The Hidden Impact: Noise Pollution's Effect On Marine Life

Ocean noise pollution is one of the deadliest threats to marine animals. Human activities such as shipping, boating, and energy exploration have increased noise levels in the ocean, interfering with the ability of marine animals to hear natural sounds. This disruption can negatively impact their survival and reproduction. Marine animals rely on sound to communicate, locate food and mates, and avoid predators. Noise pollution can cause behavioural changes, hearing loss, injury, and even death. It is important to address this issue through awareness, legislation, and technological advancements to reduce noise levels and protect marine life.

Marine mammals are harmed by loud noise

Over the last few decades, noise pollution in the marine environment has increased dramatically, threatening the natural soundscape of the ocean. Ships, seismic surveys, explosions, construction, and sonar devices have turned the once peaceful ocean into a loud, chaotic environment, which is extremely harmful to marine wildlife.

Loud noises can cause hearing loss in marine mammals, and when sound is one of their primary tools for survival, this can be fatal. If a marine mammal is too close to the source of a loud sound, it may panic and ascend too quickly, causing decompression sickness and tissue damage from gas bubble lesions. Naval sonar devices, which work similarly to echolocation used by whales and dolphins, are particularly dangerous and have been linked to mass stranding events around the world.

Noise pollution can also interfere with the detection of acoustic signals in the marine environment, masking the sounds produced by marine wildlife. This can lead to changes in individual and social behaviour, altered metabolisms, and hampered population recruitment, which can affect the health and service functions of marine ecosystems. For example, increased ship noise has caused bottlenose dolphins to simplify their vocal calls, potentially reducing the information content of their calls and decreasing effective communication.

To protect marine mammals and reduce the impact of noise pollution, policies and technologies are needed to mitigate propeller noise from ships, sonar equipment, seismic air guns, pile driving, and construction.

It can alter their behaviour

Noise pollution can alter the behaviour of marine life in several ways. Firstly, it can cause marine animals to move away from the source of the noise, fleeing their original habitats and feeding grounds, which can lead to death or injury. This is particularly true for whales, which have been known to beach themselves after tactical sonar exercises.

Secondly, noise can cause marine animals to adjust their activities to avoid noisy times of day. For example, blue whales have been observed to stop feeding and increase their swimming speed in response to active sonar, which can have significant impacts on their individual fitness, foraging ecology, and population health.

Thirdly, noise pollution can increase anti-predatory behaviour in marine animals. This is because sound is an important sensory signal for marine wildlife, particularly for marine mammals such as whales, dolphins, and porpoises, who rely on sound to communicate, locate mates and prey, avoid predators, navigate, and defend their territories. When this sensory signal is disrupted by noise pollution, it can cause confusion and disorientation in marine animals, leading to an increase in anti-predatory behaviours.

Additionally, noise pollution can interfere with communication between marine animals. It can decrease the communication range of marine mammals and cause them to change their vocal behaviour. For example, increased ship noise has been shown to simplify the vocal calls of bottlenose dolphins, which may reduce the information content of their calls and decrease effective communication.

Finally, noise pollution can also affect the reproduction cycle of marine animals. Marine mammals rely on underwater sounds to locate mates and reproduce, so insufficient mechanisms to safeguard them against underwater noise pollution can disrupt their life cycles and reproduction strategies.

Communication is hindered

Marine animals rely heavily on sound for their survival. Visibility is often low underwater, but sound is transmitted extremely well and has therefore become an important sensory signal for marine wildlife. Many marine species use sound to locate mates and prey, avoid predators, navigate, and defend their territories.

Noise pollution interferes with the detection of these acoustic signals, masking the sounds produced by marine wildlife. This leads to changes in individual and social behaviour, altered metabolisms, and hampered population recruitment, which in turn can affect the health and service functions of marine ecosystems.

Marine mammals may compensate for noise by changing their vocal behaviour. For example, increased ship noise has caused bottlenose dolphins to simplify their vocal calls. Higher whistle frequencies and a reduction in whistle complexity were recorded, and this simplification may reduce the information content of their calls, thereby decreasing effective communication. Other changes include making signals longer, increasing the volume of their calls, shifting their sound frequency, or waiting until the noise has passed before signalling. However, these adjustments can be costly.

Noise pollution does not just decrease the communication range of marine mammals; it also disrupts the regular communication between other marine animals, such as fish and sea turtles. They become unable to call their mates, look for food, or make a cry for help.

Overall, noise pollution has a significant impact on the communication of marine wildlife, affecting their ability to gather information about their environment and connect with others in their community.

Reproduction cycles are affected

Noise pollution has a detrimental impact on the reproduction cycles of marine life.

Marine mammals and other aquatic animals have evolved to use underwater sound as a primary means of communication and environmental assessment. Sound is essential for critical activities such as breeding, foraging, and maintaining social structure. For example, cetaceans (whales, dolphins, and porpoises) use complex sounds to communicate, navigate, and find food.

Noise pollution interferes with these vital functions, affecting the health and service functions of marine ecosystems. It can cause auditory masking, where the perception of one sound is affected by the presence of another, and physiological damage to the hearing system. This can lead to changes in individual and social behaviour, altered metabolisms, and hampered population recruitment, ultimately impacting reproduction cycles.

Underwater noise can lead to reduced communication in whales and dolphins, negatively impacting their reproduction. It can also cause stress responses in many fish species, increasing cortisol levels and impairing their ability to assess risk. For instance, cod exposed to noise produced eggs with higher cortisol levels, resulting in a 40% lower fertilization rate and a 50% decrease in viable egg productivity.

Noise from boats and ships can also reduce nest care in fish, increasing brood mortality and further impacting reproduction. Additionally, the presence of boat noise has impaired the risk assessment abilities of damselfish, likely affecting their survival and reproduction.

The impacts of noise pollution on reproduction cycles are not limited to marine mammals and fish. Marine turtles, for instance, may use the sound of surf breaking to orient themselves towards nesting beaches, suggesting that noise could affect their breeding success.

It can cause death

Marine life is extremely sensitive to sound, even low-frequency noise, which is inaudible to humans. As most marine species are highly dependent on sound for their survival, noise pollution is extremely damaging to marine wildlife and can even cause death.

Hearing Loss

Loud noises can cause immediate hearing loss in marine animals, and when sound is the primary tool for survival in the ocean, this can be fatal. For example, whales and dolphins use echolocation to navigate and hunt, and if they are unable to hear properly, they may beach themselves.

Decompression Sickness

If a marine animal is too close to the source of a loud sound, it may panic and ascend too quickly to escape the noise. This can cause decompression sickness, which can lead to tissue damage from gas bubble lesions.

Mass Strandings

There have been reports of mass strandings of whales and dolphins in regions where sonar exercises are common, such as Greece, Madeira, Hawaii, Spain, and the coastal US. The number of strandings that have been recorded is likely only a small percentage of what's actually happening, as severely injured animals rarely make it to shore.

Hemorrhages and Organ Damage

Underwater noise pollution can cause hemorrhages, changed diving patterns, migration to new places, and damage to internal organs. The stress and panic response to foreign sounds can be deadly.

Embryonic Stage Exposure

Exposure to noise during the embryonic stage increases the sensitivity of fish to noise impact, raising mortality rates at birth and the development of genetic anomalies.

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