Hair samples as monitoring units for assessing metal exposure of bats: a new tool for risk assessment

Metals occur naturally and are ubiquitous in the Earth's crust. In addition to their release from natural sources, larger amounts of metals enter the environment through use in diverse industries, and accumulate mostly in the pedosphere close to emission sources. Bat species foraging for prey insects in different cultural landscape types (urbanized areas, forests, agricultural areas, water bodies) may show site-specific trace metal concentrations, partly due to variations in exposure among habitats. As all European bat species are protected, a non-invasive method is required to monitor their exposure to potentially toxic metals in their foraging habitats. The analysis of hair samples offers such a possibility. In the present study, hair samples of Myotis bechsteinii, Myotis daubentonii, Myotis myotis and Pipistrellus pipistrellus were analyzed for cadmium (Cd), copper (Cu), manganese (Mn), lead (Pb) and zinc (Zn) using ICP-OES. We found the same order of trace metals concentrations (Zn > Mn > Cu > Pb > Cd) in M. bechsteinii and M. myotis, while M. daubentonii (Zn > Cu > Mn > Pb > Cd) and P. pipistrellus (Zn > Cu > Pb > Mn > Cd) differed from the above species and from each other. The observed differences between the bat species may reflect varying metal levels in their foraging areas as well as differences in preferred prey species and metal kinetics. Analysis of trace metal concentrations in hairs as a non-invasive and cost-effective method should be included in risk assessments regarding metal toxicity in bats.