Could a city-dwelling bat (Pipistrellus kuhlii) serve as a bioindicator species for trace metals pollution?

Bats are an endangered group of mammals that are very sensitive to environmental stresses. One of such stress factor is trace metals pollution which threatens populations of insectivorous bats due to their top position in the food webs and exceptionally long life span. In our research Pipistrellus kuhlii was tested as a promising indicator species (urban-dwelling, sedentary, with limited daily home-range) for trace metal exposure of bats. We measured concentrations of Pb, Cu, Zn and Cd in internal and external tissues of bats from the industrial city Mariupol and the village Karlovka, Ukraine, to answer the following questions: (1) Do metal concentrations in soil samples differ between urban and rural areas, and between populations of P. kuhlii from those areas? (2) Does metal contamination differ between individuals of different sexes and ages? (3) Whether fur and/or wing membrane, the two tissues that can be collected from live bats, can be used as proxies of metal contamination in internal tissues (liver, kidney, lung, forearm bones) of P. kuhlii? Metal concentrations in soil samples were significantly higher in the city. Bats from the city accumulated significantly more Cd, Pb and Zn in external tissues than those from the rural area. Females accumulated more Cd than males, and this-year-born did not differ significantly from adult individuals. We did not find, however, significant positive correlations between metal concentrations in external and internal tissues, indicating that external tissues cannot serve as an indicator of the metal contamination of internal tissues in P. kuhlii.