Minimizing Underwater Noise: Strategies To Protect Ocean Life

The ocean is a sonic symphony, filled with the whistles and clicks of humpback whales, the grunts of fishes, and the snapping of shrimp. However, human-made ocean noise is threatening this fragile world, with shipping noise, oil and gas exploration, naval sonar training, and construction drowning out the ocean's natural sounds. This noise pollution has harmful effects on marine life, including stress, hearing loss, difficulty feeding and finding mates, strandings, and even death. While there is no international standard for regulating ocean noise, there are some solutions that can help reduce the volume of human-made noise in the ocean, such as redesigning ship propellers, installing acoustic curtains, and reducing shipping speeds. By turning down the volume of human-made ocean noise, we can help protect the fragile and beautiful ecosystem of marine life.

Reduce shipping noise

Shipping noise is one of the most pervasive sources of noise pollution in the ocean. It can have a range of harmful effects on marine life, from whales to invertebrates, by interfering with their daily activities such as feeding, mating, and navigation. Here are some ways to reduce shipping noise and its impact:

Redesign Propellers and Hulls

Redesigning ship propellers to address the issue of cavitation can significantly reduce noise levels. Cavitation is the formation and implosion of water vapor cavities caused by pressure variations during water movement across a propeller blade, resulting in broadband noise. By investing in more advanced propeller designs, shipping companies can minimize cavitation and, consequently, the hydroacoustic noise generated. Additionally, modifying the hull design to increase water flow into the propeller can also help drop cavitation levels.

Implement Slow Steaming

Reducing the speed of ships is a simple yet effective strategy to mitigate noise pollution. Slower-moving vessels produce lower decibel levels and reduce the overall acoustic footprint. This approach has the added benefit of decreasing fuel consumption and lowering harmful emissions.

Use Energy-Saving Devices

Energy-saving devices (ESDs) can be attached upstream of the propeller to improve its internal efficiency and reduce propeller loading, resulting in less cavitation. Retrofitting these devices to existing vessels provides a practical solution to extreme cavitation issues.

Acoustic "Curtains"

Installing acoustic "curtains" made of perforated pipes that blow a wall of air bubbles can absorb and refract noise, significantly reducing noise levels. This method has been successfully employed during pile-driving at offshore wind farms, reducing acoustic energy by up to 95%.

Reroute Shipping Lanes

Rerouting shipping lanes away from sensitive marine ecosystems and the habitats of endangered species can help minimize the impact of noise on these vulnerable areas. This strategy has been successfully implemented in some regions, such as the Vancouver Fraser Port Authority in British Columbia, where ships voluntarily reroute to avoid the feeding areas of endangered killer whales.

Reduce oil and gas exploration noise

Oil and gas exploration activities are a major source of ocean noise pollution, which poses a significant threat to marine life. The use of air guns for seismic surveys emits noise of up to 260 decibels, raising background noise levels that can be deadly for marine species, from crustaceans to whales.

To reduce noise pollution from oil and gas exploration, there are several measures that can be implemented:

• Adopting Quieter Technologies: Marine vibroseis is a promising alternative to traditional airguns used in seismic surveys. It produces less noise while generating equal or better seismic data. This technology uses vibrations instead of compressed air pulses, resulting in a continuous, lower-amplitude signal that reduces overall sound pressure levels.
• Incentivizing Quieter Practices: An incentive-based approach, following the polluter-pays principle, can be implemented. Revenue from levies on oil and gas companies can be used to fund the development of alternative technologies and research on the impacts of surveys on marine life.
• Regulating Noise Levels: Regulatory pressure is necessary to encourage the adoption of quieter technologies. Policies should be crafted to set specific limits on noise emissions, with economic incentives for companies that go beyond these limits.
• Spatiotemporal Restrictions: Implementing restrictions on seismic survey activities in certain areas during sensitive periods, such as fish spawning season, can help reduce the impact on marine life. For example, temporarily halting a survey if a whale is detected within a certain radius.
• Noise Dispersal Techniques: In some cases, using additional noise to disperse animals before emitting noise at more harmful levels can be considered. However, this approach should be carefully evaluated, ensuring that it does not cause long-term harm and is based on sufficient and up-to-date data.
• Collaboration and Research: Oil and gas companies can collaborate with researchers and marine life advocates to identify and implement best practices for noise reduction. This includes funding research to better understand the impacts of noise on different marine species and developing technologies to mitigate these impacts.

By implementing these measures, it is possible to reduce the noise pollution associated with oil and gas exploration activities, minimizing the harmful effects on marine ecosystems.

Reduce naval sonar noise

Naval sonar noise is a significant contributor to ocean noise pollution, which has harmful effects on marine life. To reduce naval sonar noise, several measures can be implemented:

Redesigning Ship Propellers

Redesigning ship propellers can help lower the volume of noise generated by naval vessels. Propeller cavitation, a design issue that causes a breakdown in water flow over the blades, is a major source of noise. By addressing this issue, naval forces can significantly reduce the noise produced by their ships.

Acoustic Curtains

The use of acoustic "curtains", such as bubble curtains, can be employed to dampen the noise created by naval activities. These curtains consist of perforated pipes that release a wall of air bubbles, which absorb and refract the noise, resulting in a significant reduction in acoustic energy.

Ship Speed Restrictions

Slowing down the speed of naval vessels can also help reduce sonar noise. Studies have shown that slower-moving ships produce lower cumulative sound exposure levels, creating quieter periods that benefit whale communication and behaviour.

Regular Maintenance

Regular maintenance and monitoring of naval equipment can help identify and address noise-generating components. This includes the repair or replacement of faulty isolation devices, bearings, valves, and other machinery that may contribute to unwanted noise.

Noise Control Features

Naval forces should also invest in building noise control features into their ships. This includes the use of sound isolation devices, resilient mounts, distributed isolation materials, and flexible piping connections to minimize the transmission of noise.

Quiet Ship Procedures

Implementing quiet ship procedures can help reduce both sonar self-noise and radiated noise. This includes optimizing equipment lineup and speeds, as well as ensuring cavitation-free operation of pumps and piping to minimize noise emissions.

By adopting these measures, naval forces can play a crucial role in reducing sonar noise pollution, protecting marine life, and promoting a healthier ocean ecosystem.

Reduce construction noise

Construction noise is one of the many human-caused sources of ocean noise pollution, which has harmful effects on marine life. Here are some ways to reduce construction noise in the ocean:

Redesign and Optimise Construction Equipment

The equipment used in construction activities can be redesigned or modified to reduce noise emissions. For example, pile drivers, which are commonly used in the construction of offshore wind farms, can be surrounded by acoustic "curtains" or bubble curtains to absorb and refract the noise, resulting in a significant reduction in noise levels. Additionally, construction companies can invest in modern and quieter equipment, such as electric and hybrid models, to minimise noise pollution while maintaining operational efficiency.

Implement Best Practices for Underwater Noise Management

Construction companies should adopt best practices for underwater noise management during construction activities. This includes conducting thorough environmental impact assessments, selecting appropriate construction sites away from sensitive marine habitats, and implementing noise reduction technologies. Collaborating with governments, researchers, and other stakeholders is crucial to stay informed about the latest advancements and guidelines in underwater noise management.

Prioritise Green Engineering and Sustainable Practices

Construction companies can prioritise green engineering practices by transforming or adapting machinery and equipment to be more sustainable and silent. This includes engines, hydraulic systems, ventilation systems, and pumps. Additionally, innovative isolation solutions can be developed to minimise noise emissions. By integrating sustainability into their construction processes, companies can contribute to both noise reduction and environmental conservation.

Optimise Construction Traffic and Scheduling

Construction activities often involve a significant amount of traffic and machinery movement. To reduce noise, it is essential to optimise the traffic arrangement and scheduling. This can be achieved by minimising the number of ships or vehicles operating simultaneously and reducing queuing in port waters. Advanced management techniques can help reduce the overall noise generated by construction operations.

Continuous Monitoring, Research, and Collaboration

To effectively reduce construction noise, it is vital to continuously monitor noise levels and sources. Port operators can invest in connected sensors to assess the intensity, quantity, and root causes of noise emissions. Additionally, construction companies can collaborate with researchers and scientists to develop and implement noise reduction technologies specifically for construction activities. By staying informed about the latest advancements and working together with stakeholders, construction companies can play a crucial role in reducing their noise impact on marine life.

Implement policy changes

Policy changes are essential to reducing ocean noise pollution and its harmful effects on marine life. Here are some detailed suggestions for implementing such changes:

Command-and-Control (CAC) Strategies

CAC strategies involve setting specific limits on the amount of noise pollution emitted by various industries. While these strategies offer no incentives for going beyond the set limits, they provide a clear framework for noise reduction. Governments can implement CAC policies by enacting laws and regulations that:

• Impose strict noise limits on commercial shipping, the most widespread source of underwater noise.
• Regulate the use of seismic air guns in surveys, mandating the use of quieter alternatives like marine vibrator systems or marine vibroseis.
• Restrict pile driving activities, especially in ecologically sensitive areas, and encourage the use of alternative methods like BLUE piling.
• Implement speed restrictions on ships, as slower speeds significantly reduce noise levels.
• Establish acoustic refuges and buffer zones around marine protected areas to minimize noise intrusion.

Incentive-Based Measures (IBM)

IBM approaches provide more flexibility to industries and can encourage noise reduction through economic incentives. Some possible IBM policies include:

• Cap-and-trade systems, where companies can trade pollution permits, creating a market-based approach to reducing noise pollution.
• Emissions subsidies or taxes, providing financial incentives for companies to reduce noise emissions.
• Polluter pays principle (PPP), where levies are imposed on noise polluters, and the revenue is used to develop quieter technologies and study the impacts of noise on marine life.
• Incentivizing the use of fewer, larger vessels in shipping, as larger ships produce less noise.
• Encouraging offshore wind farm developers to adopt alternative foundations, such as floating bases, and acoustic barriers like bubble curtains to reduce construction noise.

International Cooperation

Ocean noise pollution is a global issue, and addressing it effectively requires international cooperation. Governments and organizations should work together to:

• Develop and adopt international standards and best practices for reducing ocean noise, such as the "best available technologies" and "best environmental practices" referenced in agreements like the Convention on the Conservation of Migratory Species of Wild Animals (CMS).
• Share research and data on ocean noise pollution and its impacts, ensuring that policies are informed by the best available science.
• Establish international agreements and treaties specifically targeting ocean noise reduction, similar to those addressing other forms of environmental pollution.

Public Education and Advocacy

Educating the public about the harmful effects of ocean noise pollution can help build support for policy changes:

• Governments and conservation organizations can launch awareness campaigns to inform people about the issue, emphasizing the impact of noise on marine life and the potential solutions.
• Marine life advocates can play a crucial role in pushing for stronger policies and bringing public attention to the issue.
• Encouraging public support for renewable energy sources, such as offshore wind farms, can help drive the adoption of quieter construction methods and technologies.

By implementing these policy changes and working together globally, we can effectively reduce ocean noise pollution and protect the diverse and vulnerable marine ecosystems that depend on sound for their survival.

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