Restoration cannot be scaled up globally to save reefs from loss and degradation

Abstract

Coral restoration is gaining popularity as part of a continuum of approaches addressing the widespread, recurring mass mortality events of corals that-together with elevated and chronic mortality, slower growth and recruitment failure-threaten the persistence of coral reefs worldwide. However, the monetary costs associated with broad-scale coral restoration are massive, making widespread implementation challenging, especially with the lack of coordinated and ecologically informed planning. By combining a comprehensive dataset documenting the success of coral restoration with current and forecasted environmental, ecological and climate data, we highlight how such a coordinated and ecologically informed approach is not forthcoming, despite the extent of previous and ongoing efforts. We show that: (1) restoration sites tend to be disproportionally close to human settlements and therefore more vulnerable to local anthropogenic impacts; (2) the immediate outcomes of restoration do not appear to be influenced by relevant ecological and environmental predictors such as cumulative impact; and (3) most restored localities have a high and severe bleaching risk by the middle of this century, with more than half of recently restored sites already affected. Our findings highlight the need for the coral reef community to reinforce joint development of restoration guidelines that go beyond local objectives, with attention to ocean warming trends and their long-term impacts on coral resilience and restoration success.