Dolphins Forced To Simplify Calls As Human Noise Pollution Grows

Bottlenose dolphins have been forced to simplify their speech due to a variety of noisy human activities, according to new research out of the University of Maryland Center for Environmental Science. The change in calls was discovered by researchers who placed microphones on the Atlantic Ocean's floor to monitor noise levels near Maryland.

Humans are noisy and that's a problem. Loud sounds resulting from human activity have been implicated as harmful in both animal and human health studies, and may have a disruptive effect on bird calls. The latest study also highlights potential trouble for underwater creatures that rely on complex calls for speech.

The noise caused by recreational boats, shipping vessels, and similar watercraft are creating ambient noise in ocean waters that are too loud for dolphins to easily ignore. Attempting to call out to each other in these regions has become difficult, and so researchers say dolphins are simplifying their messages.

This change is akin to someone shouting single words and simple sentences over the roar of a loud bar or restaurant, researchers explain. The change was observed using hydrophones located about 20 miles off the coastline. The findings raise questions over the long-term effects of these noise levels on dolphins.

Dolphins aren't the only aquatic animal impacted by human noises. Past research found that noise pollution — including sonar testing — in the ocean can compel whales to beach themselves, get decompression sickness from rising to the surface too quickly, and more. Researchers have called for the development of quieter shipping vessels, as well as restrictions on loud underwater sonar testing.

SOURCE: University of Maryland