Melt water from Antarctic glaciers is changing the composition of the region’s oceans more than previously known, a new study finds. The measurements that made these findings possible were collected by a special group of researchers: seals.
The study, published Friday in Communications: Earth and Environment, uses water temperature and salinity measurements to show how glacier water changes the composition of the ocean near Pine Island Glacier. one of the fastest retreating glaciers on the continentThe researchers found that the warmer, fresh meltwater was scattered across the ocean in chunks, including parts that rise close to the surface. Those surface layers bring iron and other nutrients to the top of the ocean, causing algae and other biomass to grow and the ocean to remain relatively ice-free.
“In this part of the sea the glaciers are melting so fast, they call them”Doomsday Glaciers, ‘”Said Yixi Zheng, the study’s lead author and a postdoctoral fellow at the University of East Anglia. “We really care about what’s going on in that region. We want to know how fast they are melting and what the impact of those glaciers is on the climate system. “
While ice melt water is best measured in winter, when the hydrographic signature is most evident, this has always been a problem for scientists. Not only is the Pine Island Glacier extremely remote, but the ocean near the glacier is covered with ice for 10 months of the year, making access to deeper parts of the ocean with human instruments nearly impossible.
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However, seals can and do swim under sea ice. Zheng and her team used a data set collected by seals swimming near the Pine Island Glacier equipped with sensors that recorded water temperature, salinity and pressure. The seals were then checked between July and September 2014.
“The seals, they are so great,” said Zheng. “They are very good at finding small holes in the sea ice. Sometimes I feel like we should get them promoted. They do better than many scientists. “
As versatile as seals are, they are not perfect researchers. You have no control over where a seal goes to swim, so you cannot ask if they are patrolling a particular area. That makes them somewhat erratic employees, but the team got lucky with the ones they had.
“We were really very lucky in this region. Just before the glacier, we hung out a seal on a winter vacation, ”said Zheng. It is not surprising that a seal chooses to settle near a melting glacier: As Zheng’s research shows, the meltwater at the surface of the ocean in glaciers encourages algae, which means more food for seals.
Researchers have used seals in other studies as well. Some of Antarctica’s most charismatic mammals also helped solve the cause of one huge hole to form in the sea ice of the region. Scientists also have controlled seals from space as a measure of how healthy different Antarctic ecosystems are. Those ecosystems support critical fisheries that humans rely on, and what happens to the continent’s vast ice reserves is impacting coastal populations around the world. In a region that is rapidly changing, all the extra data that researchers can gather so they can get to grips with what’s going on is vital in planning for what comes next.
Zheng, who herself tagged seals on a trip to Antarctica in 2019, said she sees many opportunities for seals to help scientists collect measurements, and thinks seal tag data will gain popularity in future studies. The sensors mounted on seals cost between $ 4.1,000 and nearly $ 7,000, according to Zheng. That may seem expensive, but it’s astronomically cheaper than sending a team of scientists with expensive equipment to Antarctica to collect comparable data.
“We really like the seal tag data and we try to get the best out of it,” said Zheng.