HEAVY-METALS IN DIADEMA-SETOSUM (ECHINODERMATA, ECHINOIDEA) FROM SINGAPORE CORAL-REEFS

Concentrations of Zn, Pb, Cd, Fe, Cr, Cu and Ti were measured in body compartments of the echinoid Diadema setosum and in the silt fraction of surface sediment from eight coral reefs in Singapore coastal waters . Metal concentrations in the echinoid varied with the body compartmen t analysed and with the site of sampling. Amongst the body compartment s studied, Zn, Cd, Fe, Cr and Cu were preferentially accumulated in th e gonads, whereas Pb and Ti were accumulated mainly in the calcified b ody compartments. The concentrations of most metals differed according to the reef sampled. A decreasing north-south gradient of metal conce ntrations was observed in D. setosum populations, correlating to the d istance from Singapore. A similar gradient was observed for metal conc entrations in sediment. It is suggested that D. setosum could be a val uable bioindicator for assessing heavy metal contamination in coral re ef ecosystems of the Indo-West Pacific.