The impact of noise from open-cast mining on Atlantic forest biophony

- We compared soundscapes in sites close and far from an open-cast mining.
- We compared species richness and spectral characteristics of calls in the two sites.
- The mining noise sources were identified and described.
- Species richness was higher at the site far from the mine.
- We suggest that mining noise can affect animal acoustic dynamics in a tropical forest.

The sound produced by human-made machinery (technophony) is known to exert negative effects on animal communication and well-being. Mining is an important economic activity in Brazil, which is often conducted close to forested areas and produces a diffuse noise. In this study, the impact of such noise on biophony (biological sounds) was investigated by characterizing and comparing the soundscapes of two different sites (close versus distant from an open-cast mine) in the same Atlantic forest fragment, matched for habitat type, in Southeast Brazil. Six automated recorders were installed at each site and were programmed to record continuously during seven consecutive days every two months between October 2012 and August 2013. Technophony and biophony values were derived from power spectra and the Acoustic Complexity Index (ACI). Mann-Whitney U tests demonstrated that the biophony exhibited a switch in daily dynamics, resulting in a statistically higher biophony during the day at the site close to the mine and a higher biophony during the night at the site far from the mine. Potential species richness was found to be higher at the site that was distant from the mine. The species composition and spectral characteristics of the calls were also found to differ between the two sites. These results provide the first investigation of potential disturbances caused by mining noise on biophony, demonstrating that it can cause alterations in the temporal dynamics and daily patterns of animal sounds, which are symptoms of altered behaviors or variations in community-species composition. These findings suggest remarkable insights that should be taken into consideration in the regulating of the use of natural areas for mining.