Distinguishing between environmental and species-specific physiological signals, recorded in coral skeletons, is one of the fundamental challenges in their reliable use as (paleo)climate proxies. To date, characteristic biological bias in skeleton-recorded environmental signatures (vital effect) was shown in shifts in geochemical signatures. Herein, for the first time, we have assessed crystallographic parameters of bio-aragonite to study the response of the reef-building coral Stylophora pistillata to experimental seawater acidification (pH 8.2, 7.6 and 7.3). Skeletons formed under high pCO2 conditions show systematic crystallographic changes such as better constrained crystal orientation and anisotropic distortions of bio-aragonite lattice parameters due to increased amount of intracrystalline organic matrix and water content. These variations in crystallographic features that seem to reflect physiological adjustments of biomineralizing organisms to environmental change, are herein called crystallographic vital effect (CVE). CVE may register those changes in the biomineralization process that may not yet be perceived at the macromorphological skeletal level.
Bibliographical noteFunding Information:
This work was partially supported by National Science Centre (Poland) research grant 2017/25/B/ST10/02221 to J.S. and Polish-Norwegian Research Programme Project Contract No Pol-Nor/196260/81/2013. We also give our sincere thanks to Mr. Francisco Coruña Llopis from CAI of Geological Techniques of Complutense University of Madrid (Spain) for their help and dedication in the thermal gravimetric measurements. We thank the anonymous reviewers and the editor for their help and constructive comments on the text.
© 2019, The Author(s).