Human Activities: Ocean Noise Pollution Culprits

Marine noise pollution is a growing concern, threatening the natural soundscape of the ocean and causing severe damage to marine wildlife. Human activities such as commercial shipping, oil exploration, seismic surveys, and military sonar generate excessive and unnatural sounds that interfere with marine species' ability to communicate, navigate, and survive. The impact of these noises can be immediate, causing hearing loss, altering behaviours, and even leading to the death of marine animals. With noise levels in some ocean regions doubling every decade since the 1950s, addressing marine noise pollution is crucial to protect the health and biodiversity of our oceans.

Commercial shipping

The impact of commercial shipping noise on marine life is significant. Marine mammals, such as whales, dolphins, and porpoises, rely on sound for critical activities like breeding, foraging, maintaining social structure, and avoiding predators. They use complex vocalizations to communicate with each other and navigate their environment. When ship noise overwhelms or masks these natural sounds, marine animals can struggle to hear and find each other, coordinate hunts, and detect predators. For example, increased ship noise has caused bottlenose dolphins to simplify their vocal calls, potentially reducing the effectiveness of their communication.

Noise from commercial shipping can also cause behavioural changes in marine life. Some species may move away from noisy areas, adjust their activities to avoid loud times of day, or increase their anti-predatory behaviour. In an experiment, blue whales were observed to stop feeding, swim faster, and move away from the sound source when exposed to sonar, even at much lower sound levels than military sonars. Additionally, noise pollution can lead to elevated stress levels in marine mammals, making them more vulnerable to other challenges like water pollution and climate change.

The International Maritime Organization (IMO) has recognized the adverse effects of commercial shipping noise on marine life and has issued guidelines to reduce underwater noise. These guidelines aim to assist designers, shipbuilders, and ship operators in implementing noise reduction measures. Local governments and individual ports have also established their own regulations, such as the Port of Vancouver offering discounts to vessels that voluntarily comply with environmental guidelines. While these efforts are a step in the right direction, the lack of international standards for regulating ocean noise pollution remains a concern.

Oil exploration

Seismic surveys and air guns used in oil exploration are among the loudest human-generated activities in the ocean. These activities can produce noise levels of up to 260 decibels, which is much louder than a plane taking off or a rock concert. The intense low-frequency noise generated by these activities can be heard over thousands of kilometres in the ocean and has been detected as far away as 4,000 kilometres from the source.

The use of air guns in oil exploration involves firing pressurized air towards the ocean floor to create acoustic patterns that help map the location of oil and gas deposits. This process is extremely loud and disruptive to marine life, with air guns firing around the clock for months at a time. The noise from these activities can mask the natural sounds and vocalizations that marine animals use for communication, navigation, and foraging.

The increasing noise pollution from oil exploration and other human activities in the ocean has severe consequences for marine ecosystems. As many marine species rely on sound for critical activities such as breeding, foraging, and maintaining social structures, the disruption caused by oil exploration can lead to changes in behaviour, altered metabolisms, and impaired population recruitment. The complex and interconnected nature of marine ecosystems means that the effects of noise pollution on one species can have far-reaching impacts on others.

Military sonar

The powerful sound waves produced by military sonar can have detrimental impacts on the behaviour, health, and survival of marine mammals. Studies have shown that exposure to sonar can alter the feeding behaviour of whales, even at sound levels much lower than those of military sonar. For example, in an experiment conducted in Southern California, blue whales were observed to stop feeding, increase their swimming speed, and move away from the source of sonar sounds.

The intense noise from military sonar can also cause whales to rapidly change their depth, leading to physical injuries such as bleeding from the eyes and ears. In some cases, whales have been known to beach themselves in an attempt to escape the sound, which can result in stranding and even death. In January 2005, 34 whales from three different species died after stranding along North Carolina's Outer Banks during Navy sonar training.

While the direct physiological effects of sonar on marine species are not fully understood, there is evidence that the loud and low-frequency sounds produced by military sonar can interfere with the natural behaviours and communication of marine mammals. The noise can mask their vocalizations, making it difficult for them to hear, find each other, coordinate hunts, and detect predators. This is especially problematic for species that rely on echolocation, such as dolphins and toothed whales.

The use of military sonar has been a subject of controversy, with environmental groups campaigning to ban or restrict its use in areas rich in marine wildlife. Despite legal challenges, the military continues to test and use sonar, citing national security concerns. However, there is a growing recognition of the need to understand and mitigate the impacts of ocean noise pollution on marine life. Initiatives such as the development of a "noise budget" for the oceans and the implementation of local regulations aim to address this complex issue.

Seismic surveys

Marine seismic surveys are a major source of noise pollution in the oceans. They involve the use of airguns to map the seabed and explore for hydrocarbons. These airguns produce high-intensity, low-frequency impulsive sounds, with sound source levels typically reaching 248–255 dB re 1 µPa-m. This noise pollution has been shown to negatively impact a diverse range of species, including fish, invertebrates, zooplankton, and marine mammals.

The noise from these surveys can interfere with the natural behaviours and communication of marine mammals, masking their ability to hear natural sounds in the ocean. This disruption can affect their breeding, foraging, social structure, and ability to avoid predators. For example, seismic survey noise has been shown to negatively affect humpback whale singing activity and alter blue whale acoustic communication.

In addition to the direct impacts on marine life, seismic surveys can also have indirect effects. For instance, loud noises can cause hearing loss and lead to decompression sickness and skin damage if animals ascend too quickly to escape the noise. The response of sea turtles to seismic survey noise has not been extensively studied, but airgun surveys have been found to cause temporary hearing damage in these animals.

While there are currently no international standards for regulating ocean noise pollution, some local governments and individual ports have established their own regulations. Global spending on seismic data acquisition has been increasing, with US$10 billion spent on marine seismic surveys in 2013. More research is needed to fully understand the broad-scale ecological impacts of seismic surveys on marine ecosystems.

Construction

The natural soundscape of the ocean, with its waves, wind, and the vocalizations of whales and other marine life, is being drowned out by the noise from human activities, including construction. This noise pollution has severe impacts on the marine ecosystem, as many marine animals depend heavily on sound for their survival. They use sound to communicate, locate mates and prey, avoid predators, navigate, and defend their territories.

To mitigate the impact of construction on marine noise pollution, several measures can be implemented. These include the use of "bubble curtains" to muffle construction noise, modifying and retrofitting propellers, and operational changes such as slowing down ships to reduce noise output. Implementing policies that mandate acoustic mitigation in the marine environment and establishing noise standards for ships, similar to those for cars and trucks, are also crucial steps toward reducing construction-related noise pollution.

Additionally, it is important to identify critical or sensitive marine habitats and ensure that these areas are off-limits to intense noise-generating activities, including construction. By taking these steps, we can work towards reducing the detrimental effects of construction noise on marine life and help restore the natural soundscape of the ocean.

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