Marine biologists have documented that dolphins, when faced with underwater noise from drilling and other industrial activities, raise their voices — literally. A study published in the journal Current Biology shows that two dolphins at the Dolphin Research Center in the Florida Keys altered their calls to compensate for the racket, but their efforts often fell short.
The experiment, led by researchers including Pernille Sørensen, a PhD candidate at the University of Bristol, involved two dolphins named Delta and Reese. The animals were fitted with recording tags and exposed to a range of sounds played through underwater speakers, mimicking the loud, low-frequency noise generated by military operations, oil exploration, and shipping traffic.
In response to the increasing noise, Delta and Reese lengthened their calls and boosted their volume — a behavior the researchers describe as shouting. However, even with these adjustments, the dolphins' ability to communicate effectively diminished. At the highest noise levels, the pair succeeded in exchanging signals only 62.5 percent of the time, a notable drop from quieter conditions.
“It was surprising to see how much the success rate dropped,” Sørensen told the New York Times, highlighting the severity of the impact.
Why This Matters for Wild Dolphins
While the study was conducted in captivity, it addresses a long-standing gap in understanding how dolphins respond to human-generated underwater noise. Previous research, such as a 2006 Australian study that linked reduced dolphin sightings to increased tourism boat traffic, suggested behavioral changes, but direct evidence of communication disruption was lacking.
Mauricio Cantor, a behavioral ecologist at Oregon State University, noted that such experiments are difficult to carry out in the wild, making the controlled environment of the Dolphin Research Center a valuable setting. The findings offer a plausible explanation for how wild dolphins might struggle to coordinate, find food, or maintain social bonds in increasingly noisy oceans.
A Willing Pair of Participants
Delta and Reese, the study subjects, were reportedly eager to take part in the tasks. Sørensen described them as “the most motivated animals” and noted they were “really excited about doing the task.” Their enthusiasm, however, does not diminish the gravity of the results, which underscore the potential consequences of underwater noise pollution on marine life.
The study adds to a growing body of evidence that anthropogenic noise is not merely an annoyance but a significant environmental stressor. As industrial activities in the oceans expand, the ability of dolphins and other marine mammals to communicate may be increasingly compromised, with unknown long-term effects on their populations.
