With the progress of human civilization, sonar technology is extensively used for navigation, fishing, and marine geological exploration. Similarly, machines are employed for underwater oil and gas exploration, resembling their land-based counterparts in construction activities.
However, these machines operating in the ocean emit various frequencies and levels of noise, contributing to significant noise pollution in the oceans.
The impact of noise on marine life is profound, altering the behavior of marine animals. It can lead to changes in swimming and diving patterns, modifications in vocalization characteristics such as volume and rhythm, and even fatal collisions when animals are unable to avoid obstacles.
For instance, beluga whales, known for their vocalizations, are highly sensitive to noise pollution. When a ship is 50 kilometers away, beluga whales display specific reactions such as swimming away, breaching the water to breathe, and altering their diving patterns.
Over time, these disturbances can result in population decline and a change in vocalizations, making them more high-pitched.
Scientists attribute this behavior to sonar noise interfering with whales' and dolphins' ability to use sound for hunting and causing fear among certain cetaceans, particularly those prone to breaching.
Noise exposure also impacts the hearing of marine animals. High-intensity sounds can lead to temporary hearing loss or reduced sensitivity. In extreme cases, permanent hearing loss or reduced sensitivity can occur.
Research conducted on the effects of underwater pile drivers during offshore wind farm construction revealed that broad-snouted dolphins within a 100-meter range of the site experienced hearing organ damage, while dolphins within a 50-kilometer radius displayed erratic behavior or were compelled to avoid the area.
Moreover, studies on cephalopods exposed to low-frequency noise (similar to that generated by oil and gas exploration) demonstrated varying degrees of damage.
Autopsies conducted on these animals revealed equilibrium-related impairments, including the disappearance of small hair-like structures in the cells.
The damage worsened over time, with more severe equilibrium damage observed in animals dissected 96 hours after exposure. At the end of their lives, the animals exhibited minimal movement, no longer swimming or eating.
Noise pollution can also lead to biological deaths among marine organisms. Sonar, in particular, has been linked to long-term behavioral changes, hearing loss, and even mortality.
Studies have consistently shown a strong connection between sonar and whale deaths, including mass strandings and fatalities caused by mid-frequency sonar testing.
Marine noise pollution has far-reaching and intricate consequences, affecting various aspects of marine life. Sudden noises startle marine animals, causing them to abandon their regular feeding areas, leading to food scarcity.
Frequent noise can also put fish on high alert, forcing them to spend more time on guard duty and reducing their ability to feed and care for their young.
