Seeing the invisible: XRF reveals lead distributions in coral organisms grown in the Red Sea (Gulf of Aqaba)

Abstract

Lead (Pb) contamination in marine ecosystems poses a significant ecological threat. Not much is known about its effects on coral reefs, which serve as vital biodiversity hotspots and climate refuges. This study revealed bioaccumulation of Pb in the organism of two stony coral species, Stylophora pistillata and Pocillopora verrucosa widely studied in the Gulf of Aqaba. Microfocus X-ray fluorescence (XRF) imaging revealed widespread accumulation of Pb within the coral tissues but not in the skeletons. The finding that Pb predominantly accumulates in the soft tissues with no evidence of Pb in the mineral suggests that exposure was short or of low concentration. Both highlight the great sensitivity of coral organisms to Pb uptake, with likely negative impacts on the organism. Pb may originate in dust arising from a transient desert storm. We suggest that anthropogenic Pb contamination, intensified by factors such as urban runoff or industrial discharges, still poses a serious risk to coral health and resilience despite years of efforts to curb exposure. Future research should focus on the kinetics of Pb bioaccumulation, effects of short-term versus long-term exposure and the combined effects of heavy metals and temperature on coral physiology.