Manganese exposure and histology of northern quolls ( Dasyurus hallucatus ) and northern brown bandicoots ( Isoodon macrourus ) on Groote Eylandt, Australia

Abstract

Groote Eylandt, Australia, is an island of international conservation significance as well as the site of one of the world's largest manganese (Mn) mines. Endangered northern quolls (Dasyurus hallucatus) living near active Mn mining sites on Groote Eylandt accumulate Mn at higher concentrations in the hair, testes, and brain than do animals living far from the mine. However, little is known about the potential developmental effects of Mn exposure on the tissues of quolls or other marsupials, and marsupial histology and ecotoxicology are relatively under-studied. We examined relationships between exposure to Mn and other toxic metals with histological endpoints of quolls and northern brown bandicoots (Isoodon macrourus). Male quolls (n =  18) and bandicoots (n = 9) were live trapped both near and far from mining activities, euthanized, and then dissected for target tissues (liver, lung, muscles [bicep, quadricep, skull], olfactory bulb), which were preserved in formalin for histology. Tissues were prepared using H&E staining and analyzed with Leica imaging software. Although we did not find differences in most tissues between animals collected near vs. far from the mine, we found that Mn exposure was associated with altered muscle histomorphology of quolls, potentially affecting their ability to find food and avoid predators. Our results showed clear differences between the muscle histology of quolls and bandicoots. Given the ecological importance of Groote Eylandt and the conservation needs of species such as quolls and bandicoots, information on exposure to contaminants and effects on health and development is critical to successful management, including environmental remediation.