Rediscovery of Seriatopora corals in shallow reefs of Okinawa Island, Japan

Abstract

Mass coral bleaching events are caused by elevated water temperatures and irradiance stress causes mass mortality in many coral reefs. Heat-sensitive coral Seriatopora spp. were greatly reduced during acute mass bleaching along the Ryukyu Archipelago, Japan, in 1998, and were considered locally extinct on Okinawa Island. In this study, many Seriatopora spp. coral colonies were discovered in shallow coral reefs (<10 m depth) in the northern part of Okinawa Island in August 2022, similar to counts preceding 1998. In the summer of 2022, a mass bleaching event occurred along the Ryukyu Archipelago, and most colonies of Seriatopora spp. and other corals at the study site were bleached. This study reports the quick survey for prevalence, abundance, bleaching rate, and mortality of Seriatopora spp.