Dataset Information

When the noise goes on: received sound energy predicts sperm whale responses to both intermittent and continuous navy sonar.

ABSTRACT: Anthropogenic noise sources range from intermittent to continuous, with seismic and navy sonar technology moving towards near-continuous transmissions. Continuous active sonar (CAS) may be used at a lower amplitude than traditional pulsed active sonar (PAS), but potentially with greater cumulative sound energy. We conducted at-sea experiments to contrast the effects of navy PAS versus CAS on sperm whale behaviour using animal-attached sound- and movement-recording tags (n=16 individuals) in Norway. Changes in foraging effort and proxies for foraging success and cost during sonar and control exposures were assessed while accounting for baseline variation [individual effects, time of day, bathymetry and blackfish (pilot/killer whale) presence] in generalized additive mixed models (GAMMs). We found no reduction in time spent foraging during exposures to medium-level PAS (MPAS) transmitted at the same peak amplitude as CAS. In contrast, we found similar reductions in foraging during CAS (d.f.=1, F=8.0, P=0.005) and higher amplitude PAS (d.f.=1, F=20.8, P<0.001) when received at similar energy levels integrated over signal duration. These results provide clear support for sound energy over amplitude as the response driver. We discuss the importance of exposure context and the need to measure cumulative sound energy to account for intermittent versus more continuous sources in noise impact assessments.

SUBMITTER: Isojunno S

PROVIDER: S-EPMC7157582 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

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When the noise goes on: received sound energy predicts sperm whale responses to both intermittent and continuous navy sonar.

Isojunno Saana S Wensveen Paul J PJ Lam Frans-Peter A FA Kvadsheim Petter H PH von Benda-Beckmann Alexander M AM Martín López Lucía M LM Kleivane Lars L Siegal Eilidh M EM Miller Patrick J O PJO

The Journal of experimental biology 20200408 Pt 7

Anthropogenic noise sources range from intermittent to continuous, with seismic and navy sonar technology moving towards near-continuous transmissions. Continuous active sonar (CAS) may be used at a lower amplitude than traditional pulsed active sonar (PAS), but potentially with greater cumulative sound energy. We conducted at-sea experiments to contrast the effects of navy PAS versus CAS on sperm whale behaviour using animal-attached sound- and movement-recording tags (<i>n</i>=16 individuals) ...[more]

PMID: 32107307

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Project description:Why do humpback whales sing? This paper considers the hypothesis that humpback whales may use song for long range sonar. Given the vocal and social behavior of humpback whales, in several cases it is not apparent how they monitor the movements of distant whales or prey concentrations. Unless distant animals produce sounds, humpback whales are unlikely to be aware of their presence or actions. Some field observations are strongly suggestive of the use of song as sonar. Humpback whales sometimes stop singing and then rapidly approach distant whales in cases where sound production by those whales is not apparent, and singers sometimes alternately sing and swim while attempting to intercept another whale that is swimming evasively. In the evolutionary development of modern cetaceans, perceptual mechanisms have shifted from reliance on visual scanning to the active generation and monitoring of echoes. It is hypothesized that as the size and distance of relevant events increased, humpback whales developed adaptive specializations for long-distance echolocation. Differences between use of songs by humpback whales and use of sonar by other echolocating species are discussed, as are similarities between bat echolocation and singing by humpback whales. Singing humpback whales are known to emit sounds intense enough to generate echoes at long ranges, and to flexibly control the timing and qualities of produced sounds. The major problem for the hypothesis is the lack of recordings of echoes from other whales arriving at singers immediately before they initiate actions related to those whales. An earlier model of echoic processing by singing humpback whales is here revised to incorporate recent discoveries. According to the revised model, both direct echoes from targets and modulations in song-generated reverberation can provide singers with information that can help them make decisions about future actions related to mating, traveling, and foraging. The model identifies acoustic and structural features produced by singing humpback whales that may facilitate a singer's ability to interpret changes in echoic scenes and suggests that interactive signal coordination by singing whales may help them to avoid mutual interference. Specific, testable predictions of the model are presented.

Project description:BackgroundSouth Korea and surrounding countries in East Asia are believed to have the highest proportion in the world of high frequency hearing loss due to occupational noise exposure, yet there has been limited information published in international journals, and limited information for control of noise in local workplaces beyond strategies from western countries. We exploit medical surveillance information from two worker groups to enhance local knowledge about noise-induced hearing loss and explore the possible importance of shift work to risk.MethodsFour-years of hearing data were evaluated for 81 male farm machine factory workers and 371 male firefighters who had successfully completed a health examination and questionnaires for the duration of the study period. The averages of hearing thresholds at 2, 3, and 4 kHz were used as the primary end-point for comparison. Repeat measure analysis adjusted for age, exposure duration and smoking status was used to measure the difference in hearing threshold between the two groups.ResultsNoise levels were measured in the factory at a mean of 82 dBA, with a range of 66-97. No concurrent measurements were taken for the firefighters, but historic comparison values showed a wider range but a similar mean of 76-79 dBA. Although losses during follow-up were negligible, the factory workers had significantly (P < 0.0001) more hearing loss at the baseline of the study than the firefighters in both ears at 2, 3, and 4 kHz, adjusted for age, duration of employment and smoking status. Among those with 10 years of employment, mean losses at these frequencies among the factory workers fell into the impairment range (> 25 dB loss). Firefighters also showed increased losses associated with longer exposure duration, but these were significantly less marked. Losses at lower frequencies (< or = 1 kHz) were negligible in both groups.ConclusionsKorean work environments with continuous noise exposure in the measured range should consider implementation of a hearing conservation program. Further evaluation of hearing loss in workers exposed to irregular or intermittent high noise levels, such as firefighters, is also warranted.

Dataset Information

When the noise goes on: received sound energy predicts sperm whale responses to both intermittent and continuous navy sonar.

Publications

When the noise goes on: received sound energy predicts sperm whale responses to both intermittent and continuous navy sonar.

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