[A-OS20] Chemical and Biological Oceanography

[AOS20-P03] Spatiotemporal variation of heat stress and its relation to coral bleaching in the ocean around the Maritime Continent

*Sayaka Yasunaka¹, Anindya Wirasatriya², Parichat Wetchayont³, Lowell Jay Tupaz⁴, Dwi Haryanti², Hanani Adiwira¹, Rhea Mae Luciano⁴, Maria Vanessa Baria-Rodriguez⁴, Toshio Suga¹ (1.Tohoku University, 2.Diponegoro University, 3.Navamindradhiraj University, 4.University of the Philippines-Diliman)

Keywords:SST, Degree heating week, ENSO, Indian Ocean Dipole

Coral bleaching occurs when symbiotic dinoflagellate algae leave corals due to warming surface waters. Since the early 1980s, the number and intensity of coral bleaching events have significantly risen globally, and many coral reefs are concerned to undergo irreversible phase shifts due to global warming. This study integrated coral bleaching data, and elucidated the spatiotemporal variations of coral bleaching and heat stress in the ocean around the Maritime Continent from 1998 to 2022. Climatological mean of heat stress is large where interannual variation of SST is large, and it reaches maximum 20-70 days after the day of maximum SST climatology. Heat stress averaged over the ocean around the Maritime Continent is increasing and at the rate of 0.24 °C-day/yr from 1990 to 2022. Occurrence of coral bleaching corresponds well with the heat stress both in time and space, and the strong heat stress and severe coral bleaching were observed in the wide region of the ocean around the Maritime Continent in 1998, 2010, 2014, 2016, and 2020. Most of these years are in the transition from El Nino to La Nina and negative Indian Ocean Dipole.