Ocean Acidification: Mechanisms of Coral Biomineralization

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This research seeks to understand how corals make their skeletons. The skeletons of stony corals are critically important biological structures that support huge areas of tropical and subtropical marine life as well as providing natural barriers against waves, storms, and floods. However, it is not yet known how corals construct their skeletons, nor is it fully understood what the effect of ocean acidification will have on this process. To address these fundamental questions, this project follows a two-pronged approach that utilizes information in the genes of living corals coupled with ultra high-resolution microscopy and physical chemical techniques to understand the mechanism that underlies precipitation of the carbonate mineral that forms the skeleton of stony corals. This effort will further develop techniques that will allow the culturing of coral tissues and the analysis of coral genomes to infer gene functions. The research is relevant to understanding the potential threat of ocean acidification to the viability of corals in the coming decades. Although biomineralization in corals has been studied for decades, the basic mechanism responsible for the precipitation of the aragonite skeleton remains enigmatic. Using a forward genetic approach, a group of highly acidic proteins derived from the common stony coral, Stylophora pistillata was recently identified and cloned. All of the cloned proteins precipitate aragonite in seawater at pH 8.2 and at 7.6 in vitro. However, it is not clear if the expression of these proteins in vivo is sufficient for the formation of an aragonite skeleton at seawater pH values below ~7.8. Using a combination of molecular, biophysical, genomic, and cell biological approaches the core hypothesis to be tested here is that, unless wounded or otherwise having skeletal material exposed directly to seawater, stony, zooxanthellate corals will continue to calcify at pH values projected for the CO2 emissions scenarios for 2100. The multi-disciplinary research approach is designed to inform how pH of the ocean influences the key physiological processes responsible for calcification in zooxanthellate scleratinian corals. The research team will create online learning modules for undergraduate students. In addition, the research will be incorporated into the Education and Public Outreach group at Rutgers University for marine science education of K-12 students and training of K-12 teachers. Finally, the project includes training and career development for two post-doctoral fellows.