Abstract
The Mediterranean Sea is at a crossroads. It is one of the world’s richest biodiversity hotspots and a cultural cradle shaped by millennia of human–sea interactions, yet it now faces two intertwined imperatives: the urgent need to decarbonize energy systems in response to climate change, and the equally pressing obligation to preserve marine ecosystems and the livelihoods they support. This semi-enclosed sea is already among the most intensively used and environmentally stressed marine regions on the planet, its waters hosting a dense mosaic of shipping lanes, fishing grounds, aquaculture sites, and coastal tourism infrastructure. In recent years, a wave of new maritime industries—including floating offshore wind energy (FOWE)—has begun to take shape, marking a profound shift in how space and resources in the Mediterranean are contested and managed.
In the northwestern Mediterranean, particularly in the Cap de Creus and Gulf of Roses, these developments unfold in an environment already marked by cumulative pressures. Habitats of high ecological value, from seagrass meadows to coralligenous reefs, are fragmented or degraded; key species face population declines; and climate change is altering environmental baselines through warming waters, shifting currents, and extreme events. Against this backdrop, FOWE emerges both as a potential driver of climate action and as a source of new ecological and socio-economic conflicts. This thesis explores that duality, aiming to chart a pathway toward a truly sustainable energy transition in the Mediterranean—one that reconciles the expansion of renewable energy with the protection of biodiversity and the well-being of coastal communities.
The research integrates regional-scale spatial analyses, trait-based species and habitat vulnerability assessments, and socio-ecological perspectives. It begins by mapping human pressures across the Costa Brava (Chapter 2.1), revealing that even without new industrial developments, marine ecosystems are already under significant stress. These baseline conditions highlight that any additional use—particularly one of the scale and permanence of FOWE—cannot be considered in isolation.
Spatial conflict analysis (Chapter 2.2) shows extensive overlap between proposed offshore wind development areas and zones of high conservation value, including Natura 2000 sites. This mismatch reflects a systemic gap in current governance, where industrial zoning and conservation planning occur in parallel rather than through integrated frameworks. Such overlaps risk under mining both biodiversity goals and public support for renewable energy projects. Species-level assessments bring these conflicts into sharper focus. Chapter 2.3 examines species of conservation concern—e.g. cetaceans, seabirds, elasmobranchs, fishes, invertebrates and sea turtles—against multiple FOWE-related stressors such as underwater noise, electromagnetic fields, vessel traffic, and habitat displacement. Many species show high vulnerability to one or more stressors, suggesting that impacts are likely to be cumulative or synergistic. Chapter 2.4 applies the same approach to commercially important fish species targeted by trawling, purse seining, and small-scale fishing. Vulnerability is high across all fleets, dispelling assumptions that certain fishing sectors may be less affected. In the Mediterranean, fisheries are more than an economic activity; they are integral to cultural identity and community cohesion. Loss of fishing grounds or declines in target species could therefore reverberate far beyond economic metrics, eroding social fabric and intergenerational knowledge systems.
Habitat assessments in Chapter 2.5 underscore the physical and biological sensitivities of benthic ecosystems. Seagrass meadows, maërl beds, and sponges reefs emerge as particularly vulnerable to seabed disturbance from cable installation, anchoring systems, and sediment resuspension. Beyond direct damage, the introduction of artificial hard substrates can facilitate the spread of non-indigenous species, potentially shifting community composition in ways that conflict with conservation objectives. The findings point to the need for habitat-specific avoidance and mitigation strategies, integrated early into site selection and project design.
When considered together, these results reveal that FOWE-related impacts are not isolated within individual ecological components but ripple through the broader socio-ecological system. The potential loss of access to fishing grounds, declines in stock abundance, and alterations to the seascape have consequences that extend into community well-being, social cohesion, and governance legitimacy. The thesis shows that a “just transition” in the Mediterranean must be both environmentally sound and socially equitable, ensuring that the shift to renewable energy does not exacerbate existing inequalities or marginalize those most dependent on marine resources.
This synthesis leads to a central conclusion: current maritime spatial planning approaches in the Mediterranean are insufficient to manage the complexity and interconnectedness of these challenges. Instead of sector-by-sector zoning, planning must evolve into adaptive, ecosystem-based frameworks that explicitly account for cumulative impacts, recognize socio-ecological inter dependencies, and apply the precautionary principle. Strategic siting should prioritize already degraded or industrialized areas, avoiding high biodiversity sites and their buffer zones. Early stage projects should serve as learning opportunities, with robust monitoring frameworks capable of triggering adaptive management as new evidence emerges.
The thesis acknowledges the constraints of working with an emerging technology. The scarcity of empirical data from operational FOWE farms in the Mediterranean necessitated reliance on predictive modeling and trait-based assessments, which, while robust, carry inherent uncertainties. The localized focus on the Cap de Creus and Gulf of Roses means that certain findings may not directly extrapolate across the basin without additional region-specific studies. The absence of decommissioning data represents another major gap in understanding the full life-cycle impacts of FOWE.
From these limitations arise clear priorities for future research: long-term ecological and socio-economic monitoring of operational projects; Mediterranean-specific evaluations of mitigation measures; advanced planning tools capable of simulating trade-offs between biodiversity, energy production, and social outcomes; investigations into the interactions between FOWE impacts and other pervasive stressors such as marine heatwaves, acidification, and chronic noise; and full life-cycle assessments that include decommissioning.
In its concluding message, the thesis positions the Mediterranean as both a testing ground and a cautionary tale. The basin’s unique ecological richness, deep cultural ties to the sea, and complex governance landscape mean that solutions cannot simply be transferred from other regions. Instead, they must be tailored to local realities, informed by high-resolution data, and guided by principles that integrate climate action with biodiversity conservation and social justice. This work provides not only the scientific basis for such integration but also a framework for decision-making that can help steer the Mediterranean toward a blue economy that is genuinely sustainable—one that safeguards the integrity of its ecosystems while meeting the urgent demands of the energy transition.