Rapidly obtained ecosystem indicators from coral reef soundscapes

Freeman, Lauren A.; Freeman, Simon E.

doi:10.3354/meps11938

Cited by 43 publications

(35 citation statements)

References 53 publications

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“…A future goal of passive acoustic monitoring is to be able to relate soundscape characteristics to seascape characteristics in an effort to monitor habitats (e.g., [ 27 – 28 ]). Although there was only a weak positive relationship between call rate and oyster density across the eight sites, when grouped by restoration status, there is a significant difference in call rates between restored (spat on shell added) and unrestored reefs—with restored reefs having nearly twice as many calls as unrestored reefs.…”

Section: Discussionmentioning

confidence: 99%

Oyster toadfish (Opsanus tau) boatwhistle call detection and patterns within a large-scale oyster restoration site

et al. 2017

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During May 2015, passive acoustic recorders were deployed at eight subtidal oyster reefs within Harris Creek Oyster Sanctuary in Chesapeake Bay, Maryland USA. These sites were selected to represent both restored and unrestored habitats having a range of oyster densities. Throughout the survey, the soundscape within Harris Creek was dominated by the boatwhistle calls of the oyster toadfish, Opsanus tau. A novel, multi-kernel spectral correlation approach was developed to automatically detect these boatwhistle calls using their two lowest harmonic bands. The results provided quantitative information on how call rate and call frequency varied in space and time. Toadfish boatwhistle fundamental frequency ranged from 140 Hz to 260 Hz and was well correlated (r = 0.94) with changes in water temperature, with the fundamental frequency increasing by ~11 Hz for every 1°C increase in temperature. The boatwhistle call rate increased from just a few calls per minute at the start of monitoring on May 7th to ~100 calls/min on May 10th and remained elevated throughout the survey. As male toadfish are known to generate boatwhistles to attract mates, this rapid increase in call rate was interpreted to mark the onset of spring spawning behavior. Call rate was not modulated by water temperature, but showed a consistent diurnal pattern, with a sharp decrease in rate just before sunrise and a peak just after sunset. There was a significant difference in call rate between restored and unrestored reefs, with restored sites having nearly twice the call rate as unrestored sites. This work highlights the benefits of using automated detection techniques that provide quantitative information on species-specific call characteristics and patterns. This type of non-invasive acoustic monitoring provides long-term, semi-continuous information on animal behavior and abundance, and operates effectively in settings that are otherwise difficult to sample.

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Section: Discussionmentioning

confidence: 99%

Oyster toadfish (Opsanus tau) boatwhistle call detection and patterns within a large-scale oyster restoration site

et al. 2017

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“…These techniques can yield spatially integrative and long-term continuous observations that can be collected autonomously with inexpensive recorders, but the sources of many reef sounds are challenging to identify [ 9 ]. Previously we established positive correlations (Pearsons ρ) between benthic macroalgal cover and aspects of coral reef soundscapes (acoustic pressure spectral density levels in the 2 to 20 kHz band) at 17 sites over a 2570 km transect from Kure Atoll to the Island of Hawaii [ 10 ]. These correlations were only observed during the day when overall sound levels were typically lower ( Table 1 ), and correlations of this nature did not exist between sound and any other non-acoustic environmental metric.…”

Section: Introductionmentioning

confidence: 99%

Photosynthesis by marine algae produces sound, contributing to the daytime soundscape on coral reefs

Freeman

Giorli

et al. 2018

PLoS ONE

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We have observed that marine macroalgae produce sound during photosynthesis. The resultant soundscapes correlate with benthic macroalgal cover across shallow Hawaiian coral reefs during the day, despite the presence of other biological noise. Likely ubiquitous but previously overlooked, this source of ambient biological noise in the coastal ocean is driven by local supersaturation of oxygen near the surface of macroalgal filaments, and the resultant formation and release of oxygen-containing bubbles into the water column. During release, relaxation of the bubble to a spherical shape creates a monopole sound source that ‘rings’ at the Minnaert frequency. Many such bubbles create a large, distributed sound source over the sea floor. Reef soundscapes contain vast quantities of biological information, making passive acoustic ecosystem evaluation a tantalizing prospect if the sources are known. Our observations introduce the possibility of a general, volumetrically integrative, noninvasive, rapid and remote technique for evaluating algal abundance and rates of primary productivity in littoral aquatic communities. Increased algal cover is one of the strongest indicators for coral reef ecosystem stress. Visually determining variations in algal abundance is a time-consuming and expensive process. This technique could therefore provide a valuable tool for ecosystem management but also for industrial monitoring of primary production, such as in algae-based biofuel synthesis.

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“…Acoustic and visual indicators of reef health can be linked across spatial and temporal scales. Sound-pressure level (particularly at frequencies below 2 kHz) can positively correlate with coral cover, invertebrate abundance, and fish diversity (Kennedy et al, 2010;Kaplan et al, 2015Kaplan et al, , 2018Nedelec et al, 2015;Freeman and Freeman, 2016). Several other acoustic indices such as rates of invertebrate snapping sounds (Butler et al, 2017) and the acoustic complexity index (Pieretti et al, 2011) may also correlate with visual measures of diversity (Nedelec et al, 2015;Bertucci et al, 2016), although the generality of these trends is not fully established (Staaterman et al, 2017).…”

Section: Acoustic Techniquesmentioning

confidence: 99%

Coral Reef Monitoring, Reef Assessment Technologies, and Ecosystem-Based Management

et al. 2019

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Rapidly obtained ecosystem indicators from coral reef soundscapes

Cited by 43 publications

References 53 publications

Oyster toadfish (Opsanus tau) boatwhistle call detection and patterns within a large-scale oyster restoration site

Oyster toadfish (Opsanus tau) boatwhistle call detection and patterns within a large-scale oyster restoration site

Photosynthesis by marine algae produces sound, contributing to the daytime soundscape on coral reefs

Coral Reef Monitoring, Reef Assessment Technologies, and Ecosystem-Based Management

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