Skeletal isotopic responses of the Scleractinian coral Isopora palifera to experimentally controlled water temperatures

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.