Nitrogen isotopes of organic nitrogen in reef coral skeletons as a proxy of tropical nutrient dynamics

Understanding tropical nutrient dynamics is essential for quantifying marine productivity. In tropical and subtropical oceans, however, the spatial and continuous observation of nutrients has been scarce because of low nutrient concentration. The nitrogen isotopes of organic nitrogen in coral skeletons (delta(15)Ncoral) could be used to record nitrogenous nutrient origins at oceanic surfaces. Here, we show the intra- and inter-reef variations of delta(15)Ncoral in the western Pacific. The zonal distribution of delta(15)Ncoral was found inside a coral reef corresponding with delta(15)N of seawater nitrate (delta(15)N(nitrate)). The extended analysis of delta(15)Ncoral among various coral reefs also shows a latitudinal gradient from tropical to temperate in the western Pacific. The delta(15)Ncoral records high-resolution dynamics of nitrogenous nutrients through the geologic time scale. Citation: Yamazaki, A., T. Watanabe, and U. Tsunogai (2011), Nitrogen isotopes of organic nitrogen in reef coral skeletons as a proxy of tropical nutrient dynamics, Geophys. Res. Lett., 38, L19605, doi:10.1029/2011GL049053.