Trace elements found to be variable in two coral reef species,Heliofungia actiniformis andGalaxea fascicularis, collected from the ryukyu islands

Biominerals and metals of intertidal corals of two species (Heliofungia actiniformis, Quoy and Gaimard;Galaxea fascicularis, Linnaeus), collected from the Iriomote Island of Ryukyu, were examined with an inductively coupled plasma atomic emission spectrometer (ICP-AES). Twelve elements were detectable in the coralline skeletons dissected radially along the growth axis. The relative content (RC) of Hg periodically fluctuated and was minimum at the hollow sites of the coralline slab ofHeliofungia sp., corresponding to the cyclic growth. There were two types of elements: constant elements and variable elements along the growth axis. RCs of Ca, Mg, A1, Si, and P were nearly constant. RCs of Fe, Mn, Cu, and Ba were variable, but not as regularly changed as Hg. There were positive mass correlations of Hg to Mn, Cu and Zn, but not to Ba and Fe. In contrast, these relationships were not prominent and were likely degraded by aging in the skeleton ofGalaxea sp., suggesting a different mode from that of theHeliofungia sp.