As anomalous heat waves are causing the widespread decline of coral reefs worldwide, there is an urgent need to identify coral populations tolerant to thermal stress. Heat stress adaptive potential is the degree of tolerance expected from evolutionary processes and, for a given reef, depends on the arrival of propagules from reefs exposed to recurrent thermal stress. For this reason, assessing spatial patterns of thermal adaptation and reef connectivity is of paramount importance to inform conservation strategies. In this work, we applied a seascape genomics framework to characterize the spatial patterns of thermal adaptation and connectivity for coral reefs of New Caledonia (Southern Pacific). In this approach, remote sensing of seascape conditions was combined with genomic data from three coral species. For every reef of the region, we computed a probability of heat stress adaptation, and two indices forecasting inbound and outbound connectivity. We then compared our indicators to field survey data, and observed that decrease of coral cover after heat stress was lower at reefs predicted with high probability of adaptation and inbound connectivity. Last, we discussed how these indicators can be used to inform local conservation strategies and preserve the adaptive potential of New Caledonian reefs.

Coral cover survey data is made available by the Réseau d'observation des récifs coralliens of New Caledonia for collecting and sharing the field survey data. Job,S.New Caledonia network of coral reef observation (RORC) - Fieldcampaignreport2017–2018. (French title:Réseaud'observation des récifs coralliens (RORC) de Nouvelle-Calédonie. Campagne 2017–2018. Rapport Pays. Rapport CORTEX. Pour le compte de : Conservatoire d'espaces naturels de Nouvelle-Calédonie - Province des îles Loyauté - Observatoire de l'environnement). (CORTEX, New Caledonia, 2018). Environmental data is processed from publicly available data from the Copernicus Ocean Products database (https://marine.copernicus.eu/) Further information on data and scripts is displayed in the readme.pdf documentation.