Development and comparison of methods for measuring heavy metal concentrations in coral tissues

Two procedures for measuring cadmium, lead, copper, zinc, nickel, and chromium concentrations in scleractinian coral tissues were compared. The procedures were: (a) physically separating tissues from skeleton by water-pik, using buffered washings designed to prevent loss of labile metals from tissue proteins, and (b) chemically extracting tissues from skeletons using hydrogen peroxide, pH adjusted to 8.2 to prevent dissolution of aragonite coral skeletons. The water-pik extraction procedure had lower detection limits, and produced consistently higher concentrations of all six metals, than the hydrogen peroxide extraction procedure. Although not proven, these procedural differences may result from consistent overestimations in biomass of chemically extracted tissues, or from interactions of tissue-metals with coral skeletons during sample preparation.