The ocean is far from human territory, but it turns out scientists can tap seals as a partner in observing the depths of the Antarctic Ocean.
Lia Siegelman, a research student from the University of Western Brittany in France who's visiting NASA's Jet Propulsion Laboratory in California, found that tagging seals are an effective way to collect data under the ocean's surface.
Seals And The Ocean
While seals may appear slow, lazy creatures on land, they are speedy, agile athletes in the ocean. Every year, nine to 10 months of a seal's life is spent in the water, swimming thousands of miles and diving as deep as 3,300 feet. An average seal dives about 80 times a day, each one about a mile apart from the last.
"Even when they sleep, they dive — they float down like a leaf," said Siegelman. A seal can spend up to two hours underwater at a time, surfacing for air briefly in between.
Diving so many times to great depths, a tagged seal is able to collect massive amounts of data from the entire top layer of the Antarctic Ocean, also known as the Southern Ocean. Some seals go so far as to venture underneath the Antarctic sea ice, a place that traditional ocean instruments can't even access.
These abilities make seals incredibly valuable to scientists like Siegelman, especially as the ocean currents shifts and affects the ice in response to global warming.
Scientists Use Seal Data To Learn About Ocean Depths
In a study published in the journal Scientific Reports, Siegelman and the other researchers followed the journeys of a foraging female seal for three months, during which the animal traveled 3,520 miles and dove 6,942 times.
While most seals from the Kerguelen Islands forage in the direction of the east, this female went west to a region in the Antarctic Circumpolar Current. In this area, there's a standing meander, which is a spot where the topography of the ocean floor causes a permanent bend in the current's path.
Few data and measurements have been collected about this area, but the seal that Siegelman's team followed spent about one-third of its voyage traveling through this meander.
With the data collected, the researchers located "fronts," which are sudden changes in water density. These fronts pull nutrients from the bottom of the ocean, fertilizing phytoplankton and creating more food for elephant seals.
For their research, the team used a new type of sensor from 2014 that allows them to collect very high-resolution oceanographic data sets. The sensors are glued to the seal heads and removed once the seals return to land in order to breed or molt.
"I hope this [result] will encourage physicists and biologists to use those very rich data from seals," said Siegelman.