Effects of cadmium and lead on the life-cycle parameters of juvenile earthworm Eisenia fetida

Abstract

Juveniles Eisenia fetida were exposed to cadmium (1-500µgCdg(-1)) and lead (20-2500µgPbg(-1)) for fourteen weeks in order to evaluate the impact on life-cycle parameters (survival, growth, sexual maturation, and cocoon production) and lipid peroxidation (expressed as concentration of malondialdehyde (MDA)). Both metals were found to significantly affect survival of the juveniles (fourteen-week LC50 296±125µgCdg(-1) and 911±164µgPbg(-1)) and alter their development. Cd and Pb severely affected the weight of the juveniles, prolonged the time to sexual maturation (at the highest concentrations, earthworms did not reach sexual maturity at all), and reduced cocoon production. LC50 significantly decreased with the time of earthworm exposure, indicating that chronic exposure to the same levels of contaminants in the soil may have more detrimental consequences than short-term exposure. A survival model showed that the survival probability for the juveniles decreased significantly with time and the concentration of metals in the soil. The metals induced a significant increase in MDA concentration (2.98-fold and 1.54-fold at 250µgCdg(-1) and 2500µgPbg(-1), respectively), and the content of MDA was negatively related to the weight of the juveniles and the percentage of mature individuals (p<0.05).

Keywords: Growth; Juvenile earthworms; Malondialdehyde; Maturity; Mortality; Reproduction.