Image: Brian Hopkinson and collaborators from other institutions have recently published a paper reporting new measurements on the chemistry of the calcifying fluid in corals. Corals deposit their mineral skeletons from a thin layer of fluid known as the calcifying fluid. The chemistry of this fluid in part determines how fast the skeleton is made and so how fast corals grow. In the new paper published in Nature Communications, they used microelectrodes to access the calcifying fluid and measure pH and the concentration of carbonate, one of the ions that makes up the skeleton. This work improves our understanding of the mechanisms corals use to build their skeletons and how they will respond to ocean acidification. For more information see: http://www.udel.edu/udaily/2016/apr/coral-ph-ocean-acidification-040416.html