Coral bleaching has generally been recognized as the main reason for tropical coral reef degradation, but the time of coral bleaching monitoring is disproportionally short.In this study, trace metals, including chromium (Cr), copper (Cu), molybdenum (Mo),manganese (Mn), lead (Pb), tin (Sn), titanium (Ti), vanadium (Ⅴ), and yttrium (Y), were analyzed in two Porites corals collected from Meiji Reef in the tropical South China Sea (SCS) to assess differences in concentration related to bleached and unbleached bands.Trace metals Ti, V, Cr, and Mo generally showed irregular fluctuations in both corals.Mn, Cu, Sn,and Pb displayed very high levels in the bleached corals tissue layer, indicating an abnormal pattern of trace metal distribution.However, only Mn and Cu showed moderately high levels in the tissue layer of unbleached coral.The different distribution of trace metals in Porites may be attributable to different selectivity on the basis of vital utility or toxicity.Ti, V, Cr,and Mo are discriminated against by both coral polyps and zooxanthellae, but Mn, Cu, Sn,and Pb are accumulated by zooxanthellae and only Mn and Cu are accumulated by polyps as essential elements.The marked increase in Cu, Mn, Pb, and Sn was associated with bleaching processes, including mucus secretion, tissue retraction, and zooxanthellae expulsion and occlusion.It is here suggested that variation in skeletal trace elements (like Mn, Cu, Sn, and Pb) can be used as potential tracers of short-lived bleaching events.