Effect of heavy metals on the survival, growth and development of earthworm Eisenia fetida
The present laboratory study was carried out to determine the effect of the metal contaminated soil on the survival, growth and development of Eisenia fetida. Metal contaminated soil samples were collected from five different sites of Ludhiana city which is an industrial hub of Punjab. Maximum heavy metal concentrations were recorded in soil sample taken from hambran around the Buddha Nullah and minimum concentration of heavy metal from haibowal. The level of heavy metals chromium and nickel (347 ppm and 189 ppm) were higher than permissible limits according to CCME (2001), whereas lead (42.6 ppm) was within permissible limits. Adult E. fetida were exposed to different concentrations of heavy metals in artificial soil for 28 days. Significant effects were observed on growth and reproduction of the tested organisms. There was 100% survival of E. fetida in soil amended with lead, chromium and nickel along with morphological abnormalities such as extrusion of coelomic fluid. It was observed that the worms in the low and high doses of heavy metal treated substrate produced cocoons with a one week and two week delay, respectively, vis-a-vis the control group. Furthermore, the emergence of hatchlings started one week earlier in control than in soil treated with medium and high concentration of metals. It is safely concluded that presence of heavy metal in soils adversely affects the growth, reproduction and development of E. fetida. Results ofthe study indicated that reproduction was more sensitive to higher concentrations of heavy metal contaminated soil than survival or weight change.