Heavy metal contamination in the fishes of Inland wetlands of India.

Abstract

Heavy metals are one of the most toxic, persistent and widespread group of contaminants in aquatic systems. Their effects may often occur and remain unrecognized at the individual level but slowly, over a period of time, show up at population level. It is well known that heavy metals measured in tissues of aquatic organisms can reflect past exposures. They can also be a reasonable measurement for public health standards and in the point of view of animals' health. Over a few decades globally there has been growing interest to determine levels of heavy metals in the aquatic environment and public food supplies, particularly fish due to their known hazards. In India heavy metals although have not created any major problems, varying magnitudes of heavy metal contamination do exist in various biotic and abiotic components. Information on heavy metal contamination in fishes lay scattered and many of them do illustrate the toxic effects at laboratory conditions. Further information on the suitability of fishes for human consumption, in the perspective of metal contamination, is limited. The current study has attempted to document the heavy metal contamination status of select wetlands spread across the country using fish as an indicator. Altogether 8S9 fishes comprising 19 species were collected from 90 wetlands spread across 10 states in the country and examined for heavy metal contamination, Further, biomarkers of metal contamination, namely Metallothionein and Glutathione were also quantified in a few species of fishes collected from select wetlands in Tamil Nadu. Biomarkers are expected to indicate the stress in fishes and serve as an early warning signal. Suitability of fishes for human consumption was evaluated as it will help assess the impact on human beings in tong run.