EFFECTS OF METAL CONTAMINATED SOILS ON THE GROWTH AND REPRODUCTION OF THE EARTHWORM Eisenia fetida (Savigny) Thesis
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Date
2010
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Punjab Agricultural University
Abstract
To study the effects of heavy metals on the growth and reproduction of the earthworm Eisenia
fetida (Savigny), four different metal contaminated soil sites (viz. Chand Cinema, Sunder Nagar,
Tajpur Road and Shivpuri) were selected to collect the soil samples and one uncontaminated
sample of soil was collected from PAU campus. Heavy metals i.e. lead, cadmium and nickel were
present in high concentrations in all the contaminated soil samples as compared to control
uncontaminated sample of soil. Juvenile and adult earthworms were exposed for 11 weeks to
uncontaminated and metal contaminated soil samples. In juvenile earthworms, high mortality was
observed in contaminated soil sample of Tajpur Road and reduced growth was observed in
contaminated soil sample of Chand Cinema. Moreover in juveniles longer duration to reach
maturity was also recorded in soil sample of Sunder Nagar, in which lead and nickel were present
in high concentrations. The effects of metal contaminated soils could be attributed both to the
direct toxicity of the metals and to changes in the “scope for growth” of the exposed worms. In
adult earthworms, survival was reduced in soil sample of Tajpur Road and weight was reduced in
soil sample of Sunder Nagar. Low cocoon production and hatchling emergence was also observed
for earthworms exposed to soil sample of Tajpur road as compared to control soil. Results of the
study indicated that reproduction of E. fetida was more sensitive to metal exposure.
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Keywords
earthworms, zoology