Chatterjee S., Chattopadhyay B., Mukhopadhyay S.K. 2006. Trace metal distribution in tissues of cichlids (Oreochromis niloticus and O. mossambicus) collected from wastewater-fed fishponds in East Calcutta Wetlands, a Ramsar site. Acta Ichthyol. Piscat. 36 (2): 119-125.
Background. Metals discharged in wastes from different industries into wetland ecosystems pose a serious threat to the receiving environment. Biotic components grown in the area amass such metals within their body through nutritional uptake and accumulation. The present investigation was carried out to study the extent of accumulation of different waste metals in tissues of cichlids commonly cultured in composite industrial wastewater-fed fishponds (Bheris) in East Calcutta Wetlands (ECW), a Ramsar site in India.
Materials and methods. AAS studies were employed to estimate metal (Cr, Mn, Fe, Cu, Zn, and Pb) concentrations in water, and bottom sediment of fishponds and fish tissues (gill, liver, muscle, and bones) of cichlids: Nile tilapia, Oreochromis niloticus L. and Mozambique tilapia, O. mossambicus (Peters, 1852), collected from contaminated and control sites.
Results. The concentrations of metals in bottom sediment were found higher than those of the overlying water. It was
evident from the experiment that, either bone or liver was the site of maximum accumulation for the elements while muscles were the site of least metal accumulation in both fish species. Chromium, which was a highly publicised contaminant of tannery effluents, showed a similar distribution pattern (muscle < gill < liver < bone) in these fishes. Concentrations of non-essential metals like Pb were highest in Nile tilapia liver (17.9 mg • kg-1) followed by Mozambique tilapia liver (14.7 mg • kg-1). Principal component analysis with Varimax rotation revealed that Fe and Mn were in the first and second component, respectively, to influence metal uptake and bioaccumulation.
Conclusion. Tissue-specific and species-specific patterns of metal concentration and partitioning were apparent from
our experimentation. Dendrograms showed two definite clustering pattern, gill and muscle in one cluster with bone and liver in the other, two important organs so far as partitioning (in bone) and detoxification (in liver) were concerned.
Keywords: fish, Cichlidae, Oreochromis niloticus, Oreochromis mossambicus, heavy metals, wastewater, East Calcutta Wetlands, Ramsar site