Most marine animals, particularly mammals and fish, are very sensitive to sound. They use sound for almost all important aspects of their life including reproduction, feeding, avoiding hazards like predators, and navigation.
Sound can travel long distances underwater, sometimes hundreds or even thousands of kilometers, whereas vision is only useful for tens of meters underwater. Therefore, it is not surprising that much marine life uses sound as its principal sense. Unwanted sound, or noise, can have a large impact on the marine environment, because noise can blanket a very large area, potentially preventing fish or whales from hearing their prey or predators, finding their way, or connecting with mates, group members, or their young. Consequences Key points:
Despite the myth of the "Silent World" propagated in part by French oceanographers, many marine environments are alive with natural soundscapes, and most marine animals rely on sound and hearing in some form for survival. Mixed in between the large range of frequencies used by cetaceans are the sounds introduced by humans. The primary sources of noise pollution are commercial shipping, seismic airgun exploration (for oil and gas), and naval and mapping sonars. These sources of noise have the potential to cause negative impacts over hundreds of thousands, to millions of square kilometres (Weilgart, 2018). Documented impacts include:
Sources of noise pollution - Shipping and watercraft Ship noise has become the most ubiquitous source of anthropogenic noise in the oceans and is responsible for increases in ambient noise at low frequencies (10–100 Hz) at a reported rate as high as 3 dB/decade. The noise field around a ship is not uniform and is dependent upon the source frequency, the surrounding environment, and vessel direction, speed, load and size. The strongest noise source is caused by propellers when cavitation occurs. |
- Whale Watching
In the last few decades, whale-watching has garnered a reputation for being a sustainable alternative to commercial whaling and a form of green, eco-friendly tourism. Whilst whale watching can promote knowledge and pro-conservation intentions amongst tourists, previous studies have uncovered variable results (Erbe, 2006: Clemente et al, 2018: Argüelles et al, 2016) with responses often different between species and individuals of a species. Documented responses include changes to surfacing and dive patterns, swim speed and direction, and a decrease in the time spent feeding and/or resting (New et al, 2015). The vessel simulated a whale-watching boat as it approached the whales compared to control/low treatments, during high noise playbacks, the proportion of time mothers spent resting decreased by 30%, respiration rate doubled, and swim speed increased by 37%.
- Seismic surveys
Seismic surveys are used for natural resource exploration. The displacement of cetaceans during seismic surveys has been previously reported and there have been possible links between surveys and stranding’s for a dozen events. There is an overall lack of causal evidence between seismic activity and cetacean deaths, though this absence should be considered as the consequence of a lack of comprehensive analysis of the circumstances rather than the surveys being an issue.
McGeady et al, (2016) investigated the effects of seismic surveying and environmental variables on deep diving odontocete stranding rates along Ireland’s coast. Their analysis indicated that the occurrence of seismic surveying operations off the coast of Ireland may have increased the number of stranding events for long-finned pilot whales, as well as all species grouped together. The increased effect for long-finned pilot whales may result from their high abundance in the area.
- Drilling and Dredging
Richardson et al, (1990) had previously found that bowhead whales (Balaena mysticetus) in the Canadian Beaufort Sea showed individual sensitivity to playback of industrial noise from drill ships and dredges. Some whales moved away from the source of the noise and roughly half responded when noise was 20 - 30 dB above ambient. During some of the playback tests, the call rates of whales decreased, feeding ceased, and cycles of surfacing, respiration and diving may have changed.
The calling rates of whales are affected when in an area where industrial noise is to be found. The calls of whales peaked where increasing noise was present before decreasing. This increase in calling is consistent with previous studies and is seen in many invertebrate groups when individuals wish to maintain communication in a high noise environment. To be heard above background noise, an individual may increase the amplitude of their signal, change the frequency of their signal, or increase the repetition rate of their signal..
Useful links:
-https://www.marineinsight.com/environment/effects-of-noise-pollution-from-ships-on-marine-life/
-https://awionline.org/sites/default/files/uploads/documents/Weilgart_Biodiversity_2008-1238105851-10133.pdf
-http://marineconnection.org/wp-content/uploads/2020/08/Ship-Interactions-noise-pollution-and-disturbance.pdf
-https://www.environmentalpollutioncenters.org/noise-pollution/#:~:text=What%20Is%20Noise%20Pollution%3F%20Noise%20pollution%20is%20generally,of%20how%20long%20or%20consistent%20the%20exposure%20is.
-https://www.iberdrola.com/environment/what-is-noise-pollution-causes-effects-solutions
-https://www.ppsthane.com/blog/how-to-reduce-noise-pollution
Videos:
https://www.youtube.com/watch?v=0f6xWoYfGj0
https://www.youtube.com/watch?v=PHXcnrM65NA
https://www.youtube.com/watch?v=t0DHEldqfIc
In the last few decades, whale-watching has garnered a reputation for being a sustainable alternative to commercial whaling and a form of green, eco-friendly tourism. Whilst whale watching can promote knowledge and pro-conservation intentions amongst tourists, previous studies have uncovered variable results (Erbe, 2006: Clemente et al, 2018: Argüelles et al, 2016) with responses often different between species and individuals of a species. Documented responses include changes to surfacing and dive patterns, swim speed and direction, and a decrease in the time spent feeding and/or resting (New et al, 2015). The vessel simulated a whale-watching boat as it approached the whales compared to control/low treatments, during high noise playbacks, the proportion of time mothers spent resting decreased by 30%, respiration rate doubled, and swim speed increased by 37%.
- Seismic surveys
Seismic surveys are used for natural resource exploration. The displacement of cetaceans during seismic surveys has been previously reported and there have been possible links between surveys and stranding’s for a dozen events. There is an overall lack of causal evidence between seismic activity and cetacean deaths, though this absence should be considered as the consequence of a lack of comprehensive analysis of the circumstances rather than the surveys being an issue.
McGeady et al, (2016) investigated the effects of seismic surveying and environmental variables on deep diving odontocete stranding rates along Ireland’s coast. Their analysis indicated that the occurrence of seismic surveying operations off the coast of Ireland may have increased the number of stranding events for long-finned pilot whales, as well as all species grouped together. The increased effect for long-finned pilot whales may result from their high abundance in the area.
- Drilling and Dredging
Richardson et al, (1990) had previously found that bowhead whales (Balaena mysticetus) in the Canadian Beaufort Sea showed individual sensitivity to playback of industrial noise from drill ships and dredges. Some whales moved away from the source of the noise and roughly half responded when noise was 20 - 30 dB above ambient. During some of the playback tests, the call rates of whales decreased, feeding ceased, and cycles of surfacing, respiration and diving may have changed.
The calling rates of whales are affected when in an area where industrial noise is to be found. The calls of whales peaked where increasing noise was present before decreasing. This increase in calling is consistent with previous studies and is seen in many invertebrate groups when individuals wish to maintain communication in a high noise environment. To be heard above background noise, an individual may increase the amplitude of their signal, change the frequency of their signal, or increase the repetition rate of their signal..
Useful links:
-https://www.marineinsight.com/environment/effects-of-noise-pollution-from-ships-on-marine-life/
-https://awionline.org/sites/default/files/uploads/documents/Weilgart_Biodiversity_2008-1238105851-10133.pdf
-http://marineconnection.org/wp-content/uploads/2020/08/Ship-Interactions-noise-pollution-and-disturbance.pdf
-https://www.environmentalpollutioncenters.org/noise-pollution/#:~:text=What%20Is%20Noise%20Pollution%3F%20Noise%20pollution%20is%20generally,of%20how%20long%20or%20consistent%20the%20exposure%20is.
-https://www.iberdrola.com/environment/what-is-noise-pollution-causes-effects-solutions
-https://www.ppsthane.com/blog/how-to-reduce-noise-pollution
Videos:
https://www.youtube.com/watch?v=0f6xWoYfGj0
https://www.youtube.com/watch?v=PHXcnrM65NA
https://www.youtube.com/watch?v=t0DHEldqfIc