Effects of cadmium upon longevity of Diplostomum sp. (Trematoda: Diplostomidae) cercariae

Laboratory experiments were conducted to examine the impact of cadmium (Cd) on survival of Diplostomum sp. cercariae. Freshly emerged cercariae were exposed to Cd solutions at concentrations ranging between 0.2 and 200 μg/l. The mortality patterns and mean survival times (MSTs) of the exposed parasites were determined by the Kaplan–Meier estimator and were compared (Log–Rank test) to corresponding patterns and estimators of the unexposed controls. Cd concentrations >20 μg/l caused statistically significant changes in the mortality pattern of Diplostomum sp. cercariae and reduced MST by at least five hours compared to the control group, where MST was 52 h. The results show that longevity of the free-living Diplostomum sp. cercariae can be reduced by direct exposure to heavy metals. Cd contamination of aquatic habitats thus potentially can have an impact on parasite populations and communities.