PASSIVE ACOUSTIC MONITORING OF BIOLOGICAL AND ANTHROPOGENIC SOUNDSCAPES IN THE RIDEAU RIVER SYSTEM.

Passive acoustic monitoring, well established in marine and terrestrial research, remains underused in freshwater ecosystem assessment. To demonstrate its potential, we conducted soundscape surveys in the Rideau River (Ottawa, Ontario) using low-cost, open-source HydroMoth hydrophones. Recorders were deployed for 8 days (06–13 August 2025) at two contrasting sites: a lower-disturbance no-wake zone adjacent to James Island and a higher-disturbance reach near W.A. Taylor Conservation Area, characterized by frequent boat traffic. Each unit recorded 20 minutes of 32-kHz audio every hour, producing 6,760 minutes of data. Machine-learning models were used to autonomously detect and classify acoustic events from biological and anthropogenic sources. Across sites, we compared diel patterns of biophony and anthropophony, quantified the contribution of boat noise to the overall soundscape, and examined how elevated noise conditions influence the occurrence of biological activity based on frequency and duration of detected events. Biological detections were greater at the lower-disturbance site, while boat noise contributed more strongly to the soundscape at the higher-disturbance site, revealing clear spatial and temporal differences in freshwater acoustic activity. The results illustrate how Passive Acoustic Monitoring, paired with machine-learning detection, captures meaningful differences in freshwater soundscapes and supports emerging applications of acoustic monitoring in freshwater environments.  

Presentation Preference: Poster

Primary Presenter: Curtis Hunter, Carleton University (curtishunter@cmail.carleton.ca)

Authors:

Curtis Hunter, Carleton University  (curtishunter@cmail.carleton.ca)

Steven Robinson, Carleton University  (steverobinson@cmail.carleton.ca)

Steven Cooke, Carleton University  (steven.cooke@carleton.ca)

Jesse Vermaire, Carleton University  (jesse.vermaire@carleton.ca)