Today, underwater noise pollution is a scourge for aquatic ecosystems. Invisible but real, it is, because of human activities, a major threat to the marine environment.
Underwater noise pollution is a little-known phenomenon. Yet, it is a real catastrophe for the environment. Sound is essential for marine animals to communicate, locate and feed. In the calm of the seas and oceans, human activities spread sound underwater, up to several hundred kilometers away. This is because sound travels much faster underwater than in the air.
3 Types of underwater noises
There are three types of underwater sound:
- Geo-phonics : it includes sounds arising from natural activity, such as rain or falling ice in the water.
- Bio-phonics : it concerns the sounds emitted by marine animals. Marine sounds are vital to the underwater ecosystem, as they enable animals to communicate with each other to locate fellow creatures or food.
- Anthropophony : it covers sounds emitted by human activity, causing underwater noise pollution.
Humans: the main cause of animal pain
Global maritime traffic noise’s dazes the oceans
Human presence at sea has increased sharply since the advent of globalization. Humans are constantly active at sea. This presence results in noise pollution that disrupts the marine ecosystem. Maritime trade, an essential cog in our economy, is largely responsible for underwater noise pollution. According to UN statistics, in 2023, 106,715 ships were in perpetual circulation. If sea transport accounts for 90% of the movement of goods and food, these movements are a burden on marine animals. The engines of these ships can easily produce more than 190 decibels. By comparison, the human ear is capable of handling 160 decibels maximum.
The injurious oceans exploitation of humans
This increase in production and trade translates into a growing need for natural resources. To this end, mankind has developed offshore oil and gas exploitation. In oil prospecting, an explosion is directed towards the seabed to obtain an echo and samples of the sediment to determine its composition. These operations are very noisy, and can reach 260 decibels.
In this capitalist quest at the expense of the underwater ecosystem, recreational and tourist activities are also guilty of noise pollution. Jet ski sessions and underwater excursions, for example, are a major source of noise pollution.
Military activities can kill…whales
Military activities add to this worrying toll. Between warships, maritime training, sonar and underwater explosions, the world’s armies are making a major contribution to the erosion of the marine ecosystem. As early as 1996, the extremely powerful Low Frequency Active Sonar was responsible for the stranding of 12 beaked whales off the coast of Greece. Sonar, essential for detecting enemy military vessels, can reach 235 decibels and be heard 160 kilometers away.
Underwater noise pollution: a global suffering
The submarine ecosystem mentally affected
As a result, the impact of underwater noise pollution is terrible. Marine animals are considerably affected by sound vibrations. These disturb the entire underwater ecosystem, starting with the food chain. For example, blue whales use vocalizations to locate their food and inform other whales of their food source. Underwater sound waves produced by humans temporarily or permanently deafen marine mammals. Noise pollution complicates communications, forcing whales to refrain from feeding or to change their behavior. As a result, some species are forced to leave their habitat for quieter areas. Such is the case of the gray whales of the Huerrerro Negro lagoon in Baja California, Mexico. This community has been forced to abandon their territory due to extremely noisy shipping and dredging activities.
Underwater noise pollution destroyed the submarine ecosystem
Noise pollution causes physiological stress in underwater species. Sperm whales subjected to military sounds change their behavior abruptly, making shorter dives, both in terms of immersion time and depths reached. This is highly detrimental to their lifestyle, which requires space and a relatively long hunting time. In right whales, sound vibrations in excess of 133 decibels cause them to return to the surface more quickly. This panic is not insignificant. In fact, sound waves create nitrogen bubbles if their intensity exceeds 200 decibels. This leads to an increase in pressure, which, coupled with the animals’ rapid ascent to the surface, can cause pulmonary embolism and even lesions in vital organs. Underwater noise pollution is therefore not only a threat to the animals’ way of life, but also to their lives and society.
Between issues and solutions, what is the future of underwater noise pollution ?
Human activities at sea, whatever their type, are a definite environmental disaster. The resulting noise pollution is too much for marine animals to bear. An entire ecosystem on a global scale is threatened and affected by this phenomenon. Animals are affected both physically and mentally. As we have seen, underwater noise pollution kills. So how can we save this ecosystem when human activities seem necessary to our society?
Firstly, by hoping that new, quieter technologies will be developed, and that the field of bio-acoustics will expand. Some countries, including France and the European Union in general, seem to have worked in this field, which is still little known to the general public. In this sense, these countries are looking at other potential solutions, namely better regulation of the underwater sound environment. However, if this legal process takes time, it seems complicated to regulate military technologies that are indispensable to the detection of potential enemies. What’s more, the new generation would have to be prepared to change their way of life and consume locally, in order to curb the development of commercial maritime traffic.
However, this is not the turn the world seems to be taking. In view of China’s expressionist economic policies and its Belt and Road Initiatives, commercial maritime traffic is set to increase, at the cost of hundreds of thousands of animal lives.
