Rest-Art Project: Restoration of marine forests on Artificial Reefs

Artificial reefs (ARs) are at the core of this PhD research, serving as the foundation for experiments conducted during the doctoral period. These structures, whether intentionally designed or incidental, play a crucial role in marine conservation, habitat restoration, and biodiversity enhancement. This study explores the ecological impacts of ARs and coastal infrastructures, analysing their role in biodiversity enhancement, habitat complexity, and marine ecosystem restoration. The research focuses on the Mediterranean Sea, where extensive urbanisation and coastal development have significantly altered natural habitats. While ARs offer opportunities for ecological restoration and marine conservation, their design often lacks the structural complexity needed to support diverse marine life. To address this issue, I conducted an experimental study on the restoration of Ericaria amentacea, a key habitat-forming intertidal algal species, on artificial breakwaters. Using 3D-printed concrete structures, I introduced habitat-enhancing units to improve biodiversity and ecological functionality. The pilot study carried out in the Ligurian Sea involved collaboration with marine technology companies to develop structurally resilient, biologically favourable substrates. Our findings suggest that eco-engineered ARs can significantly enhance biological colonisation and support marine biodiversity when designed with ecological principles in mind. The Mediterranean Sea is warming faster than the oceans (Rossellò et al., 2023, Pastor et al., 2023), and thermal anomalies are occurring with increasing intensity, frequency and duration because of climate change. Marine macroalgal forests (i.e., Ericaria amentacea) are also facing unprecedented challenges due to the accelerating impacts of thermal anomalies and anthropogenic stressors. In summer 2022, extreme thermal anomalies were recorded, with sea temperatures exceeding historical averages by up to 4.3°C and heatwaves lasting 78 days. In this scenario, several ex-situ restoration attempts of Ericaria amentacea along Italian coasts have been conducted. The extreme thermal conditions negatively affected embryo culture, reducing fertilisation, growth, and survival rates. The findings highlight the vulnerability of Mediterranean algal forests and stress the need for adaptive restoration strategies, long-term monitoring, and deeper ecological understanding. These events are discussed in detail and examined in the first chapter of this thesis. Beyond their ecological implications, ARs also hold socio-economic significance, contributing to eco-tourism, fisheries, and coastal protection. Recent advancements in eco-engineering and the Integrated Greening of Grey Infrastructure (IGGI) offer new opportunities to enhance the multifunctionality of marine structures, particularly in areas where nature-based solutions alone may not be viable. The IGGI approach focuses on modifying artificial structures to support biodiversity while maintaining their primary functions, such as coastal defence or port infrastructure. Techniques such as material manipulation, increasing topographic complexity, and organism transplantation have shown promise in improving the ecological performance of built environments. In this study, I applied the IGGI approach in a pilot site to assess its potential for marine habitat restoration. This research contributes to the growing field of marine eco-engineering, demonstrating that strategic modifications of artificial structures can mitigate negative anthropogenic impacts on coastal ecosystems. By integrating eco-engineering principles with restoration science, ARs can better mimic natural reef structures, enhance connectivity, and provide refuges for species under stress. However, careful planning is required to address environmental concerns, including habitat alteration and invasive species risks, ensuring that ARs fulfil their potential as a sustainable tool for marine conservation and ecosystem resilience.