Trace metal accumulation with age in bats: a case study on Pipistrellus kuhlii lepidus from a relatively unpolluted area.

Bats, as exceptionally long-lived small mammals, are at particular risk of metal poisoning due to the tendency of metals to bioaccumulate throughout their lives. In our study, we investigated the general question of how trace metal concentrations change with age in different bat tissues on the example of Pipistrellus kuhlii lepidus, which lives for years in one area and is strongly associated with urban environments. To determine the exact age of the individuals, osteochronology was applied, counting the number of dentine rings in cross-sections of the upper canine tooth of each individual. The age of 57 individuals of P. kuhlii lepidus, representing ca. 10% of the colony, was identified. Whole internal organs (liver, kidneys, lungs, and forearm bones) and samples of external tissues (fur and wing membrane) were analyzed for concentrations of Cd, Cu, Pb, and Zn using atomic absorption spectrometry. We found that concentrations of Cd, Pb, and Zn, but not Cu, increase with the age of the bats, but in relatively unpolluted areas, metal concentrations do not reach the level which can cause chronic adverse effects. Nevertheless, due to the confirmed accumulation of metals in bat tissues with age, toxic effects can be expected in older individuals in areas where trace metal concentrations are elevated.