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Interdisciplinary approaches to freshwater ecoacoustics

Abstract

Freshwater ecoacoustics is an emerging field that involves underwater audio recordings to detect the presence, location, and density of species in noninvasive and unbiased ways. Conducted long-term, ecoacoustics provides information on biophysical changes and environmental patterns that can advance freshwater conservation. River Listening is an interdisciplinary research project exploring the possibilities of freshwater ecoacoustics in the conservation and management of global river systems. The project works at the intersection of art and science by investigating the cultural and biological diversity of freshwater ecosystems through real-time listening and underwater recording used for biodiversity monitoring and public engagement. We use noninvasive recording techniques with accessible hydrophone kits and participatory workshops to engage local communities in the process and outcomes. The resulting database of hydrophone recordings is used for ongoing scientific research and diverse creative projects disseminated worldwide. The artistic outcomes from River Listening are central to our public engagement efforts, which include mobile phone applications with soundscapes triggered by GPS along rivers as well as live-streaming hydrophone arrays. These artistic projects have assisted in the advancement of scientific recording techniques and ecoacoustic methods. In this article, we introduce the foundations of River Listening and acknowledge a series of artists who have pioneered the use of hydrophone recording for both scientific and artistic purposes. The integration of art and science is further explored through a case study of our workshops and sound walks that have become the core public engagement tool for River Listening. We argue that interdisciplinary approaches are critical to the emerging field of freshwater ecoacoustics and call for further collaborations between artists, scientists, and communities to record and share the soundscapes of freshwater ecosystems.

River Listening Foundations

The effects of ecological changes are often readily visible in terrestrial environments, but conservation is challenging in aquatic ecosystems when we cannot see beneath the surface. Conventional environmental monitoring in freshwater ecosystems remains problematic because it is highly invasive, expensive, and constrained to restricted areas and manual processing of observations by specialists (Linke et al. 2018b). Rapid advancements in digital technology have provided opportunities for noninvasive acoustic monitoring that is now accessible, affordable, and viable. The term ecoacoustics has recently been adopted to define a new interdisciplinary field that studies sound along a broad range of spatial and temporal scales to understand environmental changes. In aquatic ecosystems, sound enables continuous observation in environments, such as rivers and lakes, where populations are notoriously difficult to monitor (Desjonquères et al. 2019). Passive acoustic monitoring can substantially mitigate the effort, expense, and invasive nature of traditional monitoring techniques, as it avoids human intrusion and facilitates the collection of large amounts of data.

Ecoacoustics approaches are being increasingly used in terrestrial systems, particularly for bird populations (Farina and Gage 2017), tropical coastal habitats for fish monitoring (Staaterman et al. 2017), and marine realms for cetacean monitoring (Tavolga 2012). However, the use of ecoacoustics in freshwater environments is still underdeveloped. Recent research has provided the foundations to advance the field of freshwater ecoacoustics, including detailed characterizations and taxonomic distinction of sounds that can offer the basis for automatic detection algorithms. For example, multi-taxon characterization by Gottesman et al. (2018) and Desjonquères et al. (2015) catalogued insect and physicochemical sounds. Other studies have characterized calls by piranhas in Peru (Rountree and Juanes 2018) and estimated the population of spadefoot toads (Pelobates fuscus) based on the acoustic temporal patterns in a target frequency band (Dutilleux and Curé 2018).

Freshwater ecoacoustics require further advancements and community engagement prior to being operational as a standard monitoring method. The needed groundwork includes expanding acoustic repositories to make data accessible, characterizing sounds, improving analysis and automatic detection methods, and verifying links between acoustic data and ecological conditions. Nonetheless, rapid advancements are now being made in the field. For instance, Desjonquères et al. (2018a) revealed both amplitude and duration of acoustic activity in aquatic Hemiptera are significantly higher in open water than in vegetated areas. Linke and Deretic (2019) characterized the acoustic responses of waterbird and amphibian assemblages to environmental water allocations, proving that acoustic monitoring is able to resolve both human-induced and natural variation over longer timescales. Gottesman et al. (2018) and Linke et al. (2018a) examined the importance of diurnal and lunar cycles influencing acoustic variation, particularly the nightly insect choruses (Hemiptera and Coleoptera) revealing decreased acoustic activity in bright moonlight.

In addition to advancing science, listening to rivers can help human communities understand freshwater biodiversity in accessible and engaging ways (Barclay 2016, 2018). Mobile applications and interactive experiences that augment real acoustic data with creative responses and community voices have the capacity to encourage public engagement and environmental stewardship at a time when the conservation of freshwater ecosystems is a critical priority (Barclay et al. 2018). The integrated nature of ecoacoustics calls for greater collaboration with other disciplines, including electronics, remote sensing, data science, humanities, and social sciences (Sueur and Farina 2015). This interdisciplinary potential was the inspiration for River Listening, an ongoing research project initiated in 2014 through a Synapse Residency awarded to Dr Leah Barclay and the Australian Rivers Institute at Griffith University. The Synapse program, a joint initiative of the Australia Council for the Arts and the Australian Network for Art and Technology, supports research between leading artists and scientists in Australia to explore questions through interdisciplinary collaborations.

The first phase of River Listening was designed to explore the artistic and scientific possibilities of hydrophone recording and inspire community engagement through interactive workshops, recording expeditions, and art installations designed to draw attention to the sounds beneath the surface of the river. The project explored ways we could use acoustics to understand aquatic biodiversity and involved extensive experimentation with recording techniques, new technologies, and community collaborations to compare aquatic soundscapes and the most effective methods for recording in freshwater ecosystems. River Listening was initially developed across 4 Queensland river systems: the Brisbane River, the Mary River, the Noosa River, and the Logan River. Our project draws inspiration from a large body of creative work in ecological sound art (Gilmurray 2017) and R. Murray Schafer’s pioneering work in acoustic ecology. In fact, Schafer’s initial premise was that people should attempt to hear the acoustic environment as music and take responsibility for its composition (Schafer 1977).

Underwater Recording in Artistic Practice

Hydrophones have been used in the context of creative work since the 1970s, with composers including Maggi Payne, Jana Winderen, Douglas Quin, Chris Watson, and David Monacchi regularly incorporating the underwater sounds of freshwater and marine environments into their creative works. Rather than drawing from recordings in scientific databases, each of these composers is also a specialist in environmental field recording and works in situ to record aquatic environments. These approaches to active listening in the field have been influential in the development of recording techniques for both scientific and artistic purposes.

New Zealand-born American composer Annea Lockwood is renowned for her Sound Maps of river systems that have been exhibited throughout the world. The trilogy of artistic works focuses on the Hudson, Danube, and Housatonic rivers, with each Sound Map acting as both an acoustic representation and artistic interpretation with social, political, ecological, and sonic explorations of the river from source to delta (Lockwood 2004, 2007). The Sound Maps draw on recordings from the river systems, woven with interviews and creative responses to guide the audience along a rich narrative that encourages deep listening through a compelling sonic environment. These works evolved from Lockwood’s existing work with rivers. In the 1960s, she began assembling a River Archive, which included recordings of rivers, streams, and springs. This sound archive pioneered what we now call an ecoacoustic approach and was the first to focus on recording river soundscapes, although there were existing sound archives focused on cataloguing individual species.

On the Danube River (2001–2004), Lockwood began deeper explorations of hydrophones in her creative work through recording in quiet river stretches that were rich in aquatic insects and fishes. Moving downstream, Lockwood observed the interconnected nature of the river continuum by listening to the changing soundscapes through hydrophones, a process which revealed how valuable rivers are for ear-training because they demand a very specific type of listening. Her resulting works have been a catalyst for conversations around river health, and the inclusion of interviews and voices mean ecological issues are explicitly explored in sections of the work. Lockwood believes the next step for this endeavor is working in more participatory contexts, and she has remarked that projects such as River Listening are an exceptional way to engage communities and young people in freshwater conservation (Lockwood 2015).

As an artist in residence at the Melbourne Aquarium in 2004, Australian composer Ros Bandt introduced hydrophones into her practice to use recordings in live performances. Working in collaboration with Iain Mott, Bandt used hydrophones to run a series of experiments at the aquarium, including 24-h recordings in shark tanks where they observed a daily dawn chorus of fishes. As an artist primarily using hydrophone recordings for creative works, these aquarium observations informed her approach to recording freshwater environments. In her freshwater dam at the Acoustic Sanctuary in remote Victoria, Bandt has installed an underwater camera with hydrophones in an attempt to identify species that correlate with the recordings. Bandt has spent extensive time annotating hydrophone recordings to identify sound sources. Her artistic practice and research have provoked others to think deeply about the role of sound in the environment (Bandt and Barclay 2017).

The foundations for River Listening emerged out of Leah Barclay’s artistic practice as a composer and sound artist spanning 10 years of collaboration with river communities across the world. Barclay’s creative work began with compositions inspired by rivers and shifted into participatory sound experiences, site-specific live performances, and immersive installations designed to bring attention and awareness to rivers as the lifeblood of communities. Hydrophone recording became central to Barclay’s practice in 2006 as a way to reveal the sounds beneath the surface of aquatic environments. Such revelations were the key intention of the Sound Mirrors project (2009–2012), which was realized as an immersive sound installation focused on specific rivers around the world. The project involved 2 years of fieldwork throughout Australia, Brazil, India, Korea, and China recording rivers and working with their surrounding communities in participatory workshops and public engagement experiences. The recordings revealed dramatic variations in aquatic soundscapes, and the value of hydrophone recordings as a possible monitoring tool for river health became apparent through this project. Sound Mirrors toured internationally and regularly sparked conversations, with audiences enthralled by the unfamiliar soundscapes of freshwater fishes, aquatic insects, and a large diversity of unidentified sounds. During the Sound Mirrors project, the lack of verified data around the sound sources and their uncertain correlation to ecological conditions made it difficult to suggest an application to facilitate freshwater conservation. Since that time, preliminary research has revealed acoustics can be used as tools for freshwater monitoring (Linke et al. 2018b), which also inspired the interdisciplinary possibilities of hydrophone recording.

The DAM(N) Project (2011–2013) provided another catalyst to conducting interdisciplinary research with freshwater soundscapes through collaborations with remote communities in the Narmada Valley of North India, displaced by large-scale dam development to secure hydropower for Indian cities. The construction of large dams on the River Narmada in India and its impact on millions of people living in the river valley has become one of the most important social issues in contemporary India. Barclay worked with an interdisciplinary creative team recording the river and collaborating with communities living on its banks. The resulting hydrophone recordings were mostly silent, and there were no signs of life in the stagnant and polluted waters (Barclay 2017b). This observation suggested that the density and complexity of aquatic soundscapes could correlate with river health. However, such a correlation conflicts with Barclay’s recordings of a polluted river in California where the sounds of an invasive fish provided a rich and compelling listening experience, and the nearby healthy stream was silent. These observations resulted in tensions in the creative work, as in some instances the sounds that were the most dynamic and rich were indications of environmental degradation. Such findings also demonstrate that the link between soundscapes and river health is not straightforward (see Desjonquères et al. 2018a, Linke et al. 2018b).

Barclay’s approach to composing with freshwater material has always revolved around having deep understanding of the environment and presenting the material in an authentic way to inspire public engagement and reveal the sonic characteristics of the rivers. Voices and soundscapes may be layered in the compositions, but the hydrophone recordings were never manipulated in implausible ways. Yet, it was clear if the intention of these recordings was public engagement and freshwater conservation, an enhanced understanding of the sound material and its relationship to river health was essential. This recognition resulted in Barclay developing stronger scientific foundations for all creative practice and establishing long-term collaborations with freshwater ecologists to advance this research.

Interdisciplinary Public Engagement and Community Workshops

River Listening was designed as an inherently-interdisciplinary project, with an equal balance between artistic and scientific methods throughout the fieldwork and resulting outcomes. Barclay’s creative practice and extensive experience with hydrophone recording was paired with freshwater ecologist Simon Linke and computational musician Toby Gifford. Linke spent his early career in the field of bioassessment (Linke et al. 1999) and later moved into the field of systematic conservation planning in freshwater systems (Linke et al. 2011) and new technologies for conservation monitoring (Reis et al. 2017, Turak et al. 2017). Gifford has an interdisciplinary background in computer music and artificial intelligence. River Listening sits at the intersection of art and science by using noninvasive hydrophone recording techniques to ask ecological questions for both artistic and scientific purposes. The research team has established an interdisciplinary framework through participatory action research that works directly with local communities. River Listening is scalable and responsive to each community and river system, and the adaptable nature of the project means it has been effective in a range of international contexts. In addition to major rivers systems in Australia, the project has worked with freshwater ecosystems throughout Europe, North America, and the Asia-Pacific.

The initial phase for each iteration of River Listening involves permission from traditional custodians, community consultations, and interdisciplinary workshops prior to hydrophone recordings. The workshops are accessible for conservation groups, specialists, and local school groups. The youth workshops are often most effective, with young people enthralled by the underwater soundscapes and eagerly wanting a hydrophone. This success has resulted in a River Listening workshop series where students make their own hydrophones, which they can keep to continue recording after the workshop. The current series of workshops involves studying local soniferous species that are added to a public database, learning hydrophone techniques, and setting up live-streaming hydrophone arrays so the community can listen to the river in real time through a global sound map. The River Listening team has been developing a range of tools to encourage ongoing community engagement outside of scheduled workshops. These efforts include a customized digital platform, virtual sound maps with live streaming hydrophones, and a mobile application that allows communities to record, upload, and compare sounds in a global database (Barclay 2016). These digital outcomes underpin the major creative projects and also facilitate the collection of recordings for scientific monitoring.

River Listening Sound Walks

The central tools for public engagement around River Listening have been creative outcomes, including site-specific performances and installations that have toured internationally. The most effective tool for public engagement has been the River Listening Sound Walks, which require audiences to visit their river to experience the work. The sound walks involve a custom-built mobile application that transforms the listener’s phone into a sonic compass to guide them along the riverbank and explore the cultural and biological diversity of the river through sound (Barclay 2017a). The installation triggers geo-located soundscapes that are accompanied by images and text identifying the sounds that are drawn from a local database of hydrophone recordings. Sounds could include local species of fish, aquatic insects, snapping shrimp, platypuses, or any species that is endemic or invasive to the area. Points along the map also trigger live hydrophone streams, allowing listeners access to the world beneath the surface in real time. The sound walks are educational, highly curated, and composed with sonic interludes to guide audiences through an immersive and engaging listening experience. The outcomes from River Listening workshops, including hydrophone recordings, are integrated into the sound walks, and communities feel a sense of ownership of the work when they can hear the sounds they recorded in the final experience. The accessibility of the creative outcomes has been vital for River Listening, and the participatory nature of these experiences has been the most effective way to maintain community engagement over time. By positioning sounds in very specific locations, the sound walks are designed to use mobile technologies to reveal underwater sounds, educate listeners about ecoacoustics, and inspire freshwater conservation.

Future Directions

River Listening continues to expand with an equal balance between artistic and scientific approaches and advancements. The River Listening Sound Walks, which have an audience of 23,000 listeners, have been presented across 16 global river systems, including the Hudson River for Climate Week New York City in 2015 and the Seine River for the United Nations Climate Change Conference in Paris. The education programs continue to expand, ranging from hydrophone-building and acoustic-recording curriculum for primary school children to masterclasses for acoustic monitoring with the United Nations Educational, Scientific and Cultural Organization across the Asia-Pacific region. The scientific implications of freshwater ecoacoustics are rapidly gaining traction, with an emerging body of high-impact publications calling for the global freshwater ecology community to adopt ecoacoustic monitoring (Servick 2014, Deichmann et al. 2018, Desjonquères et al. 2018b, Linke et al. 2018b, Rountree et al. 2018). The scientific and artistic outcomes from River Listening would not be possible without the interdisciplinary dialogue and design that provided the foundation for the research. Artistic approaches inform scientific outcomes and vice versa, as outlined in the timeline in Figure 1. This interdisciplinary balance is inherent to our Indigenous collaborators, who often comment that the separation of art and science is a recent construct and the only way forward is collaboration. Young participants in our workshops, who are yet to be confined by disciplinary boundaries, are often the most open minded to the art–science explorations. As this project continues to draw on emerging science, new technologies, and experimental art practice, we prioritize pathways for young people to engage with River Listening.

Figure 1. 
Figure 1. 

River Listening: Timeline of artistic and scientific engagement.

The next phase of River Listening involves the development of a public acoustic database and a live sound map that will stream real-time freshwater soundscapes for biodiversity monitoring and immersive sound installations that will be disseminated worldwide. The live streams will contribute towards establishing new long-term databases for scientific research, art–science collaborations, and public engagement. We believe that interdisciplinary approaches are critical to the emerging field of freshwater ecoacoustics and call for further collaborations between artists, scientists, and communities to document and share the soundscapes of freshwater ecosystems.

Author contributions: LB wrote the initial draft of the paper. All authors contributed and approved the final version of the manuscript.

We are grateful for support from The Australian Network for Art and Technology and Australian Council for the Arts in the development of the River Listening project. We also thank the Australian Rivers Institute at Griffith University and the University of the Sunshine Coast for hosting the research project.

Notes

*BRIDGES is a recurring feature of FWS intended to provide a forum for the interchange of ideas and information relevant to FWS readers, but beyond the usual scope of a scientific paper. Articles in this series will bridge from aquatic ecology to other disciplines, e.g., political science, economics, education, chemistry, or other biological sciences. Papers may be complementary or take alternative viewpoints. Authors with ideas for topics should contact BRIDGES Co-Editors, Sally Entrekin () and Allison Roy ().

Literature Cited