Coral restoration is only practical when local human pressure levels are low

Coral reefs are threatened by interacting local (fishing, coastal development) and global (cli-mate change) stressors that degrade coral cover. Adding coral to the reef (coral restoration) is gaining prominence as a management strategy, however it is unclear whether restoration alone can ensure self-sustaining high coral cover under interacting stressors. We assess how much restoration is needed for a self-sustaining healthy coral reef using a mathematical model and real-world restoration case studies. We find that a reef with low macroalgal cover and high coral recruitment requires low levels of restoration to ensure self-sustaining high coral cover but as nutrient enrichment and fishing increase, more restoration is re-quired. Thus, if the reef is facing high local human stressors, restoration is unlikely to ensure self-sustaining high coral cover, suggesting that under such conditions conservation resources should first be allocated towards reducing the impact of stressors, prior to any restoration.