Brian Barton
Noise pollution in the ocean is a growing concern, with human activities such as shipping, energy exploration, and military exercises contributing to the increasing noise levels in our oceans. This has severe impacts on marine life, particularly marine mammals such as whales, dolphins, and porpoises, which rely on sound for communication, navigation, and survival. The excessive and unnatural sounds generated by human activities can mask the vocalizations of these animals, disrupting their natural behaviours and impairing their ability to locate mates, find food, and avoid predators. With noise travelling faster in water than in air, the effects of ocean noise pollution extend over vast distances, affecting a wide range of marine ecosystems and species.
| Characteristics | Values |
|---|---|
| Sources of ocean noise pollution | Cargo ships, naval vessels, oil exploration, seismic surveys, wind turbine installation, sonar equipment, pile driving, construction, airguns, seismic tests, oil drills |
| Affected marine life | Dolphins, Whales, Fish, Invertebrates, Porpoises |
| Impact on marine life | Interference with communication, hunting, reproduction, hearing, navigation, feeding, social structure, metabolism, population recruitment, health, and service functions of marine ecosystems |
| Solutions | Slower shipping speeds, quieter technologies, reduced propeller noise, reduced sonar noise, ban on seismic activities for oil and gas exploration, strict environmental impact assessments |
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What You'll Learn
Cargo ships and other vessels
Commercial shipping is the primary contributor to underwater noise pollution in the ocean. A cargo vessel emits around 190 decibels of noise, which is louder than a jet engine at takeoff. The sound of a large ship can mask the natural sounds of marine life, such as whales singing to their mates, and can cause them to leave their preferred habitats. The number of vessels in the world's commercial fleet tripled from 1955 to 2005, and the gross tonnage increased sixfold during the same period. The total carrying capacity of the global fleet nearly quadrupled between 1996 and 2020, with new and larger ships added to accommodate the growing global economy. As a result, noise emissions from shipping are expected to double every 11.5 years, with the largest contributions coming from container ships, dry bulk vessels, and liquid tanker vessels.
The noise produced by cargo ships and other vessels can be attributed to several factors, including the ship's propulsion systems, machinery, and cavitation at the propeller blade tips. Cavitation occurs when the rotating blades cause a local drop in water pressure, leading to the formation of bubbles. The flow of water past the ship's hull also generates broadband sound, especially at higher speeds. The noise level is influenced by various factors, such as ship type, size, hull shape, propulsion system, speed, load, and sea conditions.
The impact of noise pollution from cargo ships and other vessels on marine life has been well-documented. Studies have shown that it can interfere with the natural behaviours and communication of marine mammals, such as whales and dolphins. Noise pollution can drive them away from their feeding and breeding grounds and force them to alter their migration routes. In some cases, sudden and intense noise can lead to strandings, with fatal consequences for the affected animals. Additionally, the death of marine animals can occur hours after exposure to extreme underwater noise due to hemorrhages, changed diving patterns, migration to unfamiliar places, damage to internal organs, and a panic response to foreign sounds.
To address the issue of noise pollution from cargo ships and other vessels, several measures have been proposed and implemented. The International Maritime Organization (IMO) has established guidelines for reducing underwater radiated noise from shipping, including strategies for noise reduction in design, construction, modification, and operation. These guidelines aim to mitigate the adverse impacts of noise on marine life, which include disruptions to critical life functions for a wide range of species, such as marine mammals, fish, and invertebrate species. Additionally, initiatives such as the Blue Speeds campaign advocate for the regulation of underwater noise and promote the reduction of ship speeds to decrease noise emissions. During the COVID-19 pandemic, the reduction in vessel traffic resulted in a decrease in global shipping noise source energy, providing further evidence of the significant impact of shipping on ocean noise levels.
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Military activities
Sonar technology, employed to detect submarines, operates at intensities reaching 240 decibels and screens vast ocean areas. This noise pollution has been linked to abnormal whale strandings, with potential consequences for the overall health of marine ecosystems. Whales play a vital role in these ecosystems, and their stranding can deprive seafloor-dwelling organisms of a critical food source.
Additionally, sonar noise can directly harm whales and dolphins, inducing panic and causing them to ascend or descend too rapidly, leading to decompression sickness and, in some cases, haemorrhaging in the heart and brain. The impact of sonar noise on dolphins is particularly severe due to their reliance on echolocation for hunting and navigation. They may become separated from their pods, leading to population displacement and further challenges in hunting and reproduction.
The use of detonations in military activities, even during peacetime, contributes to underwater noise pollution. These explosions can result from weapon tests, the disposal of old ammunition, firing during manoeuvres, material tests, or assessing the durability of new equipment. The noise generated by these detonations adds to the overall noise pollution in the ocean, exacerbating its adverse effects on marine life.
To address the issue of noise pollution caused by military activities, collaboration between environmental organizations and governmental bodies is essential. Efforts should focus on establishing regulations that balance military operations with the protection of marine ecosystems. By recognizing the impact of noise pollution on marine life and incorporating mitigation strategies, such as limiting noise levels or employing alternative technologies, the negative consequences of military activities on ocean life can be reduced.
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Oil and gas exploration
Seismic surveys, a type of geophysical research activity, are used to map the seafloor and locate oil and gas deposits. These surveys involve blasting powerful air guns every ten seconds and measuring the echoes off the seafloor. This process can severely damage the internal organs of marine life, such as giant squid, and kill zooplankton within a 1.2-kilometre radius of each shot.
The oil and gas industry's activities are widespread, occurring along many continental margins and in major areas such as northern Alaska, the Gulf of Mexico, offshore Venezuela, Brazil, West Africa, the Middle East, Australia, and more. The recent shift towards exploring deeper waters, such as in the deep-water U.S. Gulf of Mexico and offshore West Africa, has brought noise pollution to previously quieter areas.
Noise levels associated with oil and gas exploration can vary depending on the specific company and economic factors. The use of drill ships, floating production systems, and oil tankers in deep-water fields contributes to the noise levels. Additionally, the setting up and operating of offshore drilling platforms generate intense noise.
The impact of noise pollution on marine life is significant. Excessive noise can mask the natural vocalizations of dolphins, whales, and fish, making it harder for them to communicate, coordinate hunts, and detect predators. It can also cause stress responses in fish, disturb nesting habits, affect coordination, and damage hearing. For animals that rely on echolocation, such as whales and dolphins, noise pollution can lead to disorientation and difficulties in hunting and navigating.
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Construction activity
The noise created by construction activity can be wide-ranging in frequency and intensity, from high-intensity and acute sounds to lower-level and chronic noises. These sounds are measured in hertz and decibels, respectively. Construction noise often falls within the 10-100 Hz band, which is also occupied by shipping, explosives, seismic surveying sources, aircraft sonic booms, industrial activities, and naval surveillance sonars. The noise from these activities can extend up to the 1,000-10,000 Hz band, which includes underwater communication and naval tactical sonars.
The introduction of anthropogenic noise from construction activity can have significant impacts on marine life, particularly marine mammals such as whales, dolphins, and porpoises. These animals rely on underwater sound as a primary means of communication, navigation, foraging, and avoiding predators. When construction noise masks these natural sounds, it becomes harder for the animals to hear and locate each other, coordinate hunts, and detect predators. This process, known as "masking," can lead to changes in individual and social behaviour, altered metabolisms, and hampered population recruitment, ultimately affecting the health and functioning of marine ecosystems.
Noise pollution from construction can also cause physical changes in marine organisms, including growth abnormalities and negative immune system responses. Additionally, it can interfere with essential life activities and even cause indirect injuries. For example, sudden and intense construction noise can startle marine mammals, causing them to ascend too quickly and suffer from decompression sickness and skin damage from gas bubble lesions.
To mitigate the impacts of construction activity on ocean noise pollution, several strategies can be employed. Firstly, implementing noise reduction technologies and developing quieter construction techniques can help minimize the sound emitted into the ocean. Secondly, policies and guidelines can be established to regulate and reduce noise levels, such as those proposed by the International Maritime Organization (IMO) for shipping noise. Finally, increasing research funding can lead to a better understanding of the effects of construction noise on marine life and the development of more effective mitigation measures.
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Naval exercises
The impact of naval sonar on marine life has been well-documented, with mass strandings of whales occurring in several regions where sonar exercises are common, including Greece, Madeira, Hawaii, Spain, and the coastal US. Post-mortem examinations of whales stranded in these incidents revealed physical trauma and internal bleeding, indicating the devastating physiological stress caused by intense sound exposure.
To address the issue of noise pollution from naval exercises, there have been suggestions for specific guidelines and modifications. The International Maritime Organization (IMO) has established voluntary guidelines to minimize underwater noise pollution, including modifications to hull designs and the use of quieter propellers. Additionally, shifting navy exercises away from known feeding grounds and tracking whales can help reduce the impact on marine life.
Furthermore, technologies such as bubble curtains, which create barriers of bubbles to absorb and scatter sound waves, can be used during naval exercises to mitigate noise transmission. While some measures have been proposed and implemented, there is still a need for further research and more diverse solutions to effectively address noise pollution caused by naval exercises and protect marine ecosystems.
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Frequently asked questions
Ocean noise pollution is a form of environmental pollution caused by human activities that generate unnatural and excessive sound underwater.
Global shipping, oil and gas exploration, construction, naval exercises, and military sonar are among the biggest contributors to ocean noise pollution.
Marine mammals and other aquatic animals have evolved to rely primarily on sound for communication, navigation, foraging, and avoiding predators. Ocean noise pollution interferes with these critical activities, disrupting their natural behaviors and ability to communicate. It can also cause hearing loss and increase stress and anxiety levels.
Cetaceans (whales, dolphins, and porpoises) are particularly vulnerable to ocean noise pollution as they depend on complex sounds and echolocation to navigate, communicate, and find food. Other marine animals, such as fish and invertebrates, also use sound for basic life functions and are impacted by the increased noise levels.
Organizations like OceanCare and IFAW have been campaigning to reduce noise emissions in the ocean. The International Maritime Organization (IMO) is also working on revising guidelines to reduce noise emissions from shipping, expected to be issued in 2023. Additionally, there is a growing focus on developing quieter technologies and conducting environmental impact assessments for seismic activities.
