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.
Address: SACON, Coimbatore 641 108, Tamil
Nadu. India
Phone: 0422 657102 - 108
Fax: 0422 657088
E-mail: ecot_mur@yahoo. commurli_sacon@hotmail.com
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