Knowledge Bank

Bleaching events are predicted to increase in frequency and intensity as a result of rising sea surface temperatures. Paired fragments of the Caribbean corals Montastraea faveolata, Porites astreoides, and Porites divaricata were experimentally bleached (treatment) or nonbleached (control) in outdoor flow-through seawater tanks. Half of the fragments were immediately collected, and half were returned to the reef to recover for one year at ambient temperature, followed by repeat bleaching the following summer. Our findings show that the mounding coral P. astreoides is the most tolerant, and the branching coral P. divaricata is the least tolerant, of single bleaching. Unexpectedly, it is the branching P. divaricata that appears to be the most tolerant of repeat bleaching and indicates that the underlying mechanisms for bleaching resilience are fundamentally different in repeat bleached corals compared to singly bleached corals. This study provides insight into how coral species’ diversity and abundance could shift on Caribbean coral reefs in the coming decades.