ABSTRACT

We cultivated Isopora palifera clone colonies at six different temperatures for testing the utility of its skeletal δ¹⁸O as a paleotemperature proxy. Specimens cultivated at higher temperatures exhibited lower calcification rates, especially at 31.0°C, than those cultured at lower temperatures. The skeletal δ¹⁸O of the specimens cultured at 21.1-29.5°C correlated strongly with water temperature, and δ¹⁸O-temperature sensitivity was -0.15‰ °C^-1. When we removed the thermal factor from the skeletal δ¹⁸O and δ¹³C trends at 21.1-29.5°C by subtracting the estimated equilibrium values of inorganic aragonite from the analyzed δ¹⁸O and δ¹³C values, we found that the calcification rate variation has little influence on the isotopic compositions of the specimens examined. Thus, the skeletal δ¹⁸O of I. palifera corals without severe bleaching can be a good temperature proxy at temperatures below ∼30°C.