A Weddell seal fitted with a measuring instrument on its head basks on sea ice near the Japan's Syowa Station in Antarctica in March 2017. (Provided by Nobuo Kokubun, an assistant professor of ecology at the National Institute of Polar Research)

Japanese researchers in Antarctica are deploying Weddell seals fitted out with high-tech head-mounted measuring devices to survey waters under the thick ice sheet at the South Pole.

It allows team members from the National Institute of Polar Research (NIPR) and Hokkaido University to collect observation data in areas where it is unrealistic to even launch submersibles to remotely collect data during the winter season.

The practice also helps scientists to trace the animals’ behavioral patterns and ecology. Penguins are also used for research programs in Antarctica. So-called bio-logging involving sea creatures is gaining growing attention in the scientific community as a means to measure water temperature, salinity and other marine conditions in areas where the environment is extremely harsh.

Eight Weddell seals equipped with 580-gram devices on their heads to record water temperatures and salt levels were used for the project between March and September 2017, when the researchers were wintering over at Japan’s Syowa Station.

The project was overseen by Nobuo Kokubun, an assistant professor of ecology at the NIPR.

The information collected was relayed via satellite when the seals, which have an average body weight of 326 kilograms, emerged from the water. Data was recovered from seven of the seals.

It showed that one of the animals traveled as astonishing 633 kilometers from Syowa Station while another had descended to a depth of 750 meters.

Analyzing the data, the researchers learned that warm seawater from the upper layer in the open sea reached Antarctica from the autumn season in March and April through the winter that year. The warmer water flowed below the ice, allowing seal populations to catch food efficiently.

“Antarctic krill and other creatures that serve as food (for seals) can be found in vast numbers in the top layer of the open sea,” said Kokubun. “They streamed in along with seawater, likely bolstering biological productivity near the coast.”

Scientists from Hokkaido University, who research changes brought on by oceanic conditions to the amount of ice in Antarctica, examined the warm seawater’s impact on coastal areas.

“A good point is that seals can collect data in a wider area beneath the thick ice surface, even during periods when vessels cannot be used for monitoring,” said Shigeru Aoki, an associate professor of climate change studies at the university.