Concentrations of Heavy Metals in Muscle with Relation to the Growth of Two Marine Fish Species

Heavy metal concentrations in muscle and their relation to the growth of two marine fish species, including tonguefish (Cynoglossus arel) and mullet (Mugil cephalus), were studied. The samples were collected in Bach Dang estuary and concentrations of heavy metals (As, Cd, Co, Mn, Cu, Zn, Pb, and V) in muscle of the fishes were determined. The result showed that the accumulated trend of heavy metal is different between fish species. The concentration of As, Zn, Mn, V, Cu, Pb, Co and Cd in tonguefish were 73.7±30.6, 22.82±4.87, 3.44±2.13, 1.61±0.15, 0.71±0.13, 0.45±0.24, 0.03±0.02, and 0.02±0.02, g·g^-1, respectively. Meanwhile the concentration of Zn, As, V, Mn, Cu, Pb, Co and Cd in mullet were 83.41±19.68, 9.78±1.92, 1.36±0.54, 1.29±0.51, 0.65±0.12, 0.42±0.20, 0.06±0.03 and 0.03±0.01, g·g^-1, respectively. Comparison of metal levels among these species indicated that the concentrations of As and Mn in tonguefish were significantly higher than those in mullet, whereas Zn levels in mullet were found to be higher than that in tonguefish. There is no significant differences of Cd, Co, Cu, Pb and V levels in muscle between two species. Significant inversed relationships between concentration levels of metals and lengths of tonguefish were found for Mn, Cu and Zn, but not for As, Cd, Pb, and V. There were no significant relationships between the heavy metal concentrations and the length of mullet. In general, decreases of the heavy metal concentrations corresponded to the increases of fish body lengths, particularly for As, Co, Cu, Mn and V and the exception for Cd. Terefore reduced risks were associated with consuming bigger mullet fish, and increased risks of As and Cd were associated with consuming bigger tonguefish in Bach Dang river mouth.