Seasonal testicular morphometry of European brown bears in relation to pollutants

Inorganic and organic pollutants are capable of affecting the reproductive health of both animals and humans. The resulting pollutant-induced phenotype disorders have been rarely studied in wildlife males that commonly associate with diminished sperm quality leading to subfertility. We investigated testicular morphometry in Dinara-Pindos population of protected European brown bears (Ursus arctos) in relation to metal(loid)s (N = 44), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) (N = 27), while controlling for age, body condition, and season. The principal approximating generalized linear models included following predictors of testicular mass and size: age (greater mass and larger size in adults than in subadults), toxic As (↓), Pb (↑), and Hg (↓), and essential Mn (↓), Se (↑), and Cu (↓) levels in the testes and/or epididymides. When organic pollutants were included in models explaining testicular mass and size variation instead of metal(loid)s, subcutaneous fat levels of PCB-118 (↑) and PCB-180 (↓), age (greater mass and larger size in adults) and season (higher in breeding than in non-breeding season) showed significant contribution. Higher mass and size of testes were found in breeding season (Mar-Apr) compared to non-breeding season (Oct). Metal(loid) concentrations, reported for the first time in ursid testicular and epididymal tissue, add to very scarce body of data from other wild terrestrial mammals. Associations between morphometric indices of male reproductive organs and certain endocrine-disrupting pollutants highlight potential toxicological relevance for wildlife chronically exposed to diffuse, global pollution sources.