Noise Pollution From Shipping Makes Dolphins Whistle Louder But Less Effectively, Research Reveals

According to recent research, loud human activities like drilling and shipping may alter dolphin behavior and make it more difficult for them to hunt and reproduce.

They whistle longer and louder than usual, which is less effective.

According to new research, dolphins appear to shout at one another due to the increased underwater noise pollution.

Scientists from the University of Bristol claimed that the noise produced by humans may drive animals to produce louder and less effective whistles.

Noise Pollution vs. Echolocation

Because dolphins use echolocation for both reproduction and hunting, industrial activities like drilling and shipping may have an impact on the health of wild dolphin populations.

According to the study's first author, Pernille Sorensen, there has been a noticeable rise in the amount of noise pollution and man-made noise in the oceans over the last few decades.

She continued, saying that the same factors that make sound such a useful tool for animals also make them vulnerable to disturbance from outside noise.

Delta and Reese vs Underwater Speakers

Two dolphins, Delta and Reese, were placed in an experimental lagoon which required them to cooperate to press a button at either end of the lagoon within a second of one another.

One dolphin was released into the lagoon five to ten seconds after the other during some trials, so they had to coordinate the button press using vocal communication.

The volume and duration of Delta and Reese's calls changed when the amount of background noise played from an underwater speaker was increased, the researchers found.

The study discovered that between the highest and lowest levels of noise, their button-pressing success rate decreased from 85% to 62.5%.

Dolphins Compensate

This, according to Sorensen, demonstrated that noise interfered with the dolphins' communication despite their use of these compensatory mechanisms.

The team's research demonstrates that the dolphins' ability to successfully coordinate was still hampered by the noise despite their efforts to make up for it, despite their high motivation, and even though they are very familiar with this cooperative task.

The dolphins were more inclined to face each other or swim to the opposite side of the lagoon to get closer as the speaker's volume rose.

Although the study involved dolphins kept in human care, researchers contend that noise produced by people may be harmful to wild dolphins.

Stephanie King, an associate professor at the University of Bristol and co-author of the study, explained that for example, if a group of wild animals is less effective at foraging together, this will have a negative impact on individual health, which in turn will have an impact on population health, Sky News reported.

The study by Sorensen, King, and several colleagues was recently published in the Current Biology journal.

Other Animals Using Echolocation

Bats, dolphins, and other animals use the echolocation technique to locate objects by listening for the reflected sound.

This enables the animals to move about in complete darkness so that they can hunt, navigate, recognize allies and enemies, and avoid dangers.

There are several animals known to echolocate, including bats, dolphins, whales, a few birds such as the nocturnal oilbird as well as some swiftlets, some shrews, and the related tenrec from Madagascar.

Hedgehogs are another potential candidate, and astonishingly, some people who are blind seem to have also acquired echolocation skills, Discover Wildlife reported.