By Jan Pachner • Giulia Liguori • Dr. Sandro Carniel

Seagrass meadows are among the most valuable marine ecosystems on the planet, providing critical ecological services such as carbon sequestration, habitat provision and coastal protection. In the Mediterranean Sea, Posidonia oceanica meadows play a pivotal role in sustaining marine biodiversity and mitigating climate change impacts.

The Blue Forest Project at Cala di Volpe, Sardinia, Italy, spearheaded by One Ocean Foundation in collaboration with a network of scientific and private partners, is an innovative marine restoration initiative focused on reforesting degraded Posidonia oceanica meadows using biodegradable geocomposite mats (biomats). This article outlines the project’s rationale, methodology, and broader implications for ocean resource development and blue carbon ecosystem restoration.

Background

Coastal ecosystems worldwide face increasing threats from human activities and climate change. In particular, seagrass meadows such as Posidonia oceanica are experiencing alarming rates of decline due to coastal development, pollution and anchoring pressure from recreational boating. These meadows are crucial not only for marine biodiversity but also for their role in stabilizing sediments, sequestering carbon and improving water quality.

The Blue Forest Project aims to address this ecological crisis by restoring degraded seagrass habitats through scientifically validated restoration techniques. Positioned within the broader discourse of sustainable ocean resource development, the project embodies the principles of integrated marine management and ecological engineering.

The Blue Forest Project is a collaborative effort led by One Ocean Foundation with technical contribution from the International School for Scientific Diving (ISSD), responsible for restoration operations and diving logistics. Other key partners include Safe Bay S.r.l., holder of the maritime concession for the Cala di Volpe mooring field; the Department of Chemical, Physical, Mathematical, and Natural Sciences, University of Sassari, responsible for ecological monitoring and research activities; and Geomars Srl, a spin-off of the University of Sassari, responsible for sediment analysis and habitat mapping.

Restoration Technique

The restoration methodology applied in Cala di Volpe draws on naturalistic engineering techniques traditionally employed in terrestrial environments. ISSD adapted these methods for marine applications, integrating them with biodegradable geocomposite mats (R.E.C.S. coconut-fiber biomats).

This technique has undergone years of experimental refinement and field validation since early trials in 2007. The approach involves laying biomats over degraded Posidonia substrates, called  “matte morte,” to support the anchoring of the new plants, stabilize the sediment, reduce hydrodynamic stress, and promote seagrass rhizome establishment.

Recent successful applications of this methodology include projects in the Ligurian and Tyrrhenian Seas, notably in the marine protected area of Portofino and Bergeggi, and the Natural Reserve of the Strait of Bonifacio.

 

 

Site Description

Cala di Volpe is a semi-enclosed bay in northeastern Sardinia, historically impacted by unregulated anchoring and coastal tourism. The bay hosts a mooring field managed by Safe Bay, which has replaced free anchoring with environmentally managed moorings, mitigating further seabed damage.

A preliminary environmental survey conducted by ISSD in May 2024 revealed significant areas of “matte morte” interspersed with patches of living Posidonia. These degraded areas, especially on the eastern and shallow portions of the mooring field, were prioritized for restoration based on ecological suitability and accessibility.

The total area available for future restoration spans approximately 800,000 sq. m. The initial pilot intervention focuses on select zones near mooring points identified during the site survey.

Environmental Mapping and Baseline Studies

The project’s first operational phase involves detailed biocenotic mapping of the Posidonia meadow using advanced technologies, such as side scan sonar for seabed characterization and ROV inspections for direct habitat assessment.

The baseline data are critical for assessing the status of the meadow and selecting the most suitable areas for the restoration activity in order to ensure the success of the project and support ecosystem recovery trajectories.

Additionally, sediment traps will be deployed to analyze organic and inorganic deposition rates, nutrient loads, and potential contaminants.

Implementation, Monitoring and Evaluation

Following site selection and mapping, biodegradable coconut-fiber biomats will be installed over areas of matte morte at depths ranging from 10 to 15 m. The mats serve multiple functions: supporting the transplanted fragments, stabilizing the substrate against hydrodynamic forces, providing a microhabitat for seagrass propagules, facilitating rhizome attachment, and reducing sediment resuspension.

Planting will be carried out exclusively by professional scientific divers using manual techniques to insert Posidonia rhizomes into the mats. Rhizome sourcing follows strict ethical and regulatory guidelines, using naturally detached fragments uprooted by storms and/or anchors to give them a second chance.

The ecological performance of the restoration site will be monitored through a combination of: in-situ diver surveys (measuring shoot density, survival rates, and canopy cover); photogrammetric surveys (high-resolution 3D mapping of restored plots); and biodiversity monitoring (visual survey, ecoacoustic).

Monitoring data will be compared to healthy control sites within the same meadow to evaluate restoration efficacy and inform adaptive management strategies.

 

 

Environmental, Economic and Governance Considerations

The Blue Forest Project exemplifies how marine restoration can be integrated into ocean resource development strategies by: enhancing blue carbon sequestration capacity, contributing to climate mitigation; supporting biodiversity recovery; protecting shorelines from erosion through habitat restoration; and creating sustainable tourism opportunities and promoting marine education and awareness initiatives.

From an economic perspective, seagrass restoration can yield significant returns by preserving ecosystem services that support fisheries, recreation, and carbon credits under emerging blue carbon markets.

The success of marine restoration projects such as Blue Forest depends on robust policy frameworks and intersectoral cooperation. For example, the project benefits from alignment with EU marine conservation directives (e.g., Habitats Directive, Marine Strategy Framework Directive). In addition, collaboration with local stakeholders, including tourism operators and coastal authorities, is essential to international objectives such as the United Nations Decade on Ecosystem Restoration (2021 to 2030).

Conclusion

The Blue Forest Project at Cala di Volpe is a replicable model for integrating habitat restoration within sustainable ocean resource development. By combining science-based techniques with private-public partnerships and community engagement, the project advances both ecological resilience and socioeconomic sustainability of coastal marine systems.

Such initiatives highlight the critical role of proactive marine management in safeguarding ocean health and demonstrate how restoring nature can deliver tangible benefits for climate, biodiversity, and local economies.

Learn more here.

Jan Pachner is secretary general of One Ocean Foundation.

Giulia Liguori is a marine scientist and sustainability specialist at One Ocean Foundation.

Dr. Sandro Carniel is research director at CNR, Institute of Polar Sciences, Italy.