Heavy Metals in Three Commonly Available Coral Reef Fish Species From the Jordan Gulf of Aqaba, Red Sea

The concentrations of the heavy metals Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were determined in the muscles, livers,, gills, gonads, and the stomachs of two detritus feeder (Ctenochaetus striatus and Zebrasoma xanthurum) and one herbivorous (Scarus ferrugineus) fish species collected from the Gulf of Aqaba. The mean concentrations of heavy metals among the organs of fish examined were generally significantly different (P O.05). In general, muscles contained lower metal concentrations than other organs. Comparing species, there was no significant difference in the mean concentration of metals except Zn in the muscles of the examined fish species. By comparison, the mean concentrations of Zn, Cd and Cu were significantly different among the livers of these species. In gills, only Mn varied significantly. Only Cu and Pb varied among the stomachs of species examined. In gonads, there were significant differences between the mean concentrations of Cd, Cr, Cu, Mn, and Zn in one of the detritus feeder fishes and the herbivorous fish. The concentration of metals in the muscle tissues were generally low and within the ranges expected for metals in muscle of fish from relatively uncontaminated locations. The ranges are generally lower or within the ranges of the concentrations for these elements in fishes of the Red Sea (Hanna, 1989). Moreover, the values fall below the acceptable levels for human consumption recommended by FAO (1983) and WHO (1978, 1989, 1993) which means that they do not pose a significant threat to the health of human consumers. The results indicate that relatively high concentrations of heavy metals were found in liver and gill of the examined species, which suggest the possibility of using these two organs, particularly the liver, as bioindicators of metals present in the surrounding environment.