Seal Bulls in the Service of Science

"Gustavo" is an imposing bull always in search of the best feeding grounds. The elephant seal weighing 3 tons and measuring 4 metres in length belongs to a group of 14 animals that serve researchers of the Alfred Wegener Institute as scientific assistants since recently.

At the beginning of the Antarctic winter -- from mid-March to the end of April -- the mighty elephant seal bulls were tagged with state-of-the-art satellite transmitters at the Dallmann Laboratory on King George Island. In the coming months marine biologists Dr. Joachim Plötz and Dr. Horst Bornemann will follow (from their desks in Bremerhaven) where the animals migrate, where they find prey at what depth and under what oceanographic conditions the food supply is good in the Southern Ocean.

"We have just returned from the Antarctic Peninsula and still have fresh impressions of the incredible experience when you have numerous elephant seal bulls with their loud deep roar in front of you and imagine attaching a satellite transmitter the size of your palm to some of these huge creatures," Joachim Plötz describes a not entirely everyday situation even for the experienced seal researcher. Every year from March to April the males of the only reproduction colony of the Southern elephant seal in the Antarctic come to the South Shetland Islands, a group that also includes King George Island, for moulting. The scientists from the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association took advantage of this narrow time window to furnish some of the animals with transmitters that operate using the satellite-aided ARGOS location system. Once moulting is over after three weeks, the bulls go back to their migratory life and do not return to land until six months later to mate with the females in the Antarctic spring.

During the annual migrations to their oceanic feeding grounds elephant seals cover thousands of kilometres. They dive down to depths of over 2000 metres and remain under water for periods of over an hour. When a seal with a transmitter dives, it collects data -- even under the ice -- and then appears on the surface again to breathe after some time. While it breathes fresh air, the recorded data package is sent to a satellite that passes on the signals received. With a little luck the transmitter will continuously transfer data for a year. When the next moulting takes place, the wonder of microelectronics developed by the Scottish Sea Mammal Research Unit will then fall off. Immediately after evaluation the measured data from this German-Argentinian-South African joint project will be made available to other world data centres via the Publishing Network for Geoscientific & Environmental Data (PANGAEA) at the Alfred Wegener Institute and used by various international cooperative scientific ventures.

During the extended travels through the Southern Ocean the transmitters not only send the geographic position and diving depth of the respective seal, but at the same time data on the temperature and salt concentration of the body of water through which the animal is swimming and thus important physical parameters from which, for example, conclusions can be drawn on the currents in the ocean. "Elephant seals mainly feed on fish and squid," Plötz's colleague Horst Bornemann explains why the researchers can draw conclusions regarding the spatial and temporal distribution of particularly productive zones in the Southern Ocean based on seal migrations. "They lead a nomadic life in the ice desert of the Antarctic Ocean and are always looking for regions with ample prey. Based on seasonal changes in the migration behaviour of seals, we thus obtain indications of when, where and at what depth exceptionally high numbers of fish and squid occur and with what oceanographic conditions a good supply of food correlates."

Even though the transmitters can hold out for a year, the data in the coming months are especially sought after. During this period the Antarctic winter prevails, the Southern Ocean is covered with ice and continuous measured data, particularly from the winter months, are rare. "Research vessels cannot yet sail continously in the Antarctic Ocean at this time. Our seals," say Plötz and Bornemann full of conviction, "are therefore genuine pioneers of research."

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Helmholtz Association of German Research Centres.

Rare white seal caught on camera

The young elephant seal rests alongside another of normal colour (R Reisinger).A white southern elephant seal has been spotted on a sub-Antarctic beach.It is the first confirmed sighting of such an animal. Eared seals, which include sea lions and fur seals are more usually seen sporting unusual colours, but not true seals, a group which includes elephant seals. Details of the seal, which has creamy white fur but normal brown eyes and nose, have been published in the journal Polar Biology. "It's quite something in a species which is well-known," says Ryan Reisinger of the University of Pretoria in South Africa, one of the researchers who discovered the animal on Marion Island. For example, southern elephant seals from many colonies were hunted for decades within the nineteenth and twentieth centuries. In more recent times, scientists have also extensively studied the animals. "Yet this is the first confirmed case of leucism in the species," says Reisinger. The white seal, a young female, is leucistic, rather than albinistic. Albino animals lack pigment in just their eyes, or in their eyes, skin and hair, and they inherit the condition. Leucistic animals have little pigment and appear white all over, but with dark coloured eyes.White fur but normal brown eyes (R Reisinger). The white seal has a uniformly creamy white coat of fur, with normal dark brown eyes and nose. Its whiskers, eyebrows and fingernails on its flippers are also light coloured compared to the species' usual dark colour. "To our knowledge, we're the first to provided detailed evidence of such an animal anywhere," says Reisinger. The research team sighted the white seal on 23 August 2008 on Whale Bird beach on Marion Island, which lies in the sub-Antarctic region of the Indian Ocean. On 30 August, the researchers saw the seal again and got close enough to confirm its leucism, tag it and take a skin biopsy. They estimate the animal was between one and two years old, and was likely born either on nearby Prince Edward Island or further afield on Iles Crozet. Reisinger says it's impossible to say precisely how rare the animal is. "We can't put it in terms of one in a million, or one in a hundred thousand." But he and his colleagues have been monitoring and tagging elephant seals for years on the island without having seen one. While there have been a few rare previous records of lighter coloured elephant seals, none have been confirmed as leucestic.The young seal resting on Marion Island (R Reisinger). The researchers were actually on the look out for leucestic Antarctic fur seals when they spotted the white elephant seal. Antarctic fur seas are usually grey and brown, but numerous white Antarctic fur seals have been spotted before. Last year five unusually coloured Antarctic fur seals were seen on Livingston Island, including one partially leucistic pup that had fur like a tiger's stripes and another piebald individual, the first time such coat patterns have been seen. In February 2007, researchers also spotted the first known leucestic South American sea lion on the coast of Paso Shag, near the Magellan Strait in Chile.BBC

Elephant seals join fight against climate change

Elephant seals swimming under Antarctic ice and fitted with special sensors are providing scientists with crucial data on ice formation, ocean currents and climate change, a study released on Tuesday said. The seals swimming under winter sea ice have overcome a "blind-spot" for scientists by allowing them to calculate how fast sea ice forms during winter.Sea ice reflects sunlight back into space, so less sea ice means more energy is absorbed by the earth, causing more warming."They have made it possible for us to observe large areas of the ocean under the sea ice in winter for the first time," said co-author Steve Rintoul from Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO).Conventional oceanographic monitoring from ships, satellites and drifting buoys, cannot provide observations under sea ice."Until now, our ability to represent the high-latitude oceans and sea ice in oceanographic and climate models has suffered as a result," said Rintoul, who also works with the Antarctic Climate and Ecosystems Cooperative Research Centre in Hobart.The elephant seals have provided scientists with a 30-fold increase in data recorded in parts of the Southern Ocean, said the study by a team of French, Australian, U.S. and British scientists and published in the Proceedings of the National Academy of Sciences.Between 2004 and 2005, the seals swam up to 65 kilometers (40 miles) a day, supplying scientists with 16,500 ice profiles. The seals dived to a depth of more than 500 meters (1,500 feet) on average and to a maximum depth of nearly 2 km (a mile)."If we want to understand what's going to happen to climate in the future we need to know what the sea ice is going to do. Will there be more or less and will it form more or less rapidly?" Rintoul told Australian Broadcasting Corp. radio.The experiment involved 85 seals with sensors attached to their heads."They measure temperature and salinity as a function of depth as they dive down and up through the water column," he said."From that information we can determine what the ocean currents are doing and so they provide us with a very detailed record of how temperatures and salinity's changed," he added.The polar regions play an important role in the earth's climate and are changing more rapidly than any other part of the world, with the Southern Ocean warming more rapidly than the global ocean average.Sea ice not only affects the amount of energy reflected back into space, but also the amount of dense water around the Antarctic which drives ocean currents that transports heat around the globe.Sea ice also provides a critical habitat for krill, penguins and seals.

Secret life Of Elephant Seals Revealed

The measurements reveal in detail where the seals go on their winter feeding trips, where they find food and where they don’t, and help explain why some populations have remained stable since 1950 while others have declined।

The work was carried out by an international team including scientists from France, the United States and the United Kingdom and included Australian researchers Professor Mark Hindell from the University of Tasmania’s Animal Wildlife Research Unit, Dr Steve Rintoul, from the Antarctic Climate and Ecosystem Cooperative Research Centre and CSIRO (through the Wealth from Oceans Flagship), and Professor Nathan Bindoff from the University of Tasmania and the Flagship. Lead author of the PNAS paper is Dr Martin Biuw, from the Sea Mammal Research Unit at the University of St Andrews in the UK.
Until recently, the response of large marine predators to environmental variability has been almost impossible to observe directly.
Sensors were deployed on 85 elephant seals from key colonies in January and February 2003 and lasted throughout most of the Antarctic winter season. The longest track was 326 days and up to 30,000 profiles of temperature and salinity were obtained.
By simultaneously recording movements, dive behaviour and oceanographic conditions, the new sensors allow researchers to examine in detail how elephant seals respond to changes in ocean conditions.
“Most of what we know about these seals has been based on observations made when the seals haul out on sub Antarctic islands to breed, such as the number and physical condition of the animals,” Professor Hindell said। “In particular, we have had no way to study how the seals interact with their environment and the prey within it.”

By monitoring changes in the rate at which seals drift up or down during passive “drift dives,” the scientists could determine where the seals were gaining fat (and becoming more buoyant) and where food was harder to find and the animals lost fat.
“These measurements have allowed us for the first time to make circumpolar maps of the areas that provide good foraging for seals, and areas where conditions are less favourable for them,” Professor Hindell said.
The oceanographic measurements collected by the seals provided a detailed view of the feeding behaviour of the seals in relation to oceanographic features. “The measurements of temperature and salinity collected by the seals show that the seals target very specific water bodies,” Dr Rintoul said.
“An intriguing surprise was that the feeding preferences of the Atlantic seals were very different from seals tagged on Kerguelen and Macquarie Islands, in the Indian and Pacific sectors of the Southern Ocean,” Dr Rintoul said.
The Atlantic seals preferred the open ocean waters of the Antarctic Circumpolar Current. The Kerguelen and Macquarie seals spent the winter feeding season in the sea ice pack, near the Antarctic continent.
“We think the fact that these seal populations have different foraging strategies may explain why seal numbers in the Indian and Pacific declined between the 1950s and 1970s, while Atlantic populations remained stable,” said Professor Hindell.
“The Indian and Pacific seals have to travel more than 1000 km further during their winter migration than Atlantic seals. The extra energy expended would mean less energy for breeding in years of low food abundance,” he said.
“Studies suggest that the amount of sea ice declined during the 1950s to 1970s off east Antarctica; since the Indian and Pacific seals prefer to feed in the sea ice zone, the decline in sea ice may have contributed to the decline in those seal populations,” added Dr Rintoul.
Support for the Australian component of the research was provided by the Australian Research Council, the Australian Antarctic Science Grants Scheme, CSIRO (through the Wealth from Oceans Flagship) and the Antarctic Climate and Ecosystems Cooperative Research Centre.
Background on elephant seals
By providing detailed information on how animals at the top of the Southern Ocean food chain respond to variability in the ocean, this study will guide development of effective strategies for management of living resources in the Southern Ocean and predictions of how animals will respond to climate change.
Oceanographic sensors with satellite transmitters were deployed on southern elephant seals (Mirounga leonina) in three locations – Macquarie Island south of Tasmania, the French sub-Antarctic island of Kerguelen and South Georgia in the Atlantic.
The tags are glued to the fur of the elephant seals before they leave on long foraging journeys. The tags are retrieved when the animals return to the same beach to moult, which is up to 10 months later.The tags record the position of the animal, monitor its diving cycle with a pressure sensor, and record water temperature and salinity – data which they upload to satellite while they are at the surface.
Southern elephant seals can dive to 1,500 metres but more commonly frequent depths of 200-500 metres.
This research was recently published in the Proceedings of the National Academy of Sciences.
Note: This story has been adapted from a news release issued by CSIRO Australia.