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News from "The Ice" and beyond

New evidence points to impact of high ultraviolet radiation levels

Biologists from Northeastern University and the University of Texas report the first direct evidence that increased levels of ultraviolet-B (UVB) radiation, caused by the depletion of ozone over Antarctica and its surrounding oceans each autumn, have a destructive effect on the natural animal populations in the area. An article published in the 17 February 1997 issue of the Proceedings of the National Academy of Sciences (http://www.pnas.org/) details findings of DNA damage to the eggs and larvae of a hemoglobinless antarctic icefish-damage that coincides with the increased intensity of UVB in the study area around the Antarctic Peninsula. "Ozone depletion has previously been shown to harm one-celled marine plants in Antarctica," observed William Detrich, one of the authors of the study. "We've now documented significant damage at a higher level of the food chain." The researchers speculate that the excess UVB radiation may slow a fish's growth, hamper its cellular processes such as transcription and mitosis, and divert its store of energy to DNA repair. Ultimately, these biologists believe, the damage done by increased UVB levels may mean that fewer eggs and larvae survive to adulthood. For more information, see also 
http://www.nsf.gov/od/lpa/news/press/pr9719.htm and http://sciencenow.sciencemag.org/archives.297.shtml (Friday, 21 February 1997) 

Aboard the National Science Foundation research vessel Nathaniel B. Palmer, other researchers have discovered that algae in the Weddell Sea are extremely sensitive to the annual increases in UVB. Patrick Neale, a biologist from the Smithsonian Institution's Environmental Research Center, found that UVB exposure led to a greater reduction in photosynthesis in Weddell Sea algae than in algae from the Chesapeake Bay and other marine waters. Reasons for this hypersensitivity in polar algae are unknown and will be the focus of Neale's follow-up studies in 1997 and 1998. (http://www.nsf.gov/od/lpa/news/tips/tip70527.htm#second

The protective ozone layer over Antarctica has thinned each autumn for the past two decades as human-created chemicals called chlorofluorocarbons (or CFCs) have risen to the stratosphere and played a part in the destruction of ozone. The release of CFCs into the atmosphere has now been limited by an international treaty, but pre-treaty CFCs, still circulating in the atmosphere, are expected to deplete the ozone for decades to come. In fact, some scientists believe that the ozone depletions will spread over more of the globe before they begin to decrease in the next century. 

Antifreeze gene in polar fish demonstrates convergent evolution

New research shows that notothenioid fish from the southern oceans around Antarctica and Arctic cod from the other end of the globe each developed, independently of the other, an antifreeze glycoprotein (AFGP) to keep their blood and organs from freezing as global temperatures began to cool. Research by three University of Illinois biologists, Arthur L. DeVries, Liangbiao Chen, and Chi-Hing C. Cheng, traces for the first time the genetic process by which a novel protein evolved and adapted to environmental change. 

DeVries first discovered AFGP in antarctic icefish in the 1960s, and when a similar substance was found in Arctic cod, biologists speculated that the two species had somehow shared a common ancestry. DeVries's recent work, however, demonstrates that although the AFGP in the Arctic cod is nearly identical to that in the notothenioids, the gene that codes for it isn't, proving that the two AFGPs developed independently. DeVries, Chen, and Cheng located the parent gene, a digestive enzyme called trypsinogen, for the AFGP in the antarctic species and then determined that the AFGP gene for the antarctic species differs very little (only 4 to 7 percent) from this parent gene. For comparison, the researchers sequenced and analyzed the Arctic cod's AFGP gene and found that it does not resemble the gene for trypsinogen and that it differs from its southern counterpart in gene structure and coding as well. 

The AFGP in the antarctic notothenioids, which constitute the majority of fishes in the southern oceans, appears to have developed between 5 million and 14 million years ago, when the southern oceans first began to freeze. Formation of the AFGP allowed the icefish to adapt to the cooling climate by preventing ice crystals from forming in their tissues and allowing them to exploit the newly evolving ecological niche. 

The two articles ("Evolution of antifreeze glycoprotein gene from a trypsinogen gene in Antarctic nototheniod fish" and "Convergent evolution of antifreeze glycoproteins in Antarctic nototheniod fish and Arctic cod") describing this work in detail are available online in the April 1997 issue of the Proceedings of the National Academy of Sciences at http://www.pnas.org/. See also 
http://www.nsf.gov/od/lpa/news/press/pr9729.htm 
http://www.sciencenow.sciencemag.org/archives.497.shtml (Monday,14 April 1997) 
http://www.oc.uiuc.edu/NB/97.05/9705fishtip.html 

Glaciologists process ice cores from Siple Dome, West Antarctica

During the 1996­1997 austral summer, 10 individual ice cores, constituting about 700 meters, were drilled near Siple Dome, Antarctica, and shipped to the U.S. National Ice Core Laboratory (NICL) at the U.S. Geological Survey in Denver. During June and July at NICL, the cores were processed and analyzed by 10 to 12 principal investigators and students from universities and laboratories around the United States. 

Ice cores contain a wealth of information about past climate and help scientists predict future changes. As snow falls, it traps samples of the cloud water, atmospheric gases, and dust and carries them to the ground. Over time, the fallen snow accumulates into an ice sheet, which can be several kilometers thick and can contain ice that fell as snow over 100,000 years ago. By analyzing the ice, glaciologists can plot a climate history containing, among other measures, 

  • temperature, 
  • snow accumulation rate, 
  • relative wind speeds, 
  • the occurrence of volcanic eruptions anywhere on the globe, 
  • general ocean and atmospheric circulation patterns, and 
  • concentration of carbon dioxide and other greenhouse gases. 
Understanding the natural changes to Earth's climate helps scientists determine human influence on climate change. 

In the Siple Dome area of Antarctica, glaciologists are analyzing cores from two distinct areas, one far inland and one near the coast. Comparing the ice record from the two regions should help glaciologists understand more fully 

  • the relationship between atmospheric carbon dioxide and temperature, 
  • the influence of the west antarctic ice sheet on sea level and the likelihood for unexpected rapid changes in sea level, 
  • the influence of southern ocean and atmospheric circulation patterns on climate, and 
  • the cause of changes in the southern ocean and atmospheric circulation patterns. 
For more information, see 
http://www.usgs.gov/public/press/public_affairs/press_releases/pr272m.html and http://www.maxey.dri.edu/WRC/waiscores/

Long-time researcher spots a rare white emperor penguin

Gerald Kooyman, a biologist from the University of California­San Diego's Scripps Institution of Oceanography has studied penguins in Antarctica for over 30 years, but the austral winter of 1997 brought a surprise: he reported what is believed to be the first sighting of an all-white emperor penguin. 

Kooyman was conducting a census of a colony of penguins on the snow-covered sea ice in the western Ross Sea when he spotted the unusual bird. Because its white feathers caused it to blend in with the background, he almost missed it. "There are thousands of penguins in the colony, and they are quite spread out," Kooyman recalled, "but we were counting every chick and that's how we spotted it." Normally, emperor chicks are covered in a grayish down coat and their wing and tail feathers are dark as are their bills and feet. Usually, they have dark rings around their eyes. The chick Kooyman spotted was completely white. "It was really a spectacular bird," he said. Because it didn't have the characteristic red eyes, the white chick is not believed to be an albino. A photo of the rare white bird can be found on the Web at http://sio.ucsd.edu/supp_groups/siocomm/pressreleases/WhitePenguin.html

Kooyman believed that the chick fledged, and thus, he does not expect it to return to the colony for 4 or 5 years. "The survival rate of the birds from the time they leave the colony until they return is quite low," Kooyman commented. "So the chance of seeing the penguin again is really pretty low." 

Satellite data confirm existence of hypothetical "Bellingshausen plate"

Scientists have long known that the topography of the ocean floor and variations in rock density cause minute changes in the strength of gravity in undersea regions. By measuring these marine gravity anomalies, scientists have been able to map the ocean floor and decipher the ancient movement of the tectonic plates that form the Earth's crust. When it came to mapping the ocean floor in the polar regions, however, the seasonal pack ice as well as the permanent ice cover in some areas made the ocean water opaque to all types of electromagnetic wave used to detect marine gravity anomalies elsewhere on the globe. As a result, whole sections of the sea floor, some the size of the United Kingdom, have gone unsurveyed, and in some areas, less has been known about the ocean floor than is known about the surface of Mars or the Moon-until recently. 

British scientist Seymour Laxon of the Mullard Space Science Laboratory in Surrey, England, and U.S. scientist David McAdoo of the National Oceanic and Atmospheric Administration have developed a technique to analyze satellite data and retrieve accurate topographic measurements even when sea ice is present. In the 25 April 1997 issue of Science, Laxon and McAdoo describe what they uncovered when they applied this technique in the southern oceans and the Arctic Ocean (http://msslsp.mssl.ucl.ac.uk/people/swl/esa97/index.html). 

Tectonic plate movement in the south polar region has been a mystery. Some scientists held to the hypothesis that in the earliest stages of the breakup of the ancient supercontinent of Gondwanaland, two plates, rather than just one, represented what is now the continent of Antarctica. About 65 million years ago, the two plates fused into the current "Antarctic plate." The now-missing tectonic plate, revealed by a mismatch of geological data between findings from the Campbell plate which became New Zealand and the Antarctic plate, was named the "Bellingshausen plate" and remained just a hypothesis in the absence of good sea floor data. Using their new technique, Laxon and McAdoo have re-analyzed satellite data from the southern ocean floor and conclude that the Bellingshausen plate did, in fact, exist after the breakup of Gondwanaland and was the long-hypothesized missing piece in the puzzle of ancient continent formation. For more information, see 
http://msslsp.mssl.ucl.ac.uk/people/swl/grav_background/how.html
http://ibis.grdl.noaa.gov/SAT/curr_res/polar.html
http://msslsp.mssl.ucl.ac.uk:80/people/swl/polar-gravity.html, and http://www.ngdc.noaa.gov/mgg/announcements/announce_predict.html

ASA employee Charles Gallagher dies at McMurdo Station

On 1 May 1997, Charles (Chuck) Gallagher, 50, died of heart failure following a brief bout of pneumonia, dehydration, and fluid build up around the heart. At the time of his death, plans were underway for the U.S. Air Force to transport him to a medical facility in New Zealand, a 9-hour flight from McMurdo. Gallagher, a U.S. Navy retiree, was an employee of Antarctic Support Associates of Englewood, Colorado, the civilian company that provides support for U.S. science bases in Antarctica. He was in charge of recreational activities for the 155 military and civilian personnel spending the winter at McMurdo Station. His home was in Denver. 

Gallagher, who like all winter-over personnel had passed a thorough physical exam before deployment, became ill in late April, just about the time the sun sets for the last time, marking the start of the winter darkness. Winter conditions are so dangerous in Antarctica that flights in and out are suspended from February until supplies are airdropped during August. Regular flights are not resumed until October. The decision to evacuate Gallagher was made on 28 April when staff at McMurdo determined that Gallagher's unexpected illness required treatment beyond the capabilities of the station's medical facilities. The ice runway had been prepared, and all members of the McMurdo community, as well as those from New Zealand's nearby Scott Base, stood ready to help. 

After Gallagher's death, the U.S. Air Force flew a C-141 into McMurdo Station on 8 May to retrieve his remains. The National Science Foundation (NSF) released statements lauding Gallagher's work and expressing sympathy to his family, friends, and colleagues. Dr. Neal Lane, NSF Director, remarked, "Antarctica is often called 'the last frontier.' If that is so, then Chuck was a true frontiersman." Dr. Lane praised Gallagher for "his life of courage, adventure, and exploration" and expressed gratitude for his years of service. (See also http://www.nsf.gov/od/lpa/news/media/nl5197.htm and http://www.nsf.gov/od/lpa/news/press/pr9733.htm.)

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