It has long been known that dolphins, as extremely social animals, communicate a lot with each other under water using special sounds. The specificity of this exchange always brings new insights to researchers. The latest study: When there is noise in their environment, dolphins increase the volume and duration of the whistles they use to communicate. Despite these attempts to compensate, marine mammal communication can be significantly impaired by loud noises, reports a team led by Pernille Sørensen of the University of Bristol in Britain.
Dolphins communicate using various underwater sounds – they produce, among other things, whistles and special click-to-echo sounds. However, if animals are in a particularly noisy environment, they even have to “scream” to communicate. Humans are the main culprits for this. Underwater drilling or shipping by sea generates a lot of noise, which means that animals can no longer communicate normally and cannot coordinate complex behaviors properly.
affects life
The results, published in the journal Current Biology, show how underwater noise can affect dolphins’ lives. So far, these behaviors have only been demonstrated in single individuals. The international team has now investigated how two bottlenose dolphins – a type of dolphin – reacted to increased noise as they were required to solve a task together.
Male Delta and Reese dolphins were asked to simultaneously press two underwater buttons located at opposite ends of the experimental pond. In previous tests, the pair had already proven that they could solve such a task through precise communication. The new challenge was to complete the task in different background noises – from normal ambient noise to the huge noise of a pressure washer.
Result: Success decreased with increasing ambient noise. To compensate for the increased noise pollution, some animals use their specific calls louder, longer, or more frequently. Or leave the site to go to quieter areas.
limitations
Although the study was only carried out on dolphins in human care, the researchers assume that human-made noise also affects wild dolphins. “For example, background noise can make foraging less efficient,” said co-author Stephanie King (also from the University of Bristol). “This not only harms the health of individuals, but ultimately the entire population.”