MEPS 675:199-205 (2021)  -  DOI: https://doi.org/10.3354/meps13837

ABSTRACT: Coral bleaching in Hawai‘i was first reported in 1996 and subsequently occurred in 2014 and 2015. These largely summer events did not persist past November. In autumn 2019, Hawai‘i experienced persistent warm water until December, resulting in bleaching of many pocilloporid coral colonies, particularly Pocillopora meandrina. We followed the fates of 357 adult P. meandrina and 377 juvenile Pocillopora spp. off Waikīkī on the south shore of O‘ahu. Water temperatures at 5-18 m depth at this site consistently remained above a bleaching threshold of 28°C from September until mid-December. For adult colonies, 96% bleached at least partially, 4% bleached fully, and 11% died by March. Among juvenile colonies, 21% bleached, of which 47% died by March 2020. While mortality was low compared to previous bleaching events in Hawai‘i, such protracted bleaching late into the autumn increases the annual period of temperature stress, which may not bode well for the future of Hawaiian and other high-latitude coral reefs.

KEY WORDS: Coral bleaching · Pocillopora · Hawai‘i