Alteration of above and below-Water Soundscapes by Roads

Abstract

Soundscapes are the array of natural and anthropogenic sounds occurring in an area, and can consist of both natural and human derived components. In this study, we compared soundscapes in wetlands disturbed by road-traffic noise to wetlands distant from major roads. In each wetland, above-water and below-water soundscapes were recorded in Spring, Summer, and Fall. Wetlands near roads had higher sound intensity, more anthropogenic noise occurrences, and lower acoustic diversity above and below the water. In contrast, wetlands distant from roads had more natural sounds above and below the water, including a higher number of birdcalls. When soundscapes were subdivided by frequency, most anthropogenic sounds occurred in low frequencies (0–5 kHz), but natural sounds were found in all frequencies. Soundscapes changed during the year, with more natural sounds occurring in Spring and the highest acoustic diversity recorded in Spring and Fall. These findings indicate that nearby roads change wetland soundscapes by increasing noise pollution, which masks natural sounds such as bird calls and reduces biodiversity. The altered soundscapes of freshwater wetlands, near roads potentially could alter biotic communities by affecting animal behavior such as intraspecies communication, interaction of predator and their prey, and resource acquisition.