engleski

Brown bear hair as indicator of exposure to environmental toxic metals

Cadmium, lead and mercury are inorganic, persistent environmental pollutants confirmed as toxic for wildlife. Because of their long life and apex trophic position, bear species have been proven to reflect the toxic metal levels from the environment well. In the European brown bear, toxic metals were thus far monitored in soft tissues, bone and blood, samples necessitating death of an animal or invasive sampling. Non-invasive samples, like hair, have not been explored as indicators of metals in brown bears, although it was successfully used to study changes in metal accumulation in Canadian brown bears feeding on salmon and assess exposure to mercury in polar bears. Keratin, the key structural protein of hair is abundant with thiol groups (-SH) that have high affinity for binding metals. Deposition of metals in hair from endogenous sources (blood) is carried out in periods of hair growth, so hair metal levels represent a medium-term exposure indicator, in contrast to blood (recent exposure) or soft tissues and bone (long-term exposure indicators). The aim of this study was to explore hair as a bioindicator for prominent inorganic pollutants in two European brown bear populations, Dinara- Pindos and Carpathian. Hair was sampled between 2009 and 2017 from free-living bears in Croatia (N=88) and Poland (N=21). Cadmium (mean±SD, median ; 0.027±0.024, 0.018 mg/kg dry mass) and lead level (0.635±0.753, 0.367 mg/kg) did not differ in the hair of the two populations. Mercury in hair of bears in Croatia (0.291±0.2012, 0.277 mg/kg) was higher (t=4.65, p<0.001) than in Poland (0.141±0.117, 0.104 mg/kg). Measured mercury in European brown bear hair was somewhat lower than in Canadian bears and much below the threshold for subclinical alterations observed in polar bears (5.4 mg/kg). Cadmium and lead levels were similar to those found in Canadian brown bears.

cadmium ; lead ; mercury ; pollutant ; wildlife

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