Mercury Bioaccumulation in Two Species of Insectivorous Bats from Urban China: Influence of Species, Age, and Land Use Type

Mercury (Hg) is a widespread, toxic pollutant, and China is the world’s largest emitter. We investigated Hg concentrations of fur in Japanese pipistrelles ( Pipistrellus abramus ) and Chinese noctules ( Nyctalus plancyi ) from Chengdu, Sichuan Province, in relation to degree of urbanization. Bats were mist-netted in June and July 2013, and the fur was analyzed via atomic absorption. Statistical comparisons were made between ages, species, and site types with unpaired t tests and between Hg concentration and body condition with Spearman’s rank correlations. Across sites, adult pipistrelles ( n = 10) had significantly greater concentrations than adult noctules ( n = 16). Adult N. plancyi ( n = 16) had significantly greater concentrations than juvenile N. plancyi ( n = 14). Contrary to our predictions, there was no significant difference in Hg values between urban ( n = 3) and peri-urban ( n = 6) locations for P. abramus . While small sample sizes precluded additional comparisons, the highest value (33 mg/kg) came from an adult female P. abramus in the agricultural area. The relationship between body condition and Hg concentration was insignificant. However, most pipistrelles (7/13) and no noctules (0/31) had concentrations > 10 mg/kg, a threshold associated with disruption of homeostatic control and mobility. All bats had concentrations > 0.2 mg/kg, which is associated with compromised immunity. These are the first published records of contaminant concentrations from bats in China. For future studies, we recommend P. abramus as a regional bioindicator, longer term assessments of pre- and post-exposure effects, and simultaneous assessment of blood and fur Hg concentrations.