Mass coral bleaching due to unprecedented marine heatwave in Papahānaumokuākea Marine National Monument (Northwestern Hawaiian Islands)

A unprecedented marine heatwave in 2014 triggered the most severe and widespread coral bleaching event recorded in Papahānaumokuākea Marine National Monument (PMNM), with up to 91% bleaching at shallow habitats of Lisianski Island. This event, characterized by extreme heat stress, differed significantly from previous bleaching events due to variations in heat exposure and potential local acclimatization. Researchers analyzed in situ surveys and satellite data across four islands/atolls to assess the drivers of bleaching patterns, its impact on coral mortality and community structure, and long-term changes in heat stress. The study found that the 2014 event was unprecedented in terms of duration and intensity, with cumulative heat stress reaching around 20°C-weeks, and highlighted a significant increase in exposure to bleaching-level heat stress since 1982, underscoring the escalating threat of climate change to these fragile ecosystems.

Couch, C. S., Burns, J. H. R., Liu, G., Steward, K., Gutlay, T. N., Kenyon, J., Eakin, C. M., & Kosaki, R. K. (2017). Mass coral bleaching due to unprecedented marine heatwave in Papahānaumokuākea Marine National Monument (Northwestern Hawaiian Islands). Plos One, 12(9), e0185121. https://doi.org/10.1371/journal.pone.0185121