Principles for coral reef restoration in the anthropocene

Coral reefs are critically important ecosystems that support coastal societies and economies throughout the tropical oceans. However, many of the word's coral reefs are already seriously degraded, especially by over-fishing, pollution, and anthropogenic climate change. Consequently, a resurgence of ecological restoration programs is underway in an attempt to halt or reverse reef degradation and to develop new approaches in anticipation of further declines in coming decades. Some forms of rehabilitation of assem-blages of corals may be feasible, affordable, and ethical-using currently available methods and capabil-ities-for very small areas (typically <<1 km2) of high economic value, such as tourist sites. However, our review of the current and proposed restoration interventions indicates that more ambitious outcomes remain elusive and may even be counter-productive. In light of these challenges, we provide recommendations and a conceptual framework to guide future restoration projects and emerging approaches, highlighting that coral restoration is likely to continue to fail even at small scales unless climate change and other anthropogenic impacts are urgently reduced.