How do corals make rocks?

Paul G Falkowski1, Tali Mass2, Jeana Drake2, Morgan F Schaller3, Yair Rosenthal1, Oscar Schofield4, Robert M Sherrell5 and and the coral calcification team at Rutgers, (1)Rutgers University, Department of Marine and Coastal Sciences, New Brunswick, United States, (2)Rutgers University, New Brunswick, NJ, United States, (3)Rensselaer Polytechnic Institute, Earth and Environmental Sciences, Troy, NY, United States, (4)Rutgers University, Center of Ocean Observing Leadership, School of Environmental and Biological Sciences, New Brunswick, United States, (5)Rutgers University, Department of Marine and Coastal Sciences and Department of Earth and Planetary Sciences, Piscataway, United States
Abstract:
We have developed a three pronged approach to understanding how corals precipitate aragonite crystals and contain proxy biogeochemical information. Using proteomic and genomic approaches, we have identified 35 proteins in coral skeletons. Among these are a series of coral acidic proteins (CARPs). Based on their gene sequences, we cloned a subset of these proteins and purified them. Each of the proteins precipitate aragonite in vitro in unamended seawater. Antibodies raised against these proteins react with individual crystals of the native coral, clearly revealing that they are part of a biomineral structure. Based on the primary structure of the proteins we have developed a model of the precipitation reaction that focuses on a Lewis acid displacement of protons from bicarbonate anions by calcium ligated to the carboxyl groups on the CARPs. The reactions are highly acidic and are not manifestly influenced by pH above ca. 6. These results suggest that corals will maintain the ability to calcify in the coming centuries, despite acidification of the oceans.
Back to: Biogenic Carbonates: From Biocalcification to Geochemical Proxies II