US EPA

4961560 

Journal Article 

Impacts of mine-related contaminants on bats 

O'Shea, TJ; Clark, DR; Boyle, TP 

2001 

205-215 

WOS:000178264200028 

Although the impact of mining-related toxic substances on bat populations is an important conservation concern, it has not been studied intensively. We will review a few case studies in this paper and point out the potential for negative impacts of metal contamination on bat foraging habitat and insect prey. Modem gold mining operations that use cyanide extraction methods usually result in cyanide solutions stored in ponds. Small pools also are formed on heap piles. Large numbers of such mining operations have developed in the United States and abroad, and cyanide pools can be attractive to wildlife as sources of drinking water, particularly in and locations. Surveys have shown that bats are among the most numerous of mammals found dead of cyanide poisoning at these pools. This method of mining also occurs in Alaska, the Great Plains, and the southeastern United States, with mortality of bats reported in ponds in South Carolina with cyanide concentrations that were surprisingly low. Straightforward management measures are available to reduce or eliminate some of these problems. There are no direct studies of the degree to which bats are exposed to or impacted by elevated concentrations of potentially toxic elements stemming from mining activities; however, we suggest this potential is strong. One study has shown a correlation of mercury in guano deposits with regional mine production of copper. It has been demonstrated that bats accumulate metals from the food chain in areas of pollution from other industrial sources. Emergent aquatic insects can have elevated metals in areas downstream from mining sites. More than half of the species of bats in the continental United States can be characterized as at least occasionally foraging over water and on emergent aquatic insects. Documentation on mortality of bats in sludge pits associated with western oil exploration is reviewed. Exposure to harmful levels of radiation is a potential issue to bats that roost in abandoned mines. Indirect impacts of toxic substances from mining can come from spills, alkaline or acidic discharges altering emergent insect or riparian-based food supplies, lowered water tables, and other sources of contamination and pollution. Further research is needed on impacts of mine-related toxic substances on bats, including determination of exposure levels, health effects, and possible population impacts.