Non-invasive sampling of bats reflects their potential as ecological indicators of heavy metal and trace metal contamination due to open cast diamond mining, northern Limpopo Province, South Africa

Abstract

Bats have been proposed as reliable bioindicators for monitoring bioaccumulation of elements and chemicals in natural and transformed ecosystems. Non-invasive methods are becoming more popular as research moves away from destructive methodologies. We present the first concentrations of 23 elements in Mops condylurus and Tadarida aegyptiaca (Molossidae) fur and blood from an opencast diamond mine and control site using inductively coupled plasma mass spectrometry (ICP-MS). Concentrations of boron (B), potassium (K), rubidium (Rb) and cadmium (Cd) in the fur of bats were significantly higher in bats from the opencast diamond mine compared with the control site (P = 0.004, 0.02, 0.006 and 0.03 respectively). Manganese (Mn), zinc (Zn), antimony (Sb) and mercury (Hg) were significantly higher in the blood of bats from the mining footprint than the control area. Fifteen of the 22 elements (excluding barium (Ba)) were significantly higher in the fur samples than in the blood due to elements being incorporated over time into the fur as it grows, whereas blood reveals short-term exposure to elements. Concentrations of most of the elements were reasonably low except Al, Fe and Zn. In general, the element concentrations particularly in the fur samples were comparable with other international studies reporting elemental fur concentrations from anthropogenically impacted and natural areas. Pending further research on toxic thresholds and physiological and ecological unknowns around element concentrations in bat tissues and organs, fur has the potential to be a viable indicator of toxicity.