The 2022 summer marine heatwaves and coral bleaching in China's Greater Bay Area

Yu Zhao, Mingru Chen*, Tzu Hao Chung, Leo Lai Chan, Jian Wen Qiu*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

5 Citations (Scopus)


From July to August 2022, scleractinian coral communities in China's Greater Bay Area (GBA) in the northern South China Sea (nSCS) experienced an unprecedented bleaching event, despite the fact that coral communities in this area are often considered coral thermal refugia due to their high latitude distribution. Field surveys of six sites covering three main coral distribution areas of the GBA revealed that coral bleaching occurred at all sites. Bleaching was more severe in shallow water (1–3 m) than in deep water (4–6 m), as indicated by both percent bleached cover (51.80 ± 10.04% vs. 7.09 ± 7.37%) and bleached colonies (45.86 ± 11.22% vs. 6.58 ± 6.53%). Coral genera Acropora, Favites, Montipora, Platygyra, Pocillopora, and Porites showed high susceptibility to bleaching, and Acropora and Pocillopora suffered high post-bleaching mortality. In the three areas surveyed, analysis of oceanographic data detected marine heatwaves (MHWs) during the summer, with mean intensities between 1.62 and 1.97 °C and durations between 5 and 22 days. These MHWs were primarily driven by increased shortwave radiation due to strong western Pacific Subtropical High (WPSH), combined with reduced mixing between the surface and deep upwelling waters due to reduced wind speed. Comparing with histological oceanographic data showed that the 2022 MHWs were unprecedented, and there was a significant increase in the frequency, intensity, and total days of MHWs during 1982–2022. Furthermore, the heterogeneous distribution of summer MHW characteristics indicates that the coastal upwelling may modulate the spatial distribution of summer MHWs in nSCS through its cooling effect. Overall, our study indicates that MHWs may have affected the structure of the subtropical coral communities in the nSCS, and impaired their potential as thermal refugia.

Original languageEnglish
Article number106044
JournalMarine Environmental Research
Early online date5 Jun 2023
Publication statusPublished - Jul 2023

Scopus Subject Areas

  • Oceanography
  • Aquatic Science
  • Pollution

User-Defined Keywords

  • Climate change
  • Coastal waters
  • Greater Bay Area
  • High-latitude reef
  • Marginal coral reef
  • Upwelling
  • Western pacific subtropical high


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