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Antarctica: East of the Transantarctic Mountains

Antarctica remains the only unspoiled continent on our planet. Almost entirely covered in a permanent ice cap that reaches as much as 4,776 meters in thickness, conditions for life are quite extreme. Terrestrial vegetation is limited in Maudlandia, though the Dry Valley region of continental Antarctica is a fascinating ecosystem of flora and fauna highly adapted to polar desert conditions. Colonies of seabirds, penguins, and seals abound around the coasts, obtaining their sustenance from the highly productive Antarctic seas. While this continent has had relatively little direct interference from humans, it is activity elsewhere that may have the greatest effect on Antarctica. Production of certain gases has contributed to a serious depletion of ozone in the atmosphere over Antarctica, as well as contributing to global warming, which could potentially lead to the melting of vast quantities of ice and a significant change in the landscape of populated areas of the world.

  • Scientific Code
    (AN1102)
  • Ecoregion Category
    Antarctic
  • Size
    816,800 square miles
  • Status
    Relatively Stable/Intact
  • Habitats

Description
Location and General Description
Antarctica is the coldest, driest, windiest, on average highest, and most isolated continent on the planet. It covers almost 10 percent of the land surface on Earth, at 13.9 million km2. However, 98% of this area is covered by a permanent sheet of ice, which contains 90% of the world’s ice and almost 70% of the Earth’s fresh water. The remaining 2% of land area, restricted primarily to the coastal fringes of the continent, is where the majority of Antarctica’s limited terrestrial life exists. Ice-free Antarctica can be roughly divided into two biogeographic regions: the Antarctic Peninsula, here termed Marielandia, and the continental coast, or Maudlandia. The Transantarctic Mountains extend 3200 km dividing the continent into East (Maudlandia) and West (Marielandia). The average elevation of the range is 2300 m, with highs reaching 4270 m, similar to the U.S. Rockies. Some volcanic activity occurs along the Transantarctic Mountains, for example, Mt. Erebus (77.5°S) at the edge of the McMurdo Sound, is the world’s southernmost active volcano (EPA 2001).

Maudlandia covers a greater area than Marielandia, about two-thirds of the continent. However, the whole of this region is subject to a harsh continental Antarctic climate, which is cold and arid. Mean monthly temperatures only exceed 0°C for a month or less during the summer, and winter averages range from –5 to -25°C (EPA 2001). The ice-free portions of the region are characterized by semi-desert with moss and algae vegetation on ahumic soil. While the flora is restricted in species and extent, there are many lichens present that are capable of forming local, extensive stands. Snow algal growth can be found in some places. Rain is quite rare, with an annual precipitation just above 10-15 cm. Invertebrates can be locally abundant. Farther inland from the coast, in the mountain and glacier zone that encircles the central ice sheet, the climate becomes colder and drier. All monthly average temperatures are below -5°C, there is no rainfall, and precipitation is only the water equivalent of 10 cm annually (EPA 2001). This area is considered Antarctic Desert, and is concentrated within three parallel valleys, Victoria, Wright, and Taylor, near the McMurdo Sound. The unique Dry Valley ecosystem covers about 1500 m2 of ground kept bare by strong winds that blast snow and precipitation away, preventing the build-up of ice. Several large lakes occur in the valleys, some of which are frozen solid, though a few are not. For example, one lake maintains 43°C water below its 3 m thick ice ceiling, because the salinity of the water traps enough heat to keep it liquid (Parfit 1998). One 18 mile river flows with glacier melt during 1-2 months of summer. Generally, the limited vegetation consists of open, discontinuous lichen growth, with occasional patches of moss near scarce snow patches, bird colonies, or other favorable spots. A poor assemblage of mites, springtails, and other invertebrates are present.

Outstanding or Distinctive Biodiversity Features
Maudlandia differs from Marielandia in that the larger expanses of ice-free land are found inland, rather than near the coast. It is within the McMurdo Dry Valleys that the most outstanding examples of life adapted to the extreme climate occur. In this landscape that was once assumed to be completely barren, microbiologists in the 1970’s discovered communities of microscopic algae, fungi, and bacteria living protected inside rocks. These organisms live in minute gaps between grains of sandstone, close to the surface of the semi-translucent rock where they can receive some sunlight and moisture, and also receive nourishment from the minerals in the stone. Other agal species, such as Hemichloris antarctica, are specially adapted to repeated freezing and rethawing (Parfit 1998). Recently discovered by divers, the bottom of some lakes support a microbial mat made up of many species of blue-green algae, similar to those thought to be the earliest life-forms and the original sources of oxygen on the planet (Parfit 1998). The unlikely top predator within the Dry Valleys is a bacteria-eating nematode that can survive multiple years of being freeze-dried, entering a state called anhydrobiosis (Parfit 1998). Certain lichen species, such as Buellia frigida, might grow as little as 1 cm in 1000 years (EPA 2001). These harsh conditions and the organisms that have adapted to them are often considered to be an approximation of life that may exist on Mars.

Certain areas within Maudlandia have been designated as Specially Protected Areas due to their unique flora. Barwick Valley (approx. 77°S, 161°E) has one of the least disturbed or contaminated of the Dry Valleys of Victoria Land (Headland 1996). Cryptogam Ridge on Mount Melbourne, Victoria Land (74°21'S, 164°42'E) has geothermal activity that supports a unique community of bryophytes, algae, and microbiota (including the only known occurrence in the Antarctic of the moss, Campylopus pyriformis) and the very rare continental occurrence of the liverwort, Cephaloziella exiliflora (Headland 1996). This site can only be compared with one other known high-altitude geothermally-influenced ice-free area near the summit of Mount Erebus (Headland 1996)..

As all larger animals of the terrestrial ecosystem of Antarctica obtain their food from the productive waters of the Southern Ocean, it is the coastal areas of Maudlandia that are populated with large colonies of birds and seals. The characteristic animal of Antarctica, the flightless penguin, can exist in the southern polar regions only due to a lack of any significant predators. In the Arctic, penguins would be far too vulnerable to carnivores such as polar bear and Arctic fox. Of the estimated total of 350 million birds of all species in the Antarctic, about 175 million are penguins, and the rest are flying birds. Six species of penguin are considered native to the Antarctic region: Adélie penguin (Pygoscelis adeliae), chinstrap penguin (P. antarctica), gentoo penguin (P. papua), emperor penguin (Aptenodytes forsteri), king penguin (A. patagonicus), rockhopper penguin (Eudyptes crestatus), and macaroni penguin (E. chrysolophus) (EPA 2001). Four of these breed on the continent: the Adélie, emperor, chinstrap, and gentoo penguins. Adélie penguins are by far the most plentiful penguin species on the continent.

The emperor penguin is the largest (100-130 cm tall, 30 to 33 kg) and perhaps most unusual penguin of the group. Of all the penguin species, only the emperor breeds during the cold, dark winter months in Antarctica. Breeding colonies are generally found on sea-ice far from the open ocean where temperatures are as low as -60° C and winds can reach 180 km per hour. Females lay a single egg in May after a 63-day gestation period, and then pass the egg over to their mate, leaving to feed at sea. During incubation, the male penguin fasts for 9 weeks, and may lose as much as one-third of his body weight. Males huddle together for warmth and protection, each balancing an egg on his feet, where it is insulated by a thick roll of skin and feathers. When the female returns, she takes over feeding the hatchling for a period of six weeks, while the male takes his turn making the long journey over the ice (up to 100 km) in search of food. When the young are about seven weeks old, they join other chicks in a crèche, which is protected by a few adults. By January the sea-ice begins to break out, and chicks have begun to shed their soft down allowing them to fend for themselves. A possible explanation for the emperor penguin’s winter breeding behavior is that it developed to allow the chick to grow to independence at a time when food is most plentiful. This pattern leads to one concern associated with global warming. Were sea ice to break early, entire generations of emperor penguin could be lost if the incubation of eggs was disturbed or if chicks were exposed to sea spray before shedding their vulnerable down.

Thirty-seven flying seabird species are native to Antarctica (EPA 2001). Species breeding in Maudlandia include southern fulmar (Fulmaras glacialoides), southern giant fulmar (Macronectes giganteus), cape pigeon (Daption capense), snow petrel (Pagodroma nivea), Wilson’s storm petrel (Oceanites oceanicus), south polar skua (Catharacta maccormicki), and Antarctic petrel (Thalassoica antarctica) (Watson et al. 1975). Several areas have been given specially protected status due to large colonies of breeding birds. Taylor Rookery, in Mac Robertson Land (67°26'S, 60°50'E) contains a colony of emperor penguins which is one of the few, and probably the largest, of the known colonies of this species breeding entirely on land (Headland 1996). Other important breeding sites on the continent are the Rookery Islands, Holme Bay; Ardery Island and Odbert Island, Budd Coast; Cape Crozier; and Cape Hallett, Victoria Land.

Six seal species are native to Antarctica, crabeater seal (Lobodon carcinophagus), Ross seal (Omimatophoca rossii), leopard seal (Hydrurga leptonyx), Weddell seal (Leptonychotes weddellii), southern elephant seal (Mirounga leonina), and southern fur seal (Arctocephalus gazella) (EPA 2001). The elephant seal and fur seal are more often associated with the open ocean, while the others spend a significant amount of time on sea ice. Seals hauling out on land can have a significant impact on vegetation communities. While seals primarily feed on krill, squid, and other marine species, some, such as the leopard seal, will occasionally eat small penguins.

Terrestrial invertebrates of Antarctica are limited to arthropods, primarily being springtails, mites, and midges that are associated with plant communities along the coasts. One mite, Nanorchestes antarcticus, which has the widest distribution of any Antarctic arthropod, was also reported as the southernmost occuring animal when it was located at 85°32’ S, 153°W, about 500 km from the South Pole (Fogg 1998).

Biodiversity Features
Maudlandia differs from Marielandia in that the larger expanses of ice-free land are found inland, rather than near the coast. It is within the McMurdo Dry Valleys that the most outstanding examples of life adapted to the extreme climate occur. In this landscape that was once assumed to be completely barren, microbiologists in the 1970’s discovered communities of microscopic algae, fungi, and bacteria living protected inside rocks. These organisms live in minute gaps between grains of sandstone, close to the surface of the semi-translucent rock where they can receive some sunlight and moisture, and also receive nourishment from the minerals in the stone. Other agal species, such as Hemichloris antarctica, are specially adapted to repeated freezing and rethawing (Parfit 1998). Recently discovered by divers, the bottom of some lakes support a microbial mat made up of many species of blue-green algae, similar to those thought to be the earliest life-forms and the original sources of oxygen on the planet (Parfit 1998). The unlikely top predator within the Dry Valleys is a bacteria-eating nematode that can survive multiple years of being freeze-dried, entering a state called anhydrobiosis (Parfit 1998). Certain lichen species, such as Buellia frigida, might grow as little as 1 cm in 1000 years (EPA 2001). These harsh conditions and the organisms that have adapted to them are often considered to be an approximation of life that may exist on Mars.

Certain areas within Maudlandia have been designated as Specially Protected Areas due to their unique flora. Barwick Valley (approx. 77°S, 161°E) has one of the least disturbed or contaminated of the Dry Valleys of Victoria Land (Headland 1996). Cryptogam Ridge on Mount Melbourne, Victoria Land (74°21'S, 164°42'E) has geothermal activity that supports a unique community of bryophytes, algae, and microbiota (including the only known occurrence in the Antarctic of the moss, Campylopus pyriformis) and the very rare continental occurrence of the liverwort, Cephaloziella exiliflora (Headland 1996). This site can only be compared with one other known high-altitude geothermally-influenced ice-free area near the summit of Mount Erebus (Headland 1996)..

As all larger animals of the terrestrial ecosystem of Antarctica obtain their food from the productive waters of the Southern Ocean, it is the coastal areas of Maudlandia that are populated with large colonies of birds and seals. The characteristic animal of Antarctica, the flightless penguin, can exist in the southern polar regions only due to a lack of any significant predators. In the Arctic, penguins would be far too vulnerable to carnivores such as polar bear and Arctic fox. Of the estimated total of 350 million birds of all species in the Antarctic, about 175 million are penguins, and the rest are flying birds. Six species of penguin are considered native to the Antarctic region: Adélie penguin (Pygoscelis adeliae), chinstrap penguin (P. antarctica), gentoo penguin (P. papua), emperor penguin (Aptenodytes forsteri), king penguin (A. patagonicus), rockhopper penguin (Eudyptes crestatus), and macaroni penguin (E. chrysolophus) (EPA 2001). Four of these breed on the continent: the Adélie, emperor, chinstrap, and gentoo penguins. Adélie penguins are by far the most plentiful penguin species on the continent.

The emperor penguin is the largest (100-130 cm tall, 30 to 33 kg) and perhaps most unusual penguin of the group. Of all the penguin species, only the emperor breeds during the cold, dark winter months in Antarctica. Breeding colonies are generally found on sea-ice far from the open ocean where temperatures are as low as -60° C and winds can reach 180 km per hour. Females lay a single egg in May after a 63-day gestation period, and then pass the egg over to their mate, leaving to feed at sea. During incubation, the male penguin fasts for 9 weeks, and may lose as much as one-third of his body weight. Males huddle together for warmth and protection, each balancing an egg on his feet, where it is insulated by a thick roll of skin and feathers. When the female returns, she takes over feeding the hatchling for a period of six weeks, while the male takes his turn making the long journey over the ice (up to 100 km) in search of food. When the young are about seven weeks old, they join other chicks in a crèche, which is protected by a few adults. By January the sea-ice begins to break out, and chicks have begun to shed their soft down allowing them to fend for themselves. A possible explanation for the emperor penguin’s winter breeding behavior is that it developed to allow the chick to grow to independence at a time when food is most plentiful. This pattern leads to one concern associated with global warming. Were sea ice to break early, entire generations of emperor penguin could be lost if the incubation of eggs was disturbed or if chicks were exposed to sea spray before shedding their vulnerable down.

Thirty-seven flying seabird species are native to Antarctica (EPA 2001). Species breeding in Maudlandia include southern fulmar (Fulmaras glacialoides), southern giant fulmar (Macronectes giganteus), cape pigeon (Daption capense), snow petrel (Pagodroma nivea), Wilson’s storm petrel (Oceanites oceanicus), south polar skua (Catharacta maccormicki), and Antarctic petrel (Thalassoica antarctica) (Watson et al. 1975). Several areas have been given specially protected status due to large colonies of breeding birds. Taylor Rookery, in Mac Robertson Land (67°26'S, 60°50'E) contains a colony of emperor penguins which is one of the few, and probably the largest, of the known colonies of this species breeding entirely on land (Headland 1996). Other important breeding sites on the continent are the Rookery Islands, Holme Bay; Ardery Island and Odbert Island, Budd Coast; Cape Crozier; and Cape Hallett, Victoria Land.

Six seal species are native to Antarctica, crabeater seal (Lobodon carcinophagus), Ross seal (Omimatophoca rossii), leopard seal (Hydrurga leptonyx), Weddell seal (Leptonychotes weddellii), southern elephant seal (Mirounga leonina), and southern fur seal (Arctocephalus gazella) (EPA 2001). The elephant seal and fur seal are more often associated with the open ocean, while the others spend a significant amount of time on sea ice. Seals hauling out on land can have a significant impact on vegetation communities. While seals primarily feed on krill, squid, and other marine species, some, such as the leopard seal, will occasionally eat small penguins.

Terrestrial invertebrates of Antarctica are limited to arthropods, primarily being springtails, mites, and midges that are associated with plant communities along the coasts. One mite, Nanorchestes antarcticus, which has the widest distribution of any Antarctic arthropod, was also reported as the southernmost occuring animal when it was located at 85°32’ S, 153°W, about 500 km from the South Pole (Fogg 1998).

Status and Threats

Current Status
The Antarctic Treaty was signed in 1959 and now holds signatures of 44 nations. The treaty applies to the area south of 60° south latitude, including all islands and ice shelves. It includes prohibitions on the killing, wounding, capturing or molesting of any native mammal or native bird except in accordance with a permit, as well as regulations on the importation of exotic species, parasites, and diseases. Permits may only be issued by persons authorized by a participating government. Also, numerous conservation areas are designated in several categories, and carry further regulations. For example, vehicles are prohibited to enter Specially Protected Areas (Headland 1996).

The Antarctic Treaty has, for the time being, put a ban on any nuclear testing, radioactive waste disposal, and oil or other mineral drilling. It does not, however, prevent environmental degradation altogether. Much of the Antarctic ecosystem, particularly its flora, is extremely vulnerable to even the slightest disturbance. Several thousand researchers and tourists visit the continent each year. While the majority of tourism is concentrated at the more accessible Antarctic Peninsula, it is a growing industry on the continental portion, corresponding with the rising interest in adventure tours. Ship-based tours visit McMurdo Sound in the Ross Sea, viewing historic huts and science stations, and helicopter tours to the Dry Valleys are part of one tour-operator’s itinerary (EPA 2001). A few studies have been done on the impact of human disturbance in Antarctica. It was found that the nesting pairs of Adélie penguins in a rookery close to McMurdo Station dropped by half after the station was established and disturbance by humans and helicopters began (Fogg 1998). The rookery has partially recuperated since more protective measures were put in place.

Current Status
The Antarctic Treaty was signed in 1959 and now holds signatures of 44 nations. The treaty applies to the area south of 60° south latitude, including all islands and ice shelves. It includes prohibitions on the killing, wounding, capturing or molesting of any native mammal or native bird except in accordance with a permit, as well as regulations on the importation of exotic species, parasites, and diseases. Permits may only be issued by persons authorized by a participating government. Also, numerous conservation areas are designated in several categories, and carry further regulations. For example, vehicles are prohibited to enter Specially Protected Areas (Headland 1996).

The Antarctic Treaty has, for the time being, put a ban on any nuclear testing, radioactive waste disposal, and oil or other mineral drilling. It does not, however, prevent environmental degradation altogether. Much of the Antarctic ecosystem, particularly its flora, is extremely vulnerable to even the slightest disturbance. Several thousand researchers and tourists visit the continent each year. While the majority of tourism is concentrated at the more accessible Antarctic Peninsula, it is a growing industry on the continental portion, corresponding with the rising interest in adventure tours. Ship-based tours visit McMurdo Sound in the Ross Sea, viewing historic huts and science stations, and helicopter tours to the Dry Valleys are part of one tour-operator’s itinerary (EPA 2001). A few studies have been done on the impact of human disturbance in Antarctica. It was found that the nesting pairs of Adélie penguins in a rookery close to McMurdo Station dropped by half after the station was established and disturbance by humans and helicopters began (Fogg 1998). The rookery has partially recuperated since more protective measures were put in place.

Types and Severity of Threats
As the last unspoiled continent on the planet, conservation in Antarctica is far more organized and effective than anywhere else on Earth. Potential future threats to the Antarctic environment would likely result from activities undertaken far from the isolated wilderness. The dramatic loss of ozone in the atmosphere over Antarctica was first noticed by the British Antarctic Survey over Halley Station in Queen Maud Land in 1984 (Fogg 1998). It is believed to be the result of widespread use of CFC’s (chloroflurocarbons) as cooling agents. This possibility had been raised in the 1970’s, and restrictions had been put on the use of CFC’s. However, their persistance in the atmosphere, combined with the unique circulation in the stratosphere that is centered over the stable Antarctic vortex, led to this unexpected, massive depletion of ozone. A smaller hole was found in the Arctic, though its vortex is less stable, producing conditions less likely to create an ozone hole (Fogg 1998).

Though UV-B radiation accounts for less than 1% of the Earth’s total sunlight, it has the ability to damage organisms by disrupting basic biological processes. It is also a well-known contributor to the development of skin cancer. The study of lichens in Antarctica, which are adapted to high levels of UV-B radiation, may lead to beneficial discoveries. Certain species of lichens (e.g. Usnea aurantiaco-atra) produce higher levels of usnic acid when levels of UV-B are higher (Purvis 2000). Usnic acid levels in old lichen specimens from herbariums show lower levels of usnic acid than recent specimens from the same place, indicating that UV-B levels were lower in recent history (Purvis 2000).

Global warming, as a result of human production of greenhouse gases, threatens to melt large amounts of the ice that makes up most of the Antarctic. Were this to take place rapidly, flora and fauna highly adapted to the particular conditions of polar regions could be drastically disrupted, for example in the case mentioned earlier with the emperor penguin. The continent of Antarctica cannot be considered as entirely separate from the populated portions of the Earth. The polar region play a key role in worldwide weather patterns. To an extent, the polar seas act as ‘heat sinks’, partially counteracting the greenhouse effect from build-up of carbon dioxide in the atmosphere (Fogg 1998). Changes in climate in Antarctica would certainly carry tangible effects to the populated continents of the planet.

Justification of Ecoregion Delineation
Udvardy (1975, 1987) differentiates two antarctic provinces within the Antarctic continent. The East Antarctic Province, or Maudlandia, from Queen Maud Coast in the northwest sector, encompasses the majority of mainland Antarctica, excluding the Antarctic Peninsula. The ecoregion boundary corresponds to coastal fringes of the continent that are free of permanent ice.

References
EPA. 2001. Chapter 2: Affected Environment - the Physical and Biological Environment. Final Environmental Impact Statement for the Proposed Rule on Environmental Impact Assessment of Nongovernmental Activities in Antarctica. Retrieved (2001) from: <http://es.epa.gov/oeca/ofa/antarc/ch_02.pdf>.

Fogg, G. E. 1998. The Biology of Polar Habitats. Oxford University Press, New York, N.Y.

Headland, R. K. 1996. Protected Areas in the Antarctic Treaty Region. Retrieved (2001) from: <http://www.spri.cam.ac.uk/bob/protect.htm#aa>.

Parfit, M. 1998. Timeless Valleys of the Antarctic Desert. National Geographic October: 120-135.

Purvis, W. 2000. Lichens. Smithsonian Institution Press, Washington, D. C.

Udvardy, M.D.F. 1975. A classification of the biogeographical provinces of the world. IUCN Occasional Paper No. 18. International Union of Conservation of Nature and Natural Resources, Morges, Switzerland.

Udvardy, M.D.F. 1987. The Biogeographical Realm Antarctica A Proposal. Journal of the Royal Socirty of New Zealand 17:187-194.

Watson, G. E., J. P. Angle, and P. C. Harper. 1975. Birds of the Antarctic and Sub-Antarctic. American Geophysical Union, Washington, D. C.

Prepared by: Leann Trowbridge


 

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