HOW VEGETATION REMOVAL IMPACTS FRESHWATER SOUNDSCAPES: INSIGHTS FROM TWO ONTARIO LAKES USING SOUNDSCAPE ANALYSIS

Freshwater lakes are vital for ecological balance and provide essential services, supporting diverse communities of sound-producing organisms and geophysical processes. Passive acoustic monitoring (PAM) offers a non-invasive way to study these soundscapes, yet many aspects of aquatic bioacoustics, especially in infra- and ultra-sonic ranges, remain understudied. This study analyzes broadband acoustic data (2 Hz–250 kHz) collected from Lake Scugog and Canal Lake, two Ontario lakes with excessive aquatic vegetation growth, to examine how vegetation removal influences soundscapes. Three methods of removal were used: aquatic thruster, weed sickle, and lake rake. Biweekly acoustic and water quality recordings were collected three times before and after removal using a Song Meter SM4 hydrophone and an EXO2 sonde. Vegetation removal was expected to reduce acoustic complexity by eliminating habitat and plant sound production, while potentially increasing detectability of remaining organisms. Preliminary analyses show a slight increase in detected sounds after removal in both lakes. Control sites remained acoustically stable, while treatment sites showed method-specific responses: in Lake Scugog, thruster and weed sickle sites showed post-removal declines, and in Canal Lake all methods showed a brief decline followed by recovery, with thruster sites exhibiting the strongest decrease. These results suggest that vegetation removal effects are subtle, variable across methods, and that temporal variation remains an important factor when interpreting freshwater soundscape patterns.

Presentation Preference: Standard Oral (12 Minutes)

Primary Presenter: Husnah Azmi, Toronto Metropolitan University (stephajm@gmail.com)

Authors:

Husnah Azmi, Toronto Metropolitan University  (hazmi@torontomu.ca)

Stephanie Melles, Toronto Metropolitan University  (stephanie.melles@torontomu.ca)