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Noise pollution is the unwanted and disturbing sound intensity or volume that may lead to negative effects on one’s health and well-being. Just as noise pollution is a known and pressing problem for animals on land, the same is true for many marine animals. Many marine animals rely on their ability to hear for their survival. By emitting short pulses of sound, they listen for echoes in order to find their prey, navigate around certain objects, or find potential mates and create offspring in a process known as echolocation. However, this vital ability that helps ensure their survival is largely obstructed due to the increasing amount of ocean noise caused by human activities.
Propellor Noise and Cavitation
When the propellers of a ship rotate underwater to propel it forward, water is forced to flow very quickly around the propellers. This ultimately creates a few low-pressure areas. When pressure is reduced to a critical value, bubbles form, and then these bubbles suddenly collapse, a loud acoustic sound is created. This process is known as cavitation, and the underwater noise it creates could harm marine animals. The amount of noise that these propellers can create depends on the size of the propellers as well as the speed at which they rotate.
Seismic Surveys (248 dB - 255 dB)
Seismic surveys play a crucial role in helping us gain an understanding of what lies within the Earth’s subsurface. Through seismic surveys, it is possible to locate groundwater, investigate appropriate locations for landfills and predict how earthquakes could affect certain areas. However, it is impossible to conduct these surveys without blasting the seafloor with high-powered airguns every ten seconds to measure the echoes. As such, it really comes as no surprise that this type of forceful surveying would inevitably cause a lot of noise pollution for any nearby marine animals.
Underwater construction (> 200dB)
As humanity’s population is set to only increase in the future, the natural inclination to explore alternate ways of creating buildings has started to arise. One avenue of thought is to start building underwater. However, just as above-ground construction may feel loud to a passerby, underwater construction is a source of noise pollution as well as to any nearby marine animals. Furthermore, hammering down giant steel piles into the ocean floor in order to secure and support buildings, docks, and piers ultimately creates an incredible amount of noise in the marine environment.
Solutions and mitigation
In order to reduce and mitigate the severity of ocean noise pollution, practices such as modifying propellers and performing regular maintenance have become regulated. The faster and larger ships are, the more noise they create. As such, organizations such as OceanCare are campaigning for reducing vessel speed as it is believed to be the most
effective measure in reducing underwater noise. Bubble curtains are a way to dampen the noise that is created through pile driving. Placing several perforated pipes that create bubbles around the pile driver, a wall of air bubbles is formed. This wall will help refract the noise and reduce it by as much as 15
In conclusion, the well-being of marine animals not only contributes to aquatic life, but to the ecosystem above ground as well. The ocean provides humans with food to eat, works to regulate climate, and also generates a substantial amount of oxygen for life on land. Ensuring that marine animals live in a safe environment in which they are able to survive helps maintain the ocean as a sustainable resource for the human population now and in the future.
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References:
Mark, Hannah. “Hate construction noise? Turns out marine animals aren't fond of it either. –
Broader Impacts Group.” WHOI Websites, 23 October 2017,
Polidoro, Joseph. “A Few Fixes Could Cut Noise Pollution That Hurts Ocean Animals.”
Scientific American, 23 February 2021, https://www.scientificam erican.com/article/a-
“Seismic Blasting.” Center for Biological Diversity,
“What is ocean noise?” National Ocean Service, 20 January 2023,