The depths of Antarctica sound like “spaceships”

Composite image of Antarctica, constructed from numerous individual and smaller photos taken from satellites. Credits: NASA.

The depths of Antarctica reveal a variety of “impressive” hums and sounds that can be used to study its marine life, says Colombian scientist Andrea Bonilla during an expedition to the confines of the frozen continent.

The biologist from Cornell University in New York submerges a hydrophone covered in titanium and tied to a buoy, in the middle of the imposing ocean crowned by ice floes, in the archipelago of the South Shetland Islands.

The device - which detects sound waves underwater - will allow you to understand the behavioral patterns of marine mammals and their movements in the area during the southern winter, a time when Antarctica becomes almost uninhabitable. It is a kind of camera trap, but for auditory purposes and for the aquatic environment.

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Aerial shot of marine animals in AntarcticaImage: Sebnem Coskun/Anadolu/picture alliance

“Awesome” and fundamental sounds

“There are species here that sound impressive, literally like Star Wars (the film saga), they sound like spaceships. "Very few ears have the privilege of monitoring this type of species," the 32-year-old scientist told AFP, aboard the Colombian Navy ship "ARC Simón Bolívar."

Bonilla, who is pursuing a doctorate in marine acoustics, has, together with other scientists from the 10th Colombian Antarctic Expedition, a double task: to collect the hydrophones left last year by a Turkish mission for subsequent analysis and also to submerge new devices.

For Bonilla “in a marine environment, sound is essential.” Noise or hearing disturbances can affect the communication of species or prevent the normal development of their natural activities, such as hunting, adds the expert.

“My first encounter with a whale was a singing whale and I think that changed my life,” recalls Bonilla.

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Scientist Andrea Bonilla in Antarctica in February 2023Image: Sebnem Coskun/AA/picture alliance

An investigation with further purposes

Guided by established coordinates, the group of scientists follows the trail of the buoy left by Bonilla in the sea a year ago.

When they are within a radius of about 300 meters from the location point, the scientist can begin to send remote signals to the hydrophone to locate it using a command box. Submerged at about 500 meters, the device responds to the waves transmitted by Bonilla and then to the order to free itself from the attached anchor and return to the surface.

His excited companions give him small pats on the back for the feat that will leave scientific fruit.

“Super excited because it was the first time we did this maneuver in these waters (…) Everything went super well,” Bonilla says happily after the procedure that took eight minutes.

Once on dry land, the Colombian scientist will analyze a year of recordings, which survived innumerable risks such as the loss of the device or technical problems.

This research has a subsequent purpose: “to support the proposal” promoted by Chile and Argentina since 2012 to convert the Antarctic Peninsula into “a marine protected area.”

Bonilla works with spectrograms that visually represent sound frequencies. Their findings will not only be used for monitoring marine mammals, but also for geophysical research.

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Octavio Alonso