thesis provides new insights into the seasonal physiology, bioactive potential, and population genetics of Ericaria amentacea. The results establish essential baseline data and methodological tools that can support restoration monitoring, conservation planning, and the sustainable valorization of this key Mediterranean macroalga.