Mercury accumulation, distribution, and isotopic composition in tissues of the Collared Scops Owl (Otus lettia).

Mercury is a ubiquitous contaminant known to accumulate in wildlife, particularly bird species at higher trophic levels. Knowledge of tissue-specific Hg distributions aids our understanding of Hg bioaccumulation in organisms. In this study, one adult and three juvenile Collared Scops Owls (Otus lettia) were studied to elucidate the bioaccumulation of Hg in body tissues. Six tissues and organs (feathers, nails, heart, liver, gizzard, and muscle), as well as gastric contents, were examined for total Hg (THg) and methylmercury (MeHg) contents, Hg isotopic compositions including mass-dependent fractionation (MDF; δ202Hg) and mass-independent fractionation (MIF; Δ199Hg and Δ201Hg), and C (δ13C) and N (δ15N) isotopic compositions. Tissue-specific THg and MeHg concentrations in the adult were in the ranges of 150–1360 ng/g and 17–1060 ng/g, and lower in the juveniles at 91–419 ng/g and 67–350 ng/g, respectively. The δ202Hg values in the adult were strongly negative at −1.75‰ ± 0.17‰ compared with the juveniles at −0.99‰ ± 0.25‰. The adult exhibited lower MIF values than the juveniles, at 0.23‰ ± 0.07‰ for Δ199Hg and 0.2‰ ± 0.11‰ for Δ201Hg, compared with 0.81‰ ± 0.09‰ and 0.66‰ ± 0.07‰, respectively. The lower adult MDF and MIF values suggest that the adult tended to accumulate negative Hg isotopes but the juvenile's positive Hg isotopes. Differences between adult and juvenile tissue Hg concentrations indicate that metabolic processes play an important role in Hg accumulation. [ABSTRACT FROM AUTHOR]