ELEPHANT seals swimming beneath the Antarctic ice are providing crucial data in the quest to learn more about climate change.
As the creatures dive and hunt in one of the most inaccessible environments on Earth, they are feeding back information that is helping to shed light on the climate, using sensors that have been stuck to their coats.
The transmitters, developed by
St Andrews University, are glued to the elephant seals and effortlessly measure the physical properties of the ocean, until the mammals shed their coats and lose the small devices after about a year.
Scientists usually collect data to characterise the ocean using satellite sensing, buoyant floats and ship expeditions, but winter sea ice renders the Southern Ocean virtually impenetrable to all three.
Professor Mike Fedak, of the university's Gatty Marine Laboratory, said: "I think it's quite exciting to imagine these animals swimming around down there and getting this data that helps us understand the weather and the climate."
Marine biologists from across the world have been involved in catching the seals when they go ashore, sticking a tag to their fur and then leaving them to return to the icy depths.
Elephant seals can dive as deep as 2km in search of food, while ranging across much of the Southern Ocean.
The instruments attached to them measure temperature, pressure and salinity, and transmit data, as well as the seals' positions, to satellites when the animals surface.
From this, researchers are able to amass data for a vast range of previously inaccessible ocean, including areas deep within the sea ice in winter.
Prof Fedak said: "The Southern Ocean is a hot spot for climate research, because its circulation is critical to under-standing the Earth's climate and its huge ice sheet is sensitive to climate change.
"Southern elephant seals are wide-ranging predators that roam all over the Southern Ocean, even under the sea ice in the wintertime – a time when conventional ocean observation methods are unable to gather data."
The transmitters have enabled scientists to follow the yearly rise-and-fall cycle of sea-ice production and should help to refine computer models of the Southern Ocean circulation.
Thanks to this innovative technology, the only remaining area with limited coverage is the Pacific sector, which contains no islands where the seals can breed. The project – which is called Marine Mammals Exploring the Oceans Pole to Pole – has so far equipped 100 seals with oceanographic sensors, and these now routinely send large quantities of near real-time information from the undersampled polar regions.
They have contributed 35,000 observations from the polar seas in the past year, and these are automatically distributed, using the World Meteorological Organisation Global Telecommunication System, to operational forecasting centres, where they can be assimilated into models that are run to provide ocean forecasts and long-range seasonal and climate predictions.
Prof Fedak said: "The idea that these animals have become our partners in providing real-time data about the state of our climate, while helping us to understand their ecological requirements, has captured the imagination of biologists, oceanographers and the public."
The latest developments are described in an article, "Southern Ocean frontal structure and sea ice formation rates revealed by elephant seals", in the journal Proceedings of the National Academy of Scientists.
FACTFILEELEPHANT seals take their name from the large proboscis on the adult male, used to produce extraordinarily loud roaring noises, especially during the mating season.
The male is bigger than the female – it can reach a length of 16ft and weigh 6,000lb.
The creatures often live for more than 20 years.
The mammals were hunted near to extinction by the end of the 19th century, but have since recovered.
Elephant seals spend up to 80 per cent of their time in the ocean and can hold their breath for 80 minutes. Their favourite foods are skate, ray, squid, octopus, eel and small sharks.
On land, they can move faster than humans.
Their blubber, more than their fur, shields them from the cold.
