Experimental Investigations of Coral Biomineralization
How do corals manage to secrete calcium carbonate aragonite crystals so rapidly when the process occurs many orders of magnitude more slowly abiotically under normal conditions? It is thought that corals must actively take up Ca2+ and CO32- ions from the seawater and concentrate them at the internal site of calcification within the coral polyps. While there is some evidence in support of this hypothesis it is not agreement with the observation that small changes in the concentrations of Ca2+ and CO32- have an immediate and direct impact on the rate of calcification by the coral. In this NSF funded study Langdon and Anne Cohen at the Woods Hole Oceanographic Institution are growing corals under well controlled temperature and CO2 conditions and are seeing if they can relate the morphology of the aragonite crystals that the corals lay down to the differing chemical conditions in the external environment. They hypothesize that they will be able to infer the saturation state of the internal calcifying solution from the morphology of the crystals observed under atomic force microscopy.
Montastrae faveolata in natural habitat