Noise fills the ocean. The coming and going of ships, the exploration for hydrocarbons, or the installation of offshore wind turbines make a shrill screech that drives the seabed crazy. It is a noise that affects many fish and cetaceans, forcing them to go elsewhere or dooming them to disappear in the wide sea. it’s like this because This underwater noise prevents these animals, on which their breeding and feeding depend, from communicating, except for the direct harm they suffer. in the most extreme cases. The consequences of noise are enormous, leading a group of scientists to warn of its effects and propose solutions.
To get an idea of how sound is transmitted underwater, With the right instruments, ships can be heard across Europe as they enter and leave New York Harbor, scientists say, thousands of kilometers away.
One of the alternatives to reduce the endless noise that human beings make up to the depths of the sea is water. Reduces the speed of ships by 11%. “Ships are the main source of noise, but with this small move we can greatly reduce the noise,” says José Antonio Díaz, a member of the Saturn consortium and a technician at the Canary Islands Ocean Platform (Plocan). La Plocan is one of 20 centers working on the Saturn Europe project (Developing Solutions to Underwater Noise), spent three years researching solutions to reduce underwater noise.
Led by the Science Foundation of Ireland and organized by University College Cork, the project includes a broad consortium of EU participants with 20 partners in 10 European countries, and an interdisciplinary team of acoustic experts, marine biologists and marine engineers.
Most boats cruise at speeds between 20 and 24 knots, so reducing their speed by 11% means they will have to travel between 18 and 21 knots, enough to alleviate most of the acoustic problem. “Contrary to what might be expected, ships make noise not because of their engines, but because of their propellers.”Highlights Diaz.
“Contrary to what might be expected, ships make noise not because of their engines, but because of their propellers.”
Specifically, when the propellers spin, they produce bubbles that burst, making that incessant sound that torments marine life. While slowing down is the best short-term solution, Project Saturn researchers believe: Much of the noise can also be avoided by changing the “shape of the impeller to produce less bubbles”. as the researcher insisted.
Reducing the speed of boats can have other benefits as well. This was already revealed in 2019 by consulting firm Reynolds Environmental Sustainability Consultants (RESC), who estimated that reducing the speed of ships by 20% could reduce fuel consumption by more than 24%. This, In addition to reducing greenhouse gas emissions, it will reduce noise pollution by 67% and cetacean deaths from ship collisions by 78%.according to that report.
One of the biggest threats to sperm whales, pilot whales or whales is, collisions with ships while moving across the sea. Damage can range from a simple scratch to complete mutilation or death of the animal, often slowly and painfully.
“Permanent or temporary deafness”
There is great variation in the oceans in terms of noise levels. “We compare virgin regions without any noise pollution and those with the greatest economic activity and shipping,” Díaz emphasizes. There was a 10,000 times greater difference in noise between the two areas. “This is barbaric”says the Saturn project researcher.
By comparison, it would be like going from being in a field where only the sounds of nature can be heard, to parking next to a jet about to take off. The most affected area in Spain is the Strait of Gibraltar, through which about 300 ships pass every day.. That is, every five minutes.
“There are places in the sea that are as noisy as being next to a plane about to take off”
“Underwater noise affects all species,” emphasizes José Antonio Díaz. And historically, the focus has been on large mammals such as cetaceans and dolphins. It’s not surprising, as their communication is accomplished with sounds. There are two possible effects for them: the physical one, can cause permanent or temporary deafnessand another communication, because the “noise” overlaps with their “dialogue”.
This prevents them from listening to each other, so they drift away or drift away from the rest of their group. But they are not the only ones affected. The rest of the fish also tend to escape from very noisy places, which affects both ecosystems (losing one of their bonds) and human activities such as fishing.
“Noise is a little-known problem and now is the time to propose solutions,” Díaz emphasizes. We need to go further and define the measures to be taken more clearly.”
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REPORT. Txema Brotons, marine biologist and scientific director of Tursiops
“The problem is that we use the sea as a highway”
From a speed of 10 knots or a length of 90 meters a boat triggers the capacity to kill marine mammals
While underwater noise can directly kill a cetacean, it often puts them under chronic stress, making them more vulnerable to other influences. Tursiops is an organization investigating this issue.
-To what extent does underwater noise affect marine mammals?
– The noise we make is mostly concentrated in the low frequencies where boats are heard the most. These low frequencies have a very high dispersion capacity and affect some species more than others. For example, a fin whale emits at very low frequencies, and a dolphin does so at higher frequencies. While this chronic noise is not a lethal shock per se, it causes a high degree of stress and makes these animals more susceptible to other shocks. It is as if you have a wound and if you are in a stressful situation for any reason, this wound will increase the chance of getting an infection many times.
-Can this noise directly cause death in some cases?
-Seismic survey to look for hydrocarbons [se realizan potentes detonaciones submarinas] It can be lethal if it catches an animal from a distance. A military sonar can cause flight reactions that cause direct death of deep-diving animals.
-Can it be effective in reducing the scanning speed?
– By reducing the speed, we reduce not only the noise, but also the risk of collision with marine mammals. As new ships go to sea, industry may be asked to design more efficiently. In fact, a ship making a lot of noise is sometimes a sign of a ship malfunction. Also, there are countless large ships that can sail. For example, Cristiano Ronaldo does not sail on a sailboat. The problem is, we use the sea like a highway.
-The other big problem is the collision of marine mammals and ships…
-Large ships are the ships with the highest death toll. Colliding with a 12-foot sailboat traveling at six mph is not the same as colliding with a 25-metre yacht traveling at 30 mph or a 120-metre ferry at 24 mph. The chance of fatal injury increases with speed and length. Scientific studies identify thresholds at which there is a very marked change in the survivability curve in the event of a collision, and they are 10 nautical miles and 90 meters long. That doesn’t mean a slower or smaller ship can’t kill an animal as well. On our last expedition, we saw two sperm whales within a week, and both had collision marks.
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