The chemistry of coral skeletons records climatic information at the time the coral lived i.e. skeletal Sr/Ca is affected by seawater temperature. The analysis of fossil coral skeletons offers an excellent opportunity to reconstruct past ocean temperatures and therefore to predict past climates. However skeletal Sr/Ca is also affected by biological processes and corals of different growth rates deposit different skeletal Sr/Ca equating to errors in reconstructed seawater temperature of up to ~3 degrees C. In this research we will identify the cause of the Sr/Ca variations between fast and slow growing corals. We have devised a research programme to study how Sr and Ca are transported across the coral tissue to the calcification site. We will culture corals and use biochemical inhibitors to switch off various ion transport mechanisms to determine how skeletal chemistry is affected. We will identify how each mechanism varies between fast and slow growing corals and will develop a methodology to correct for variations in ion transport processes between corals, allowing the accurate reconstruction of SSTs from skeletal Sr/Ca.