Rapid onsets of warming events trigger mass mortality of coral reef fish

Amatzia Genin, Liraz Levy, Galit Sharon, Dionysios E. Raitsos, Arik Diamant

Research output: Contribution to journalArticlepeer-review


Our study reveals a hitherto overlooked ecological threat of climate change. Studies of warming events in the ocean have typically focused on the events' maximum temperature and duration as the cause of devastating disturbances in coral reefs, kelp forests, and rocky shores. In this study, however, we found that the rate of onset (Ronset), rather than the peak, was the likely trigger of mass mortality of coral reef fishes in the Red Sea. Following a steep rise in water temperature (4.2 °C in 2.5 d), thermally stressed fish belonging to dozens of species became fatally infected by Streptococcus iniae. Piscivores and benthivores were disproportionately impacted whereas zooplanktivores were spared. Mortality rates peaked 2 wk later, coinciding with a second warming event with extreme Ronset. The epizootic lasted ~2 mo, extending beyond the warming events through the consumption of pathogen-laden carcasses by uninfected fish. The warming was widespread, with an evident decline in wind speed, barometric pressure, and latent heat flux. A reassessment of past reports suggests that steep Ronsetwas also the probable trigger of mass mortalities of wild fish elsewhere. If the ongoing increase in the frequency and intensity of marine heat waves is associated with a corresponding increase in the frequency of extreme Ronset, calamities inflicted on coral reefs by the warming oceans may extend far beyond coral bleaching.

Original languageEnglish
Pages (from-to)25378-25385
Number of pages8
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number41
StatePublished - 13 Oct 2020

Bibliographical note

Publisher Copyright:
© 2020 National Academy of Sciences. All rights reserved.


  • Epizootic
  • Heat flux
  • Red Sea
  • Streptococcus
  • Warming rate

ASJC Scopus subject areas

  • General


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