Passive acoustic monitoring as a potential tool to survey animal and ecosystem processes in freshwater environments

Abstract

Biodiversity in freshwater habitats is decreasing faster than in any other type of environment, mostly as a result of human activities. Monitoring these losses can help guide mitigation efforts. In most studies, sampling strategies predominantly rely on collecting animal and vegetal specimens. Although these techniques produce valuable data, they are invasive, time‐consuming and typically permit only limited spatial and temporal replication. There is need for the development of complementary methods. As observed in other ecosystems, freshwater environments host animals that emit sounds, either to communicate or as a by‐product of their activity. The main freshwater soniferous groups are amphibians, fish, and macroinvertebrates (mainly Coleoptera and Hemiptera, but also some Decapoda, Odonata, and Trichoptera). Biophysical processes such as flow or sediment transport also produce sounds, as well as human activities within aquatic ecosystems. Such animals and processes can be recorded, remotely and autonomously, and provide information on local diversity and ecosystem health. Passive acoustic monitoring (PAM) is an emerging method already deployed in terrestrial environments that uses sounds to survey environments. Key advantages of PAM are its non‐invasive nature, as well as its ability to record autonomously and over long timescales. All these research topics are the main aims of ecoacoustics, a new scientific discipline investigating the ecological role of sounds. In this paper, we review the sources of sounds present in freshwater environments. We then underline areas of research in which PAM may be helpful emphasising the role of PAM for the development of ecoacoustics. Finally, we present methods used to record and analyse sounds in those environments. Passive acoustics represents a potentially revolutionary development in freshwater ecology, enabling continuous monitoring of dynamic bio‐physical processes to inform conservation practitioners and managers.

Spatio‐temporal heterogeneity in river sounds: Disentangling micro‐ and macro‐variation in a chain of waterholes

“…This allowed inspection of the most common classes of sounds and their temporal distribution and frequency band. Although sound‐based species identification is still impossible for most species in freshwater environments due to the limits of scientific knowledge and the lack of sound libraries (Anderson et al, ; Desjonquères, Gifford, & Linke, ; Desjonquères, Rybak, Castella, Llusia, & Sueur, ; Desjonquères et al, ; Linke, Decker, et al, ), we had sufficient knowledge to recognise major biological groups signalling in these sites as well as abiotic sounds.…”

The role of freshwater bioacoustics in ecological research

“…Many species of arthropod are ecologically significant, such as the signal crayfish Pacifastacus leniusculus and the killer shrimp Dikerogammarus villosus , which are highly invasive in freshwater ecosystems around the world (Bubb, Thom, & Lucas, ; MacNeil, Boets, & Platvoet, ). Several species of crayfish are known to produce sound, including the invasive red swamp crayfish (Favaro, Tirelli, Gamba, & Pessani, ) and the endangered white‐clawed crayfish (Desjonquères, ). Furthermore, mayflies, stoneflies, caddisflies, water beetles and crayfish exist across broad environmental gradients and are useful indicators of environmental change (Muralidharan, Selvakumar, Sundar, & Raja, ).…”

Six steps towards operationalising freshwater ecoacoustic monitoring

“…In freshwater environments, four main groups are known to produce sounds: amphibians, crustaceans, fish, and insects (for a detailed discussion, see Desjonquères, Gifford & Linke, , also see Figure ). Unlike terrestrial bioacoustics, where the organisms emitting sounds are often clearly visible, underwater acoustics is often not accompanied by visual surveys.…”

“…We hope that both scientists and practitioners will use this special issue both as a compendium and an inspiration to operationalise ecoacoustic analysis in freshwater ecosystem. In this issue, we provide a compendium to get users started with principles of underwater acoustics and applied analysis methods (Desjonquères, Gifford, et al, ). The issue then follows on to demonstrate applications, both underwater and for water‐dependent ecosystems.…”