Today, underwater noise has become one of the main problems facing marine wildlife. This problem, together with the growing pollution of the oceans, has a negative impact on the marine ecosystem, putting all its inhabitants at risk.

Chile’s seas have been suffering from this problem for several years, mainly due to the high volume of maritime traffic in the area. All of this has had multiple consequences for the species that inhabit the area, especially on their hearing systems.

Next, we will talk about the impact that underwater noise has on the ecosystem, its main causes and how to reduce its pollution levels.

How underwater noise impacts aquatic species

To understand how underwater noise influences the life of aquatic species, we need to understand how sound behaves underwater. In this way, we will understand why ocean noise pollution is a problem that must be tackled before it is too late.

How does sound behave underwater?

Due to the difference between the density of air and water, the behavior of sound in both media is totally different. Some of these differences are:

• The speed of sound in water is 4 times the speed of sound in air.
• Due to these propagation velocities, sound waves are of greater magnitude in water than in air.
• In water, sound is able to reach much farther than air and can propagate for many kilometers.

What impact does noise have on marine wildlife?

Underwater noise in Chile is an issue that can have catastrophic consequences if not addressed in time. An increase in underwater noise impedes the normal development of species by modifying their behavior.

In the oceans, the life of their inhabitants depends mainly on their auditory system, even more than on their vision. Because of this, increased underwater noise pollution can be the cause of various problems such as disorientation.

Disorientation in marine species makes daily tasks such as finding food, migration and even reproduction difficult. Noise pollution generates cumulative damage, which means that if it persists for a prolonged period of time it can lead to permanent hearing loss.

Main sources of underwater noise in Chile

Globally, the main cause of underwater noise is the increase of human activities in the oceans. This intensification of maritime activities has been occurring for the last 100 years, introducing various types of artificial noise into the marine ecosystem.

So far, the main causes of anthropogenic underwater noise are:

• Ship traffic. According to different studies, maritime traffic is the main source of continuous noise worldwide. This noise comes not only from the engines that drive the vessels, but also includes the sonar navigation systems used for different purposes.
• Pile driving operations. This activity generates high levels of impulsive noise. To reduce their acoustic impact on marine fauna, the use of microbubble air curtains applied around these construction sites, which attenuate sound propagation by acting as an acoustic barrier, has recently increased.
• Truncations. Underwater blasting is one of the largest sources of anthropogenic noise, generating sound pulses that can propagate over great distances.
• Dredging and construction. Dredging and tunnel construction both in and near the sea generate sonic waves and vibrations that result in significant underwater noise pollution.
• Noise produced by drilling in oil and gas production.
• Noises generated in geophysical investigations. On some occasions, certain studies require the generation of seismic waves that are produced by very loud noises of short duration. Some methods used to generate such noises are air cannons, gas cannons, explosives, and sea floor pounding.
• Submarine eruptions and earthquakes. Although they do not depend on us, when they occur they provoke great expansive waves capable of destroying everything in their path.

How can underwater noise be reduced?

Since underwater noise pollution is mainly caused by human activity, measures to reduce it are also up to us. One of the main recommendations made by underwater noise specialists is to reduce the noise generated by vessels.

To achieve this goal, various measures have been proposed for the protection of aquatic species around the world. One of them is the use of electric motors instead of the traditional combustion engines found in ships.

On the other hand, the reduction of vessel speed has also been studied in order to reduce the shock waves they produce. Another alternative for the protection of marine fauna would be the implementation of new laws and regulations to regulate man-made underwater noise levels.

How is underwater noise legally regulated in Chile?

Although there is currently no specific law in Chile regulating underwater noise emissions, the issue is addressed by other legislation. According to Law 19,300 of the Ministry of the Environment, any project that may generate adverse effects on the marine ecosystem must present an environmental impact study in reference to international standards before being executed.

At present, there are several international studies and documents developed in this field, such as the Technical Guide for the Evaluation of Anthropogenic Noise Effects on Marine Mammals (United States) or the Guide to Underwater Noise from Pile Driving (Australia).

On the other hand, the Operational Committee for the Control of Underwater Noise seeks to reduce the impact of underwater noise on Chilean ecosystems. This committee is composed of various state institutions and seeks to strengthen protection against noise pollution of the seas.

Underwater noise is everyone’s problem

Underwater noise pollution is not only a problem in Chile. On the contrary, its negative effects are damaging marine ecosystems around the world and a concerted effort is required to control it.

Various initiatives have been implemented around the world to minimize the amount of noise reaching the oceans. It only remains for us to become aware of how noise can affect entire ecosystems and harm the well-being of various marine species.