Heavy metals and helminthological status in fallow deer from Bulgaria

Wild animals are important bio-indicator organisms because they are continuously exposed to the bioaccumulation of heavy metals. Several studies have shown a relationship between heavy metal tissue concentration and parasitic infections in the animals. Because the fallow deer are frequently infected with parasites it is necessary to follow their possible influence on heavy metal levels in the host. The aim of the present study was to compare metal and helminthological status, and their interaction in fallow deer from different regions in Bulgaria. Fallow deer were shot in state game stations (SGS) Ropotamo and Zjenda during two hunting seasons. The concentration of Fe, Zn, Cu, Mn, Co, Cd and Pb were determined in liver, muscle and kidney using an atomic absorption spectroscopy. Liver, lungs and gastrointestinal tracts were examined for presence of helminthes by helminthological techniques. The helminthological studies in all animals showed common invasions with gastrointestinal and lung nematodes with different extensity. Very high extensity of invasion with Dicrocoelium dendriticum (Trematoda) was observed in the liver of fallow deer from the SGS Ropotamo. There were some differences in the concentrations of metals between the studied animals but they were within the normal range. Deviations were found in liver and kidney Cd and Pb concentration between the invaded with nematodes v/s non-invaded fallow deer. The animals with dicrocoeliosis had significantly lower liver Cu concentration in comparison with non-infected ones. It was below the normal range. The generic composition of helminthic populations in the animals from both SGS was similar but their extensity was different. The dicrocoeliosis may lead to reduced Cu liver level. No significant difference in the metal levels was observed in the target tissues as biomonitors, in connection with possible changes caused by nematodes.