Thursday, October 9, 2014

Antarctic sea ice reaches new record maximum

Date:
October 8, 2014
Source:
NASA/Goddard Space Flight Center
Summary:
Sea ice surrounding Antarctica reached a new record high extent this year, covering more of the southern oceans than it has since scientists began a long-term satellite record to map the extent in the late 1970s.









On Sept. 19, 2014, the five-day average of Antarctic sea ice extent exceeded 20 million square kilometers for the first time since 1979, according to the National Snow and Ice Data Center. The red line shows the average maximum extent from 1979-2014.
Credit: NASA's Scientific Visualization Studio/Cindy Starr



Sea ice surrounding Antarctica reached a new record high extent this year, covering more of the southern oceans than it has since scientists began a long-term satellite record to map sea ice extent in the late 1970s. The upward trend in the Antarctic, however, is only about a third of the magnitude of the rapid loss of sea ice in the Arctic Ocean.
The new Antarctic sea ice record reflects the diversity and complexity of Earth's environments, said NASA researchers. Claire Parkinson, a senior scientist at NASA's Goddard Space Flight Center, has referred to changes in sea ice coverage as a microcosm of global climate change. Just as the temperatures in some regions of the planet are colder than average, even in our warming world, Antarctic sea ice has been increasing and bucking the overall trend of ice loss.

"The planet as a whole is doing what was expected in terms of warming. Sea ice as a whole is decreasing as expected, but just like with global warming, not every location with sea ice will have a downward trend in ice extent," Parkinson said.

Since the late 1970s, the Arctic has lost an average of 20,800 square miles (53,900 square kilometers) of ice a year; the Antarctic has gained an average of 7,300 square miles (18,900 sq km). On Sept. 19 this year, for the first time ever since 1979, Antarctic sea ice extent exceeded 7.72 million square miles (20 million square kilometers), according to the National Snow and Ice Data Center. The ice extent stayed above this benchmark extent for several days. The average maximum extent between 1981 and 2010 was 7.23 million square miles (18.72 million square kilometers).

The single-day maximum extent this year was reached on Sept. 20, according to NSIDC data, when the sea ice covered 7.78 million square miles (20.14 million square kilometers). This year's five-day average maximum was reached on Sept. 22, when sea ice covered 7.76 million square miles (20.11 million square kilometers), according to NSIDC.

A warming climate changes weather patterns, said Walt Meier, a research scientist at Goddard. Sometimes those weather patterns will bring cooler air to some areas. And in the Antarctic, where sea ice circles the continent and covers such a large area, it doesn't take that much additional ice extent to set a new record.
"Part of it is just the geography and geometry. With no northern barrier around the whole perimeter of the ice, the ice can easily expand if conditions are favorable," he said.
Researchers are investigating a number of other possible explanations as well. One clue, Parkinson said, could be found around the Antarctic Peninsula -- a finger of land stretching up toward South America. There, the temperatures are warming, and in the Bellingshausen Sea just to the west of the peninsula the sea ice is shrinking. Beyond the Bellingshausen Sea and past the Amundsen Sea, lies the Ross Sea -- where much of the sea ice growth is occurring.

That suggests that a low-pressure system centered in the Amundsen Sea could be intensifying or becoming more frequent in the area, she said -- changing the wind patterns and circulating warm air over the peninsula, while sweeping cold air from the Antarctic continent over the Ross Sea. This, and other wind and lower atmospheric pattern changes, could be influenced by the ozone hole higher up in the atmosphere -- a possibility that has received scientific attention in the past several years, Parkinson said.

"The winds really play a big role," Meier said. They whip around the continent, constantly pushing the thin ice. And if they change direction or get stronger in a more northward direction, he said, they push the ice further and grow the extent. When researchers measure ice extent, they look for areas of ocean where at least 15 percent is covered by sea ice.

While scientists have observed some stronger-than-normal pressure systems -- which increase winds -- over the last month or so, that element alone is probably not the reason for this year's record extent, Meier said. To better understand this year and the overall increase in Antarctic sea ice, scientists are looking at other possibilities as well.

Melting ice on the edges of the Antarctic continent could be leading to more fresh, just-above-freezing water, which makes refreezing into sea ice easier, Parkinson said. Or changes in water circulation patterns, bringing colder waters up to the surface around the landmass, could help grow more ice.

Snowfall could be a factor as well, Meier said. Snow landing on thin ice can actually push the thin ice below the water, which then allows cold ocean water to seep up through the ice and flood the snow -- leading to a slushy mixture that freezes in the cold atmosphere and adds to the thickness of the ice. This new, thicker ice would be more resilient to melting.

"There hasn't been one explanation yet that I'd say has become a consensus, where people say, 'We've nailed it, this is why it's happening,'" Parkinson said. "Our models are improving, but they're far from perfect. One by one, scientists are figuring out that particular variables are more important than we thought years ago, and one by one those variables are getting incorporated into the models."

For Antarctica, key variables include the atmospheric and oceanic conditions, as well as the effects of an icy land surface, changing atmospheric chemistry, the ozone hole, months of darkness and more.

"Its really not surprising to people in the climate field that not every location on the face of Earth is acting as expected -- it would be amazing if everything did," Parkinson said. "The Antarctic sea ice is one of those areas where things have not gone entirely as expected. So it's natural for scientists to ask, 'OK, this isn't what we expected, now how can we explain it?'"

Story Source:
The above story is based on materials provided by NASA/Goddard Space Flight Center. Note: Materials may be edited for content and length.


NASA/Goddard Space Flight Center. "Antarctic sea ice reaches new record maximum." ScienceDaily. ScienceDaily, 8 October 2014. <www.sciencedaily.com/releases/2014/10/141008122102.htm>.

Penguins Use Their Personalities to Prepare for Climate Change

Birds’ individual personalities may be among the factors that could improve its chances of successfully coping with environmental stressors. Credit: John F. Cockrem, PhD

Date: October 8, 2014

Source: American Physiological Society (APS)

As the global climate continues to change, the ability of many animal species to adapt is being put to the test. Bird populations may be at particular risk. According to the Audubon Society, nearly half of all North American bird species are severely threatened by shifts in climate. The threat reaches beyond North America and could have similar effects on global bird populations.

John Cockrem of the Institute of Veterinary, Animal and Biomedial Sciences at Massey University in New Zealand suggests that a bird's individual personality may be among the factors that could improve its chances of successfully coping with environmental stressors. He studied differences in the level of the stress hormone corticosterone that native little penguins (Eudyptula minor) secreted when exposed to stressful stimulus.

"There is considerable individual variation in corticosterone responses, and a stimulus that initiates a large response in one bird may initiate a small response in another bird," Cockrem wrote. "Corticosterone responses and behavioral responses to environmental stimuli are together determined by individual characteristics called personality. Birds with low corticosterone responses and proactive personalities are likely to be more successful (have greater fitness) in constant or predictable conditions, whilst birds with reactive personalities and high corticosterone responses will be more successful in changing or unpredictable conditions."

These findings may help in predicting the adaptability of bird species as they face a new normal. Cockrem will present the talk "Corticosterone responses and the ability of birds to cope with environmental change" at the American Physiological Society (APS) intersociety meeting "Comparative Approaches to Grand Challenges in Physiology" on October 8, 2014.

 Story Source:
The above story is based on materials provided by American Physiological Society (APS). Note: Materials may be edited for content and length.

American Physiological Society (APS). "Penguins Use Their Personalities to Prepare for Climate Change." ScienceDaily. ScienceDaily, 8 October 2014. <www.sciencedaily.com/releases/2014/10/141008140933.htm>.



Wednesday, October 1, 2014

How dinosaur arms turned into bird wings

Date:
September 30, 2014
Source:
PLOS
Summary:
Although we now appreciate that birds evolved from a branch of the dinosaur family tree, a crucial adaptation for flight has continued to puzzle evolutionary biologists. During the millions of years that elapsed, wrists went from straight to bent and hyperflexible, allowing birds to fold their wings neatly against their bodies when not flying. A resolution to this impasse is now provided by an exciting new study.










(A) Whole-mount alcian blue staining confirms the ulnare is the first carpal formed in avian embryos, distal to the ulna. Thereafter, a distal carpal 3 (referred to as “element x” in previous embryological descriptions) is formed distal to the ulnare, coexisting with it. Finally, the ulnare disappears, whereas dc3 persists.
Credit: J. Botelho et al.; DOI: 
10.1371/journal.pbio.1001957




Although we now appreciate that birds evolved from a branch of the dinosaur family tree, a crucial adaptation for flight has continued to puzzle evolutionary biologists. During the millions of years that elapsed, wrists went from straight to bent and hyperflexible, allowing birds to fold their wings neatly against their bodies when not flying.
How this happened has been the subject of much debate, with substantial disagreement between developmental biologists, who study how the wings of modern birds develop in the growing embryo, and palaeontologists who study the bones of dinosaurs and early birds. A resolution to this impasse is now provided by an exciting new study publishing on September 30 in PLOS Biology.

Underlying this striking evolutionary transformation change is a halving in the number of wrist bones, but developmental biologists and palaeontologists have different names for most of them, and seldom agree on the correspondence between specific dinosaur bones and those of their bird descendants. Indeed, each field has radically different data sources, methods, and research objectives, talking little to each other.

The critical advance made in the new study involved combining these two strands of research. Using an interdisciplinary approach, the lab run by Alexander Vargas at the University of Chile has re-examined fossils stored at several museum collections, while at the same time collecting new developmental data from seven different species of modern birds. Joao Botelho, a Brazilian student in Vargas' lab, developed a revolutionary new technique that allows him to study specific proteins in 3D embryonic skeletons. By combining these data from both fossils and embryos, the research team has made a major step forward in clarifying how the bird wrist evolved.

From early dinosaur ancestors with as many as nine wrist bones, birds have only kept four during the course of evolution, but which of the original bones are they? The identity of each of these bones was debated. For instance, the late Yale professor John Ostrom famously pointed out in the 1970's that the wrists of both birds and bird-like dinosaurs possess a very similar, half-moon shaped bone called the semilunate, and that this bone resulted from the merging of two bones present in dinosaurs. This formed part of Ostrom's then-controversial argument that birds descended from dinosaurs. However, the failure of developmental biologists to confirm this raised doubts that it was the same bone, and even that birds came from dinosaurs.

Now, the new data obtained by the Vargas lab has revealed the first developmental evidence that the bird semilunate was formed by the fusion of the two dinosaur bones. They go on to show that another bone -- the pisiform -- was lost in bird-like dinosaurs, but then re-acquired in the early evolution of birds, probably as an adaptation for flight, where it allows transmission of force on the downstroke while restricting flexibility on the upstroke. Combined, the fossil and developmental data provide a compelling scenario for a rare case of evolutionary reversal.

The study by the Vargas lab also settled the identity of the other two bones of the bird wrist, which were commonly misidentified in both fields. This emphasizes the downsides of not integrating all data sources, and reveals a situation perhaps akin to that of astronomy and experimental physics in the pursuit of cosmology: Together, palaeontology and development can come much closer to telling the whole story of evolution -- this integrative approach resolves previous disparities that have challenged the support for the dinosaur-bird link and reveals previously undetected processes, including loss of bones, fusion of bones, and re-evolution of a transiently lost bone.

Story Source:
The above story is based on materials provided by PLOS. Note: Materials may be edited for content and length.

Journal Reference:
  1. João Francisco Botelho, Luis Ossa-Fuentes, Sergio Soto-Acuña, Daniel Smith-Paredes, Daniel Nuñez-León, Miguel Salinas-Saavedra, Macarena Ruiz-Flores, Alexander O. Vargas. New Developmental Evidence Clarifies the Evolution of Wrist Bones in the Dinosaur–Bird Transition. PLoS Biology, 2014; 12 (9): e1001957 DOI: 10.1371/journal.pbio.1001957


PLOS. "How dinosaur arms turned into bird wings." ScienceDaily. ScienceDaily, 30 September 2014. <www.sciencedaily.com/releases/2014/09/140930144157.htm>.

Friday, September 26, 2014

Dinosaur family tree gives fresh insight into rapid rise of birds


Date:
September 25, 2014
Source:
Swarthmore College
Summary:
The study shows that the familiar anatomical features of birds – such as feathers, wings and wishbones – all first evolved piecemeal in their dinosaur ancestors over tens of millions of years. However, once a fully functioning bird body shape was complete, an evolutionary explosion began, causing a rapid increase in the rate at which birds evolved. This led eventually to the thousands of avian species that we know today.
 
















Researchers examined the evolutionary links between ancient birds and their closest dinosaur relatives, by analyzing the anatomical make-up of more than 850 body features in 150 extinct species, and used statistical techniques to analyze their findings and assemble a detailed family tree.
Credit: Steve Brusatte



The most comprehensive family tree of meat-eating dinosaurs ever created is enabling scientists to discover key details of how birds evolved from them.

The study, published in the journal Current Biology, shows that the familiar anatomical features of birds -- such as feathers, wings and wishbones -- all first evolved piecemeal in their dinosaur ancestors over tens of millions of years.

However, once a fully functioning bird body shape was complete, an evolutionary explosion began, causing a rapid increase in the rate at which birds evolved. This led eventually to the thousands of avian species that we know today.

A team of researchers, led by the University of Edinburgh (UK) and including Swarthmore College Associate Professor of Statistics Steve C. Wang, examined the evolutionary links between ancient birds and their closest dinosaur relatives. They did this by analyzing the anatomical make-up of more than 850 body features in 150 extinct species and used statistical techniques to analyze their findings and assemble a detailed family tree.

Based on their findings from fossil records, researchers say the emergence of birds some 150 million years ago was a gradual process, as some dinosaurs became more bird-like over time. This makes it very difficult to draw a dividing line on the family tree between dinosaurs and birds.

Findings from the study support a controversial theory proposed in the 1940s that the emergence of new body shapes in groups of species could result in a surge in their evolution.

"The evolution of birds from their dinosaur ancestors was a landmark in the history of life," says Wang. "This process was so gradual that if you traveled back in time to the Jurassic, you'd find that the earliest birds looked indistinguishable from many other dinosaurs."

Wang invented a novel statistical method that was able to take advantage of new kinds of data from the fossil record, which reached the conclusion that early birds had a high rate of evolution. He adds that "birds as we know them evolved over millions of years, accumulating small shifts in shape and function of the skeleton. But once all these pieces were in place to form the archetypal bird skeleton, birds then evolved rapidly, eventually leading to the great diversity of species we know today."

"There was no moment in time when a dinosaur became a bird, and there is no single missing link between them, " says Steve Brusatte of the University of Edinburgh's School of GeoSciences, who led the study. "What we think of as the classic bird skeleton was pieced together gradually over tens of millions of years. Once it came together fully, it unlocked great evolutionary potential that allowed birds to evolve at a super-charged rate."

The work was supported by the European Commission, National Science Foundation, the University of Edinburgh, Swarthmore College's Research Fund, Swarthmore College's James Michener Faculty Fellowship, Columbia University, and the American Museum of Natural History.

Story Source:
The above story is based on materials provided by Swarthmore College. Note: Materials may be edited for content and length.

Journal Reference:
  1. Stephen L. Brusatte, Graeme T. Lloyd, Steve C. Wang, Mark A. Norell. Gradual Assembly of Avian Body Plan Culminated in Rapid Rates of Evolution across the Dinosaur-Bird Transition. Current Biology, 2014; DOI: 10.1016/j.cub.2014.08.034


Swarthmore College. "Dinosaur family tree gives fresh insight into rapid rise of birds." ScienceDaily. ScienceDaily, 25 September 2014. <www.sciencedaily.com/releases/2014/09/140925130506.htm>.

Tuesday, September 16, 2014

Glaciers in northern Antarctic Peninsula melting faster than ever despite increased snowfall


NASA Photo by: Jim Ross - NASA Photo: ED04-0056-137


Date:
September 14, 2014
Source:
University of Royal Holloway London
Summary:
Increased snowfall will not prevent the continued melting of glaciers in the northern Antarctic Peninsula, according to new research. Scientists have discovered that small glaciers that end on land around the Antarctic Peninsula are highly vulnerable to slight changes in air temperature and may be at risk of disappearing within 200 years.
 











Increased snowfall will not prevent the continued melting of glaciers in the northern Antarctic Peninsula, according to new research published in the journal Nature Climate Change. 


An international team of researchers, led by Dr Bethan Davies, from Royal Holloway, University of London, has discovered that small glaciers that end on land around the Antarctic Peninsula are highly vulnerable to slight changes in air temperature and may be at risk of disappearing within 200 years.

Temperatures are currently rising rapidly in the Antarctic Peninsula. Because warmer air holds more moisture, the amount of snowfall has also increased. Some researchers have suggested that this may offset the melting of the glaciers, however this study found that just a small rise in air temperature increased melting so much that even large amounts of extra snowfall could not prevent glacier recession.

"These small glaciers around the edge of the Antarctic Peninsula are likely to contribute most to rising sea levels over the coming decades, because they can respond quickly to climate change," said Dr Davies, from the Department of Geography at Royal Holloway. "This study is the first to show how glaciers in this vulnerable region are likely to respond to climate change in future. Our findings demonstrate that the melting will increase greatly even with a slight rise in temperature, offsetting any benefits from increased snowfall."

The researchers carried out extensive fieldwork on James Ross Island, northern Antarctic Peninsula, to map and analyse the changes to a glacier, which is currently 4km long, over the past 10,000 years. They used a combination of glacier and climate modelling, glacial geology and ice-core data.
Dr Davies added: "Geological evidence from previous studies suggests that the glacier grew by 10km within the last 5,000 years, before shrinking back to its current position. It was argued that this occurred during a warmer but wetter period, suggesting that increased precipitation in the future would offset the melting of the glaciers. However, our study shows that this growth occurred during the colder 'Little Ice Age', reaching its largest size just 300 years ago."

Researcher Dr Nicholas Golledge, from Victoria University of Wellington, in New Zealand, said: "This glacier, though small, is typical of many of the small glaciers that end on land around the Antarctic Peninsula. This research is important, because it helps reduce some of the uncertainties about how these glaciers will react to changing temperature and precipitation over the next two centuries."

Professor Neil Glasser, from Aberystwyth University, added: "We found that this glacier remained roughly the same size for thousands of years until it started to grow again 1,500 years ago. However, it is now melting faster than anything seen before, and over the next 200 years will become far smaller than at any point over the last 10,000 years. This unprecedented glacier recession, in response to climate change, will result in significant contributions to sea level rise from this and similar Antarctic Peninsula mountain glaciers and ice caps."




Story Source:
The above story is based on materials provided by University of Royal Holloway London. Note: Materials may be edited for content and length.



Journal Reference:
  1. Bethan J. Davies, Nicholas R. Golledge, Neil F. Glasser, Jonathan L. Carrivick, Stefan R. M. Ligtenberg, Nicholas E. Barrand, Michiel R. van den Broeke, Michael J. Hambrey, John L. Smellie. Modelled glacier response to centennial temperature and precipitation trends on the Antarctic Peninsula. Nature Climate Change, 2014; DOI: 10.1038/nclimate2369



University of Royal Holloway London. "Glaciers in northern Antarctic Peninsula melting faster than ever despite increased snowfall." ScienceDaily. ScienceDaily, 14 September 2014. <www.sciencedaily.com/releases/2014/09/140914211024.htm>.

Saturday, September 6, 2014

Detection by Dung: Don’t Eat the Brown Snow

2590002176_8c3725fdd8_o
Researchers in Antarctica on a mission to locate penguin colonies found two groups of seabirds, thanks to a little help from satellites, helicopters, and the detection of more “primitive” evidence: penguin poop.

Our favorite tuxedo-clad Emperor penguin is native to Antarctica, but harsh winter conditions and the remoteness of some colonies can make it difficult for biologists to gain a comprehensive population assessment of this “hiding” bird. The first breeding penguin colony was discovered in Antarctica in 1902, and in 1999 thousands of birds were sighted near the Mertz glacier in Antarctica, but for the last century, suspected colonies of Emperor Penguins in the area had yet to be confirmed.

In this recently published PLOS ONE study, the authors used both survey- and satellite-based methods to locate the presence of Emperor penguin colonies on the Mertz glacier, where a previous sighting of thousands of birds had occurred 15 years ago, but a drastic habitat change—the glacier’s “tongue” broke off in February 2010—may have disrupted.

journal_pone_0100404_g002
Aerial surveys captured two new potential breeding grounds for colonies, the Eastern and Western (~7,400 breeding pairs total).  Satellite images from a thousand feet in the sky helped the authors detect the Eastern colony by the presence of fecal marks—or in bird specialist speak, “guano”—in the snow.

The red arrow in the image above points out the lovely brown streak of guano strewn across the ice shelf, which indicates the Eastern colony’s previous breeding ground. The authors used this streak as an indication that the Eastern colony was likely close by. Below the guano-streaked, snow-packed shelf, the presence of the Eastern colony was confirmed by researchers trekking across treacherous terrain to visually confirm the presence of the birds.

Unlike the Eastern colony, who mobilized to a fresh home post-breeding, the Western colony seemingly didn’t mind remaining in their breeding muck. This colony was discovered not by satellite but by chance during helicopter flight operations in Antarctica. Although the authors had difficulties finding the Western colony by aerial footage, as pictured in the below image, these social gatherers appeared to differ from the Eastern colony in that they inhabited a large flat surface, and the colony appeared to be much larger.
journal_pone_0100404_g003
In the cases of both colonies, aerial surveys appeared to be very effective for locating them. So, until humans evolve warmer winter coats, scientists conducting surveys by foot are still limited by frigid conditions and isolated locations in future South Pole endeavors. To obtain a more accurate picture of total penguin counts, the authors suggest taking multiple aerial images during the breeding season and conducting several-year surveys to confirm numbers in suspected Antarctic penguin colonies. But for now, the game of Hide and Go Poop will continue.

Citation: Ancel A, Cristofari R, Fretwell PT, Trathan PN, Wienecke B, et al. (2014) Emperors in Hiding: When Ice-Breakers and Satellites Complement Each Other in Antarctic Exploration. PLoS ONE 9(6): e100404. doi:10.1371/journal.pone.0100404

Image 1: Emperor Penguins by Lin Padgham
Image 2-3: Figures 1 and 2 from article

source

Wednesday, September 3, 2014

Extinctions during human era one thousand times more than before

Date:
September 2, 2014
Source:
Brown University
Summary:
The gravity of the world's current extinction rate becomes clearer upon knowing what it was before people came along. A new estimate finds that species die off as much as 1,000 times more frequently nowadays than they used to. That's 10 times worse than the old estimate of 100 times.









 

Vintage engraving of the Dodo (Raphus cucullatus), a flightless bird endemic to the Indian Ocean island of Mauritius. The dodo has been extinct since the mid-to-late 17th century.

Credit: iStockphoto




The gravity of the world's current extinction rate becomes clearer upon knowing what it was before people came along. A new estimate finds that species die off as much as 1,000 times more frequently nowadays than they used to. That's 10 times worse than the old estimate of 100 times.


It's hard to comprehend how bad the current rate of species extinction around the world has become without knowing what it was before people came along. The newest estimate is that the pre-human rate was 10 times lower than scientists had thought, which means that the current level is 10 times worse.

Extinctions are about 1,000 times more frequent now than in the 60 million years before people came along. The explanation from lead author Jurriaan de Vos, a Brown University postdoctoral researcher, senior author Stuart Pimm, a Duke University professor, and their team appears online in the journal Conservation Biology. "This reinforces the urgency to conserve what is left and to try to reduce our impacts," said de Vos, who began the work while at the University of Zurich. "It was very, very different before humans entered the scene."

In absolute, albeit rough, terms the paper calculates a "normal background rate" of extinction of 0.1 extinctions per million species per year. That revises the figure of 1 extinction per million species per year that Pimm estimated in prior work in the 1990s. By contrast, the current extinction rate is more on the order of 100 extinctions per million species per year.

Orders of magnitude, rather than precise numbers are about the best any method can do for a global extinction rate, de Vos said. "That's just being honest about the uncertainty there is in these type of analyses."

From fossils to genetics

The new estimate improves markedly on prior ones mostly because it goes beyond the fossil record. Fossils are helpful sources of information, but their shortcomings include disproportionate representation of hard-bodied sea animals and the problem that they often only allow identification of the animal or plant's genus, but not its exact species.

What the fossils do show clearly is that apart from a few cataclysms over geological periods -- such as the one that eliminated the dinosaurs -- biodiversity has slowly increased.

The new study next examined evidence from the evolutionary family trees -- phylogenies -- of numerous plant and animal species. Phylogenies, constructed by studying DNA, trace how groups of species have changed over time, adding new genetic lineages and losing unsuccessful ones. They provide rich details of how species have diversified over time.

"The diversification rate is the speciation rate minus the extinction rate," said co-author Lucas Joppa, a scientist at Microsoft Research in Redmond, Wash. "The total number of species on earth has not been declining in recent geological history. It is either constant or increasing. Therefore, the average rate at which groups grew in their numbers of species must have been similar to or higher than the rate at which other groups lost species through extinction."

The work compiled scores of studies of molecular phylogenies on how fast species diversified.
For a third approach, de Vos noted that the exponential climb of species diversity should take a steeper upward turn in the current era because the newest species haven't gone extinct yet.
"It's rather like your bank account on the day you get paid," he said. "It gets a burst of funds -- akin to new species -- that will quickly become extinct as you pay your bills."

By comparing that rise of the number of species from the as-yet unchecked speciation rate with the historical trend (it was "log-linear") evident in the phylogenies, he could therefore create a predictive model of what the counteracting historical extinction rate must have been.

The researchers honed their models by testing them with simulated data for which they knew an actual extinction rate. The final models yielded accurate results. They tested the models to see how they performed when certain key assumptions were wrong and on average the models remained correct (in the aggregate, if not always for every species group).

All three data approaches together yielded a normal background extinction rate squarely in the order of 0.1 extinctions per million species per year.

A human role

There is little doubt among the scientists that humans are not merely witnesses to the current elevated extinction rate. This paper follows a recent one in Science, authored by Pimm, Joppa, and other colleagues, that tracks where species are threatened or confined to small ranges around the globe. In most cases, the main cause of extinctions is human population growth and per capita consumption, although the paper also notes how humans have been able to promote conservation.

The new study, Pimm said, emphasizes that the current extinction rate is a more severe crisis than previously understood. "We've known for 20 years that current rates of species extinctions are exceptionally high," said Pimm, president of the conservation nonprofit organization SavingSpecies. "This new study comes up with a better estimate of the normal background rate -- how fast species would go extinct were it not for human actions. It's lower than we thought, meaning that the current extinction crisis is much worse by comparison."

Other authors on the paper are John Gittleman and Patrick Stephens of the University of Georgia.

Story Source:
The above story is based on materials provided by Brown University. Note: Materials may be edited for content and length.

Journal Reference:
  1. Jurriaan M. De Vos, Lucas N. Joppa, John L. Gittleman, Patrick R. Stephens, Stuart L. Pimm. Estimating the Normal Background Rate of Species Extinction. Conservation Biology, 2014; DOI: 10.1111/cobi.12380


Brown University. "Extinctions during human era one thousand times more than before." ScienceDaily. ScienceDaily, 2 September 2014. <www.sciencedaily.com/releases/2014/09/140902151125.htm>.

Monday, August 25, 2014

Adult survival declines as African Penguin population plummets

Sherley_DSC2401_015_1LR
The African Penguin population is in freefall, with adult survival rates over the last decade desperately low. Urgent management action is required to secure both the prey requirements and future of one of Africa’s most charismatic seabirds.

Richard B Sherley
Animal Demography Unit and Marine Research Institute, University of Cape Town, South Africa

Linked IBIS paper
Age-specific survival and movement among major African Penguin Spheniscus demersus colonies. Sherley, R.B., Abadi, F., Ludynia, K., Barham, B.J., Clark, A.E. & Altwegg, R.


Globally, seabirds are in trouble. With 28% of species listed as globally threatened by the IUCN, no other similarly sized group of birds has a poorer conservation status. Seabirds are susceptible to a wide range of anthropogenic pressures, but some of the most substantial threats they face stem from the deterioration of their marine environment through unsustainable fishing practices and climate change.

Penguins may be particularly sensitive to changes in the oceans that they inhabit compared to flying seabirds, because they must swim to find their food (Boersma 2008). The African Penguin Spheniscus demersus, endemic to South Africa and Namibia, has decreased by more than 90% since the 1930s. In South Africa numbers have dropped by more than 10% a year since 2004, resulting in the species being up-listed to Endangered in 2010. Off the Namibian coast, heavy commercial fishing collapsed the stocks of sardine Sardinops sagax and anchovy Engraulis encrasicolus (the penguins’ main prey) in the 1960s and 1970s. The stocks have never recovered and today penguins in Namibia rely on a diet of junk food (Ludynia et al. 2010).

In South Africa, large-scale changes in the marine environment (possibly linked to global climate change) have caused a change in the spawning grounds of sardine and anchovy. These fish now mostly spawn further east than they did two decades ago and are out of reach of penguin colonies on South Africa’s West Coast for much of the year. However, because many of the fish canning factories are also on the West Coast and fishing vessels, like birds, are limited in how far they can go to find fish, the result has been relatively heavy fishing pressure in areas where the fish have become scarce. This is particularly true for adult sardine, a valuable commercial fish and a key source of energy for African penguins when they need to build up body condition to breed each year (Sherley et al. 2013a).

Sherley (Gaglio) IMG_0231_1
Seabirds will often respond to a scarcity of food by skipping or abandoning breeding, opting not to re-lay after losing clutches of eggs, or reducing the amount of food brought to the chicks leading to slow growth, poor chick condition and mortality through starvation. African penguins have shown all of these responses in recent years. Over time, these behavioural responses can lead to population declines through poor breeding success and juvenile survival, but they usually allow adult seabirds to buffer periods of poor food availability. Although their body condition may fall below a critical threshold needed for breeding, in long-lived animals like seabirds, adult survival is rarely compromised except in cases of extreme food shortage.

Our work, published this week in IBIS (Sherley et al. 2014), demonstrates that this is exactly what has happened with African penguins breeding in South Africa’s Western Cape. Over the course of our study period (1994/95 to 2011/12), we noted substantial decreases in adult survival as the availability of adult sardine decreased on the West Coast. At what was formerly the largest colony, Dassen Island, adult survival dropped from around 80% per year in the late 1990s and early 2000s to a low of 43% in 2007/08 (Figure 1) and a similar decline was noted at nearby Robben Island. During this period, heavy fishing pressure persisted in areas with low fish abundance because of the distribution of land-based processing plants, leading to sardine exploitation rates between 2004 and 2007 which were more than double the long-term average.
R Graphics OutputFigure 1. Time-dependent survival estimates (and 95% confidence intervals) for adult African Penguins from Dassen Island, Western Cape between 1994/95 and 2011/12.

These poor adult survival rates indicate that the population is unsustainable and are, in a large part, the reason for the recent dramatic decline in the number of African penguins breeding in South Africa. Ecologists working in the country have been recommending spatial management of the fishery to offset losses of penguins since 2006 and, in response to the species’ worsening conservation status, the government’s fisheries department has begun to investigate the potential benefits to penguins of spatial closures. Experimental small-scale fishing exclusions have been implemented around several breeding colonies, in the hope that this may take some pressure off of the penguins during the breeding season, allowing them to balance their energy budgets more easily.

However, despite the closures having reduced the energetic costs of foraging at one colony (Pichegru et al. 2012) and encouraging results from a modelling study (Weller et al. 2014), evidence for demographic benefits has been scarce and the experimental closures may be removed at the end of 2014. Even if they remain in place, recent biologging studies have demonstrated that non-breeding and juvenile African penguins travel over hundreds of kilometres and feed in areas far from their breeding colonies (e.g. Sherley et al. 2013b). Thus, these closures as a stand-alone management action will not be adequate to reverse the rapid decline in Africa’s only endemic penguin. Rather, a suite of management measures is encouraged to mitigate the multiple factors contributing to the worrying decline of African penguins (Weller et al. 2014, Ludynia et al. 2014). Impacts on adult survival, such as those noted in our study, make it essential that government organizations rapidly implement effective fisheries management actions over large spatial scales to ensure food security for marine top predators.

References

Boersma, P. 2008. Penguins as marine sentinels. Bioscience 58: 597–607. View
Ludynia, K., Roux, J.-P., Jones, R., Kemper, J. & Underhill, L.G. 2010. Surviving off junk: low-energy prey dominates the diet of African penguins Spheniscus demersus at Mercury Island, Namibia, between 1996 and 2009. African Journal of Marine Science 32: 563–572. View
Ludynia, K., Waller, L.J., Sherley, R.B., Abadi, F., Galada, Y., Geldenhuys, D., Crawford, R.J.M., Shannon, L.J. & Jarre, A. 2014. Processes influencing the population dynamics and conservation of African penguins on Dyer Island, South Africa. African Journal of Marine Science 36: 253–267. View
Pichegru, L., Ryan, P.G., van Eeden, R., Reid, T., Gremillet, D. & Wanless, R. Industrial fishing, no-take zones and endangered penguins. Biological Conservation 156: 117–125. View
Sherley, R.B., Underhill, L.G., Barham, B.J., Barham, P.J., Coetzee, J.C., Crawford, R.J.M., Dyer, B.M., Leshoro, T.M. & Upfold L. 2013a. Influence of local and regional prey availability on breeding performance of African penguins Spheniscus demersus. Marine Ecology Progress Series 473: 291–301. View
Sherley, R.B., Ludynia, K., Lamont, T., Roux, J.-P., Crawford, R.J.M. & Underhill, L.G. 2013b. The initial journey of an endangered penguin: implications for seabird conservation. Endangered Species Research 21: 89–95. View
Sherley, R.B., Abadi, F., Ludynia, K., Barham, B.J., Clark, A.E. & Altwegg, R. 2014. Age-specific survival and movement among major African Penguin Spheniscus demersus colonies. Ibis. DOI: 10.1111/ibi.12189.
Weller, F., Cecchini, L.-A., Shannon, L., Sherley, R.B., Crawford, R.J.M., Altwegg, R., Scott, L., Stewart, T. & Jarre A. 2014. A system dynamics approach to modelling multiple drivers of the African penguin population on Robben Island, South Africa. Ecological Modelling 277: 38–56. View

Sherley Richard_Sherley
About the author
Richard Sherley is a Postdoctoral Researcher with the Animal Demography Unit and Marine Research Institute at the University of Cape Town. He has conducted research on seabirds in southern Africa for the last seven years, focusing on understanding how their productivity, survival and dispersal are influenced by the anthropogenic and environmental changes occurring in their marine ecosystem. In particular, he is interested in research that applies ecological theory to create tangible conservation benefits and in understanding how the conditions that animals experience early in life may influence later fitness and impact on population dynamics.
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Photo images
TOP: African Penguin © Richard Sherley
BOTTOM: Moulting African Penguin © Davide Gaglio davygaglio.wix.com

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Marine biologists unlock the secrets of Antarctica

Among the discoveries are crabs that are able to live within the clouds of sulphur emitted by live underwater volcanoes









Marine biologists from across the world have produced an atlas of sea life in the Antarctic Ocean from microbes to whales, finding thousands of new species in the process. Among the discoveries were crabs that are able to live within the clouds of sulphur emitted by live underwater volcanoes and a new type of barnacle that has stems 50 times longer than its head. They also found that climate change had potentially caused changes in the breeding patterns of penguins.

The project was the first of this magnitude since the publication of the Antactic Map Folio Series 45 years ago. Dr Katrin Linse, an expert in Antarctic molluscs at the British Antartic Survey, told The Independent: “Since 1969 there has been no update but lots of science done in that period and lots of species discovered. “We had knowledge of 3,000 or 4,000 species when this process began, but now we know of more like 9,000 -- so it has hugely increased the number of known species.”

She added: “A lot of nations came together and put a lot of information together and specialists were chosen to analyse the data and when you do that you suddenly start to see changes.” The atlas, published this week by the Scientific Committee on Antarctic Research, follows four years work by leading oceanographers and biologists compiling everything they know about ocean species including microbes, fish, mammals and birds. Dr Linse added: “Now if we observe distribution changes or breeding areas, we can say for sure if it represents a change rather than just a year that is different for some reason.”

Claude De Broyer, of the Royal Belgian Institute of Natural Sciences, said: “The data and expert opinions in the atlas will help inform conservation policy, including the debate over whether or not to establish marine protected areas in the open ocean.”

The atlas also gives scientists the ability to predict what effect climate change could have on the distribution of key species, using sophisticated environmental models coupled with the existing species distribution data. The book was a remarkable example of international co-operation. It was produced using data from 147 scientists from 91 different academic institutions in 22 countries.
Huw Griffiths, author and editor of the British Antarctic Survey, said: “The book is unique and contains an amazing collection of information and photos. “It’s been an enormous international effort and will serve as a legacy to the dedicated team of scientists who have contributed to it. “The atlas is a must-read for anyone interested in the animals living at the end of the Earth.”

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Friday, August 15, 2014

Little penguins forage together: 40% of studied penguins synchronized underwater movements while foraging

Date: August 13, 2014

Most little penguins may search for food in groups, and even synchronize their movements during foraging trips, according to a study published August 13, 2014 in the open-access journal PLOS ONE by Maud Berlincourt and John Arnould from Deakin University in Australia. 

Little penguins are the smallest penguin species and they live exclusively in southern Australia, New Zealand, and the Chatham Islands, but spend most of their lives at sea in search of food. Not much is known about group foraging behavior in seabirds due to the difficulty in observing their remote feeding grounds.

Scientists aiming to better understand this behavior used GPS-derived location and diving data to track at-sea foraging associations of little penguins during breeding season. Researchers gathered 84 separate foraging tracks and then categorized individual penguin associations into one of three groups: not associating with other penguins; associating when departing from or returning to the colony; or at sea when traveling or diving, including synchronized dives.

The authors found that ~ 70% of little penguins' foraging tracks were in association with other penguins, ~ 50% of individuals dove while associating with other penguins, and ~ 40% exhibited synchronous diving. These behaviors suggest little penguins forage in groups, may synchronize their underwater movements, and potentially cooperate to concentrate their small-schooling prey.

Story Source:
The above story is based on materials provided by PLOS. Note: Materials may be edited for content and length.

Journal Reference:
  1. Maud Berlincourt, John P. Y. Arnould. At-Sea Associations in Foraging Little Penguins. PLoS ONE, 2014; 9 (8): e105065 DOI: 10.1371/journal.pone.0105065


PLOS. "Little penguins forage together: 40% of studied penguins synchronized underwater movements while foraging." ScienceDaily. ScienceDaily, 13 August 2014. <www.sciencedaily.com/releases/2014/08/140813174225.htm>.

Wednesday, August 13, 2014

Penguins Act As Coalmine-Canaries for the Southern Ocean


Miners used to bring caged canaries down into the mines with them. The notion was that if toxic gases like methane or carbon monoxide leaked into the mine, then the canaries would die before the humans, giving the miners a chance to escape. The idea of a sentinel species is the same. Sentinels are groups of animals who are particularly or uniquely sensitive to changes to their ecosystem. If a sentinel species begins to suffer, it might mean that the broader ecosystem is under attack as well, sometimes giving us a brief window of opportunity to try to address the problem. In some ways, penguins are a sentinel species for southern ocean ecosystems.

Seabirds in general are useful indicators of ecosystem health because they are so dependent on having suitable habitats for breeding and on finding sufficient amounts of prey. Penguins in particular reflect local (or regional) conditions perhaps better than any other group of seabirds. That’s according to Head of Conservation Biology at the British Antarctic Survey Phil N. Trathan and colleagues, who reasoned that understanding the threats to penguins might allow us a better understanding of the Southern Oceans more generally.

Seabirds are the most threatened group of birds, and after albatrosses, penguins are the second most threatened group of all the seabirds. Some seabirds can travel quite far to find food; if there isn’t enough nearby, they can fly a little farther, and are therefore better able to withstand certain pressures. But penguins – all 18 species of them – tend to stick close to home. Penguin populations can therefore reflect both natural, seasonal variations in the health of the ecosystems within several hundred kilometers of their colonies, as well as the more artificial changes brought about by human activities.

In general, the regions with the most cumulative impacts from human activities are in the northern hemisphere. That makes sense, since proportionally, more humans live in the northern hemisphere. But that doesn’t mean that the southern hemisphere in unaffected by human activity. The Southern Oceans, however, are less studied. If researchers can figure out the factors that cause penguin populations to suffer, then they might be able to determine what factors are threatening the Southern Oceans more generally. For Trathan’s team, penguins might as well be canaries.

768px Location Southern Ocean.svg  Penguins Act As Coalmine Canaries for the Southern Ocean
The Southern Ocean, highlighted in blue.

They found that penguin populations are in some ways resilient and, if given sufficient habitat and food, can recover from historic threats like hunting (for oil and feathers) and egg harvesting. Given the threats we aren’t equipped to mitigate in the near- or medium-terms like climate change, infectious disease transmission, and toxic algal blooms, Trathan argues that it is more important that we address those stressors over which we do have control.

The threats from habitat degradation, invasive species, oil pollution, plastic pollution, fisheries bycatch, and competition with fisheries over their prey sources, represent major concerns and “require concerted action to mitigate future population declines for many species.” In other words, the ability for penguins to survive global pressures like climate change and ocean acidification will depend on our ability to protect their prey, to protect their breeding grounds, and to eliminate the pollution from the waters in which they swim. “A risk averse or precautionary approach to the conservation of penguins would thus take immediate action to off-set these impacts,” writes Trathan.

The best solution identified by Trathan’s group is the establishment of marine protected areas (MPAs) both in sovereign waters and on the high seas. Because penguins have different spatial needs as they age, most existing MPAs are inadequate to protect penguins throughout their lifespan. Despite the challenge of coordinating local, national, and international conservation efforts, protecting penguins would also have a positive effect on the other species who share their ecosystems, including fish and marine mammals.

MPAs alone won’t get the job done, however, which is why Trathan and colleagues say that other, flexible, creative approaches will be required to supplement them. Coastal breeding habitats should be protected, especially since penguins have such extreme site fidelity. Introduced or invasive species need to be strictly controlled. Shipping lanes ought to be routed away from critical penguin resting, transit, and foraging areas. “Concerted action to conserve penguin populations today,” they write, “will be essential to facilitate populations that are robust and resilient to climate change impacts in the future.” 

– Jason G. Goldman | 13 August 2014


Source: Trathan P.N., García-Borboroglu P., Boersma D., Bost C.A., Crawford R.J.M., Crossin G.T., Cuthbert R.J., Dann P., Davis L.S. & DE LA Puente S. et al. (2014). Pollution, Habitat Loss, Fishing, and Climate Change as Critical Threats to Penguins., Conservation biology : the journal of the Society for Conservation Biology, PMID: http://www.ncbi.nlm.nih.gov/pubmed/25102756
 
Header image: Rockhopper penguin, Patagonia, Argentina via shutterstock.com; Southern ocean graphic via Connormah/Wikimedia commons

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Thursday, August 7, 2014

Giant fossil penguin features on coin

Wednesday, 6 August 2014
Ewan Fordyce with coin image
Professor Ewan Fordyce proudly holds the 2014 collectable coin with his discovery – a Kairuku penguin – depicted on it. Photo: Sharron Bennett.

In what is thought to be a first for an Otago researcher, Geology’s Professor Ewan Fordyce has had one of his research findings emblazoned on a collectable coin issued recently by New Zealand Post.
A Kairuku penguin is depicted on the 2014 New Zealand Annual Coin. The extinct species of giant penguin was named by Professor Fordyce and a team working from the Department of Geology in 2012.

Professor Fordyce says he was “very delighted” when contacted by New Zealand Post earlier this year with the proposal and request to use the image of a Kairuku on the coin.
"It's nice to see Otago research recognised in this way."
“It's nice to see Otago research recognised in this way. Actually, the fossils can be a bit personal, if they are unusual like the Kairuku penguins (in this case, well preserved and big), and if we can remember the original discovery.”

The first discovery of Kairuku remains involved 27-million-year-old fossilised bones spotted “by chance” by Professor Fordyce in 1977. An account of the fossil’s discovery and significance can be found here.

He plans to keep his own copy of the coin at hand, bringing it out now and then to share with those who might really appreciate it from a scientific perspective – the occasional visiting paleospheniscologist (fossil penguin researcher).

Just 1500 of the commemorative coins were minted in the series produced annually by New Zealand Post to highlight endangered native species.

About Kairuku penguins:

The giant penguins are taller than any species of penguin known to have lived in New Zealand. They are thought to have lived about 27 million years ago and probably became extinct somewhere between 24 and 25 million years ago.

These penguins were much taller and heavier than their modern counterparts. When standing, they were 1.3 metres tall and stretched out to an impressive 1.5 metres when swimming. Their weight is estimated to have been at least 60 kilograms. The Kairuku has unusual proportions, with a long beak, long flippers, a slender body and short, thick legs and feet compared with modern penguins. This body type and beak suggest that they were divers that speared or snapped at their food.

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