Award: OCE-1459536

Coral reefs are among the most diverse ecosystems on the planet. Yet, climate change is causing the oceans to simultaneously warm and become more acidic (ocean acidification). Increases in the frequency and intensity of heat-stress events that can cause bleaching coupled with ocean acidification are causing mass coral mortality and decreases in reef growth. At this rate, climate change threatens to dramatically reduce living corals on reefs, reduce reef growth, and alter reef ecosystem function. We conducted 1) an extensive survey of eight species of corals around the island of Oahu, Hawaii as well as 2) the longest multi-species experimental study to date to determine which corals might acclimatize and persist in the future and if reef ecosystems could be sustained. We found that under future ocean conditions, net calcification rates decline yet remained positive, corals abundance declines but does not go extinct, and that the species composition of organisms that make up reef ecosystems shifts but remain just as diverse. The underlying coping mechanisms of coral survivors are a combination of physiological and microbiome acclimatization and pre-adaptation strategies. Our study provides evidence as to which Hawaiian corals species, and populations within species, are most likely to survive this century and could provide source material for coral restoration efforts throughout Hawaii, as well as which sites around Oahu are most vulnerable and potential targets for conservation. Overall, our results indicate that there is innate resilience to ocean warming and acidification in corals and that coral reefs may persist this century in a degraded yet partially functional state rather than collapse. Last Modified: 04/07/2021 Submitted by: Andrea G Grottoli