Seals with antennas on their heads helped scientists solve an Antarctic mystery

Stand back, this seal is going to try SCIENCE

ANTARCTICA — Scientists now have a better idea of why giant holes have been opening up in the ice of the Antarctic, and they were assisted by some unique field partners.

In 2016 and 2017, a hole of open water, called a polynya, appeared in the winter ice of the Weddell Sea in Antarctica. It eventually grew to about 19,000 square miles; roughly twice the size of Vermont. Though polynyas are not unusual, this large and frequent of a hole was a great opportunity for scientists to figure out why, exactly, these holes were appearing. A team from the University of Washington explored the hole with a combination of robots, radio equipment and seals with antennas stuck to their heads. Their findings were recently published in the journal “Nature.”

“We thought this large hole in the sea ice — known as a polynya — was something that was rare, maybe a process that had gone extinct. But the events in 2016 and 2017 forced us to reevaluate that,” lead author Ethan Campbell said in a release. “Observations show that the recent polynyas opened from a combination of factors — one being the unusual ocean conditions, and the other being a series of very intense storms that swirled over the Weddell Sea with almost hurricane-force winds.”

The team found that, in order for a polynya to occur, there need to be a perfect storm of factors, so to speak. In the area where the giant polynya opened up, there is an underwater mountain that, when met with strong storms, causes a swirl of sea water, churning saltier water from deeper parts of the ocean up to the top. Once that water is cooled, it falls to the bottom again, and the ice can’t re-form.

As for the elephant seals, the team used them to transmit data back to shore as they swam in the depths of the polynya. Historically, seals have been a serious asset to the scientific research community. For one, their movements help researchers get a good sense of a particular environment or area. And also, they are ostensibly not too bothered by having radio equipment glued (safely) to their heads.

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