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Assessing the underwater acoustics of the world's largest vibration hammer (OCTA-KONG) and its potential effects on the Indo-Pacific humpbacked dolphin (Sousa chinensis).

Wang Z, Wu Y, Duan G, Cao H, Liu J, Wang K, Wang D - PLoS ONE (2014)

Bottom Line: Therefore, a safety zone with a radius of 500 m is proposed.Although the zero-to-peak source level (SL) of the OCTA-KONG was lower than the physiological damage level, the maximum root-mean-square SL exceeded the cetacean safety exposure level on several occasions.Moreover, the majority of the unweighted cumulative source sound exposure levels (SSELs) and the cetacean auditory weighted cumulative SSELs exceeded the acoustic threshold levels for the onset of temporary threshold shift, a type of potentially recoverable auditory damage resulting from prolonged sound exposure.

View Article: PubMed Central - PubMed

Affiliation: The Key Laboratory of Aquatic Biodiversity and Conservation of the Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, P. R. China; University of Chinese Academy of Sciences, Beijing, P. R. China.

ABSTRACT
Anthropogenic noise in aquatic environments is a worldwide concern due to its potential adverse effects on the environment and aquatic life. The Hongkong-Zhuhai-Macao Bridge is currently under construction in the Pearl River Estuary, a hot spot for the Indo-Pacific humpbacked dolphin (Sousa chinensis) in China. The OCTA-KONG, the world's largest vibration hammer, is being used during this construction project to drive or extract steel shell piles 22 m in diameter. This activity poses a substantial threat to marine mammals, and an environmental assessment is critically needed. The underwater acoustic properties of the OCTA-KONG were analyzed, and the potential impacts of the underwater acoustic energy on Sousa, including auditory masking and physiological impacts, were assessed. The fundamental frequency of the OCTA-KONG vibration ranged from 15 Hz to 16 Hz, and the noise increments were below 20 kHz, with a dominant frequency and energy below 10 kHz. The resulting sounds are most likely detectable by Sousa over distances of up to 3.5 km from the source. Although Sousa clicks do not appear to be adversely affected, Sousa whistles are susceptible to auditory masking, which may negatively impact this species' social life. Therefore, a safety zone with a radius of 500 m is proposed. Although the zero-to-peak source level (SL) of the OCTA-KONG was lower than the physiological damage level, the maximum root-mean-square SL exceeded the cetacean safety exposure level on several occasions. Moreover, the majority of the unweighted cumulative source sound exposure levels (SSELs) and the cetacean auditory weighted cumulative SSELs exceeded the acoustic threshold levels for the onset of temporary threshold shift, a type of potentially recoverable auditory damage resulting from prolonged sound exposure. These findings may aid in the identification and design of appropriate mitigation methods, such as the use of air bubble curtains, "soft start" and "power down" techniques.

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Related in: MedlinePlus

1/3 octave band frequency spectrum and A-weighted sound exposure level of the SSP22 #36 driving sound.Spectrum configuration: temporal grid resolution, 76.80 ms; overlap samples per frame, 85%; frequency grid spacing, 1.95 Hz; window size, 262 144; FFT size, 262 144; window type, Hanning. The Sousa audiogram was modified from previous sources [22], [23], with the lowest threshold at each frequency defining the merged audiogram curve. n denotes the number of samples. Pile driving sounds were recorded at a distance of 80 m from the vibration hammer.
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pone-0110590-g006: 1/3 octave band frequency spectrum and A-weighted sound exposure level of the SSP22 #36 driving sound.Spectrum configuration: temporal grid resolution, 76.80 ms; overlap samples per frame, 85%; frequency grid spacing, 1.95 Hz; window size, 262 144; FFT size, 262 144; window type, Hanning. The Sousa audiogram was modified from previous sources [22], [23], with the lowest threshold at each frequency defining the merged audiogram curve. n denotes the number of samples. Pile driving sounds were recorded at a distance of 80 m from the vibration hammer.

Mentions: The recorded fundamental frequency of the OCTA-KONG vibration ranged from 15 Hz (Fig. 3) to 16 Hz (Fig. 4, 5). The noise increments were below 20 kHz, with the dominant frequency and most energy contained below approximately 10 kHz (Fig. 4, 5, 6).


Assessing the underwater acoustics of the world's largest vibration hammer (OCTA-KONG) and its potential effects on the Indo-Pacific humpbacked dolphin (Sousa chinensis).

Wang Z, Wu Y, Duan G, Cao H, Liu J, Wang K, Wang D - PLoS ONE (2014)

1/3 octave band frequency spectrum and A-weighted sound exposure level of the SSP22 #36 driving sound.Spectrum configuration: temporal grid resolution, 76.80 ms; overlap samples per frame, 85%; frequency grid spacing, 1.95 Hz; window size, 262 144; FFT size, 262 144; window type, Hanning. The Sousa audiogram was modified from previous sources [22], [23], with the lowest threshold at each frequency defining the merged audiogram curve. n denotes the number of samples. Pile driving sounds were recorded at a distance of 80 m from the vibration hammer.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4206436&req=5

pone-0110590-g006: 1/3 octave band frequency spectrum and A-weighted sound exposure level of the SSP22 #36 driving sound.Spectrum configuration: temporal grid resolution, 76.80 ms; overlap samples per frame, 85%; frequency grid spacing, 1.95 Hz; window size, 262 144; FFT size, 262 144; window type, Hanning. The Sousa audiogram was modified from previous sources [22], [23], with the lowest threshold at each frequency defining the merged audiogram curve. n denotes the number of samples. Pile driving sounds were recorded at a distance of 80 m from the vibration hammer.
Mentions: The recorded fundamental frequency of the OCTA-KONG vibration ranged from 15 Hz (Fig. 3) to 16 Hz (Fig. 4, 5). The noise increments were below 20 kHz, with the dominant frequency and most energy contained below approximately 10 kHz (Fig. 4, 5, 6).

Bottom Line: Therefore, a safety zone with a radius of 500 m is proposed.Although the zero-to-peak source level (SL) of the OCTA-KONG was lower than the physiological damage level, the maximum root-mean-square SL exceeded the cetacean safety exposure level on several occasions.Moreover, the majority of the unweighted cumulative source sound exposure levels (SSELs) and the cetacean auditory weighted cumulative SSELs exceeded the acoustic threshold levels for the onset of temporary threshold shift, a type of potentially recoverable auditory damage resulting from prolonged sound exposure.

View Article: PubMed Central - PubMed

Affiliation: The Key Laboratory of Aquatic Biodiversity and Conservation of the Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, P. R. China; University of Chinese Academy of Sciences, Beijing, P. R. China.

ABSTRACT
Anthropogenic noise in aquatic environments is a worldwide concern due to its potential adverse effects on the environment and aquatic life. The Hongkong-Zhuhai-Macao Bridge is currently under construction in the Pearl River Estuary, a hot spot for the Indo-Pacific humpbacked dolphin (Sousa chinensis) in China. The OCTA-KONG, the world's largest vibration hammer, is being used during this construction project to drive or extract steel shell piles 22 m in diameter. This activity poses a substantial threat to marine mammals, and an environmental assessment is critically needed. The underwater acoustic properties of the OCTA-KONG were analyzed, and the potential impacts of the underwater acoustic energy on Sousa, including auditory masking and physiological impacts, were assessed. The fundamental frequency of the OCTA-KONG vibration ranged from 15 Hz to 16 Hz, and the noise increments were below 20 kHz, with a dominant frequency and energy below 10 kHz. The resulting sounds are most likely detectable by Sousa over distances of up to 3.5 km from the source. Although Sousa clicks do not appear to be adversely affected, Sousa whistles are susceptible to auditory masking, which may negatively impact this species' social life. Therefore, a safety zone with a radius of 500 m is proposed. Although the zero-to-peak source level (SL) of the OCTA-KONG was lower than the physiological damage level, the maximum root-mean-square SL exceeded the cetacean safety exposure level on several occasions. Moreover, the majority of the unweighted cumulative source sound exposure levels (SSELs) and the cetacean auditory weighted cumulative SSELs exceeded the acoustic threshold levels for the onset of temporary threshold shift, a type of potentially recoverable auditory damage resulting from prolonged sound exposure. These findings may aid in the identification and design of appropriate mitigation methods, such as the use of air bubble curtains, "soft start" and "power down" techniques.

Show MeSH
Related in: MedlinePlus