Researchers find a reduction in the complexity of dolphin whistles as a result of increased ship noise.
How can this affect dolphin communication?
Dolphin Calls And Whistles
It is common knowledge that dolphins are very social animals that can communicate very cleverly. They whistle when they feed, when they talk to each other, and even whistle for calling names, be it members of their own group or members of another group. Put simply, communicating with each other is an integral part of their lives.
Their pipes are complex with rises and falls in pitch and frequency, and they also show their individual personalities through individual vocalization. However, a research team discovered that such complexities may disappear due to increasing ocean noise due to increasing human activity.
Flatlined Whistle Signatures
To test the dolphin response in areas of relatively high sea-going traffic between recreational shipping and shipping routes, researchers used hydrophones at the bottom of the ocean, about 20 miles off the coast of Maryland.
What they found was that the increases in ship noises led to higher whistling frequencies with reductions in complexity. In other words, the dolphins whistled more but with less complexity. In analyzing the data, the researchers found that the typical complex whistling of dolphins with background noise is essentially flatlined.
"The shortest answer possible"
Communication is very important to dolphins, and they rely on sounds. However, there is evidence that increased shipping traffic hinders communication with dolphins by simplifying their normally complex communication. This not only hampers communication, but also obscures individual identification and may also reduce the information in their whistles.
"It's like trying to answer a question in a loud bar and after repeated attempts to be heard, giving you only the shortest answer possible," Dr. Helen Bailey of the University of Maryland Center for Environmental Sciences, co-author of the study. "The dolphins have simplified their calls to counteract the masking effects of ship noise."
Therefore, the researchers suggest searching for other, quieter ways on the water so as not to disturb the life of marine animals.
The study is published in the journal Biology Letters .