A previous version said that cetaceans can hear up to 200Hz. This article was amended on 13 January 2023.
“So you could reduce traffic at certain times and increase it at others.” “Maybe there are times of the year that it is better not to be in a certain area,” said Sørensen. Some noises, such as ships engines, are more difficult to avoid, but the overall impact could be mitigated by better understanding how noise affects marine life and taking this into account. Sørensen said there had been some positive attempts to address the issue, such as the use of bubblenet structures around construction sites to muffle sounds. These high-intensity dives use much more energy than normal and put the marine mammals’ health at risk, scientists said. Some linked the mass stranding to underwater noise pollution.Īnother recent study found that when narwhals are exposed to seismic air guns, used for surveying in the oil and gas industry, they immediately begin diving to escape from the noise. In September 2020, Australia experienced the largest whale stranding recorded in history in which 450 pilot whales were found washed up on the west coast of Tasmania, most of which had to be euthanised due to their low chance of survival. “Those same reasons that make sound so advantageous for animals to use also make them susceptible to disturbance from noise in the environment,” said Sørensen. We use Google reCaptcha to protect our website and the Google Privacy Policy and Terms of Service apply. For more information see our Privacy Policy. Privacy Notice: Newsletters may contain info about charities, online ads, and content funded by outside parties. The increase in background noise has been linked to strandings, decompression sickness and behavioural changes. Humpback whales, singing at a low frequency, can be heard up to 16,000 kilometres away.īut during recent decades, the underwater soundscape has radically changed from one that featured mostly natural sounds to one in which some regions are dominated by human noise pollution, from shipping traffic, seismic exploration, oil drilling and offshore windfarms. Invertebrates and fish hear sounds at low frequency, while cetaceans (dolphins and whales) can hear very high frequencies, up to 200kHz and also use active sonar to detect objects, including prey. Sound travels 4.5 times faster through water than through air, meaning many marine organisms have evolved to rely on sounds to provide important cues to navigate, forage for food, avoid predators and enable communication. “Despite their attempts to compensate, despite being highly motivated and the fact that they know this cooperative task so well, the noise still impaired their ability to successfully coordinate,” said Sørensen. The highest noise levels were comparable with what are sometimes experienced in marine environments as a result of shipping and drilling. The dolphins also changed their body language, reorienting themselves to face each other more frequently at higher noise levels and swimming across the lagoon to be closer to each other. From the lowest to highest levels of noise, the dolphins’ success rate dropped from 85% to 62.5%, according to the research. Nevertheless, they could not entirely compensate. When increasing levels of noise were played from an underwater speaker, both dolphins compensated by changing the volume and length of their calls to coordinate the button press. This meant that the dolphins had to rely solely on vocal communication to coordinate the button press. They were released from a starting point during each trial, and in some trials, one of the dolphins was held back for five to 10 seconds. The dolphins were required to work together to both press their own underwater button placed at either end of a lagoon within one second of each other – a task that some humans would struggle to coordinate. The latest study involved a pair of dolphins, Delta and Reese, and looked at how their ability to cooperate was affected by background noise. So noise generated from human activity such as drilling and shipping has a potentially harmful impact on the health of marine populations. Dolphins are social, intelligent animals, relying on clicks and whistles to communicate and using echolocation to hunt and navigate.
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