Southern elephant seals fitted with battery-powered sensors have mapped a vast new territory for scientists studying climate change in Antarctic waters.
The seals, sporting high-tech satellite headgear, have provided the first information on conditions under Southern Ocean sea ice, helping an international research team track seasonal changes in ice formation and ocean salinity. CSIRO oceanographer Dr Steve Rintoul said, ''They've helped sample a part of the ocean that was invisible to us before, and made it possible for us to observe large areas under sea ice in winter for the first time.''
Although the surface area of Antarctic sea ice can be measured by satellite, the key climate change indicators of sea ice thickness and formation rate can only be measured from beneath the ice. Mammal biologists studying Antarctic seal colonies suggested enlisting the 500kg-plus elephant seals as deepwater research assistants.
''They wanted to know where the seals were feeding during winter, and the oceanographers decided the seals might also be able to measure temperatures, ice thickness and salinity changes,'' Dr Rintoul said.
A purpose-designed satellite data logger was attached to the fur on their head, allowing the seals to transmit a range of data as they foraged under the winter ice. The sensor, roughly the size of a mobile phone, falls off when the seals moult the following year.
The findings, published online today by the National Academy of Sciences, are the work of 22 scientists from Australia, France, Britain and the United States.
The results show the elephant seals increased the amount of scientific information from the sea ice zone of the Southern Ocean by more than 30 times. They typically swam up to 65km a day, diving to depths of more than 500m on average and a maximum depth of almost 2000m.
The seals provided nine times more data than conventional research methods, such as floating senor-buoys. Scientists have been able to extend mapping of the Antarctic currents by up to 85 per cent in the Southern Indian Ocean, the Ross Sea and Western Antarctic Peninsula as a result.
''The seals have given us a wealth of information about a part of the ocean we weren't able to measure before, and given us our first real look at what's happening under the ice, and the potential impact of global warming,'' Dr Rintoul said.
''Changes in sea ice are one of the most important indicators of climate change, but until recently, we didn't have the data we needed to ensure climate models would be accurate.''
The polar regions play an important role in regulating the Earth's climate and recent research suggests they are changing quicker than other regions because of global warming.
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