Trace element content in the host-parasite system in mouflons from Bulgaria

Wild animals are known to be sensitive bioindicators for heavy metal pollution in their habitats. The increasing interest in the relationship between parasitism and pollution, and the potential usefulness of parasites as indicators of the biological accumulation of metals has been focused mainly in aquatic ecosystems. In contrast, only a few studies have been published to date regarding terrestrial host-parasite systems. Our task was the comparative tracing of the migration of the mineral substances in sexually mature Dicrocoelium dendriticum and in liver tissue of mouflons invaded by them from two different regions of Bulgaria: the town of Kurdjali and the river Ropotamo. The content of trace elements (Zn, Fe, Cu, Co, Mo, Se, Ce, Cd and Pb) in sexually mature D. dendriticum and in mouflons invaded by them was determined using an atomic absorption spectrophotometry using a PU-900 (Pye Unicam) spectrometer. Eight trace elements - Zn, Fe, Cu, Co, Mo, Se, Cd and Pb were found in the tissues of sexually mature D. dendriticum. Nine elements were identified in the mouflons. No Ce was found in the helminthes, unlike the hosts. In D. dendriticum isolated from mouflons from the region of the Ropotamo river lower content of Cu and Mo was established, whereas that of Cd, Pb, Se and Zn was higher, compared to those in the liver. In D. dendriticum isolated from the region of the town of Kurdjali the level of Zn, Se, Pb and Cd was found to be higher and that of Cu was found to be lower in the parasites compared to the tissue of their hosts. Therefore, bioaccumulation general trends of heavy metals (Zn, Pb, Cd) were established in the both systems. The higher concentrations in the D. dendriticum - O. musimon system from the region of the town of Kurdjali reflect higher level of metals in the anthropocoenosis of the industrial town.