Mercury concentrations decline with age in the fur of females of an insectivorous terrestrial mammal (Myotis lucifugus)

Methylmercury (MeHg) is a toxic form of mercury that bioaccumulates in organisms and biomagnifies through food webs. MeHg concentrations can be high in aquatic environments, and this puts high trophic-level predators who derive energy originating from aquatic environments at risk of toxic effects. Due to the potential for bioaccumulation of MeHg over an individual’s life, the risk of MeHg toxicity may increase as animals age, and this risk may be especially high in species with relatively high metabolic rates. Total mercury (THg) concentrations were measured from the fur of adult female little brown bats (Myotis lucifugus) collected between 2012–2017 in Salmonier Nature Park, Newfoundland and Labrador. Using linear mixed-effects models, the effects of age, year, and day of capture on THg concentrations were evaluated and interpreted with AICc and multi-model inference. We expected that THg concentrations would increase with age, and that due to annual summer moulting, individuals captur..., Study area
The fur specimens used in this study were collected between 2012 and 2017 in and adjacent to SNP, NL, Canada (Lat: 47.3º, Long: -53.3º). Salmonier Nature Park is a 1455-ha nature reserve that is part of the Avalon Forest Ecoregion which is characterized by its ribbed moraines covered in forests that are interspersed with lakes and bogs. The atmospheric deposition rate of Hg in Newfoundland is among the highest in Canada (Chételat et al. 2020) and surface waters in SNP exhibit low pH due to the low acid neutralization ability of the soil and rock (Clair et al. 2007). Since low pH is correlated with increased methylation of Hg (Zhu et al. 2018), high mercury deposition and low surface water pH make wildlife in SNP susceptible to accumulating harmful concentrations of MeHg (Little et al. 2015a).
Sample collection
Myotis lucifugus were captured in SNP using mist nets (Avinet, Dryden, New York, USA) and harp traps (Austbat Research Equipment, Lower Plenty, Victoria, Australia) set...,