Metal Bioaccumulation and Oxidative Stress in Millipedes Experimentally Exposed to a Cocktail of Aluminium, Iron and Manganese

Forest pockets adjacent to cities are impacted by atmospheric pollution containing metals arising from urban activities. Elevated concentrations of metals have been found in forest soils and contamination thereof threatens soil biodiversity. Metals are known to induce oxidative stress and metal cytotoxicity in organisms has been linked to oxidative damage, which may threaten the health of forest soil and its biodiversity. Pill millipedes in the Afromontane forest pockets in Cape Town, South Africa are exposed to a combination of metals, arising from various sources of pollution. The objectives of this investigation were to determine the level of metal bioaccumulation and oxidative stress in millipedes experimentally exposed to a cocktail of metals. The millipedes were exposed to a high and low concentration aluminium, iron and manganese cocktail for 6 weeks. The experimental exposure resulted in bioaccumulation of these metals in millipedes in their different exposure groups. The higher tGSH concentrations, indicated activation of the endogenous antioxidant system, and the higher MDA levels, suggests lipid peroxidation by means of the increased generation of free radicals, which suggests that the pill millipedes have experienced induced oxidative stress.