Stylasterid corals build aragonite skeletons in undersaturated water despite low pH at the site of calcification. ...

• Main Authors: Stewart, Joseph A, Strawson, Ivo, Kershaw, James, Robinson, Laura F
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science and Business Media LLC 2022
• Subjects: Animals; Anthozoa; Calcification, Physiologic; Calcium Carbonate; Hydrogen-Ion Concentration; Seawater; Skeleton; Water; Antarctic; Antarc*; Ocean acidification
• Online Access: https://dx.doi.org/10.17863/cam.87096; https://www.repository.cam.ac.uk/handle/1810/339677

Funder: Antarctic Science Bursary ... : Anthropogenic carbon emissions are causing seawater pH to decline, yet the impact on marine calcifiers is uncertain. Scleractinian corals and coralline algae strongly elevate the pH of their calcifying fluid (CF) to promote calcification. Other organisms adopt less energetically demanding calcification approaches but restrict their habitat. Stylasterid corals occur widely (extending well below the carbonate saturation horizon) and precipitate both aragonite and high-Mg calcite, however, their mode of biocalcification and resilience to ocean acidification are unknown. Here we measure skeletal boron isotopes (δ11B), B/Ca, and U/Ca to provide the first assessment of pH and rate of seawater flushing of stylasterid CF. Remarkably, both aragonitic and high-Mg calcitic stylasterids have low δ11B values implying little modification of internal pH. Collectively, our results suggest stylasterids have low seawater exchange rates into the calcifying space or rely on organic molecule templating to facilitate ...