Effect of transplantation on heavy metal concentrations in commercial clams of Lake Timsah, Suez Canal, Egypt

Ruditapes decussatus and Venerupis pullastra are commercially fished clamswith a wide distribution in the shallow inshore waters of Lake Timsah, Egypt.They are usually contaminated with heavy metals. Consumption of suchcontaminated clams can pose a public health risk. To minimise this risk,therefore, the clams should be removed from the contaminated waters andtransferred to an approved area to reduce the high levels of metals beforebeing marketed. The aim of this work was to study the effect of transplantation on levels of heavy metals(Fe, Mn, Zn, Cu, Ni, Co, Cd, Pb) in these clams. The clams were removed from their polluted site and transplantedto a relatively clean area for a period of 120 days. Although the salinity atthe transplantation site was higher than at the polluted site, it was stableand did not appear to have any adverse effect on clam growth. Heavy metalswere analysed in the water, sediment and clam tissues from both the pollutedand the transplantation sites. Although in both species transplantationevidently reduced heavy metal levels, these still exceeded the maximumpermissible levels laid down by the WHO (1982).