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Session 4Limnology of Lakes, Reservoirs and Wetlands

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Chairman: Dr. Chakrapani B. K.

Rapporteur: Sudira H. S

Heavy Metal Contamination in the Fishes of Select High Altitude Water Bodies in the Nilgiris District 

Muralidharan S., Jayakumar R., Veerakumar N. and Suresh Babu N.


Fishes serve as better indicators of heavy metal contamination by virtue of their position in the food chain, nutritional value, and their ability to accumulate contaminants in their body. Hence, a study was carried out to document the magnitude of contamination in a few species of fishes namely Scale Carp Cyprinus carpio communis, Mirror carp - Cyprinus carpio specularis, Leather carp - Cyprinus carpio nudus and Rainbow trout - Salmo gairdneri gairdneri in Nilgiris district, Tamilnadu from select reservoirs, namely Upper Bhavani, Emerald, Pyakara, Kuntha, Kamaraj Sagar Dam and Ooty lake. Accumulation pattern in various organs such as gill, kidney, liver, muscle and brain was also assessed. Samples of fishes were collected between 1995 and 1997 and analysed for metals using atomic absorption spectrophotometer.

 An average of 4.35 ppm of copper, 72.4 ppm of zinc and 0.72 ppm of lead was recorded among all the four species of fishes included in the study. Lead concentration was below detectable level in 91% of the fishes studied. Of all the fishes, Cyprinus carpio nudus suffered the maximum metal load (Cu 1.47 ppm, Zn 88.78 ppm, and Pb 1.47 ppm). Zinc was present invariably in all species at appreciable concentrations. The fishes of Emerald recorded the maximum metal load and Kamraj Sagar Dam, the minimum. Among the tissues, the kidney accumulated the highest concentrations of all metals. The study has also investigated the daily dietary intake of the metals by humans through the fishes and compared with the guidelines stipulated by WHO for human safety. The study recommends further intensive investigation to document the metal contamination on long term basis as to understand the potential impact on fishes and other components of the ecosystem particularly piscivorous birds. Moreover as fishes are commercially exploited from the water bodies included in the study for human consumption, it becomes all the more essential to monitor the contamination status.

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