Apex predatory mammals as bioindicator species in environmental monitoring of elements in Dinaric Alps (Croatia).

Tissue element investigations of apex terrestrial mammals are very scarce in Europe. We quantified 16 essential and nonessential elements in the kidney cortex, liver, and muscle tissue of 467 brown bears (Ursus arctos), 125 gray wolves (Canis lupus), one Eurasian lynx (Lynx lynx), and three golden jackals (Canis aureus) from Croatia by inductively coupled plasma mass spectrometry (ICP-MS). Renal cadmium (0.6% of animals) and lead (1%) and hepatic lead (5%) were found in toxicologically relevant levels for mammals only in bears, while the other elements were within normal range. The association of age, sex, season, and region with measured tissue elements in bear and wolf was estimated by multiple regression analyses. Age-related accumulation of cadmium was observed in bears and wolves. Lead tissue content increased with the age of bears but declined in wolves. Female bears and wolves had higher arsenic, iron, and thallium than males in some tissues. Also, cadmium, mercury, copper, zinc, selenium, molybdenum, and uranium were more abundant only in female bears. Male bears had higher potassium, zinc, and magnesium, while male wolves had higher calcium in some tissues compared to female wolves. Seasonal differences were mainly observed for bears' tissues and region-specific differences only in wolves. The bear kidneys had the highest levels of cobalt, copper, molybdenum, cadmium, and lead among the four studied species. The element levels reported for bears and wolves represent baseline values for the Dinaric population.