Stylasterid corals: A new paleotemperature archive

Abstract

© 2020 The Authors Stylasterids are a ubiquitous deep-sea coral taxon that build their skeletons from either calcite, aragonite, or both. Yet, robust geochemical proxy data from these corals are limited. In this study, 95 modern stylasterids, spanning a wide range of depths (63 to 2894 m) and ambient seawater temperatures (0 to 17 °C), were tested for their potential use as paleoceanographic archives. Stable oxygen and carbon isotopic composition (δ18O and δ13C) were measured from the main trunk of all specimens and five specimens were further sub-sampled to assess internal chemical variability. The isotope data show non-equilibrium precipitation from seawater for both δ18O and δ13C, with the growing tips of colonies yielding the isotopically lowest values. Overall, the calcitic corals showed lower isotope values for δ18O and δ13C than aragonitic specimens. Within the aragonite corals, we present a δ18O:temperature calibration that exhibits a significant linear relationship with the equation δ18Ocoral-seawater = −0.22(±0.01)×T(°C) + 3.33(±0.06) across a temperature range of 0 to 30 °C, using samples from this study and published data. This work highlights the potential application of stylasterid coral δ18O data to reconstruct paleo seawater temperature.