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5 Posts tagged with the antarctica tag
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Anne Jungblut, a botany research scientist at the NHM, has been awarded the US Antarctica Service Medal. The medal was established by US Congress in 1960 to honour service personnel and civilians who contribute to US Antarctic expeditions.

 

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Anne has been taking part in Antarctic expeditions since 2005 with the New Zealand and US Antarctic Program, and has represented The Natural History Museum on these expeditions since 2009.  Her blog gives details of expeditions to look  at cyanobacteria in Antarctica, which form thick mats in meltwater pools.  We are always intrigued by the sampling equipment that appears in some of the photographs!

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Dr Anne Jungblut works in the Antarctic on cyanobacteria - a summary of her recent work is taken from the Botany annual report

 

The Antarctic is characterized by extreme cold and aquatic ecosystems that are dominated by microbes. Cyanobacteria can be found in polar lakes, ponds and streams, and often dominate total ecosystem biomass and productivity by forming benthic mats and films. These organisms are highly tolerant of the harsh polar conditions and overcome nutrient limitation by recycling and scavenging inorganic and organic nutrients.

 

In the ice-covered lakes of the Dry Valleys of Antarctica, cyanobacteria-dominated microbial mats form pinnacle structures that are potential analogues to microbialites found in fossil records. However, despite the importance of cyanobacteria to Antarctic ecosystems, ecology and geo-biology, their diversity, community structure and ecology have been little studied.

 

Two field events took place during the austral summer 2010-2011. The first project aims to evaluate the diversity of Antarctic cyanobacteria along spatial and temporal scales. During the field trip to Antarctica in collaboration with Dr Ian Hawes, Dr Jenny Webster-Brown and Hannah Christenson, University of Canterbury, Christchurch, New Zealand), collection sites were targeted on Ross Island and McMurdo Ice Shelf that were visited by the British National Antarctic Expedition (Discovery Expedition 1901–04), the British Antarctic Expedition (Terra Nova Expedition 1910-13) led by R.F. Scott and the British Antarctic Expedition (Nimrod Expedition 1907-09) led by E. H. Shackleton in order to test how present-day diversity compares with cyanobacterial mat specimens from 100 years ago. The fieldwork was supported by Antarctica, New Zealand and the project “Antarctic Aquatic Inland Ecosystems: Icebased ecosystems” (Project Leader: Dr Ian Hawes).

 

The second project is in collaboration with Dr Dale Anderson (Principal Investigator, SETI Institute, CA, USA), Dr Dawn Sumner and Tyler Mackey (US Davis, CA, USA) and Dr Ian Hawes (University of Canterbury, Christchurch, New Zealand). The objective is to gain a better understanding of pinnacle formations in cyanobacteria-dominated microbial mats in the perennial ice-covered Lakes Joyce, Vanda and Hoare in the Antarctic Dry
Valley, which will help to interpret ancient microbialite morphology in fossil records. A field event was carried out as part of the US Antarctic Program and supported by research grant from NASA. As part of the fieldwork in the Dry Valleys, pinnacle morphologies were characterized, photosynthesis capabilities examined and cyanobacterial diversity assessed by way of microscopic analysis. Ongoing research in the NHM Botany Department will determine community structure of cyanobacteria within microbialite structures to evaluate the role of cyanobacteria in the formation of microbialite structures, and to study the phylogenetics of cyanobacteria from these unique Antarctic cryo-ecosystems.

 

Anne wrote a blog on her experiences in the Antarctic - a day-by-day account from the early part of 2011.

 


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Dr Adrian Glover (Zoology) has just returned from an oceanographic research cruise to the Bransfield Strait and Scotia Sea, Antarctica, both to the south of South America, near the Antarctic Peninsula.  He was working aboard the RRS James Cook,  one of three UK research ships operating as part of the Natural Environment Research Council's activities.

 

Adrian was searching for new hydrothermal vent ecosystems with scientists from the National Oceanography Centre, Southampton and British Antarctic Survey. The team also found the dead body of a whale on the sea bed.  This is a particular interest of Adrian's because such corpses are important sources of nutrition in the sea for specialist marine species such as Osedax mucofloris.

 

During the cruise, Adrian made three live voice links to Nature Live shows in the Attenborough Studio in the Museum's Darwin Centre, coupled with video clips and images that he had already sent over the ship's satellite system. The public and science staff in the audience were able to interact directly with scientists in the field in the Antarctic, and were some of the first people to see video of Antarctic hydrothermal vents at 2500m water depth in the Scotia Sea.

 

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Adelie penguins - a photograph taken during Captain Scott's expedition in 1911-12

 

The audiences were spellbound with the live descriptions of passing penguins and albatrosses as Adrian gave a vivid account of the ups and downs of life as a research marine biologist on a research cruise. Given the size of the waves in the Southern Ocean, the ups and downs can be pretty extreme - if you can imagine living on a small rollercoaster for a week or two, you might have some idea of what it is like!

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Just over one hundred years ago in Feburary 1911, Captain R.F. Scott RN received news from Roald Amundsen that he was intending to make a bid for the South Pole in competition with Scott’s. Scott’s expedition had a range of important scientific goals: the race for the Pole for which he is best known was only one of the objectives. The science involved resulted in a number of Antarctic collections, some of which are in the Museum today.

 

These collections have been used to show a dramatic doubling in the growth of bryozoans in Antarctic seas in the last twenty years. Bryozoans are tiny colonial animals that encrust rocks, algae and other objects beneath the sea, filtering food from the water.  It is another use of older collections that could never have been anticipated at the time of collection, but shows the value and importance of these collections to modern science and current concerns.

 

Dr Piotr Kuklinski, a Scientific Associate of the Museum who works for the Polish  Academy of Sciences Institute of Oceanography, has collaborated with other scientists from the British Antarctic Survey and US institutions to examine collections to tell how growth has changed over time and to suggest reasons why this might be happening.

 

They looked at a whole series of Antarctic collections in the Museum from 1909 to the 1930s, and other collections in the US and New Zealand up to the present day.  The species Cellarinella nutti from the Ross Sea was used – it shows annual growth lines as the colony expands and so yearly growth can be measured. The growth measurements showed no particular change in rates of growth from 1890 to 1970, but there was a rapid increase in growth from the 1990s to the present day.

 

Why is this happening?  Growth seems to be increasing because of increased availability of food – tiny single-celled plants known as phytoplankton. This increase would result from higher concentrations of phytoplankton or a longer growing season. Climate change?  Probably not - the scientists point out that there is little evidence of changes to sea ice or water temperatures in the Ross Sea.

 

However, they do suggest that this may be linked to depletion of stratospheric ozone – the ozone holes that occur in the Antarctic summer.  This could be causing stronger west winds that result in currents bringing in more nutrients to the area, in turn resulting in higher growth of plankton and higher growth of bryozoans.  Our understanding of the detail of these questions helps refine our understanding of the Earth’s carbon cycle, which is closely linked to our climate system.

 

The authors conclude ‘Amundsen claimed that Scott's “..British expedition was designed entirely for scientific research. The Pole was only a side-issue…”. Being first to reach the pole was foremost in fundraising and probably in Scott's thinking but coming second in the ensuing ‘race’ and dying there completely overshadowed the many scientific achievements of the expedition. However, the baselines that they established and crucial subsequent curation may prove key to interpretation of trends with significance way beyond the polar regions.’

 

David K.A. Barnes, Piotr Kuklinski, Jennifer A. Jackson, Geoff W. Keel, Simon A. Morley, Judith E. Winston (2011) Scott's collections help reveal accelerating marine life growth in Antarctica.  Current Biology - 22 February 2011 (Vol. 21, Issue 4, pp. R147-R148) doi:10.1016/j.cub.2011.01.033

 

 

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Bryozoans are colonial invertebrates, commonly found attached to hard surfaces from the shallow subtidal zone to the deep sea. Bryozoan colonies increase in size by the budding of the numerous individuals (zooids) that make up the colony.

 

A collaborative team, including Professor Beth Okamura, Dr Tanya Knowles and Dr Paul Taylor from the NHM, explored how the size of zooids in fossil bryozoans varied as temperature changed.  This enabled them to use bryozoans to deduce the annual ranges of temperature during the Early Pliocene (around 4 million to 5.5 million years ago) in the Weddell Sea off the coast of  Antarctica.

 

Their results show that during this period the climate was warmer than that of the present day, suggesting an ice-free environment in that part of Antarctica.

 

The research shows the value of fossil bryozoans from shallow seas as a tool for reconstructing seasonal variation in climate in near-polar latitudes in past periods of the Earth's history.  This helps to understand how climates have changed naturally in the past - knowledge that in turn enables present-day changes in climate to be understood and predicted.

 

Clark, N., Williams, M., Okamura, B., Smellie, J., Nelson, A., Knowles, T., Taylor, P., Leng, M., Zalasiewicz, J. & Hayward, A. 2010. Early Pliocene Weddell Sea seasonality determined from bryozoans. Stratigraphy 7: 199-206.