EFFECT OF CADMIUM ON LIPID PEROXIDATION AND CATALASE ACTIVITY IN THE TAIL REGION OF EARTHWORM (APPORECTODEA LONGA).

This research studied the biochemical changes measured as the degree of lipid peroxidation andthe activity of catalase in the tail region of earthworms (Apporectodea longa) maintained incadmium(Cd) contaminated soils for 7,14 and 21 days. The various concentrations of Cd in theexperimentally contaminated sample expressed in mg/kg of soil were 10, 30, 50, 70, 90, 120,150, 180 and 210 respectively. The effect Cd concentrations on the tail regions of earthwormswere measured against control group that was not exposed to Cd. The malodialdehyde (MDA)levels in the control group and the low Cd concentration groups (10-30mg/kg) decreasedthroughout the study. The mid-level Cd concentration groups (50-120mg/kgCd) had lower MDAlevels on day 14 compared to day 7, with observed increase on day 21. The high Cdconcentration groups (˃120mg/kg) had the lowest MDA concentrations but the highest mortalityrates. The catalase activity on day 7 was highest in the concentration 90mgCd/kg soil at11.77±0.034 nKat/mg protein compared to the corresponding control group (1.77±0.48 nKat/mgprotein). The catalase activity on day 14 in the same group was significantly low with a value0.55±0.04 nKat/mg protein compared to control group. After 21 days, catalase activity washigher in control group compared to other groups exposed to the various concentrations ofcadmium. The results indicate that Cd contamination affects biomarkers of oxidative stress in thetail region of earthworms, a reflection of the ecotoxicological effects of Cd to the environmentand suggests inhibition of enzyme systems in free radical metabolism.