The utility of different acoustic indicators to describe biological sounds of a coral reef soundscape

Monitoring coral reefs is vital to the conservation of these at-risk ecosystems. While most current monitoring methods are costly and time-intensive, passive acoustic monitoring (PAM) could provide a cost-effective, large scale reef monitoring tool. However, for PAM to be reliable, the results must...

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Main Authors: Sean A. Dimoff, William D. Halliday, Matthew K. Pine, Kristina L. Tietjen, Francis Juanes, Julia K. Baum
Format: Article
Language:English
Published: Elsevier 2021-05-01
Series:Ecological Indicators
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S1470160X2100100X
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author Sean A. Dimoff
William D. Halliday
Matthew K. Pine
Kristina L. Tietjen
Francis Juanes
Julia K. Baum
author_facet Sean A. Dimoff
William D. Halliday
Matthew K. Pine
Kristina L. Tietjen
Francis Juanes
Julia K. Baum
author_sort Sean A. Dimoff
collection DOAJ
description Monitoring coral reefs is vital to the conservation of these at-risk ecosystems. While most current monitoring methods are costly and time-intensive, passive acoustic monitoring (PAM) could provide a cost-effective, large scale reef monitoring tool. However, for PAM to be reliable, the results must be field tested to ensure that the acoustic methods used accurately represent the certain ecological components of the reef being studied. For example, recent acoustic studies have attempted to describe the diversity of coral reef fish using the Acoustic Complexity Index (ACI) but despite inconsistent results on coral reefs, ACI is still being applied to these ecosystems. Here, we investigated the potential for ACI and sound pressure level (SPL – another common metric used), to accurately respond to biological sounds on coral reefs when calculated using three different frequency resolutions (31.2 Hz, 15.6 Hz, and 4 Hz). Acoustic recordings were made over two to three-week periods in 2017 and 2018 at sites around Kiritimati (Christmas Island), in the central equatorial Pacific. We hypothesized that SPL would be positively correlated with the number of nearby fish sounds in the low frequency band and with snapping shrimp snaps in the high frequency band, but that ACI would rely on its settings, specifically its frequency resolution, to describe sounds in both frequency bands. We found that nearby fish sounds were partially responsible for changes in low frequency SPL in the morning, during crepuscular chorusing activity, but not at other times of day. Snapping shrimp snaps, however, were responsible for large changes in high frequency SPL. ACI results were reliant on the frequency band chosen, with the 31.2 Hz frequency resolution models being chosen as the best models. In the low frequency band, the effect of fish knocks was positive and significant only in the 31.2 Hz and 15.6 Hz models while in the high frequency band snapping shrimp snaps were negatively associated with ACI in all frequency resolutions. These results contribute to a growing body of evidence against the continued use of ACI without standardization on highly energetic underwater ecosystems like coral reefs and highlight the importance of extensive field testing of new acoustic metrics prior to their adoption and proliferation.
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spelling doaj.art-d338b22886aa4e5f84f9ab6bf8cb0f4d2022-12-21T19:51:44ZengElsevierEcological Indicators1470-160X2021-05-01124107435The utility of different acoustic indicators to describe biological sounds of a coral reef soundscapeSean A. Dimoff0William D. Halliday1Matthew K. Pine2Kristina L. Tietjen3Francis Juanes4Julia K. Baum5Department of Biology, University of Victoria, PO Box 1700 Station CSC, Victoria, British Columbia V8W 2Y2, CanadaDepartment of Biology, University of Victoria, PO Box 1700 Station CSC, Victoria, British Columbia V8W 2Y2, Canada; Wildlife Conservation Society Canada, 169 Titanium Way, Whitehorse, Yukon Y1A 0E9, Canada; Corresponding authors.Department of Biology, University of Victoria, PO Box 1700 Station CSC, Victoria, British Columbia V8W 2Y2, CanadaDepartment of Biology, University of Victoria, PO Box 1700 Station CSC, Victoria, British Columbia V8W 2Y2, CanadaDepartment of Biology, University of Victoria, PO Box 1700 Station CSC, Victoria, British Columbia V8W 2Y2, CanadaDepartment of Biology, University of Victoria, PO Box 1700 Station CSC, Victoria, British Columbia V8W 2Y2, Canada; Hawai‘i Institute of Marine Biology, University of Hawai‘i, 46-007 Lilipuna Road, Kāne‘ohe, Hawai’i 96744, USA; Corresponding authors.Monitoring coral reefs is vital to the conservation of these at-risk ecosystems. While most current monitoring methods are costly and time-intensive, passive acoustic monitoring (PAM) could provide a cost-effective, large scale reef monitoring tool. However, for PAM to be reliable, the results must be field tested to ensure that the acoustic methods used accurately represent the certain ecological components of the reef being studied. For example, recent acoustic studies have attempted to describe the diversity of coral reef fish using the Acoustic Complexity Index (ACI) but despite inconsistent results on coral reefs, ACI is still being applied to these ecosystems. Here, we investigated the potential for ACI and sound pressure level (SPL – another common metric used), to accurately respond to biological sounds on coral reefs when calculated using three different frequency resolutions (31.2 Hz, 15.6 Hz, and 4 Hz). Acoustic recordings were made over two to three-week periods in 2017 and 2018 at sites around Kiritimati (Christmas Island), in the central equatorial Pacific. We hypothesized that SPL would be positively correlated with the number of nearby fish sounds in the low frequency band and with snapping shrimp snaps in the high frequency band, but that ACI would rely on its settings, specifically its frequency resolution, to describe sounds in both frequency bands. We found that nearby fish sounds were partially responsible for changes in low frequency SPL in the morning, during crepuscular chorusing activity, but not at other times of day. Snapping shrimp snaps, however, were responsible for large changes in high frequency SPL. ACI results were reliant on the frequency band chosen, with the 31.2 Hz frequency resolution models being chosen as the best models. In the low frequency band, the effect of fish knocks was positive and significant only in the 31.2 Hz and 15.6 Hz models while in the high frequency band snapping shrimp snaps were negatively associated with ACI in all frequency resolutions. These results contribute to a growing body of evidence against the continued use of ACI without standardization on highly energetic underwater ecosystems like coral reefs and highlight the importance of extensive field testing of new acoustic metrics prior to their adoption and proliferation.http://www.sciencedirect.com/science/article/pii/S1470160X2100100XSoundscapesCoral reefsUnderwater acousticsAcoustic indicesPassive acoustic monitoring
spellingShingle Sean A. Dimoff
William D. Halliday
Matthew K. Pine
Kristina L. Tietjen
Francis Juanes
Julia K. Baum
The utility of different acoustic indicators to describe biological sounds of a coral reef soundscape
Ecological Indicators
Soundscapes
Coral reefs
Underwater acoustics
Acoustic indices
Passive acoustic monitoring
title The utility of different acoustic indicators to describe biological sounds of a coral reef soundscape
title_full The utility of different acoustic indicators to describe biological sounds of a coral reef soundscape
title_fullStr The utility of different acoustic indicators to describe biological sounds of a coral reef soundscape
title_full_unstemmed The utility of different acoustic indicators to describe biological sounds of a coral reef soundscape
title_short The utility of different acoustic indicators to describe biological sounds of a coral reef soundscape
title_sort utility of different acoustic indicators to describe biological sounds of a coral reef soundscape
topic Soundscapes
Coral reefs
Underwater acoustics
Acoustic indices
Passive acoustic monitoring
url http://www.sciencedirect.com/science/article/pii/S1470160X2100100X
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