Comparison of Heavy Metal Concentrations in Tissues of Red Foxes from Adjacent Urban, Suburban, and Rural Areas

Abstract

The red fox (Vulpes vulpes) is a representative of the canid family with wide distribution in the Northern Hemisphere and Australia. The increasing utilization of urbanized habitats by red foxes prompted us to test whether this species may be used to monitor the presence of anthropogenic pollutants in cities or suburbs. For that purpose, we compared the concentrations of heavy metals (Cd, Pb, Cu, Zn) in foxes from urban, suburban, and rural areas within the municipality of Zürich (Switzerland). The kidney and liver of suburban and rural foxes contained the highest Cd concentrations, whereas urban foxes contained the highest Pb levels. In the kidney of suburban foxes, Cd concentrations increased from a median value of 0.73 mg/kg in juvenile animals to 1.82 mg/kg in adults. Similarly, the liver of suburban foxes contained increasing Cd levels from a median of 0.21 mg/kg in juvenile animals to 0.94 mg/kg in adults. An age-dependent storage of Cd was also found in foxes from the rural surroundings, but no such accumulation occurred in urban foxes from the city center, where even adult animals contained very low Cd levels. Conversely, foxes from the urban center were characterized by elevated Pb concentrations during the first 2 years of life, but this transient Pb accumulation was absent in suburban or rural animals. The liver of juvenile foxes contained a median Pb concentration of 0.99 mg/kg in the city compared to only 0.47 and 0.37 mg/kg in the suburban and rural area, respectively. Thus, we found that animals from separate environmental compartments contain different patterns of tissue residues, implying that red foxes may serve as a bioindicator species to detect certain toxic hazards in urbanized habitats.

Red Fox Vulpes vulpes (L., 1758) as a Bioindicator of Mercury Contamination in Terrestrial Ecosystems of North-Western Poland

“…It has a high position in the trophic pyramid and accumulates various xenobiotics, including Hg. Taking into account our results and findings of other authors, it may be argued that the fox exhibits a measurable response to environmental Hg pollution and meets the requirements for bioindicators [23, 24, 42, 48, 52, 53]. Thanks to the collection of data on the mercury concentration in fox liver and kidney, it is possible to make comparisons not only between European countries but entire continents (e.g.…”

“…Among mammals, primarily herbivorous ungulates are deemed good indicators of pollution: fallow deer Dama dama (L., 1758), red deer Cervus elaphus (L., 1758), moose Alces alces (L., 1758) and the omnivorous wild boar Sus scrofa (L., 1758), but they are not represented outside their natural habitats and areas of incidence [37–41]. Furthermore, the home ranges of the individuals of those species are very large, which hinders the determination of sources of pollution [42]. In contrast to the aforementioned ungulates, the fox easily adapts to a wide range of environments, including urban areas, and occupies small territories with an average home range of 0.5 km 2 [25].…”

Teeth of the red fox Vulpes vulpes (L., 1758) as a bioindicator in studies on fluoride pollution

“…It has a large geographical range, but not too large home range; its local populations are stable; it has a permanent position in the food chain; it is relatively easy to determine its age and it is also game, so it is not difficult to obtain. For these reasons, it is sometimes used in studies on different types of environmental pollution (Corsolini et al 1999; Dip et al 2001; Kalisińska et al 2009). Currently, pollution with anthropogenic substances, including F − , is so widespread that there is a reasonable need to determine concentrations in common mammals living in the vicinity of man, including the red fox.…”

Hair and bone as predictors of tissular mercury concentration in the Western Alaska Red Fox, Vulpes vulpes

“…On the other hand, relatively little is understood about these processes in wild terrestrial mammals of the Arctic (Dehn et al 2006; Gamberg et al 2005). Studies have shown a correlation of THg concentrations among various tissues (Cumbie 1975; Dip et al 2001; Kalisinska et al 2009; Piskorova et al 2003; Wren 1986). Muscle, liver and kidney are often used as bioindicators to assess biological variation among cohorts, individuals, and populations (Alonso et al 2004; Becker and Wise 2006; Brookens et al 2008; Gutleb et al 1998; McGrew et al 2013; Yamamoto et al 1987).…”