Impact of anthropogenic activities on the concentration of trace elementsin toe bones of the common toad (Bufo bufo)

Frogs and toads are frequently used as bioindicators of inorganic pollutants. Anthropogenic stress was assessed in three lakes from Hungary (Naplas, Frog Pond and Lak-volgyi Reservoir), by studying the concentration of trace elements in the toe bones of Bufo bufo . Lake Naplas was the most affected by anthropogenic effects, but Frog Pond was also characterized by higher anthropogenic activities than the Lak- volgyi Reservoir. The following trace elements were anal ysed in toe bones, water an d soil samples: Al, Ba, Ca, Cu, Fe, Mg, Mn, P, Pb, V and Zn. In toe bones no significant differences were found in the Ca, P and Zn concentrations among the studied lakes. On the other hand, the Mg, Al, Fe, Ba, Pb and V concentrations were significantly higher in toe bones at Lake Naplas than at the two other lakes. The use of the bioaccumulation factor (BAF) showed that the potent ial of bioaccumulation from the soil was low for toads. For water, the BAFs values for Cu, Mn, V and Zn indicated that to ads may accumulate these elements from water. Our results demonstrated that the accumulation rate of me tals depends on several fact ors, including dietary and exposure time, stage of development – i.e. tadpole or adult. In summary, the analysis of toe bones demonstrated that toads may be useful indicator organisms; moreover, using modern analytical methods there was no need to kill these an imals for bioaccumulation studies.