The ocean seems so serene that people put ocean sounds playlists on when they want to sleep. But for the actual animals in the sea, there's pretty much a never-ending cacophony of ship traffic.
According to the Washington Post, a recent study conducted by the University of Maryland Center for Environmental Science found that bottlenose dolphins change their vocalizations when around heavy noise. It's totally affecting how they get information across to the members of their pod.
A press release from the university reported that dolphin whistles are used in a variety of ways from social chatting, during feeding and to call each other by name.
Azula recently reported that dolphin moms even start singing their own names to their unborn babies so that the calves come out knowing who their mom is.
Being able to produce sounds is vital to dolphin socialization and survival.
It's also important for scientists. In the past, dolphins could only be identified via visual attributes. Now, marine biologists can analyze their individual calls to determine which dolphin is which, per the Washington Post.
Of course, scientists can only do that so long as the dolphins produce those signature whistles.
Unfortunately the study found that background ocean noise is making dolphins change how they talk.
According to the Washington Post, the researchers found that highly trafficked shipping areas led to flat dolphin calls. Helen Bailey, who worked on the study, likened this to having to shout in a noisy bar about a friend who lost their keys. Bailey said that at home you'd likely say, "Hey, your keys are between these couch pillows." Whereas in a noisy bar you'd just shout "Keys!"
These flat dolphin whistles lack contextual information for scientists, because the dolphins are simply shouting what they can above the din. By contrast, the Washington Post reported that whales like humpbacks don't shout in noisy water.
They simply give up on saying anything at all.
Fast ships with noisy engines and big propellers pose a big problem for those with ears in the sea. WBUR radio reported that propellers leave behind bubbles that pop — ensuring that the boat's noise lasts long after it leaves the area.
In the press release, Bailey called for noise reduction on the part of ships — via slower speeds or quieter engines. Whatever has to change, it needs to be done soon. No one deserves to live somewhere that is never quiet.
You can get a sense of the stress this causes by watching the trailer for "Sonic Sea," a documentary about ocean noise's effect on marine life.