EFFECT OF HEAVY METAL TOXICITY (LEAD AND CADMIUM) ON THE GROWTH, SURVIVAL AND REPRODUCTION OF EARTHWORM (Eisenia fetida)

Abstract

Earthworms serve as vital indicators of soil health and are integral in maintaining soil fertility through their burrowing activities, nutrient cycling, and decomposition of organic matter. Their ecological functions can be severely compromised by environmental stresses, notably heavy metal contamination, including lead (Pb) and cadmium (Cd). The goal of the present study was to evaluate the impact of heavy metals on various qualities of earthworms as well as their accumulative ability for heavy metals like Pb and Cd. Earthworms were collected from different agricultural fields and raised under laboratory conditions at the University of Agriculture Faisalabad, PARS campus, for 28 days. For this purpose, four treatment groups were created. The T1 control group was not exposed to any metal. The T2, T3, and T4 groups were given Pb at concentrations of 1.5 mg/kg, 2.0 mg/kg, and 2.5 mg/kg of soil, respectively, and Cd at concentrations of 0.1 mg/kg, 0.2 mg/kg, and 0.3 mg/kg of soil, respectively. The earthworms were kept in trays and soil for one week prior to the trial and were fed with normal feed. Total weight, length, biomass, cocoon production, and population dynamics were measured. In terms of growth, the average growth value significantly dropped in T3 to 1.108 with a standard deviation of ±0.061774, indicating high variability. Regarding the survival rate, the average survival rate significantly decreases in T3 to 5.5 with ±2.95804, indicating a very wide range of values. For cocoon production in T3, the average number of cocoons produced reached 12.25  ±4.710. Results recorded and statistically analyzed using one-way ANOVA showed the significant increase in value of (P >0.05) in growth.  The (P<0.05) which is below the significant level in survival. The reproduction showed that  (P>0.05) which is greater than significant value.