High levels of activity of bats at gold mining water bodies: implications for compliance with the International Cyanide Management Code

Abstract

Wildlife and livestock are known to visit and interact with tailings dam and other wastewater impoundments at gold mines. When cyanide concentrations within these water bodies exceed a critical toxicity threshold, significant cyanide-related mortality events can occur in wildlife. Highly mobile taxa such as birds are particularly susceptible to cyanide toxicosis. Nocturnally active bats have similar access to uncovered wastewater impoundments as birds; however, cyanide toxicosis risks to bats remain ambiguous. This study investigated activity of bats in the airspace above two water bodies at an Australian gold mine, to assess the extent to which bats use these water bodies and hence are at potential risk of exposure to cyanide. Bat activity was present on most nights sampled during the 16-month survey period, although it was highly variable across nights and months. Therefore, despite the artificial nature of wastewater impoundments at gold mines, these structures present attractive habitats to bats. As tailings slurry and supernatant pooling within the tailings dam were consistently well below the industry protective concentration limit of 50 mg/L weak acid dissociable (WAD) cyanide, wastewater solutions stored within the tailings dam posed a minimal risk of cyanide toxicosis for wildlife, including bats. This study showed that passively recorded bat echolocation call data provides evidence of the presence and relative activity of bats above water bodies at mine sites. Furthermore, echolocation buzz calls recorded in the airspace directly above water provide indirect evidence of foraging and/or drinking. Both echolocation monitoring and systematic sampling of cyanide concentration in open wastewater impoundments can be incorporated into a gold mine risk-assessment model in order to evaluate the risk of bat exposure to cyanide. In relation to risk minimisation management practices, the most effective mechanism for preventing cyanide toxicosis to wildlife, including bats, is capping the concentration of cyanide in tailings discharged to open impoundments at 50 mg/L WAD.

Bats and Water: Anthropogenic Alterations Threaten Global Bat Populations

“…Australian studies also indicate high levels of bat activity around bodies of water (Lumsden and Bennett 1995;Williams and Dickman 2004;Griffiths et al 2014a). Young and Ford (2000) found that species richness of bats, abundance, and capture success in the semi-arid Idalia National Park was greatest in areas adjacent to water, with 97 % of captures occurring at sites with water.…”

“…Lisón and Calvo 2011), cattle troughs, swimming pools and settling ponds at waste water treatment facilities (Vaughan et al 1996;Abbott et al 2009;Naidoo et al 2013Naidoo et al , 2014 and mines having natural seepage Griffiths et al 2014a).…”

“…High bat activity was recorded over gold mine water bodies containing cyanide (Griffiths et al 2014a). Griffiths et al (2014b) suggested that elevated salt levels in water bodies at gold mines may decrease bat activity, foraging, and drinking.…”

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

“…The effects and impacts of heavy metal, chemical pollutants and other elements that bats have been and are currently exposed to is gaining increased attention (Zocche et al 2010, Gri ths et al 2014, Lovett and McBee 2015, Carrasco-Rueda et al 2020). Heavy metal pollution has been shown to affect bat ecology, genetics, physiology and behaviour.…”

Aislamiento y capacidad degradadora de cianuro de Klebsiella sp. de la Planta de Tratamiento de Aguas Residuales de Magollo, Tacna – Perú

“…Actualmente, las plantas de tratamiento de aguas residuales que contienen cianuro emplean métodos físicos, químicos y biológicos para la descontaminación (Griffiths et al, 2014;Kaita et al, 2018;Copari, 2019). En los métodos químicos principalmente se emplea la oxidación química utilizando cloruros e hipoclorito de sodio (Watanabe et al, 1998); sin embargo, estas técnicas no degradan completamente todo el cianuro (Figueria et al, 1996).…”