When humans need to talk to someone and the environment is noisy, we often resort to the effective but laborious solution of raising our voices and even shouting if necessary. We are not the only animals to run into this annoying situation.
Irrefutable proof of the ability that dolphins have to communicate acoustically among themselves has been obtained in an experiment in which some dolphins were subjected to a noisier than normal environment that had to coordinate with each other to carry out a collective task.
Dolphins are social and intelligent animals that depend on the sounds they make to communicate with their peers for reproductive purposes or to coordinate when hunting in groups. Their sounds also serve them for echolocation (like a submarine sonar). This means that noise generated by human activities, such as drilling and shipping, has the potential to harm wild dolphin populations. A new study shows that dolphins “scream” when there is a lot of underwater noise and they need to communicate with their peers to do some teamwork.
The research is the work of the team of Pernille Sørensen, from the University of Bristol in the United Kingdom.
“The same reasons that make sound so advantageous for animals also make them susceptible to disturbances caused by environmental noise,” explains Sørensen, who also points to the fact that noise has increased dramatically in recent decades. of human origin in the oceans.
The two dolphins observed in the study, Delta and Reese, were placed in an experimental lagoon and fitted with devices that documented their vocalizations. The dolphins had to work together to each synchronously press their own underwater button. One button was placed at one end of the lagoon and the other at the opposite end. The buttons had to be pressed within a second of each other.
Dolphins were allowed access from a starting point during each trial, and for certain trials, one of the dolphins was not allowed to enter until several seconds after the other. In these cases, the dolphins relied exclusively on vocal communication to coordinate the pressing of both buttons.
Delta dolphin pressing the button during one of the experiments. (Photo: Current Biology / Sorensen et al. CC BY SA)
The researchers found that when increasing levels of noise were emitted from an underwater speaker and the two dolphins had increasing difficulty hearing each other, they mitigated the problem by increasing the volume and duration of the sounds used in coordinating to pulse the buttons. This alleviated the problem but did not eliminate it, as the 85% success rate for dolphins with the lowest noise level became 62.5% with the highest noise level.
The dolphins not only changed their sounds, but also their body language. As noise levels increased, the dolphins tended to position themselves more face to face, just as humans do in a noisy environment when we try to complement our words by staring at our interlocutor to emit and receive visual cues such as gestures and glances.
The study is titled “Anthropogenic noise impairs cooperation in bottlenose dolphins”. And it has been published in the academic journal Current Biology. (Fountain: NCYT by Amazings)
