Pilot 2 is implemented in the Ebro Delta Bays (Els Alfacs and El Fangar, northeast Spain), a Natura 2000 Marine Protected Area under strong pressure from rice agriculture, aquaculture, and climate change. The pilot’s main objective is to restore degraded shallow coastal and marine habitats, improve water quality and ecosystem resilience, and support sustainable aquaculture. To achieve this, an integrated nature-based restoration scheme is being tested, combining a constructed wetland, seabed remediation, seagrass recovery strategies, and innovative solutions to mitigate summer hypoxia that affects aquaculture activities.
Despite some implementation delays, several key milestones have already been achieved. A representative restoration site in Els Alfacs Bay was selected in close collaboration with local stakeholders. For the first time in this shallow coastal area, bathymetry and sediment thickness data were generated, alongside sediment characterisation and bi-monthly water quality monitoring. These data informed the development of an executive project for a constructed wetland and seabed remediation, which has been formally submitted for permitting. In parallel, the Eurecat team tested an innovative oxygenation system on a mussel platform in Fangar Bay to mitigate summer hypoxia and carried out field surveys and environmental diagnostics of Cymodocea nodosa seagrass meadows to assess their restoration potential. Continuous engagement with local stakeholders—including irrigation communities, the aquaculture sector, Natural Park authorities, and regional government—has accompanied all stages of the pilot.
Early results indicate that long-term accumulation of fine organic mud and freshwater inputs from rice drainage channels are key drivers of habitat degradation and eutrophication in shallow bay areas. The oxygenation system proved technically capable of increasing dissolved oxygen at the outlet, but its limited effects at farm scale highlighted the challenges of improving oxygen conditions in open-water aquaculture systems.
Several important lessons have emerged. Small-scale pilots are essential for validating the feasibility of nature-based solutions, yet isolating interventions from broader environmental pressures remains difficult. Another key insight is that technical feasibility must be closely aligned with governance frameworks. Ongoing dialogue with local stakeholders has been crucial, particularly in managing expectations around restoration implementation and in testing innovative approaches such as oxygenation systems and artificial biotopes.
The pilot has faced significant challenges, including working in very shallow marine environments, navigating regulatory constraints within a protected public area, and adapting to external infrastructure developments such as the construction of a new coastal dike by the regional government. While these factors have delayed implementation, they have also created new opportunities, with the constructed wetland now being discussed as a complementary nature-based solution for coastal protection. Technical challenges are being addressed through adaptive engineering solutions, close coordination with authorities, and alignment with regional climate adaptation plans.
Looking ahead, the next phase will focus on finalising permit approvals and strengthening alignment with regional authorities, followed by the tendering and implementation of the constructed wetland and seabed remediation works. In parallel, activities will continue on passive seagrass restoration planning, improved habitat mapping, and stakeholder co-design. The Eurecat team will also continue to strengthen partnerships with regional authorities and local stakeholders, with the aim of scaling up successful solutions across the Ebro Delta Bays and positioning the pilot as a replicable Mediterranean nature-based solutions case.
