- Southern elephant seals living on Kerguelen Island, a sub-Antarctic island, are helping to gather information about the Southern Ocean with data-logging devices attached to their hair.
- For instance, the elephant seals have helped gather data on sea ice formation, ocean and ice shelf interactions, and frontal system dynamics.
- The Southern Ocean provides many ecosystem services for the planet, but the region is rapidly changing due to climate change.
At the start of each year, southern elephant seals living on Kerguelen Island above Antarctica shed the thick mat of their winter fur, while growing in a fresh layer of skin and hair. Once this new hair is in place, scientists choose some of the seals on which to affix funny-looking electric boxes adorned with antennae.
When the elephant seals (Mirounga leonina) dive into the icy waters of the Southern Ocean to hunt, the electric boxes gather an assortment of information about the marine environment, from water temperature to salinity to oxygen levels. In near-real-time, the devices transmit this information to satellites thousands of miles above the planet, which beam it back down to Earth to appear on scientists’ computer screens.
Clive McMahon, an Antarctic ecologist at the Sydney Institute of Marine Science in Australia, says elephant seals are playing an essential role in understanding the changing dynamics of the Southern Ocean, also known as the Antarctic Ocean, due to human-induced climate change.
“If we know what’s happening in the High Antarctic Ocean, we have a much better grasp of global climate processes,” he said in a statement. “Obtaining high latitude observations is critical. Elephant seals can dive up to 2000 meters [6,600 feet] and have the fantastic ability to access platforms like coastal shelves that other platforms are unable to easily reach.”
The Southern Ocean is known to be one of the world’s most important carbon sinks, with nearly half of all carbon dioxide uptake occurring in its waters, according to one study. The waters around Antarctica also help to manage the Earth’s excess heat and regulate the global climate. Yet this same region is also one of the most rapidly changing oceans due to climate change, and many scientists fear that it will not be able to perform the same ecosystem services as the world shifts into a new state.
More research is needed to understand the changing dynamics of the Southern Ocean, particularly in places where it’s difficult to deploy traditional scientific instruments, such as places with large amounts of ice cover. This is where animals like elephant seals come in.
“Electronic tags attached to marine animals … have augmented the capacity of ocean observing by sampling in extreme environments,” McMahon told Mongabay in an email.
The elephant seal program is run by the Animal-Borne Ocean Sensors (AniBOS) network team in collaboration with the Global Ocean Observing System (GOOS). Since the program’s inception nearly 20 years ago, scientists working with AniBOS have tagged about 40 southern elephant seals to get information that can help us understand climate change, and also about the behavior of elephant seals themselves.
To attach the devices to the elephant seals, the researchers first need to safely anesthetize these large animals, some of which can weigh well over 3,000 kilograms (6,600 pounds).
“We have developed a really simple technique for delivering the anesthetic which is safe for the animals and for the researchers,” McMahon said. “The devices are attached to the seal’s hair only and we have no evidence that the procedure is in any way painful. Also the seals are asleep for the duration of the 30 minute procedures.”
He added that their research has shown that the devices appear to have no negative effects on the animals’ abilities to survive.
Elephant seals are not the only animal that scientists have used to gather data. According to a recent paper led by McMahon, researchers have attached similar devices to seabirds, turtles, sharks and narwhals.
McMahon said the elephant seal program has already contributed data on sea ice formation, Antarctic bottom water formation, ocean and ice shelf interactions, frontal system dynamics, changes in the seals’ predation, and Antarctic mass water characteristics.
Due to the success of the elephant seal program in gathering data for scientific purposes, McMahon said he hopes the study will continue long into the future.
“While we have learnt a lot about our oceans and the animals in them, there remains an enormous amount that remains to be studied and the studies that we need and should be doing are really only limited by our imaginations and the investment we are willing to make in developing new instruments,” he said.
Cavanagh, R. D., Melbourne-Thomas, J., Grant, S. M., Barnes, D. K., Hughes, K. A., Halfter, S., … Hill, S. L. (2021). Future risk for Southern Ocean ecosystem services under climate change. Frontiers in Marine Science, 7. doi:10.3389/fmars.2020.615214
McMahon, C. R., Roquet, F., Baudel, S., Belbeoch, M., Bestley, S., Blight, C., … Woodward, B. (2021). Animal Borne Ocean Sensors – AniBOS – An essential component of the global ocean observing system. Frontiers in Marine Science. doi:10.3389/fmars.2021.751840
Takahashi, T., Sweeney, C., Hales, B., Chipman, D., Newberger, T., Goddard, J., … Sutherland, S. (2012). The changing carbon cycle in the Southern Ocean. Oceanography, 25(3), 26-37. doi:10.5670/oceanog.2012.71
Correction (02/12/2022): This article was updated to say that Clive McMahon is currently working at the Sydney Institute of Marine Science.
Banner image caption: Elephant seal with data-logging device connected to it. Image by Clive McMahon / Sydney Institute of Marine Science.
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