Twenty southern ocean elephant seals wearing head sensors are doing their part to help scientists obtain a better understanding of how the ocean's coldest, deepest waters are formed by swimming deep beneath the Antarctic ice where human observations are very rare and ships could not go, said researchers at the Antarctic Climate & Ecosystem CRC in Tasmania.
Scientists have long known of the existence of "Antarctic bottom water," a dense, deep layer of water near the ocean floor that has a significant impact on the movement of the world's oceans.
"This is a particular form of Antarctic water called Antarctic bottom water production, one of the engines that drives ocean circulation," said Guy Williams, ACE CRC Sea Ice specialist and co-author of the study. "What we've done is found another piston in that engine."
The seals were sent out from Davis Station in east Antarctica in 2011 with a sensor, weighing about 100 to 200 grams, on their head. Each of the sensors had a small satellite relay which transmitted data on a daily basis during the five to 10 minute intervals when the seals surfaced.
"We get four dives worth of data a day but they're actually doing up to 60 dives," he said.
"Several of the seals foraged on the continental slope as far down as 1.1 miles, punching through into a layer of this dense water cascading down the abyss and found this very cold, very saline dense water in the middle of winter beneath a polynya, which is what we call an ice factory around the coast of Antarctica," Williams added.
Previous studies have shown that there are 50-year-long trends in the properties of the Antarctic bottom water, and Williams reported the latest study will help better assess those changes, perhaps providing clues for climate change modeling.