Proactive Coral Reef Restoration Using Thermally Tolerant Corals in Hawai‘i

Abstract Effective conservation of degraded ecosystems requires mitigation of the original cause of decline, but this step can be difficult in the context of global climate change. On coral reefs, persistent environmental stress which causes coral bleaching may be addressed by using coral restoration stock which is naturally more resilient, often termed “proactive restoration” in terrestrial management. To explore the feasibility and consequences of this approach, we outplanted 391 colonies of 7 species of reef-building coral designated as ‘thermally tolerant’ or ‘thermally sensitive’ during stress testing and monitored them for 2 years using photogrammetry to evaluate tradeoffs and return-on-effort. We found no growth, complexity or effort tradeoffs when using thermally tolerant corals, but tolerant corals had lower survivorship during our monitoring period, driven primarily by one genus. These data illustrate nuanced tradeoffs and consequences to proactive reef restoration and suggest that the potential benefits of this approach may only be fully realized during future coral bleaching events. Competing Interest Statement The authors have declared no competing interest. Footnotes Author Contacts: Hanalei Ho‘opai-Sylva: hanaleih{at}hawaii.edu Carlo Caruso: carloreef{at}gmail.com Spencer Miller: millersp{at}hawaii.edu Joshua R. Hancock: hancock9{at}hawaii.edu Matthew Parry: matthew_parry{at}fws.gov Kira Hughes: kirawa{at}hawaii.edu Crawford drury: druryc{at}hawaii.edu.edu Data Availability Statement All data and code needed to reproduce this analysis is available at github.com/CarloReef/RWR_Airport Conflict of Interest Statement The authors declare no conflict of interest. The findings and conclusions in this article are those of the author(s) and do not necessarily represent the views of the U.S. Fish and Wildlife Service.