Oxygen and carbon isotopic compositions in Favia coral skeletons from the northernmost coral reef

Abstract

We conducted oxygen and carbon isotopic analyses for Favia coral skeletons collected from Iki island, Japan, where the northernmost coral reef in the world occurs. Two skeletal structures, theca wall and columella in the single corallite were analyzed separately and compared with metrological factors during the growth period. The result suggested that two skeletal structures formed in different timing, and the isotopic signals in theca walls could be a more faithful environmental recorder such as past sea surface temperatures and insolation. Further investigations about selective sampling for chemical analysis based on skeletal growth mechanisms should be done prior to use the high-latitude Favia corals as a paleoenvironmental proxy.