Coral reefs are not only one of the most biodiverse ecosystem on earth hosting 25% of marine biodiversity, but they also provide countless and vital ecosystem services to around 1 billion people in terms of proteins, coastal protection and recreation. Rising ocean temperatures, ocean acidification, pollution, and overfishing are pushing these vital ecosystems toward collapse.
Efforts to restore coral reefs come with significant challenges. Restoring just 10% of the world’s degraded reefs would cost at least $1 billion—almost four times the total investment made over the past decade. Even when restoration projects succeed, their benefits are often short-lived.
The new paper, co-authored by GCC researchers M.Cabeza and F.Manca, shows that more than half (57%) of restored reefs suffer bleaching events within 5 years after intervention, undoing long-time effort and investment. Without addressing the root causes of coral decline, restoration will remain a temporary and small-scale solution. A shift in strategy is needed to ensure their survival.
In the study, researchers combine a comprehensive dataset documenting the success of coral restoration with current and forecasted environmental, ecological, and climate data to assess the effectiveness of interventions.
Their analysis reveals that despite significant past and ongoing coral restoration initiatives, there is still no well-coordinated, science-driven strategy guiding these efforts. In other words, restoration efforts are happening, but they may not be as systematically planned or informed by ecological and climate data as they should be.
One major issue is how restoration sites are chosen. Many projects focus on areas that are easy to access rather than those that have the best chance of survival or the major needs. As a result, restored reefs are often located near human settlements, where they are more vulnerable to pollution and other human activities.
Furthermore, future climate projections suggest that very few areas will remain immune to warming in the coming decades, raising concerns that restored reefs may not survive in the long term.
Another challenge is the lack of standardized data collection. Without a consistent way to measure success, it is difficult to identify which restoration techniques work best. This prevents researchers and conservationists from improving their methods and making smarter investments in reef recovery.
Effective coral restoration must be integrated into a broader strategy that accounts for the complex factors affecting coral reefs. Achieving this requires global collaboration among scientists, policymakers, and local communities to establish clear guidelines that consider ecological, environmental, socio-economic factors, which are currently lacking.
When selecting restoration sites, it is crucial to evaluate key factors such as “gravity” (the remoteness from human settlement combined with human population density), and the cumulative impacts of pollution and overfishing, and future climate conditions.
To mitigate these challenges, restoration projects can benefit from science-based techniques such as coral gardening, where coral fragments are cultivated in nurseries before being transplanted onto reefs; or direct transplantation, which can rapidly support reef recovery after disturbances like coral bleaching events.
Enhancing data collection and sharing can also improve restoration success. Standardized monitoring would help conservationists learn from past challenges, but the lack of universal protocols remains a hurdle. A centralized, open-access database could consolidate diverse data, enabling better tracking, collaboration, and data-driven decisions for improved outcomes.