TRACE ELEMENT CONCENTRATIONS IN SOME MODERN CORALS1

Abstract

Thirty‐four scleractinian coral samples, including both hermatypic and ahermatypic varieties, have been analyzed for trace elements. Acid leaching has been used to infer the distribution of elements between the coral skeleton (acid‐soluble fraction) and detrital phases (acid‐insoluble).Sr, U, Ba, Cu, B, Li, and Zn are generally present in the coral skeleton. Sr and U concentrations, relative to Ca and to Ca in seawater, show only little discrimination but small variations do exist between species from the same environment, indicating species‐specific controls. Larger differences are found between hermatypic and ahermatypic corals. The concentrations of Sr and U are independent of temperature and may be a function of the coral metabolism and rate of skeletogenesis. Ba is not discriminated against, but there is marked discrimination against B and Li. Zn is generally discriminated against but some ahermatypic species show high Zn concentrations. Si, Ti, and Cr are mostly present in the detrital phase associated with the corals; the nature of the detritus often reflects the local environment. Fe, Mn, Co, Ni, Pb, and Sc are distributed variously between the detrital and nondetrital phases. High concentrations are found in ferromanganese‐stained pelagic corals and in nearshore corals containing much detritus. The concentrations of these elements in clean, fresh corals indicate that they are discriminated against with respect to Ca uptake from seawater.