An investigation of inland water soundscapes: Which sonic sources influence acoustic levels?

Abstract

Acoustic recordings were carried out in two different glacial lakes (i.e. Lough Na Fooey, Ireland and Windermere, U.K) using different Passive Acoustic Monitoring approaches. At Lough Na Fooey, a vessel-based survey over pre-established sampling stations covering the entire lake surface (together with a bottom survey) was carried out, while a moored sampling was carried out around the clock at selected sites in the shallow, gravel littoral shores of Windermere. Lough Na Fooey soundscape lacked both the biophony and anthrophony component. Night-time recordings from Windermere were characterized by biophony sources, such as invertebrate (family Corixidae) and fish air passage sounds. Day-time acoustic recordings from Windermere were characterized by consistent boat traffic noise. Classification models were used to investigate which sonic sources contributed to the detected noise levels. The results indicate anthropogenic noise as an important factor ruling freshwater soundscapes. Based on the results obtained, it is recommended that further studies focus on a wider geographical and temporal range in order to start filling the knowledge and legislative gaps regarding anthropogenic noise monitoring in inland waters.