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News from "The Ice" and beyond
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.
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/.
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,
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
http://www.usgs.gov/public/press/public_affairs/press_releases/pr272m.html and http://www.maxey.dri.edu/WRC/waiscores/.
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."
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,
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.)