063 | Novel eco-friendly antifouling coatings derived from extracts of Ulva ohnoi and Asparagopsis taxiformis

Lorenzo Maria Ruggeri¹, Carlo Maffei², Francesco Crea², Damiano Spagnuolo³ | ¹Centro di Sostenibilità e Transizione Ecologica, Università degli studi di Palermo, Italy; ²Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, Università degli studi di Messina, Italy; ³Maripure ApS, Hirtshals, Denmark.

The increasing awareness of the ecological risks associated with conventional marine coatings, together with stricter environmental regulations, has highlighted the need for sustainable strategies to mitigate biofouling in marine environments. In particular, the growing environmental impact of synthetic antifouling coatings has stimulated the search for natural and eco-friendly alternatives [1]. In this study, alcoholic and aqueous extracts of the macroalgae Ulva ohnoi and Asparagopsis taxiformis were evaluated for their antifouling potential on aluminium substrates representative of boat hulls. The extracts were applied to gelcoat-coated plates under three different surface conditions (unworn, worn, and highly worn). The treated panels were immersed at a depth of 5 m to promote biofouling development. The plates were photographed every 96 hours using digital imaging and quantitative segmentation. All treated surfaces showed significantly lower fouling colonization compared to the untreated control (p < 0.001). Among the treatments, the aqueous extract of A. taxiformis produced the lowest degree of colonization across all surface conditions, while U. ohnoi extracts exhibited moderate antifouling activity. Increasing surface wear enhanced overall colonization but did not reduce the effectiveness of the extracts. These results demonstrate that macroalgal species contain active compounds capable of inhibiting early-stage biofilm formation on substrates exposed to the marine environment. Although these crude extracts are less effective than conventional biocidal coatings, their biodegradability and lack of ecotoxicity represent a tangible environmental advantage. Future studies will focus on the chemical characterization of active metabolites, the formulation of bio-based hybrid coatings, and long-term field testing under dynamic marine conditions.