Ocean warming is killing corals, but heat-tolerant populations exist; if protected, they could replenish affected reefs naturally or through restoration. Palau’s Rock Islands experience consistently higher temperatures and extreme heatwaves, yet their diverse coral communities bleach less than those on Palau’s cooler outer reefs. Here, we combined genetic analyses, bleaching histories and growth rates of Porites cf. lobata colonies to identify thermally tolerant genotypes, map their distribution, and investigate potential growth trade-offs. We identified four genetic lineages of P. cf. lobata. On Palau’s outer reefs, a thermally sensitive lineage dominates. The Rock Islands harbor two lineages with enhanced thermal tolerance; one of which shows no consistent growth trade-off and also occurs on several outer reefs. This suggests that the Rock Islands provide naturally tolerant larvae to neighboring areas. Finding and protecting such sources of thermally-tolerant corals is key to reef survival under 21st century climate change.
|Original language||English (US)|
|State||Published - Dec 21 2022|
Bibliographical noteKAUST Repository Item: Exported on 2022-12-26
Acknowledgements: First, we extend our sincerest gratitude to the Palau International Coral Reef Center (PICRC) as well as Palauan government for permission to conduct this work, including the states of Hatohobei, Koror, and Kayangel. We thank Yimnang Golbuu, Marine Gouezo, Joy Schmull, and Geraldine Rengiil of PICRC for assistance with permitting and sampling logistics. We thank Hannah Barkley for feedback on this manuscript, fieldwork assistance, and invaluable mentorship to HER. We also thank Kathryn Rose-Pietro, Pat Lohmann, Tom De Carlo, and the crew of R/V Alucia for fieldwork and sampling assistance, Timothy Shank for use of his thermocycler, Meghann Devlin-Durante and Jennifer Boulay for training in microsatellite analyses, and Ellie Bors for assistance with RAD techniques. We thank Ann Tarrant for laboratory space and supplies and comments on earlier versions of this manuscript, Patrick Colin from the Coral Reef Research Foundation for in situ temperature data, and Andy Solow and Vicke Starczek for guidance on statistical analyses. We also thank Carolyn Tepolt for suggestions on population genetics analyses, and Simon Thorrold, Annick Cros, and Sarah Davies for comments on earlier versions of this manuscript. Lastly, we acknowledge the following funding sources for making this work possible: To A.L.C.: National Science Foundation (OCE-2049567), The Seija Family, The Arthur Vining Davis Foundation, the Atlantic Charter Donor Advised Fund, and the Dalio Foundation, Inc. To J.R.T.: The Singapore Ministry of Education and National Research Foundation through an RCE award to Singapore Centre for Environmental Life Sciences Engineering (SCELSE), and the MIT Sea Grant Office. To H.E.R.: Woods Hole Oceanographic Institution Coastal Ocean Institute Grant and Ocean Venture Fund, National Defense Science and Engineering Graduate Fellowship Program, the Martin Family Fellowship for Sustainability, and the American Association of University Women Dissertation Fellowship. To M.D.F.: The WHOI Postdoctoral Fellowship. To K.S.M.-K. and H.E.R.: Paul M. Angell Family Foundation Grant. To I.B.B.: OCE-1537959.