HEAVY METALS ACCUMULATION IN WATER, SEDIMENT AND DIFFERENT TROPHIC LEVELS IN FISH FARMS
Amr M. A. Al-Nagaawy and Samir M. Saeed
Limnology department, Central Laboratory For Aquaculture Research, Agricultural Research Center. Egypt.
Received 2/ 2/ 2012 Accepted 29/ 2/ 2012
Abstract
Some heavy metals were estimated in different trophic levels and the aquatic environment constituents in private fish farm located in Abbassa, Sharkeya governorate, Egypt. Water, sediment, plankton, aquatic plants (Water hyacinth, Eichhornia crasippes) as well as some organs (muscles, gills and livers) of Nile tilapia (Oreochromis niloticus), Silver carp (Hypophthalmichthys molitrix), Mullet (Mugil cephalus), Common carp (Cyprinus carpio), and African cat fish (Clarias gariepinus) adults, which representing different trophic levels in consider to their feeding habits. These species were investigated for their residues of Fe, Mn, Zn, Cu, Cd and Pb. Obtained results revealed that the highest transfer factor (TF) was from water to plankton for all investigated metals. With respect to different investigated fish species muscles, the highest TF value for Fe and Pb were in phytovorous species (Silver carp). The highest TF value for Mn and Cd were in omnivorous fish (Common carp), while herbivorous fish (Nile tilapia) and detrivorous fish (Mullet) had the highest values of TF for Zn and Cu respectively. The lowest TF values of Fe, Mn and Cu were in muscles of Nile tilapia (herbivorous), while the lowest TF value for Zn and Pb were in muscles of Catfish (carnivorous) adults. The accumulation order of heavy metals in the food web was found to be plankton > aquatic plants > sediment > fish tissues > water. It’s concluded from this work that, there were no signs of biomagnification in higher levels of food chain, where the highest levels of metals were found in plankton and macrophytes followed by sediments. This study revealed Also, that a normal daily diet including these fish species could be considered quite safe for human consumption.
