Metabarcoding monitoring of scleractinian corals in Yabiji and the northern Miyako Islands using environmental DNA: Suggestions for similarities and differences in scleractinian communities in two steadily recovering areas

Coral communities on reefs are often affected by disturbances from which they must subsequently recover. As recent rapid global environmental changes cause increasingly severe disturbances, monitoring of zooxanthellate scleractinian with higher taxonomic resolution is desired. In this study we monitored 37 reefs in Yabiji and the northern Miyako Islands using the Scl-eDNA-M system, an eDNA metabarcoding method that can theoretically detect all reported zooxanthellate scleractinian genera in the Miyako Islands. Yabiji is a group of coral reefs located north of the Miyako Islands, and it experienced more severe damage than reefs in the Miyako area in the 2016 mass-bleaching event. eDNA metabarcoding analysis demonstrated a relatively high abundance of Acropora eDNA at Yabiji and the northern Miyako Islands, suggesting steady recovery of reefs in these areas. Statistical analysis using eDNA composition showed similar levels of taxonomic richness and heterogeneity, as well as differences in the most abundant taxa in the two areas. Taxa more abundant in eDNA compositions at Yabiji included genera that are tolerant to heat stress, such as Porites and Goniopora, whereas Seriatopora, a genus that is intolerant to heat stress, was more abundant in the northern Miyako Islands. Scleractinian distributions presented here will be useful as a baseline against which future changes in reef communities may be assessed.