Thursday, March 11, 2010

Suit Filed to Save Penguins at Risk From Global Warming and Fisheries





For Immediate Release, March 9, 2010

Contact:  Catherine Kilduff, Center for Biological Diversity, (415) 644-8580
Todd Steiner/Teri Shore, Turtle Island Restoration Network, (415) 663- 8590 x 103/104 
  

Suit Filed to Save Penguins at Risk From Global Warming and Fisheries

SAN FRANCISCO— The Center for Biological Diversity and Turtle Island Restoration Network (TIRN) today sued the Obama administration for illegally delaying protection of penguins under the Endangered Species Act. The Interior Department failed to meet its December 19, 2009 deadline to list seven penguin species at risk of extinction due to climate change and commercial fisheries. These penguins will not receive desperately needed Endangered Species Act protections until Interior finalizes the listings.

“While sea ice melts and oceans warm, the Obama administration is stuck like a deer in the headlights. Instead of saving penguins from the leviathan of global warming while it still can,” said Catherine Kilduff, a Center attorney, “our government is dragging its feet.”

“Penguins should be marching toward recovery, not extinction. These amazing species face a double whammy from the threats brought by climate change and industrial fisheries that deplete the penguins’ food supply and entangle and drown the penguins in longlines and other destructive fishing gear. They deserve protection under the Endangered Species Act,” said Todd Steiner, biologist and executive director of TIRN.

In 2006 the Center filed a petition to list 12 penguin species under the U.S. Endangered Species Act. In December 2008, the Interior Department proposed listing seven of those species as threatened or endangered – African, Humboldt, yellow-eyed, white-flippered, Fiordland crested, and erect-crested penguins as well as a few populations of the southern rockhopper – while denying listing to emperor and northern rockhopper penguins despite scientific evidence that they also are threatened by climate change.
Today’s lawsuit challenges the Interior Department’s illegal delay in finalizing the listing of the seven proposed penguin species; the Center and TIRN also intend to file suit against Interior for denying protections to emperor and rockhopper penguins. Warming oceans, melting sea ice, and fishery harvests have wreaked havoc on penguins’ food supply: krill, an essential nutrient for penguins, whales, and seals, has declined by up to 80 percent since the 1970s over large areas of the Southern Ocean. Reduced food supply has diminished populations of species ranging from southern rockhoppers and Humboldt penguins of South American islands to the African penguin in southern Africa.

Endangered Species Act listing would protect penguins from multiple threats, raise awareness of their plight, and increase research funding. Federal approval of fishing permits for U.S.-flagged vessels on the high seas, for example, would require analysis and minimization of impacts on penguins. The Act also has a key role in managing greenhouse gas pollution by compelling federal agencies to look at the impact of the emissions generated by their activities on listed species and reduce those impacts.

For more information on penguins, please see: http://www.biologicaldiversity.org/species/birds/penguins/index.html.

Sunday, March 7, 2010

Jellyfish to replace penguins thanks to global warming

Penguins in Antarctica to be replaced by jellyfish due to global warming

Rising temperatures in the oceans around Antarctica could lead to the continent's penguins being replaced by jellyfish, scientists have warned.

 

A Gentoo penguin feeding her young krill: A Gentoo penguin feeding her young krill
A Gentoo penguin feeding her young krill Photo: ALEX BENWELL
  
The results of the largest ever survey of Antarctic marine life reveal melting sea ice is decimating krill populations, which form an integral part of penguins' diets. The six-inch-long invertebrates, also eaten by other higher Southern Ocean predators such as whales and seals, are being replaced by smaller crustaceans known as copepods.
These miniscule copepods, measuring just half a millimetre long, are too small for penguins but ideal for jellyfish and other similarly tentacled predators. Huw Griffiths, a marine biologist, said the shifting food web, coupled with shrinking ice sheet breeding grounds, could seriously affect the world's favourite Antarctic animal. Mr Griffiths, of British Antarctic Survey (BAS), said: ''Marine animals spent millions of years adapting to the freezing, stable conditions of the Antarctic waters and they are highly sensitive to change.

''The polar oceans are rich in biodiversity. But if species are unable to move or adapt to new conditions they could ultimately die out. Copepods are 120 times smaller than krill, which is inevitably going to affect all the things that feed in that area. Penguins, sea birds, whales are all used to catching large items of prey. But creatures with tentacles - like jellyfish are going to have more food value out of smaller prey.This kind of predator will do better in this warmer environment. We already have huge numbers of amazing looking jellyfish. They are not quite invading but numbers will go up to the point where they become the dominant group. And if the waters continue to warm there will not only be a shift between species that are already there, but new species will be able to come into the area.''

Mr Griffiths said species of small invertebrates, fish and crabs that cannot currently tolerate the -2C temperatures in the Antarctica waters might start soon start to appear. Any decrease in sea ice will inevitably affect the delicate balance of the Antarctic marine food chain. For creatures such as penguins who lives on the melting sea ice, a rise in temperatures will also shrink the size of their breeding grounds.

Mr Griffith's research is based ON the Census of Antarctic Marine Life (CAML) and he presented his findings at the American Association for the Advancement of Science (AAAS) in San Diego on Thursday.
The census began in 2005 and will provide the benchmark for future studies on how the diverse sea-floor creatures living in Antarctica's waters will respond to predicted climate change.

More than 6,000 different species living on the sea-floor have been identified so far and more than half of these can only be found on the icy continent. Mr Griffith's work also describes certain creatures such as sea spiders flourish in the Antarctic waters because of the unique environment. The stunning sea spiders in Antarctica are roughly the size of dinner plates, whereas their delicate cousins around the UK coast are no bigger than a little fingernail.

Mr Griffiths added: ''This is a group that has done really well in the cold. Around 20 per cent of the world's population of sea spiders are from Antarctica. ''They are bigger than anywhere else in the world and this is probably because the environment happens to be ideal for them. It makes you realise if the waters warm and other species or predators move in these unique animals will come under competition.''


Source

Wednesday, February 17, 2010

A Solution for Saving the Penguin


African penguin. (Credit: Copyright David Grémillet)

Marine Protected Areas: A Solution for Saving the Penguin

ScienceDaily (Feb. 16, 2010) — Researchers from the Centre d'écologie fonctionnelle et évolutive (CNRS/Universités Montpellier 1, 2, 3/Montpellier SupAgro/CIRAD/EPHE) and the University of the Cape in South Africa (1) have shown that closing fishing zones in the ocean has a beneficial effect on Cape penguins, an endangered species endemic to Southern Africa that feeds exclusively on fish. This result comes from a unique experiment carried out by the researchers on two penguin colonies, with the collaboration of government authorities and the South African fishing industries.


These results are published on 10 February 2010 on the website of the journal Biology Letters.
The Cape penguin Spheniscus demersus (the only African penguin) is endangered as a result of the 60% decline in its worldwide population between 2001 and 2009. This decline can be attributed to a dearth of food, due to displacement of the banks of sardines and anchovies which these birds feed on. Competition with the fisheries which exploit the last remaining fish around the South African penguin colonies exacerbates the threat to the species. Faced with this crisis situation, and working with researchers and the South African fish industries, the South African governmental agency overseeing fisheries (Marine and Coastal Management) closed to fishing in January 2009 a 20-km radius ocean area around the largest Cape penguin colony (on the island of St Croix, Algoa Bay). A "witness" zone around another penguin colony (Bird Island), 50 km east of St Croix in the same bay, has remained open to fishing in order to enable researchers to compare penguin feeding behaviors.

The researchers studied the food-seeking behavior of 91 birds in these two colonies, thanks to GPS recorders, in 2008 and 2009, namely before and after the area was closed to fishing. The miniature recorders, in watertight hydrodynamic boxes, were attached to the feathers at the base of the birds' backs with adhesive. The goal was to record the latitude and longitude of the birds every minute, and the hydrostatic pressure (diving depth) every second. These data made it possible to calculate the effort each bird expended in searching for food, in terms of the length of time spent traveling, the distance covered, the number, depth and location of dives.

The results are striking: In 2008, before the area was closed to fishing, the St Croix penguins mainly fished (75% of dives) more than 20 km from their colony, covering up to 150 km in two days in their search for food. In 2009, on the other hand, only 3 months after the area had been closed to fishing, 70% of dives were less than 20 km away, within the protected marine area. The time devoted to searching for food also decreased by 30%, which reduced their daily energy expenditure by 40%. By way of comparison, the area within which the Bird Island penguins (the control colony) searched for food remained the same both years, with the penguins even expending more energy searching for food in 2009.

This experiment shows the immediate benefits of the creation of a Marine Protected Area for the preservation of an endangered top marine predator species. The study confirms the negative impact of industrial fishing on feeding conditions for African penguins and also demonstrates the crucial importance of Marine Protected Areas (2) on endangered species conservation. When appropriately defined, these areas can facilitate the restoration of ocean ecosystems (3) damaged by the combined effects of climate change and overfishing.

Notes:
(1) Of the Percy FitzPatrick Institute of African Ornithology.
(2) The 1992 Rio convention stipulates that 10% of marine surfaces be protected. Nonetheless, only 0,8% of these surfaces is currently reserves. In this context, the creation of Marine Protected Areas (MPA) which help preserve marine predators which feed on mobile prey such as ocean fish, is urgent. This strategy is nonetheless controversial, as it is difficult, in open water, to clearly delimit PMAs which aim to preserve species as mobiles as superior predators and their prey. The general principle is that these reserves must be very large in order to encompass the vast habitats of marine predators; this makes it more difficult to set them up and manage them.
(3) Plankton, both phytoplankton and zooplankton, fish (notably sardines and anchovies), all living organisms in the water column between the ocean surface and bottom and which play a central role in the marine ecosystem.

Story Source:
Adapted from materials provided by CNRS (Délégation Paris Michel-Ange).


CNRS (Délégation Paris Michel-Ange). "Marine Protected Areas: A Solution for Saving the Penguin." ScienceDaily 16 February 2010. 17 February 2010 <http://www.sciencedaily.com­ /releases/2010/02/100211090755.htm>.

Thursday, February 11, 2010

Bird-from-Dinosaur? OR Was It the Other Way Around?

 

An image drawn in 1915 by naturalist William Beebe suggests a hypothetical view of what early birds may have looked like, gliding down from trees - and it bears a striking similarity to a fossil discovered in 2003 that is raising new doubts about whether birds descended from ground-dwelling theropod dinosaurs.

Bird-from-Dinosaur Theory of Evolution Challenged: Was It the Other Way Around?

ScienceDaily (Feb. 10, 2010) — A new study just published in the Proceedings of the National Academy of Sciences provides yet more evidence that birds did not descend from ground-dwelling theropod dinosaurs, experts say, and continues to challenge decades of accepted theories about the evolution of flight.

A new analysis was done of an unusual fossil specimen discovered in 2003 called "microraptor," in which three-dimensional models were used to study its possible flight potential, and it concluded this small, feathered species must have been a "glider" that came down from trees. The research is well done and consistent with a string of studies in recent years that pose increasing challenge to the birds-from-dinosaurs theory, said John Ruben, a professor of zoology at Oregon State University who authored a commentary in PNAS on the new research.

The weight of the evidence is now suggesting that not only did birds not descend from dinosaurs, Ruben said, but that some species now believed to be dinosaurs may have descended from birds.
"We're finally breaking out of the conventional wisdom of the last 20 years, which insisted that birds evolved from dinosaurs and that the debate is all over and done with," Ruben said. "This issue isn't resolved at all. There are just too many inconsistencies with the idea that birds had dinosaur ancestors, and this newest study adds to that."

Almost 20 years of research at OSU on the morphology of birds and dinosaurs, along with other studies and the newest PNAS research, Ruben said, are actually much more consistent with a different premise -- that birds may have had an ancient common ancestor with dinosaurs, but they evolved separately on their own path, and after millions of years of separate evolution birds also gave rise to the raptors. Small animals such as velociraptor that have generally been thought to be dinosaurs are more likely flightless birds, he said.
"Raptors look quite a bit like dinosaurs but they have much more in common with birds than they do with other theropod dinosaurs such as Tyrannosaurus," Ruben said. "We think the evidence is finally showing that these animals which are usually considered dinosaurs were actually descended from birds, not the other way around."

Another study last year from Florida State University raised similar doubts, Ruben said. In the newest PNAS study, scientists examined a remarkable fossil specimen that had feathers on all four limbs, somewhat resembling a bi-plane. Glide tests based on its structure concluded it would not have been practical for it to have flown from the ground up, but it could have glided from the trees down, somewhat like a modern-day flying squirrel. Many researchers have long believed that gliders such as this were the ancestors of modern birds.

"This model was not consistent with successful flight from the ground up, and that makes it pretty difficult to make a case for a ground-dwelling theropod dinosaur to have developed wings and flown away," Ruben said. "On the other hand, it would have been quite possible for birds to have evolved and then, at some point, have various species lose their flight capabilities and become ground-dwelling, flightless animals -- the raptors. This may be hugely upsetting to a lot of people, but it makes perfect sense."

In their own research, including one study just last year in the Journal of Morphology, OSU scientists found that the position of the thigh bone and muscles in birds is critical to their ability to have adequate lung capacity for sustained long-distance flight, a fundamental aspect of bird biology. Theropod dinosaurs did not share this feature. Other morphological features have also been identified that are inconsistent with a bird-from-dinosaur theory. And perhaps most significant, birds were already found in the fossil record before the elaboration of the dinosaurs they supposedly descended from. That would be consistent with raptors descending from birds, Ruben said, but not the reverse.

OSU research on avian biology and physiology has been raising questions on this issue since the 1990s, often in isolation. More scientists and other studies are now challenging the same premise, Ruben said. The old theories were popular, had public appeal and "many people saw what they wanted to see" instead of carefully interpreting the data, he said.

"Pesky new fossils...sharply at odds with conventional wisdom never seem to cease popping up," Ruben wrote in his PNAS commentary. "Given the vagaries of the fossil record, current notions of near resolution of many of the most basic questions about long-extinct forms should probably be regarded with caution."

Story Source:
Adapted from materials provided by Oregon State University, via EurekAlert!, a service of AAAS.


Oregon State University. "Bird-from-Dinosaur Theory of Evolution Challenged: Was It the Other Way Around?." ScienceDaily 10 February 2010. 11 February 2010 <http://www.sciencedaily.com­ /releases/2010/02/100209183335.htm>.

Saturday, February 6, 2010

Dinosaur Had Vibrant Colors




A water color illustration of Anchiornis huxleyi, an extinct, non-avian dinosaur. (Credit: By Michael DiGiorgio/Courtesy Yale)

Dinosaur Had Vibrant Colors, Microscopic Fossil Clues Reveal

ScienceDaily (Feb. 5, 2010) — Deciphering microscopic clues hidden within fossils, scientists have uncovered the vibrant colors that adorned a feathered dinosaur extinct for 150 million years, a Yale University-led research team reports online Feb. 4 in the journal Science.

Unlike recently published work from China that inferred the existence of two types of melanin pigments in various species of feathered dinosaurs, the Science study analyzed color-imparting structures called melanosomes from an entire fossil of a single animal, a feat which enabled researchers to reveal rich color patterns of the entire animal.

In fact, the analysis of melanosomes conducted by Yale team was so precise that the team was able to assign colors to individual feathers of Anchiornis huxleyi, a four-winged troodontid dinosaur that lived during the late Jurassic period in China. This dinosaur sported a generally gray body, a reddish-brown, Mohawk-like crest and facial speckles, and white feathers on its wings and legs, with bold black-spangled tips.
"This was no crow or sparrow, but a creature with a very notable plumage," said Richard O. Prum, chair and the William Robertson Coe Professor of Ornithology, Ecology and Evolutionary Biology at Yale and a co-author of the study. "This would be a very striking animal if it was alive today."

The color patterns of the limbs, which strongly resemble those sported by modern day Spangled Hamburg chickens, probably functioned in communication and may have helped the dinosaur to attract mates, suggested Prum.

The transformation of mankind's view of dinosaurs from dull to flamboyant was made possible by a discovery by Yale graduate student Jakob Vinther in the Department of Geology and Geophysics. Vinther was studying the ink sac of an ancient squid and realized that microscopic granular-like features within the fossil were actually melanosomes -- a cellular organelle that contains melanin, a light-absorbing pigment in animals, including birds.

While some scientists thought these granules were remnants of ancient bacteria, Vinther, Prum and Derek E.G. Briggs, the Frederick William Beinecke Professor of Geology and Geophysics and director of the Yale Peabody Museum of Natural History, disagreed. First, they tested Vinther's theory on a 112 million year old feather from Brazil and later inferred the colors of an extinct 47 million-year-old bird.

The latest research team -- which also included scientists from the University of Texas at Austin, University of Akron, Peking University and the Beijing Museum of Natural History -- decided to use the same procedures to closely examine a fossil of Anchiornis huxleyi, recently described in Liaoning Province, People's Republic of China. The area has been a gold mine for paleontologists and, among other things, provided abundant evidence confirming a once-controversial theory that modern birds are descendants of theropod dinosaurs.
The Yale team and Julia Clarke, an associate professor of paleontology at the University of Texas at Austin's Jackson School of Geosciences, worked closely with Gao Keqin of Peking University and Li Quanguo and Meng Qingjin of the Beijing Museum of Natural History to select, sample and evaluate the anatomy and feathering of Anchiornis huxleyi, important in its own right as a new feathered dinosaur. The team's effort was funded by a special grant from the National Geographic Society and by the National Science Foundation.
The team closely examined 29 feather samples from the dinosaur and did an exhaustive measurement and location of melanosomes within the feathers. The team then did a statistical analysis of how those melanosomes compared to the types of melanosomes known to create particular colors in living birds, using data compiled by Matt Shawkey and colleagues at the University of Akron. The analysis allowed scientists to discern with 90 percent certainty the colors of individual feathers and, therefore, the colorful patterns of an extinct animal.

The research adds significant weight to the idea that dinosaurs first evolved feathers not for flight but for some other purposes. "This means a color-patterning function -- for example, camouflage or display -- must have had a key role in the early evolution of feathers in dinosaurs, and was just as important as evolving flight or improved aerodynamic function," Clarke said.

The new discoveries provide a wealth of insights into the compelling history of feather evolution in dinosaurs prior to the origin of modern birds. The study documents that color patterning within feathers and among feathers evolved earlier than previously believed. Further, these results indicate dinosaur feathers may have evolved for communication. "Writing the first scientifically-based 'field guide' description of the appearance of an extinct dinosaur was a exciting and unforgettable experience -- the ultimate dream of every kid who was ever obsessed with dinosaurs," Prum said. "Now that dream is really possible."


Story Source:
Adapted from materials provided by Yale University.

Journal Reference:
  1. Quanguo Li, Ke-Qin Gao, Jakob Vinther, Matthew D. Shawkey, Julia A. Clarke, Liliana D'alba, Qingjin Meng, Derek E. G. Briggs, Long Miao, Richard O. Prum. Plumage Color Patterns of an Extinct Dinosaur. Science, Online February 4, 2010 DOI: 10.1126/science.1186290

Yale University. "Dinosaur Had Vibrant Colors, Microscopic Fossil Clues Reveal." ScienceDaily 5 February 2010. 6 February 2010 <http://www.sciencedaily.com­ /releases/2010/02/100204144422.htm>.

Monday, February 1, 2010

Antarctica: A frozen hotbed of climate research for hardy scientists

 Antarctica: A frozen hotbed of climate research for hardy scientists
Ornithologist Kristen Gorman has been working in Antarctica for five years to learn more about how bird populations in the area are changing. Day after day, she hikes through penguin breeding grounds, weighing the eggs, examining the young and documenting the declining numbers.
Ornithologist Kristen Gorman has been working in Antarctica for five years to learn more about how bird populations in the area are changing. Day after day, she hikes through penguin breeding grounds, weighing the eggs, examining the young and documenting the declining numbers.
ANVERS ISLAND, Antarctica | Roald Amundsen attacked this frozen nowhere-land as a racing explorer, determined to be fastest, to be first, to be remembered.
His determination and savvy got him to the South Pole before any other, and made him a hero in an age when Antarctica existed in the human imagination as a final conquest.
Mostly for show, he brought along a scientist.
Just shy of a century later, the conquerors have given way to the curious.

Now scientists such as geologist David Barbeau and ornithologist Kristen Gorman, rugged individuals of another age, shuttle in rubber Zodiac boats from remote research stations and ice-breaking research ships. They bump aside small floes, bend against brutal polar winds and scramble up cliffs in search of their own discoveries.

They search not for fame, but for answers about the same climate that once tortured and killed their polar adventuring forebears. Around this continent, the weather has mellowed alarmingly. Giant glaciers and tiny creatures are threatened as this tip of our global iceberg warms faster than anywhere else on earth.
These modern-day researchers come not to conquer, but to understand.

Almost by accident, Barbeau’s career as a geologist has been swept up, and upward, on the wave of interest about what makes parts of the planet freeze and thaw, and what that says about climate change.
He leads Antarctic expeditions hatched and financed entirely on the strength of theories about how the continent broke off from South America and iced over.

Gorman, meanwhile, tracks how dwindling Adelie penguin colonies connect to the retreat of sea ice. She navigates guano-slick boulders.

She teams with researchers steering remote-control submersibles into undersea canyon feeding grounds to measure how the birds fare as Antarctica’s glacial edges crumble into the sea.

“We’re asking simple questions about food ecology in this larger framework,” she said of fish and shrimplike krill and their feathered hunters. “How do you better predict how climate will affect predators?”
It wasn’t so much that science drew her to the wilds of Antarctica. It was an overwhelming need to work in wild places that sucked her into ornithology.

Though Barbeau ends up climbing mountains and skiing across glaciers, he recognizes that the strain and danger don’t compare to what the men of Amundsen’s age knew. But they were just looking for fame and national bragging rights.

“The first to do this, the first to do that,” he said dismissively. “We’re just trying to understand things. … With climate science, you’re talking about something that’s critical.”

He and Gorman are just two among scores building careers in modern-day Antarctica, where climate studies promise academic status and grant money.

At the South Pole, researchers take core samples of ice, measuring the gases trapped in them to see what Earth’s atmosphere was like thousands of years ago. In the Drake Passage, measurements taken by ship and satellite reveal how much carbon dioxide is absorbed by sea life.

Observations made over decades on the Ross Ice Shelf and along the Antarctic Peninsula look at changes in temperature and ice levels, and what that’s meant to whales, seals, penguins and the krill at the nexus of the food chain.

For six weeks, late last year, electrical engineers from the University of Kansas flicked switches and toggled computer controls in a DC-8 jet sweeping back and forth over the frozen wastes. Their purpose: to peer through the continent’s miles-deep blanket of ice.

Ross MacPhee, a curator at the American Museum of Natural History, sees a particular personality in the researchers drawn south of the Polar Front. He is both a paleontologist and a scholar of polar exploration, and traveled on his own Antarctic expedition in 2009.

While the great breakthroughs of the Digital Age typically appear in laboratories using fast-developing technology, he said, a breed of scientist survives that still prefers to work in the wild. It may be as much that their science delivers them outdoors, as that they need to go the wilderness to advance their science.

“We’re talking about someone who doesn’t mind being too cold or too wet or too sweaty,” MacPhee said, “someone who actually enjoys tough conditions.”
•••
Antarctica is a hotbed of new climate patterns that serve as a nifty laboratory for understanding what’s happening to the Earth as a whole.

Its long, dark winters make it the best place on Earth for observing the heavens. Its air is the cleanest on the planet, giving researchers a baseline to compare with other regions. Some 70 percent of the world’s fresh water is locked into 30 million cubic kilometers of Antarctic ice.

The United States alone spends more than $300 million a year on research here — supply flights to the globe’s most forbidding landscapes, icebreakers plowing the seas for oceanographic research, delivering people like Gorman and Barbeau to remote coasts.

Barbeau is the point man on a $700,000 grant that has brought him here for three years running and paid for nearly 20 other researchers either to accompany him or to perform lab analysis back in the United States.
All the modern work feeds, and is driven by, findings like those of the Nobel-decorated Intergovernmental Panel on Climate Change that carbon dioxide levels are at a 650,000-year high and climbing. Such buildup of gas in the atmosphere — the IPCC attributes the steep rise chiefly to industrialization — could explain why nine out of every 10 glaciers in the world are shrinking.

Global warming remains a controversial concept, made more so when the hacking of e-mails from researchers at East Anglia’s Climate Research Unit last year revealed that they toyed with data to make for more dramatic results. Skeptics also like to point out how most of Antarctica has not warmed appreciably.

Scientists in Antarctica, though, say the climate here has changed quickly and profoundly. Shifting atmospherics mean more ice is piling up in the Ross Sea and around the South Pole — evidence of an extraordinarily dry place seeing slightly more snow.

The Antarctic Peninsula, the northernmost spit of land jutting up toward South America, is rapidly thawing. Since 1950, average midwinter temperatures there have climbed almost 11 degrees Fahrenheit and now range around 14 degrees.

Such data, goes the mainstream consensus, suggest the planet’s climate is changing faster than ever before.
The first decade of the 21st century was the warmest on record, a fact that was not missed at December’s international talks at Copenhagen. Although little came from that climate summit, political pressure to slash carbon emissions is only mounting.

Meanwhile, sea ice — formed on the ocean surface in the coldest temperatures — floats off the northern peninsula for 80 fewer days a year than it did a quarter-century ago. In 2002, a chunk of ice the size of Rhode Island broke from the peninsula’s eastern shore. In 2008, more than 150 square miles more fell off its west side.

 The warming here is the fastest on the planet, five times that of the rest of the globe.
•••
Apsley Cherry-Garrard, who barely survived a trek to collect penguin eggs in 1911 on Robert Falcon Scott’s doomed British run to the pole, described Antarctic exploration as “at once the cleanest and most isolated way of having a bad time which has been devised.”

Times have changed.

“Hi, guys!” Gorman cheerily greets her subjects on Cormorant Island.

She talks to the birds: big-footed, Technicolor cormorants; hovering, scavenging skuas; squawking, knee-high, feces-mottled penguins.

While she labors to keep her scientist’s detached powers of observation, Gorman can’t avoid an affinity for the grandeur of giant petrels or the chubby adorability of a downy penguin chick.

After five years on the Antarctic peninsula, she said, “I still think the penguins are cute.”

Sitting indoors in flip-flops and a down jacket patched with duct tape, Gorman looks younger than her 35 years.

In a schoolgirl voice, the doctoral candidate at Simon Fraser University punctuates conversations with “cool” and “super cool” — typically in appreciation of the look of a bird or the power of isotopes to reveal an animal’s diet.

Day after Antarctic day, she hikes through penguin breeding grounds, weighing the eggs, examining the young, documenting the declining numbers.

She sees the penguins arrive in the spring. Watches them tend eggs, many of which are devoured by predators. She studies their hatchlings, sees them snatched away under the rough law of this frozen jungle.
Increasingly and problematically less frozen.

That’s bad news for the Adelie penguin.

In 1975, 15,000 pairs nested along the peninsula and its scores of small islands. Now there are fewer than 4,000.

Gorman has tracked the phenomenon for the last five years while working out of the U.S.-run Palmer Station. The pace and stamina of her and her research companion, Jennifer Blum, awe even the hardy folks drawn down here.

Nearly every day of the sun-saturated Antarctic summer, the two lace hiking boots, yank on layers of fleece and Gore-Tex and climb into a tiny Zodiac outboard. They motor from one small island to the next well into the evenings.

The sea at times pounds their bow, or surrounds them in ice. Each landing requires one researcher to climb boulders with wet rope in hand while the other fights wind and current to anchor the boat out of harm’s way. Then they trek among two-ton elephant seals and irritated penguins.

Penguins look sweet enough, but they are tight bundles of muscle. With beaks. Pick one up, it will resist. Gorman’s forearms bear a constellation of penguin scars.

“They’re less cool,” she said, “when you have to handle them.”

Rain still makes her uneasy — not because she can get soaked in the cold, but because it makes for a dangerously slick slime when it mixes with bird guano on the rocky islands.

The Adelies feed in spots where the churning of warmer and cooler water stirs up nutrients and promotes the growth of fish and krill.

The birds need winter sea ice to launch their daytime hunts. As that ice has receded, the Adelies are forced farther south in the winter. Scientists call that climate migration. For the penguins, it means shorter days and less feeding time.

While Gorman’s job is to collect the sober data of science, she concedes some feeling for her subjects.
One evening in December as she plucked a guitar with friends and someone sang “Orphan Girl” (I have no mother no father/No sister no brother), Gorman put on a half-acted frown.

“This makes me think,” she said sadly, “of the penguin chicks.”
•••
Antarctica holds 91 percent of the Earth’s ice.

So KU scientists have a whole lot of measuring to do.

For six weeks, the electrical engineers peered through ice sheets so thick that only in recent years have scientists found entire mountain ranges hidden below the surface.

For much of the last two decades, the chief way to monitor ice in Antarctica was with satellite readings. But the man-moon operated by the National Aeronautics and Space Administration over the pole soon will fall out of service.

In stepped CReSIS, the Center for Remote Sensing of Ice Sheets, a collection of climate and technological experts. As a result, NASA’s “Ice Bridge” observation project will run until a replacement satellite goes into orbit in 2014.

The DC-8 is packed with gear made by engineers from KU and elsewhere especially for the job of teasing out new detail about how much ice is stored in the Earth’s natural freezers and how it’s changing.
The flights, which also go over Greenland in the summer of the Northern Hemisphere, tend to be low-altitude, ground-hugging affairs often fighting some of the strongest winds on the planet.

“You really have to hold on,” said Chris Allen, a professor in KU’s Department of Electrical Engineering and Computer Science and an associate director for CReSIS.

“It got kind of scary a couple of times. But sometimes that’s what it takes to get the job done.”
In its 11 hours aloft, the plane passed from Punta Arenas, Chile, soaring over the Antarctic sea where Ernest Shackleton’s Endurance crew was stuck for more than a year, the trail Amundsen blazed, the ice where Scott perished.

Radar signals bounce back from the gleaming white below; terabytes of data feed into the flying lab’s humming computers, enough data each day to fill more than 1,000 pickup trucks with books. This season, the plane logged enough miles to circle the planet four times.

“There was always something to deal with” — software glitches, fidgety hard drives, turbulent skies — “but that’s what makes the challenge interesting,” Allen said.
•••
Even at 35, the geologist Barbeau possesses the persona of a brainy hippie backpacking between hostels rather than that of a professor leading polar expeditions.

His work in the slow-moving field of geology plays into the rush to understand climate change by looking at a critical question: Did glaciers take over Antarctica after it split free from South America, or before?

We know the glaciers arrived 35 million years ago. But the land mass had been sitting at the pole for 100 million years before the chill set in.

The continent is cut off today by the Polar Front, an ocean current and prevailing winds circling the continent from west to east, the water moving with a force 100 times greater than that of all the world’s rivers combined.

If the breakup of the Andes mountain chain — which opened the Drake Passage between South America and the Antarctic Peninsula — occurred before the cold arrived, that suggests it was the seclusion enforced by the Polar Front that later froze it over.

But if the opening of the Drake Passage took place after the glaciers came, then it was probably a gas thing.
It would have been a reversal of what is happening today. The planet would have been experiencing a sudden flourish of plant and animal life, with great quantities of carbon absorbed. Less carbon dioxide in the atmosphere meant less greenhouse effect trapping the sun’s warming energy.

Barbeau’s polar field work could be as vital to his career as Amundsen’s conquest of the South Pole was to his. Both set off with the blessings of their patrons — the Norwegian government and sundry benefactors for Amundsen, principally the National Science Foundation for Barbeau — who had placed bets on their success.

Amundsen beat the British and got a sea named after him.

There will never be a Barbeau Bay, but Barbeau’s discovery landed the geologist a prestigious NSF grant — a huge boon to his research and important to his standing on campus. It meant hundreds of thousands of dollars for his university’s overhead. That success, Barbeau is certain, is the reason he learned while in Antarctica in December that he had achieved tenure at the University of South Carolina.

“It’s a matter of stumbling on the right problem,” Barbeau said, recognizing that by feeding the chic niche of climate science, his work stands much more likely to draw grants and prestige.

At work, he is a wiry prospector wielding a small pickax and an undersized sledge hammer and toting as much as 80 pounds of rocks over miles of snow. Where Amundsen used a compass and a sextant, Barbeau marks his finds with a Garmin satellite navigator.

And where Amundsen learned the value of dogs and fur garments, Barbeau has come to appreciate that less is more. Just enough clothing to keep an active man from shivering, just enough gear to pry rocks loose from a mountainside.

“Every minute on the ground is precious,” he said. “Fewer trips back and forth from the boat mean more time at work, more energy and more focus.”

While he feels pressure to push his science forward, to scope out possibilities for the next grant, Barbeau is constantly aware that he makes a living going to spectacular places.

The Antarctic coast is surely that. Mountaintops jut from the ocean. Glaciers show their alabaster cliffs to the shore. Whales lumber by the research ship that hauls him along the coast, penguins torpedo past its bow, albatrosses glide above it — all in a landscape painted in arresting whites, grays and blues.

“A simple glance around or a thought of how few people have been able to do geology in such a place,” he said, “can lighten a pack by 20 pounds or more.”

Editor’s note
Kansas City Star reporter Scott Canon spent five weeks at Palmer Station on the Antarctica Peninsula and on the Southern Ocean late last year. His travels there and in 2008 to Toolik Lake, Alaska, inside the Arctic Circle, were made possible by a science journalism fellowship awarded by the Marine Biological Laboratory and funded by the National Science Foundation. Photographs for this series are by Canon. Darryl Levings edited the story. The graphics are by Dave Eames. A blog of Canon’s trips to the Antarctic and Arctic is at scottcanon.blogspot.com.

Source

Thursday, January 28, 2010

More evidence for bird-dino link

An illustration depicting dinosaur Sinosauropteryx in true color, with a striped tail and orange back feathers
Sinosauropteryx is the first fossil dinosaur to have its color scientifically established.
Illustration courtesy James Robins
Chris Sloan
Published January 27, 2010

Pigments have been found in fossil dinosaurs for the first time, a new study says.


The discovery may prove once and for all that dinosaurs' hairlike filaments—sometimes called dino fuzz—are related to bird feathers, paleontologists announced today. (Pictures: Dinosaur True Colors Revealed by Feather Find.)

The finding may also open up a new world of prehistoric color, illuminating the role of color in dinosaur behavior and allowing the first accurately colored dinosaur re-creations, according to the study team, led by Fucheng Zhang of China's Institute for Vertebrate Paleontology.

The team identified fossilized melanosomes—pigment-bearing organelles—in the feathers and filament-like structures of fossil birds and dinosaurs from northeastern China.

Found in the feathers of living birds, the nano-size packets of pigment—a hundred melanosomes can fit across a human hair—were first reported in fossil bird feathers in 2008.

That year, Yale graduate student Jakob Vinther and colleagues, using a scanning electron microscope, discovered melanosomes in the dark bands of a hundred-million-year-old feather. In 2009 Vinther's group went on to show that another fossilized feather would have been iridescent in a living bird, due to microscopic light-refracting surfaces created by stacked melanosomes.

These earlier findings proved it was possible for melanosomes from dinosaur times to survive in fossils.
But until now no one had found the pigments in dinosaurs—other than birds, which many paleontologists consider to be dinosaurs. And no one had used melanosome shape and density to infer color.

End of Dinosaur-Bird Debate?

Even as the hundred-million-year-old bird melanosomes were being announced in 2008, the team behind the January 2010 report was using a scanning electron microscope to study minute details of feathered birds and dinosaurs found in Liaoning Province, China, a region famous for yielding thousands of exquisitely preserved animals that lived between 131 and 120 million years ago (prehistoric time line).

The Liaoning project put the team in a unique position to attempt the first melanosome discovery in dinosaurs.
"When we saw the Vinther paper, we said, Hey, look at this—and we found melanosomes immediately," said study co-author Mike Benton, a paleontologist at the University of Bristol in England.

The new study, published online today by the journal Nature, is "scientifically sound," said Hans Dieter-Sues, a paleontologist at the Smithsonian Institution's National Museum of Natural History in Washington, D.C., who was not involved in the research.

"I think the researchers really are looking at the fossilized remnants of melanosomes," he added in his email.
Among the fossil dinosaurs studied were several that were preserved with dino fuzz, such as the turkey-size carnivore Sinosauropteryx.

Some researchers argue that these controversial hairlike filaments, each about the width of a human hair, are fossilized internal collagen and not related to feathers.

The results reported today show that the filaments are packed with melanosomes in the same way as modern feathers.

"These filaments are probably the evolutionary precursors of true feathers," Benton said.

The Smithsonian's Sues added, "I think that one can safely say that this find invalidates some recent attempts to deny the existence of protofeathers in birdlike dinosaurs by claiming (without compelling evidence) that they are degraded collagen fibers."

University of Maryland paleontologist Thomas Holtz agreed, saying it's now up to skeptics "to either prove that internal collagen structures have melanosomes or melanosome-like elements—or to accept that dinosaurs had protofeathers."

Will this end the controversy about dino fuzz?

"It will definitely help end the debate," said Zhonghe Zhou, director of the Institute for Vertebrate Paleontology and a participant in the study.

"But there are still many issues that need to be further investigated," Zhou said. "What we've done here is to provide another line of evidence that the fiberlike filaments found in some dinosaurs are indeed protofeathers."
As for whether the discovery more securely establishes the evolutionary connection between dinosaurs and modern birds, the University of Maryland's Holtz said that, for him, previous, nonfeather discoveries had already settled the debate.

"I don't see that bonds already as strong as diamond links need any strengthening," said Holtz, who was not involved in the study.

(Related: "New Feathered Dinosaur Found; Adds to Bird-Dino Theory.")

A New World of Dinosaur Color
The discovery of melanosomes in fossil feathers also opens a window onto the previously unknown world of prehistoric color, because melanosomes contain the color-associated pigment melanin.
The two most common types of melanin found in modern birds are eumelanin, associated with black and grey feathers, and phaeomelanin, found in reddish brown to yellow feathers.

Melanosomes of both types were found during the new study, providing "the first empirical evidence for reconstructing the colors and color patterning" in dinosaurs and Chinese fossil birds, Zhang and his colleagues write.

For example, the 125-million-year-old early bird Confuciusornis was found to have color variation between blacks and browns in a single feather. And dark areas in Sinosauropteryx's tail were "absolutely packed with phaeomelanosomes," said Benton—a finding that led the team to propose that the dinosaur's tail was striped with "chestnut to rufous [reddish brown] tones."

The University of Maryland's Holtz said, "It seems reasonable to infer that the same size and shape melanosomes in dinosaurs would have resulted in the same colors as in modern birds."

But while melanosomes produce many feather colors, they can't make them all. Many bright feather colors, such as flamingo pink and canary yellow, are related to the foods birds eat.

And Sues, of the Smithsonian, said, "I would perhaps caution about direct inferences concerning coloration because the coloration on many present-day animals quickly changes after death as the color pigments degrade chemically."

Despite these limitations, the melanosome discoveries appear to mark the dawn of a new era for understanding the role of color in prehistoric worlds. Feather color in dinosaurs, for example, may reveal whether color patterns were useful for camouflage or peacock-like courtship displays, and if there were color differences between the sexes, as in many modern birds.

By searching for melanosomes and melanin not only in fossil feathers but also in other melanin-rich tissues, such as skin and hair, scientists, for the first time, won't have to guess at the colors of extinct creatures.
"All of the color reconstructions we made in the past were speculative," study co-author Zhou said. "Now we can add color to the ancient world and provide truly scientific reconstructions of extinct animals."

The University of Maryland's Holtz is "looking forward to the first really well-supported painting" of the many dinosaurs, lizards, and mammals of Liaoning. Still, he said, "I feel a little bit sorry for the paleo-artists, who've had a relatively open book as to how they colored dinosaurs.

"Now we've moved this idea of dinosaur color out of the realm of art and into the realm of science."

Wednesday, January 27, 2010

Dinosaur Extinction Grounded Ancient Birds, New Research Finds


Emus. New research suggests that ancestors of the African ostrich, Australasian emu plus cassowary, South American rheas and New Zealand moa became flightless independently, in close association with the extinction of the dinosaurs about 65 million years ago. (Credit: iStockphoto/John Carnemolla)

Dinosaur Extinction Grounded Ancient Birds, New Research Finds

ScienceDaily (Jan. 26, 2010) — An abundance of food and lack of predators following the extinction of dinosaurs saw previously flighted birds fatten up and become flightless, according to new research from The Australian National University.

The study, led by Dr Matthew Phillips, an ARC Postdoctoral Fellow at the ANU Research School of Biology, looked at the mitochondrial genome sequences of the now-extinct giant moa birds of New Zealand. To their surprise, the researchers found that rather than having a flightless relative, their closest relatives are the small flying tinamous of South America.

Their molecular dating study suggests that the ancestors of the African ostrich, Australasian emu plus cassowary, South American rheas and New Zealand moa became flightless independently, in close association with the extinction of the dinosaurs about 65 million years ago.

"Many of the world's largest flightless birds, known as ratites, were thought to have shared a common flightless ancestor. We followed up on recent uncertainty surrounding this assumption," said Dr Phillips.
"Our study suggests that the flighted ancestors of ratites appear to have been ground-feeding birds that ran well. So the extinction of the dinosaurs likely lifted predation pressures that had previously selected for flight and its necessary constraint, small size. Lifting of this pressure and more abundant foraging opportunities would then have selected for larger size and consequent loss of flight."

The finding of independent origins of flightlessness also solves a mystery of how these flightless birds dispersed across the world over marine barriers -- their ancestors flew. "Ratite birds have been thought of as relics of the former Gondwanan supercontinent, which combined Africa, South America, Australia, Antarctica, New Zealand, India and Madagascar," said Dr Phillips. "Not only have we shown that the separate ratite lineages evolved too recently to have been on Gondwana before its continents drifted apart, but from our analyses we infer that at least ostriches, and possibly ratites as a whole, have their origins in the northern continents."

The researchers' paper is published in this month's issue of the journal Systematic Biology.
 Story Source:
Adapted from materials provided by Australian National University.

Journal Reference:
  1. Phillips et al. Tinamous and Moa Flock Together: Mitochondrial Genome Sequence Analysis Reveals Independent Losses of Flight among Ratites. Systematic Biology, 2010; 59 (1): 90 DOI: 10.1093/sysbio/syp079

Australian National University. "Dinosaur Extinction Grounded Ancient Birds, New Research Finds." ScienceDaily 26 January 2010. 27 January 2010 <http://www.sciencedaily.com­ /releases/2010/01/100126105429.htm>.

Wednesday, January 20, 2010

Happy Penguin Awareness Day!!!!

Penguin Cupcakes
Originally uploaded by *kimmie*

Celebrate! 

Wear something black and white!
Read a book on penguins!
Donate to your favorite penguin charity!
Visit a penguin at the zoo or aquarium! 
Make a post about your favorite penguin!



See the penguin---be the penguin. ;-)


Penguin Cupcakes by *kimmie*.

Saturday, January 16, 2010

Alligators Breathe Like Birds

 

Computerized tomographic (CT) X-ray images of side and top views of a 24-pound American alligator, with 3-D renderings of the bones and of airways or bronchi within the lungs. The windpipe and first-tier of bronchi are not shown. A University of Utah study found that air flows in one direction through a gator's lungs. It flows from the first-tier bronchi through second-tier bronchi (blue), then through tube-like third-tier parabronchi (not shown) and then back through other second-tier bronchi (forest green). (Credit: C.G. Farmer and Kent Sanders, University of Utah.)

Alligators Breathe Like Birds, Study Finds

ScienceDaily (Jan. 15, 2010)University of Utah scientists discovered that air flows in one direction as it loops through the lungs of alligators, just as it does in birds. The study suggests this breathing method may have helped the dinosaurs' ancestors dominate Earth after the planet's worst mass extinction 251 million years ago.
Before and until about 20 million years after the extinction -- called "the Great Dying" or the Permian-Triassic extinction -- mammal-like reptiles known as synapsids were the largest land animals on Earth.
The extinction killed 70 percent of land life and 96 percent of sea life. As the planet recovered during the next 20 million years, archosaurs (Greek for "ruling lizards") became Earth's dominant land animals. They evolved into two major branches on the tree of life: crocodilians, or ancestors of crocodiles and alligators, and a branch that produced flying pterosaurs, dinosaurs and eventually birds, which technically are archosaurs.
By demonstrating one-way or "unidirectional" airflow within the lungs of alligators, the new study -- published in the Jan. 15 issue of the journal Science -- means that such a breathing pattern likely evolved before 246 million years ago, when crocodilians split from the branch of the archosaur family tree that led to pterosaurs, dinosaurs and birds.
That, in turn, means one-way airflow evolved in archosaurs earlier than once thought, and may explain why those animals came to dominance in the Early Triassic Period, after the extinction and when the recovering ecosystem was warm and dry, with oxygen levels perhaps as low as 12 percent of the air compared with 21 percent today.
"The real importance of this air-flow discovery in gators is it may explain the turnover in fauna between the Permian and the Triassic, with the synapsids losing their dominance and being supplanted by these archosaurs," says C.G. Farmer, the study's principal author and an assistant professor of biology at the University of Utah. "That's the major reason this is important scientifically."
Even with much less oxygen in the atmosphere, "many archosaurs, such as pterosaurs, apparently were capable of sustaining vigorous exercise," she adds. "Lung design may have played a key role in this capacity because the lung is the first step in the cascade of oxygen from the atmosphere to the animal's tissues, where it is used to burn fuel for energy."
Farmer emphasized the discovery does not explain why dinosaurs, which first arose roughly 230 million years ago, eventually outcompeted other archosaurs.
Farmer conducted the study -- funded by the National Science Foundation -- with Kent Sanders, an associate professor of radiology at the University of Utah School of Medicine. They performed CT scans of a 4-foot-long, 24-pound alligator.
'The Great Dying' -- Decline of the Synapsids, Rise of the Archosaurs

The synapsids -- which technically include modern mammals -- occupied ecological niches for large animals before the Permian-Triassic extinction.
"Some got up to be bear-sized," says Farmer. Some were meat-eaters, others ate plants. They were four-footed and had features suggesting they were endurance runners. Their limbs were directly under their body instead of sprawling outward like a lizard's legs. There is evidence they cared for their young.
The cause of the mass extinction 251 million years ago is unknown; theories include massive volcanism, an asteroid hitting Earth and upwelling of methane gas that had been frozen in seafloor ice.
"A few of the synapsids survived the mass extinction to re-establish their dominance in the early Triassic, and the lineage eventually gave rise to mammals in the Late Triassic," says Farmer. "However, the recovery of life in the aftermath of the extinction involved a gradual turnover of the dominant terrestrial vertebrate lineage, with the archosaurs supplanting the synapsids by the Late Triassic."
From then until the dinosaurs died out 65 million years ago, any land animal longer than about 3 feet was an archosaur, says Farmer, while mammal-like synapsid survivors "were teeny little things hiding in cracks. It was not until the die-off of the large dinosaurs 65 million years ago that mammals made a comeback and started occupying body sizes larger than an opossum."
No one knows much about the archosaur that was the common ancestor of crocodilians and of pterosaurs, dinosaurs and birds, Farmer says.
It probably was "a small, relatively agile, insect-eating animal," Farmer says. Illustrations of early archosaurs look like large lizards.
"Our data provide evidence that unidirectional flow [of air in the lungs] predates the origin of pterosaurs, dinosaurs and birds, and evolved in the common ancestor of the crocodilian and bird [and pterosaur and dinosaur] lineages," Farmer says.
Cul-de-sacs or Loops for Airflow

In the lungs of humans and other mammals, airflow is like the tides. When we inhale, the air moves through numerous tiers of progressively smaller, branching airways, or bronchi, until dead-ending in the smallest chambers, cul-de-sacs named alveoli, where oxygen enters the blood and carbon dioxide moves from the blood into the lungs.
It long has been known that airflow in birds is unidirectional, and some scientists suggest it also was that way in dinosaurs.
In modern birds, the lungs' gas exchange units are not alveoli, but tubes known as "parabronchi," through which air flows in one direction before exiting the lung. Farmer says this lung design helps birds fly at altitudes that would "render mammals comatose."
Some researchers have argued that unidirectional airflow evolved after crocodilians split from the archosaur family tree, arising among pterosaurs and theropod dinosaurs, the primarily meat-eating group that included Tyrannosaurus rex. Others have argued it arose only among coelurosaurs, a group of dinosaurs that also includes T. rex and feathered dinosaurs.
Unidirectional air flow in birds long has been attributed to air sacs in the lungs. But Farmer disagrees, since gators don't have air sacs, and says it's due to aerodynamic "valves" within the lungs. She believes air sacs help birds redistribute weight to control their pitch and roll during flight. Farmer says many scientists simply assume air sacs are needed for unidirectional airflow, and have pooh-poohed assertions to the contrary.
"They cannot argue with this data," she says. "I have three lines of evidence. If they don't believe it, they need to get an alligator and make their own measurements."
Assessing Airflow in Alligators

Farmer did three experiments to demonstrate one-way airflow in alligators' lungs:
  • She performed surgery on six anesthetized alligators and inserted flow meters called thermistors into the lungs to measure airflow speed and direction.
  • Farmer pumped air in and out of lungs removed from four dead alligators sent to her by a wildlife refuge in Louisiana. The flow was monitored, showing the air kept going the same direction to loop through various tiers of bronchi and back to the trachea.
  • Using lungs from another dead gator, she pushed and pulled water with tiny fluorescent beads through the lungs, making movies showing the unidirectional flow.
Farmer says the fact gator lungs still had unidirectional flow after being removed shows unidirectional airflow is caused by aerodynamic valves within the lungs, and not by some other factor, like air sacs or the liver, which acts like a piston to aid breathing.
How does air loop through an alligator's multichambered lungs?
Inhaled air enters the trachea, or windpipe, and then flows into two primary bronchi, or airways. Each of those primary bronchi enters a lung.
From those primary airways, the bronchi then branch into a second tier of narrower airways. Inflowing air jets past or bypasses the first branch in each lung because the branch makes a hairpin turn away from the direction of airflow, creating an aerodynamic valve. Instead, the air flows into other second-tier bronchi and then into numerous, tiny, third-tier airways named parabronchi, where oxygen enters the blood and carbon dioxide leaves it.
The air, still moving in one direction, then flows from the parabronchi into the bypassed second-tier bronchi and back to the first-tier bronchi, completing a one-way loop through the lungs before being exhaled through the windpipe.
  

Story Source:
Adapted from materials provided by University of Utah.


University of Utah. "Alligators Breathe Like Birds, Study Finds." ScienceDaily 15 January 2010. 16 January 2010 <http://www.sciencedaily.com­ /releases/2010/01/100114143014.htm>.

Wednesday, January 13, 2010