An ice-loving Weddell seal, equipped with headgear and ready to assist oceanographers. (Brice Loose)
Excerpt:
In 2014, Loose was part of a team to help tag elephant (Mirounga leonina) and Weddell seals (Leptonychotes weddellii) for a study. The seals weren’t the subjects of the study, though—they were its research assistants. Loose was helping fit the able divers with trackers so that they could collect data on the Amundsen Sea’s temperature and salinity at great depths, which would provide clues into the mechanism of the rapid ice melt in Antarctica. The research was published in Geophysical Research Letters in May 2018.
Currently, scientists theorize that Antarctic melting is partially caused by a warmer, saltier current beneath the ice known as the “circumpolar deep water.” These waters, which are present at depths of 400 meters, are brought to the surface and lick the underside of ice sheets, melting them and enabling sea levels to rise.
“In Pine Island Bay, this is particularly important,” says Helen Mallett, the lead author of the study and a postgraduate researcher at the University of East Anglia in the United Kingdom. “The circumpolar deep water there is melting the unstable, fast thinning Pine Island Glacier, which in turn drains the vulnerable and massive West Antarctic Ice Sheet.” If all the unstable ice in west Antarctica melts, sea levels could rise by up to 10.5 feet globally.
Scientists know the warm current exists in the Amundsen Sea, but they need to know more. To get a complete picture, scientists need to answer some basic questions: Where are the warm waters, exactly? How thick is the layer of warm water ? How does it vary from winter to summer?
For this, they turned to the enormous marine mammals with large puppy dog eyes.
Seals are known for their impressive diving skills, with some species torpedoing down to depths of 2,000 feet even in sub-zero temperatures. These skills made them the perfect partners for collecting temperature data at the seafloor. Researchers had not collected any winter data in this region because the conditions are too harsh for humans.
“We could see that seals dive at these extreme depths and go these vast distances,” says Mike Fedak, a seal biologist at the University of St. Andrews in the UK who has been tagging animals for the past 39 years. “These animals go where we can’t.”
