Pleistocene Coral Assemblages on Irabu-Jima, South Ryukyu Islands, Japan

Abstract

Abstract. We identified 40 genera and 83 species of scleractinian corals from middle Pleistocene reef limestones on Irabu-jima, located in the South Ryukyu Islands (South Ryukyus); these data were then combined with previously published data sets on Pleistocene coral assemblages on Okinawa-jima (southern Central Ryukyus), and Kikai-jima (northern Central Ryukyus) to perform statistical analyses, including cluster analysis and multidimensional scaling (MDS) ordination of Bray—Curtis (BC) similarity coefficients applied to coral taxa (R-type analysis) and coral assemblages (Q-type analysis). Results of the analyses, combined with field descriptions of the coral assemblages, allowed interpretations of reef paleoenvironments. Outcrops of Quaternary reef deposits in the Ryukyus comprise both shallow- and deep-water coral assemblages. Generally, coral diversity increases southward along the island chain. The statistical analyses highlight differences in the taxonomic compositions of fossil coral assemblages in ...