Northern pocket gophers (Thomomys talpoides) as biomonitors of environmental metal contamination

Abstract

We live-trapped 40 northern pocket gophers across two years from the Anaconda Smelter Superfund Site, Anaconda, Montana, USA, to determine their exposure to five metal contaminants and effects of exposure on selected measurements. Soil, gopher blood, liver, kidney, and carcass samples were analyzed for arsenic, cadmium, lead, copper, and zinc. Hematological parameters, kidney and liver porphyrins, and red blood cell delta-aminolevulinic acid dehydratase (ALAD) activity were also measured. Micronutrients Cu and Zn were detected in all tissues analyzed, and Cd, Pb, and As were detected less frequently. We report differences in metal distribution among different tissues and differences in bioaccumulation for different metals within the same tissue. No significant differences were observed in concentrations of Zn or Cu in any tissue across the study site, but relationships between lead in soil and lead in carcass proved especially strong (r2 = 0.80; p < 0.001; n = 18). Among biomarker data, we observed a negative relationship between concentration of lead in the soil and ALAD activity in gophers with detectable concentrations of lead in their blood (r2 = 0.45; p = 0.006; n = 15). Results of this study suggest that northern pocket gophers are useful biomonitors of environmental Pb, Cd, and As contamination, and their broad geographic range across North America could allow them to be an important component of site-specific metals assessments.