Mass coral bleaching event in Sekisei lagoon observed in the summer of 2016

Abstract

Thermal anomaly-induced mass bleaching status of Sekisei lagoon, Okinawa was surveyed in the summer 2016. The survey focused on 11 species of major scleractinian corals including Acropora, Pocillopora, Seriatophora, Stylophora, Favites as well as massive Porites in order to evaluate the genus-specific mass bleaching impacts. The survey was conducted by visually categorizing bleaching status of more than 6400 colonies into 5 distinguished stages of bleaching at 35 sites in the Sekisei lagoon. The result showed that bleaching of 10 species reached more than 98% while massive Porites showed around 58.5% bleaching. Although, massive coral species are usually categorized into low bleaching-impacted corals, mortality rate was clearly higher in 2016 compared with the mass bleaching survey conducted in September 2007. These results strongly suggest that the 2016 mass bleaching event in Seskisei lagoon severely impacted wide range of corals with relatively high mortality of the massive coral species. Such impact may imply longer period needed for the reef scape recovery in Seskisei lagoon.