Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How do krill survive the Antarctic winter?

15.10.2013
Two-months dive expedition with RV Polarstern ends in Cape Town

Scientists from the Alfred Wegener Institute together with international colleagues could analyse the distribution and behaviour of larval and juvenile krill beneath wintery Antarctic sea ice for the first time.


Krill swarm
Ulrich Freier/Alfred-Wegener-Institut

In order to decrypt the life cycle of this ecologically important species 51 scientists and technicians as well as 44 crewmembers sailed the Weddell Sea for 63 days. The expedition, which started in Punta Arenas (Chile) ends in Cape Town (South Africa) on Wednesday, 16 October.

Every winter the sea around Antarctica freezes, forming a new solid surface 19 million square kilometres in extent. This area has nearly twice the size of the U.S., but is so vast scientists have only very rarely visited it. The research icebreaker Polarstern is one of only a few worldwide, which is able to operate in this region even during winter. This is why Polarstern enables searching for clues to one of the big mysteries of Antarctic biology: How do krill survive the winter, when there is little to eat in the water column?

Antarctic Krill (Euphausia superba) are shrimp-like crustaceans that are key to the whole Antarctic food web. The aim of the expedition was to explore the environment under the sea ice in order to throw light on the role it plays in the life cycle of Antractic krill. Therefore chief scientist Dr. Bettina Meyer from the Alfred-Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) put together an international team of experts to study krill under sea ice.

Apart from AWI colleagues it consists of scientists from the Australian Antarctic Division (AAD), the South African Department of Agriculture, Forestry and Fisheries (DAFF), the South African Environmental Observation Network (SAEON), as well as from the South African Universities of Grahamstown, Cape Town, and Stellenbosch and the University of Istanbul (Turkey).

“Krill have the largest biomass of any wild animal on Earth,” says AWI-scientist Meyer. They are a key food source for all the iconic Antarctic species, such as whales, seals and penguins. But there has been a marked decline in krill abundance in recent decades - a decline that seems to be linked to changes in the timing and extent of sea ice formation as parts of Antarctica warm.

Making use of Polarstern’s ability to break into the winter ice pack, the scientists set up dive camps on two different floes and sent a team of scientific divers, as well as a remotely operated mini-submarine (ROV), under the ice to make measurements and record video imagery. “The footage was really extraordinary,” says Meyer. “We saw that the under ice environment can be very complex, with caves and terraces formed where one floe has rafted over another. It’s not one habitat, but a series of micro-habitats, similar to an upside-down reef,” explains Dr. Ulrich Freier, the head of the eight-member scientific diving group.

“The light which penetrates the snow and ice generates a breath taking atmosphere comparable to the colours inside a gothic cathedral,” says Freier, “blues and greens from the ocean, the white ice and browns and yellows, indicating the on-going biological processes already in late winter on the southern hemisphere.” Dr Klaus Meiners from the AAD explains: “The colours are caused by algae growing in the ice.” He used a radiometer (a device that measures the spectra of light falling on it) mounted on the ROV to quantify the algae’s biomass within the ice.

Importantly, the expedition scientists discovered huge swarms of krill larvae and juvenile krill closely associated with the ice. In places the density reached ten thousand animals per square metre. “The distribution is very patchy. They seem to prefer the caves and terraces of the over-rafted areas, which are sheltered regions where the larvae can feed,” says Meyer.

During the day the scientists filmed the krill larvae directly feeding on the ice, but the picture was different at night, when the krill seemed to abandon the ice surface and descend in the upper 20 metres into the water column, perhaps to hide from predators, which come up to the surface at night. “The first time ever we were able to observe this daily migration of young krill stages. It happened at precisely the same time each evening”, explains Dr. Mathias Teschke from the Alfred Wegener Institute. “Their disperse distribution in the water column might prevent them from predation”, presumes chronobiologist Teschke. “This suggests that krill larvae may have an internal clock,” says Teschke, who will analyse the DNA of frozen krill larvae at the AWI to investigate this possibility.

The findings of the expedition confirm the importance of sea ice to the life cycle of krill. But, according to expedition leader Meyer, the timing of sea ice formation may be as important as the extent of the sea ice. “Krill seem to need sea ice which forms early enough in the year to incorporate high amounts of biomass, and to raft and deform to create the micro-habitats the krill prefer.” As scientists try to predict the effects of climate change on the Antarctic ecosystem, they will need to take such complexities into account.

After four and a half months in the wintery Antarctic, Polarstern is going to stay in the shipyard in Cape Town for routine maintenance and repair work. The next Antarctic summer season is going to start with a five weeks expedition to the South Atlantic on 9 November according to plan. Polarstern is going to arrive its homeport Bremerhaven after one and a half years in the Southern hemisphere in April 2014.

Notes for Editors:
You can find printable images on http://www.awi.de/en/news/press_releases/.
Your scientific contact is Dr. habil. Bettina Meyer. Please contact Dr. Folke Mehrtens (phone +49 471 4831-2007, e-mail: medien(at)awi.de) in the Communications Department to arrange appointments as Bettina Meyer is travelling.

Follow the Alfred Wegener Institute on Twitter (https://twitter.com/#!/AWI_de) and Facebook (http://www.facebook.com/AlfredWegenerInstitut) to obtain all current news and information on everyday stories from the life of the Institute.

The Alfred Wegener Institute conducts research in the Arctic and Antarctic and in the high and mid-latitude oceans. The Institute coordinates German polar research and provides important infrastructure such as the research icebreaker Polarstern and stations in the Arctic and Antarctic to the international scientific world. The Alfred Wegener Institute is one of the 18 research centres of the Helmholtz Association, the largest scientific organisation in Germany.

Ralf Röchert | idw
Further information:
http://www.awi.de
http://www.awi.de/en/news/press_releases

More articles from Life Sciences:

nachricht Fingerprint' technique spots frog populations at risk from pollution
27.03.2017 | Lancaster University

nachricht Parallel computation provides deeper insight into brain function
27.03.2017 | Okinawa Institute of Science and Technology (OIST) Graduate University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Northern oceans pumped CO2 into the atmosphere

27.03.2017 | Earth Sciences

Fingerprint' technique spots frog populations at risk from pollution

27.03.2017 | Life Sciences

Big data approach to predict protein structure

27.03.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>