Tissue tropism of toxic metals in northern quolls (Dasyurus hallucatus) and northern brown bandicoots (Isoodon macrourus) on Groote Eylandt, Australia

Abstract

Mining is an essential part of the Australian economy, but can create environmental concerns due to toxic metal pollution. Surrounding active manganese (Mn) mining sites, such as those on Groote Eylandt, Australia, toxic metal exposure leads to variation in the internal distribution within animals (i.e., tissue tropism) and can exert long-term health effects on wildlife. We aimed to determine if hair of the endangered northern quoll (Dasyurus hallucatus) or of the northern brown bandicoot (Isoodon macrourus) would be sufficient to monitor internal contamination. We analyzed nine toxic metals (Al, Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn) in eight tissues/organs (cerebellum, hair, kidney, liver, lung, neocortex, olfactory bulb, testes) of quolls and bandicoots using inductively coupled plasma – optical emission spectroscopy (ICP-OES). We found six significant positive and five significant negative correlations between the concentration of metals in internal tissues and the concentration in hair in quolls, and four significant relationships in bandicoots, all negative. We also found that the concentrations of metals in quoll tissues/organs, except for hair, were significantly higher than in bandicoots. Differences in the magnitude and direction of these relationships may reflect differences in life histories or metabolic rates. The concentration of Mn in hair was significantly higher in quolls collected near the mining sites than in quolls collected at distant locations, and this also appeared to be the case for bandicoots, but we lacked a sufficient sample size to demonstrate this statistically. The concentration of Al in the hair of quolls was also significantly higher near the mining sites. The concentration of Mn in the hair of quolls reflected the concentration of Mn in the cerebellum and neocortex, while the concentration of Al in the hair of quolls reflected Al concentration in the cerebellum, neocortex, liver, and kidney. We conclude that hair analyzed with ICP-OES is an effective biomarker of local exposure to Mn and Al for quolls, and that hair Mn and Al concentration in quolls can be used as a biomarker of concentration of some tissues, such as cerebellum and neocortex. These findings point to hair as a valuable non-invasive method for assessing metal exposure in wildlife that can be useful for management and conservation efforts.