Photosynthetic oxygen bubble stream sounds from aquatic macrophytes, and their consequences for acoustic biodiversity inventories and acoustic communication in shallow freshwater settings

PLOS ONE | https://doi.org/10.1371/journal.pone.0317424 April 23, 2025 1 / 13 OPEN ACCESS Citation: Campbell K, Cerezke-Riemer Y, Acorn JH (2025) Photosynthetic oxygen bubble stream sounds from aquatic macrophytes, and their consequences for acoustic biodiversity inventories and acoustic communication in shallow freshwater settings. PLoS ONE 20(4): e0317424. https://doi.org/10.1371/journal. pone.0317424 Editor: Charles William Martin, University of South Alabama, UNITED STATES OF AMERICA Received: August 7, 2024 Accepted: December 27, 2024 Published: April 23, 2025 Peer Review History: PLOS recognizes the benefits of transparency in the peer review process; therefore, we enable the publication of all of the content of peer review and author responses alongside final, published articles. The editorial history of this article is available here: https://doi.org/10.1371/journal. pone.0317424 Copyright: © 2025 Campbell et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. RESEARCH ARTICLE Photosynthetic oxygen bubble stream sounds from aquatic macrophytes, and their consequences for acoustic biodiversity inventories and acoustic communication in shallow freshwater settings Katie Campbell *, Yelena Cerezke-Riemer, John H. Acorn Department of Renewable Resources, University of Alberta, Alberta, Canada * kgc2@ualberta.ca Abstract

The emerging field of soundscape ecology focuses on biological, geophysical, and anthro- pogenic sounds, and provides a non-invasive method to inventory ecosystems. Most of the work on freshwater soundscapes focuses on larger fishes in deeper water, or on insects. We suggest the possibility that such studies have either missed or misidentified photosyn- thetic oxygen bubble sounds (POBS) produced by bubble streams from damaged mac- rophytes in sunny shallow water. These contribute significantly to local soundscapes. We recorded such sounds in the shallows of Gull Lake, Alberta, Canada, where POBS from sago pondweed (Stuckenia pectinata), along with water boatman stridulations (Hemiptera: Corixidae), comprised almost all of the sounds we encountered. These sounds attenuate rapidly with distance, and the POBS constitute a remarkable acoustic diversity, resulting in a patchwork of very different soundscapes in these shallows. Recognition of POBS has important consequences for acoustic bioinventories in shallow water, rapid ecosystem assessments involving indices of primary production, and bioacoustics studies of such organisms as corixid bugs, communicating against a cacophonous background of POBS. Introduction Soundscape ecology, an emerging field, concerns itself with biological, geophysical, and anthropogenic sounds in nature [1,2], often with a focus on the impacts of anthropogenic sounds on vertebrate life [3,4]. Soundscapes create the acoustic backdrop for all organisms with a sense of hearing. The use of sound as an indirect, non-invasive method to assess aquatic

biodiversity is also common practice [5–9]. However, the study of sound in freshwater is still developing [5], with very little known regarding the identification of particular sound sources [5–9]. In freshwater settings, studies have focused on sounds produced by fishes, amphibians, and arthropods [9], as well as sediment transport, organic decomposition [10], and human activi- ties [10,11]. Plant sounds are less well understood [8] and most studies fail to mention sound production by plants during photosynthesis [5,9–12], with some exceptions [13–16].