School of Biology

News Item:
Seals help unlock secrets of the ocean

Elephant seals in the Southern Ocean are helping researchers to gather essential data locked beneath the icy seas.

Sensors developed by the University of St Andrews have been employed by Antarctic researchers to collect otherwise inaccessible information about the climate.

The instrumentation group of the University's Sea Mammal Research Unit has created small data logging transmitters that can be used to measure the physical properties of the ocean through which the seals swim.

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 impermeable to all three.

Professor Mike Fedak from the University's Gatty Marine Laboratory said, "The Southern Ocean is a hotspot for climate research because its circulation is critical to understanding the earths 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 instruments measure temperature, pressure, and salinity and transmit data as well as seal positions to satellites when the seals surface. From this, researchers are able to amass data for a vast range of hitherto inaccessible ocean, including areas deep within the sea-ice in winter while also learning about the animals themselves.

This new data has enabled them to follow the yearly rise-and-fall cycle of sea ice production, and should help scientists refine computer models of the Southern Ocean circulation.

Led by DrJean-Benoit Charrassin, a marine biologist at the Natural History Museum in Paris, researchers in France, the UK, Australia and the US have attached electronic dataloggers to 70 seals at the four most important breeding colonies of southern elephant seals.

The species can dive as deep as 2 km in search of food while ranging across much of the southern ocean. Thanks to this innovative technology, the only remaining area with limited coverage is the Pacific sector, which contains no islands for the seals to breed on.

Professor Fedak explained, "I think this is an extremely exciting new approach for ocean observation which has now been extended to seals roaming the seas around both Poles as part of the International Polar Year (IPY). "

The on-going MEOP project (Marine Mammals Exploring the Oceans Pole to Pole) has equipped 100 seals of 3 polar species with oceanographic sensors and these animals are now routinely sending large quantities of near real-time information from the undersampled polar regions.

Professor Fedak continued, "The MEOP animals have contributed over 35 thousand observations from the polar seas in the past year, and I think it is really fantastic to see how large a contribution the animals can make, sending data from below the ice in near real time.

"These data are automatically distributed all over the world via the World Meteorological Organization (WMO) Global Telecommunication System (GTS) 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.

"The idea that these animals have become our partners in providing real time data about the state of our climate while simultaneously helping us to understand their ecological requirements has captured the imagination of biologists, oceanographers and the public."

The article "Southern Ocean frontal structure and sea ice formation rates revealed by elephant seals," by J.-B. Charrassin, M. Hindell, S.R. Rintoul, F. Roquet, S. Sokolov, M. Biuw, D. Costa, L. Boehme, P. Lovell, R. Coleman, et al. is published today by PNAS.

contact: Prof Michael Fedak