Ecosystem-scale mapping of coral species and thermal tolerance

Abstract

The global decline of coral reefs urgently requires scalable colony-level data about phenotypic variation to improve coral conservation and management. To address this, we leveraged historical bleaching phenotypes, airborne imaging spectroscopy, and recurrent temperature stress to map coral species composition and thermal tolerance across four focal reefs with a cumulative area of ~15 ha. Spectral data accurately distinguished benthic composition and coral species, and showed substantial capacity for mapping thermal tolerance in two species of healthy coral. We used thermal stress from a 2019 marine heatwave to demonstrate high prediction accuracy during a natural bleaching event, and to strengthen the links between predictions, conserved tolerance phenotypes, and spectral signatures. Large differences in the proportion of tolerant corals at individual reefs suggest that ecosystem-scale “winners” and “losers” in future bleaching can be predicted, which may greatly increase the efficacy of management. This framework provides foundational evidence for the applicability of organismic-scale remote sensing to coral conservation.