Frontiers of Coral-Based Sclerochronological Studies in Japan

Abstract

Corals deposit calcium carbonate (CaCO3: aragonite) skeletons with paired high- and low-density bands that reflect past sea surface conditions during their growth. In addition, the elemental and isotopic compositions of a coral skeleton are affected by environmental factors during deposition, such as sea surface temperature (SST), sea surface salinity (SSS), nutrients, turbidity, pH, and dissolved inorganic carbon (DIC). Therefore, physical and chemical analyses of coral skeletons can provide a record of paleoclimatic and oceanographic changes and coral physiological responses. Because the southwestern part of Japan is at the northern habitable limit of reef-building corals, Japanese corals have distinct biological characteristics, and the area’s climatic and oceanographic setting is unique (e.g., East Asian Monsoon, Pacific Decadal Oscillation, and Kuroshio Current). Studying corals in marginal regions can facilitate understanding of the mechanisms of climatic and oceanographic changes and coral physiological responses and contribute to predicting future changes. This chapter will introduce the use of physical and chemical analyses of coral skeletons as chronological indices, highlight previous coral studies in Japan, and propose future directions for paleoenvironmental research using corals.