Study found it Dolphins are unable to communicate effectively When exposed to man-made noises, it forces them to change their voices much like people do when screaming.
An international team of researchers from the University of Bristol, the Dolphin Research Centre, Syracuse University, Woods Hole Oceanographic Institution, Aarhus University and the University of St Andrews collaborated on the study, which was published in the journal Current Biology on Thursday
“We wanted to investigate how noise affects animals working together,” Pernille Sorensen, first author of the paper and a doctoral candidate at the University of Bristol, said in an interview with CNN. “So basically looking at the entire communications network, from sender to receiver and whether there is any impact on that transmission.”
Previous studies Documenting the harmful effect that noise pollution can have on other aquatic mammals, such as whales. The constant noise from ships’ engines and military sonar makes it difficult for marine mammals to communicate with each other and has been linked to an increase in collisions between whales and ships.
Researchers honed dolphins because aquatic animals are highly social and intelligent, using whistles to communicate with each other and clicks for echolocation and hunting. Proper communication is especially critical for animals underwater, Sorensen said, because below the water’s surface “sound travels very far, very quickly.”
In addition, dolphins have an “extensive vocal repertoire” that they use for “essentially all aspects of their lives, including coordinating cooperative behaviours”.
To understand how noise pollution affects dolphins’ ability to cooperate, the scientists worked with two designated dolphins, Delta and Rhys, who live at the Dolphin Research Center in Florida. The dolphins had a task: they needed to press a button underwater at the same time. The dolphins were asked to perform the task under ambient noise conditions and under four “noise processors” intended to simulate man-made underwater noise pollution. A total of 200 experiments were performed with a dolphin pair, with each dolphin wearing a sound card that recorded its vocal output.
Sorensen said the findings are twofold. First, they found that dolphins use “compensatory mechanisms” to compensate for their impaired vocal communication. As the underwater noise gets louder, they make louder and longer sounds, and change their body language to face each other.
But the most important finding, according to Sorensen, was that despite using their attempts to compensate for noise pollution, the dolphins were still less successful in completing the task. Their success rate dropped from 85% to 62.5% from the lowest noise levels to the highest.
“We show, as far as we know, for the first time, that animals that work together are affected and that compensatory mechanisms are insufficient to overcome the effects of noise,” she explained.
This could have realistic effects on dolphins in the wild, which depend on cooperation to forage and reproduce. “They need the sound in order to communicate,” she said.
Sørensen added that the researchers would “absolutely love introducing or including more dolphins in our experiment” and that future experiments may expand the sample size to a larger group of dolphins.
In addition, more research is needed into the specific types of whistles and sounds that dolphins use in cooperative tasks.
“This research definitely contributes as part of the puzzle to our knowledge of how noise pollution affects animals,” Sorensen said.
She said she hopes the research will help support “solutions for how to better manage the noise in our oceans.”