Skeletons of massive corals are important recorders of climatic and environmental change. Density bands in coral skeletons can be used as chronometers much like tree rings, recording chemical information such as variations in carbon and oxygen isotopes. In spite of the great interest and importance of these features, little is known about how or why density bands form, and about the precise relationships between environmental parameters, coral physiology and the stable isoptope composition. This project will study the control of stable carbon and oxygen isotopes and density banding in coral skeletons through carefully controlled laboratory experiments and routinely monitored field colonies. In the laboratory corals will be grown using seven different combinations of light and temperature. Conditions of growth such as temperature, insolation, isotopic composition of the water, isotopic composition of foods, and water composition will be continually measured. At the end of the experiment skeletal growth will be analyzed for density patterns and carbon and oxygen isotopes. Similar measurements will be made on a set of field colonies.
