Noise travels through the sea. The arrival and departure of ships, the search for hydrocarbons, and the installation of offshore wind turbines all create a sharp, piercing sound that echoes along the seabed. This underwater noise affects many living beings, forcing fish and marine mammals to move away or face the risk of disappearing into the vast ocean. Scientists warn about the far-reaching consequences and propose practical remedies.
To understand how sound travels underwater, researchers rely on the right tools. From Europe they observe how ships enter and leave major harbors thousands of kilometers away. The seabed has become a loud, sometimes unbearable home for the creatures that rely on it.
Reduce speed by 11% — a practical solution
One approach to curb the ceaseless noise from human activity is to slow vessels. An 11% reduction in speed can make a meaningful difference. “Ships are the current primary source of underwater noise, and this small adjustment can substantially lower the noise levels,” notes José Antonio Díaz, a member of the Saturn consortium and a technician at the Canary Islands Ocean Platform (Plocan). Based on Gran Canaria, Plocan is one of twenty centers collaborating on the European Saturn project, which stands for Developing Solutions to Underwater Noise. The project has spent three years exploring ways to reduce underwater sound.
The initiative involving University College Cork, led by the Science Foundation Ireland’s MaREI Centre, brings together twenty project partners across ten countries and a large EU-wide consortium. It combines acousticians, marine biologists, and marine engineers in an interdisciplinary effort.
Most commercial vessels fly through waters at speeds between 20 and 24 knots. Reducing speed by 11% means they would travel roughly 18 to 21 knots. “Contrary to common assumptions, ships create much of their noise from propellers rather than their engines,” Díaz emphasizes.
“Ships generate more noise from propellers than from engines.”
When propellers spin, they create bursts of bubbles that produce the persistent noise that can disturb marine life. While this approach helps in the short term, Saturn researchers suggest that altering propeller design to minimize bubble formation could further reduce noise.
Reducing speed also lowers fuel use
Slower speeds bring additional benefits. A 2019 study by Reynolds Environmental Sustainability Consultants (RESC) showed a link between ship speed and environmental impact. The report found that a 20% speed reduction could cut fuel consumption by more than 24%, while greenhouse gas emissions drop. Noise pollution could fall by about 67%, and cetacean deaths from ship strikes by around 78% in this scenario.
The research team examined a detailed map of ocean silence, comparing pristine regions with areas heavily affected by economic activity and shipping. Díaz stresses that the difference between such regions can be vastly larger than ten-thousandfold, and he calls the current situation “barbaric.”
“Permanent or temporary deafness”
Imagine moving from a field where natural sounds dominate to a place beside a jet about to take off. In Spain, the Strait of Gibraltar, where about 300 ships pass daily, represents the most affected area. That’s roughly one vessel every five minutes.
There are spots at sea where the noise is as oppressive as being near an airplane engine.
Underwater noise affects all marine life. While attention has often focused on large mammals such as whales and dolphins because they communicate with sound, other species are also impacted. Potential effects include temporary or permanent deafness and interference with communication. When noise drowns out signals, animals lose the ability to stay with their groups or find food, which disrupts entire ecosystems and human activities like fishing.
Noise is a less visible problem, but it demands solutions now. The latest findings are public and available to all segments of society. The goal is to move forward with clear, actionable measures.
For more information: Saturn project findings are summarized by researchers and institutions involved in the consortium.
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