IMMUNITY GENES FOUND IN SEA FANS

Photo Shows Sea Fan In Back.  Credit:  U.S. NOAA

FROM:  NATIONAL SCIENCE FOUNDATION

Sick Sea Fans: Undersea "Doctors" to the Rescue

Scientists discover genes involved in immunity of sea fans to coral diseases
Like all of us, corals get sick. They respond to pathogens (disease-causing microbes) and recover or die. But unlike us, they can't call a doctor for treatment.

Instead, help has arrived in the form of scientists who study the causes of the corals' disease, and the immune factors that might be important in their response and resistance.

With support from the National Science Foundation (NSF), scientists Drew Harvell and Colleen Burge of Cornell University and their colleagues have developed a catalog of genes that, the researchers say, will allow us to better understand the immune systems of corals called sea fans.

The marine ecologists have trained their undersea eyes on a particular sea fan species, Gorgonia ventalina, or the purple sea fan, found in the western Atlantic Ocean and the Caribbean Sea.

The team has monitored sea fan health in the Florida Keys, Mexican Yucatan and Puerto Rico for the past 15 years. The most recent research, in collaboration with Ernesto Weil of the University of Puerto Rico, is underway on reefs at La Parguera, Puerto Rico.

Gorgonia ventalina is a fan-shaped coral with several main branches and a latticework of smaller branches. Its skeleton is composed of calcite and gorgonian, a collagen-like compound. Purple sea fans often have smaller, accessory fans growing sideways out of their main fans.

These large sea fans fare best near shore in shallow waters with strong waves and on deeper outer reefs with strong currents, down to a depth of about 50 feet. Small polyps on the graceful fans catch plankton drifting by on fast-flowing currents.

Turning (more) purple

Life as a purple sea fan isn't always easy. The coral may be attacked by the fungus Aspergillus sydowii, which causes the disease aspergillosis.

It results in damaged patches on the fan, extreme purpling of tissues and sometimes death. Several outbreaks of aspergillosis have occurred in the Caribbean; corals in stressful conditions such as warming waters may be especially susceptible.

"Diseases and climate change are very tightly linked," says Mike Lesser, program director in NSF's Division of Ocean Sciences, which funds the research along with the joint NSF-National Institutes of Health Evolution and Ecology of Infectious Diseases (EEID) Program.

"The role of climate change in diseases is important," Lesser says, "for understanding the spread of infectious diseases in every corner of the globe, including the oceans."

Adds Sam Scheiner, NSF EEID program director, "Human-induced climate change is having profound effects on many parts of the world. As this research shows, coral reefs are being decimated by the combination of climate change and infectious diseases."

Undersea "doctors" come to sea fans' aid

Harvell agrees.

In a paper published earlier this year in The Annual Review of Marine Science, Harvell, Burge and other scientists reviewed climate change influences on marine infectious diseases.

Now the scientists are using the purple sea fan as a model for studying ocean diseases. "We're looking at microbial infection, pathways of defense and the health of this sea fan in the face of warming waters and climate change," says Harvell.

"All animals on Earth--from humans to fish to corals--are susceptible to infection by pathogens that cause illness," she says. "What we hope to answer is: How widespread are these infections? Why do they happen? And, what can we do about them?"

Coral reefs are declining worldwide. Even very old coral colonies in remote locations are dying. "Disease-related deaths are caused in part by pathogens alone and in part by interactions between pathogens and climate change," says Burge.

Many of these pathogens are unidentified, leaving sea fans and their coral relatives at high risk.

But the mystery is slowly being solved.

The scientists have discovered two pathogens in purple sea fans. The microbes are being cultured and used to examine how sea fans' immune systems work.

Past is prologue?

A look back a decade or more may provide clues to the present--and the future--for sea fans.

From 1996 through 2004, thousands of sea fans in the Caribbean died of aspergillosis. Many survived, however, and appear resistant to further attack.

But they're far from home free.

Purple sea fans are now being infected by a new pathogen, called Aplanochytrium. Burge was the first to isolate and culture the microbe from a sick sea fan.

Aplanochytrium is a member of an order of lethal microbes known as Labyrinthulomycetes. It grows faster at warmer temperatures, leaving sea fans in "hot water."

Corals don't have "immune memory," such as the T cells and antibodies found in humans. Instead they have an ancient defense system called the innate immune system.

Studying sea fans' immunity through their genes is an important step in protecting them, says Burge.

"We used molecular biology and bioinformatics--a combination of biology, computer science and information technology--to make a set of the genes' messages, called transcripts," she says. "Then we characterized these messages, which are known collectively as a transcriptome."

The results, reported this month in a paper in the journal Frontiers in Physiology, are the first to show which genes are activated in response to pathogens in sea fans. Co-authors of the paper are Burge, Harvell and Morgan Mouchka of Cornell, and Steven Roberts of the University of Washington.

Message in a (genetic) bottle

The purple sea fan may hold messages for the oceans, and for us, but the messages come in a genetic bottle.

The scientists studied what's called messenger RNA, which transfers genetic messages, in sea fans exposed to Aplanochytrium, comparing it with that of unexposed sea fans.

They found that the sea fans' genes hold clues to questions such as how the fans recognize and kill pathogens, and how they repair injured tissues.

The scientists are increasing the sea fan genetic "catalog" by adding genes expressed, or turned on, in response to record-breaking Caribbean Sea temperatures in 2010.

The researchers, working in Puerto Rico with Weil and Laura Mydlarz of the University of Texas at Arlington, assessed the effect of the 2010 Caribbean coral bleaching event, as it's known, on sea fans' genes and immune function.

The study compared immune system genes in a heat-sensitive coral species, Orbicella annularis, the boulder star coral, with that of Gorgonia ventalina.

The purple sea fan was thought to be resilient to the stresses of warming waters. But Gorgonia ventalina, the scientists found, is also susceptible to the double whammy of disease and warming.

-- Cheryl Dybas, NSF

DECLINE OF THE POLLINATORS

FROM:  NATIONAL SCIENCE FOUNDATION
Bee Faithful? Plant-Pollinator Relationships Compromised When Bee Species Decline

Remove even one bumblebee species from an ecosystem and the effect is swift and clear: Pollination is less effective, and plants produce significantly fewer seeds.

This according to research published today in the journal Proceedings of the National Academy of Sciences that focuses on the interactions between bumblebees and larkspur wildflowers in Colorado's Rocky Mountains.

The findings show that reduced competition among pollinators disrupts floral fidelity, or specialization, among the remaining bees in the system, leading to less successful plant reproduction.

"We found that these wildflowers produce one-third fewer seeds in the absence of just one bumblebee species," says Emory University ecologist Berry Brosi, who led the study.

"That's alarming and suggests that global declines in pollinators could have a bigger effect on flowering plants and food crops than was previously realized."

The National Science Foundation (NSF) funded the research; the paper was co-authored by ecologist Heather Briggs of the University of California-Santa Cruz.

"This study shows that the loss of a single bee species can harm pollination and reproduction of all flowering plant species in an ecosystem," says Alan Tessier, program director in NSF's Division of Environmental Biology, which funded the research.

"What's equally impressive is the demonstration of the mechanisms--that the loss of a single species changes the foraging behavior of all the remaining bee species."

About 90 percent of plants need animals, mostly insects, to transfer pollen between them so they can fertilize and reproduce.

Bees are by far the most important pollinators worldwide and have co-evolved with the floral resources they need for nutrition.

During the past decade, however, scientists have reported dramatic declines in populations of some bee species.

Some studies have indicated that plants can tolerate losing most pollinator species in an ecosystem as long as other pollinators remain to take up the slack. Those studies, however, were based on theoretical computer modeling.

Brosi and Briggs were curious about whether this theoretical resilience would hold up in real-life scenarios.

The team conducted field experiments to learn how the removal of a single pollinator species would affect the plant-pollinator relationship.

"Most pollinators visit several plant species over their lifetimes, but often will display what we call floral fidelity over shorter time periods," Brosi says.

"They'll tend to focus on one plant while it's in bloom, then a few weeks later move on to the next species in bloom. You might think of them as serial monogamists."

Floral fidelity clearly benefits plants, because a pollinator visit will only lead to plant reproduction when the pollinator is carrying pollen from the same plant species.

"When bees are 'promiscuous,' visiting plants of more than one species during a single foraging session, they are much less effective as pollinators," Briggs says.

The researchers conducted their experiments at the Rocky Mountain Biological Laboratory near Crested Butte, Colo.

Located at 9,500 feet, the facility's subalpine meadows are too high for honeybees, but they are buzzing during the summer months with bumblebees.

The experiments focused on the interactions of the insects with larkspurs, dark purple wildflowers that are visited by 10 of the 11 bumblebee species there.

The researchers studied a series of 20-meter-square wildflower plots, evaluating each one in both a control state, left in its natural condition, and in a manipulated state, in which nets were used to remove the bumblebees of just one species.

The researchers then observed bumblebee behavior in both the control plots and the manipulated plots.

"We'd literally follow around the bumblebees as they foraged," Briggs says. "It's challenging because the bees can fly pretty fast."

Sometimes the researchers could only record between five and 10 movements, while in other cases they could follow the bees to 100 or more flowers.

"When we caught bees to remove target species from the system, or to swab their bodies for pollen, we released them unharmed," Brosi says.

No researchers were harmed either, he adds. "Stings were very uncommon during the experiments. Bumblebees are quite gentle on the whole."

Across the steps of the pollination process, from patterns of bumblebee visits to plants, to picking up pollen, to seed production, the researchers saw a cascading effect of removing one bee species.

While about 78 percent of the bumblebees in the control groups were faithful to a single species of flower, only 66 percent of the bumblebees in the manipulated groups showed such floral fidelity.

The reduced fidelity in manipulated plots meant that bees in those groups carried more types of pollen than those in the control groups.

The changes had direct implications for plant reproduction: Larkspurs produced about one-third fewer seeds when one of the bumblebee species was removed, compared to larkspurs in the control groups.

"The small change in the level of competition made the remaining bees more likely to 'cheat' on the larkspur," Briggs says.

While previous research has shown how competition drives specialization within a species, the bumblebee study is one of the first to link this mechanism to the broader functioning of an ecosystem.

"Our work shows why biodiversity may be key to the conservation of an entire ecosystem," Brosi says.

"It has the potential to open a whole new set of studies into the implications of interspecies interactions."

-NSF-

AMOUNT OF WATER TREES NEED AND THE CHANGING ATMOSPHERE

On the ground: looking into Harvard Forest's trees from a less lofty perch.  Credit: NSF Harvard Forest LTER Site

FROM:  NATIONAL SCIENCE FOUNDATION
Changing Atmosphere Affects How Much Water Trees Need

Spurred by increasing levels of atmospheric carbon dioxide, forests over the last two decades have become dramatically more efficient in how they use water.

Scientists affiliated with the National Science Foundation's (NSF) Harvard Forest Long-Term Ecological Research (LTER) site report the results in this week's issue of the journal Nature.

Harvard Forest is one of 26 such NSF LTER sites in ecosystems from deserts to grasslands, coral reefs to coastal waters, around the world.

Studies have long predicted that plants would begin to use water more efficiently, that is, lose less water during photosynthesis, as atmospheric carbon dioxide levels rose.

A research team led by Trevor Keenan and Andrew Richardson of Harvard University, however, has found that forests across the globe are losing less water than expected and becoming even more efficient at using it for growth.

Using data collected in forests in the northeastern United States and elsewhere around the world, Keenan and Richardson found increases in efficiency larger than those predicted by state-of-the-art computer models.

The research was done in collaboration with scientists from the USDA Forest Service, Ohio State University, Indiana University and the Karlsruhe Institute of Technology in Germany.

"This could be considered a beneficial effect of increased atmospheric carbon dioxide," said Keenan, the first author of the Nature paper.

"What's surprising is we didn't expect the effect to be this big. A large proportion of the ecosystems in the world are limited by water--they don't have enough water during the year to reach their maximum potential growth.

"If they become more efficient at using water, they should be able to take more carbon out of the atmosphere due to higher growth rates."

While increased atmospheric carbon dioxide may benefit forests in the short-term, Richardson emphasized that the overall climate picture would remain grim if levels continue to rise.

"We're still very concerned about what rising levels of atmospheric carbon dioxide mean for the planet," Richardson said.

"There is little doubt that as carbon dioxide continues to rise--and last month we just passed a critical milestone, 400 parts per million for the first time in human history--rising global temperatures and changes in rainfall patterns will, in coming decades, have very negative consequences for plant growth in many ecosystems around the world."

How do increasing carbon dioxide levels lead to more efficient water use?

The answer, Keenan said, is in the way photosynthesis works.

To take in the carbon dioxide they need, plants open tiny pores, called stomata, on their leaves. As carbon dioxide enters, however, water vapor is able to escape.

Higher levels of carbon dioxide mean the stomata don't need to open as wide, or for as long, so the plants lose less water and grow faster.

To take advantage of that fact, commercial growers have for years pumped carbon dioxide into greenhouses to promote plant growth.

To test whether such a "carbon dioxide fertilization effect" was taking place in forests, Keenan, Richardson and others turned to long-term data measured using a technique called eddy covariance.

This method, which relies on sophisticated instruments mounted on tall towers extending above the forest canopy, allows researchers to determine how much carbon dioxide and water are going into and out of the ecosystem.

With more than 20 years of data, the towers at the NSF Harvard Forest LTER site--which have the longest continuous record in the world--are an important resource for studying how forests have responded to changes in atmospheric carbon dioxide levels, scientists say.

"A goal of the NSF LTER program is understanding forest ecosystems and the basis for predicting fluxes of energy and materials in these ecosystems," said Matt Kane, program director in NSF's Division of Environmental Biology, "as well as distributions of forest biota as a result of global climate change."

"Findings from this study are important to our understanding of forest ecosystems--and how they can be managed more effectively now and in the future."

Though more than 300 towers like Harvard Forest's have sprung up around the globe, many of the earliest--and hence with the longest data records--are in the northeastern United States.

When the researchers began to look at those records, they found that forests were storing more carbon and becoming more efficient in how they used water.

The phenomenon, however, wasn't limited to a single region. When the scientists examined long-term data sets from all over the world, the same trend was evident.

"We went through every possible hypothesis of what could be going on, and ultimately what we were left with is that the only phenomenon that could cause this type of shift in water-use efficiency is rising atmospheric carbon dioxide," Keenan said.

Going forward, Keenan, who is now at Macquarie University in Sydney, Australia, is working to get access to data collected from yet more sites, including several that monitor tropical and arctic systems.

"This larger dataset will help us better understand the extent of the response we observed," he said.

"That in turn will help us build better models, and improve predictions of the future of the Earth's climate.

"Right now, all the models we have underrepresent this effect by as much as an order of magnitude, so the question is: What are the models not getting? What do they need to incorporate to capture this effect, and how will that affect their projections for climate change?"

The research was also supported by NOAA. Field measurements at the sites, which are part of the AmeriFlux network, have also been funded by the U.S. Department of Energy and the USDA Forest Service.

-NSF-

SUPEROXIDES IN THE DARK

Ocean Sunset.  Credit:  U.S. Navy.

FROM:  NATIONAL SCIENCE FOUNDATION

'Dark Oxidants' Form Away from Sunlight in Lake and Ocean Depths, Underground Soils
New findings overturn understanding of light-dependent environmental oxidants

Breathing oxygen... can be hazardous to your health?

Indeed, our bodies aren't perfect. They make mistakes, among them producing toxic chemicals, called oxidants, in cells. We fight these oxidants naturally, and by eating foods rich in antioxidants such as blueberries and dark chocolate.

All forms of life that breathe oxygen--even ones that can't be seen with the naked eye, such as bacteria--must fight oxidants to live.

"If they don't," says scientist Colleen Hansel of the Woods Hole Oceanographic Institution in Massachusetts, "there are consequences: cancer and premature aging in humans, death in microorganisms."

These same oxidants also exist in the environment. But neutralizing environmental oxidants such as superoxide was a worry only for organisms that dwell in sunlight--in habitats that cover a mere 5 percent of the planet.

That was the only place where such environmental oxidants were thought to exist.

Now researchers have discovered the first light-independent source of superoxide. The key is bacteria common in the depths of the oceans and other dark places.

The bacteria breathe oxygen, just like humans. "And they're everywhere--literally," says Hansel, co-author of a paper reporting the results and published in this week's issue of the journal Science Express.

The result expands the known sources of superoxide to the 95 percent of Earth's habitats that are "dark." In fact, 90 percent of the bacteria tested in the study produced superoxide in the dark.

"Superoxide has been linked with light, such that its production in darkness was a real mystery," says Deborah Bronk of the National Science Foundation's (NSF) Division of Ocean Sciences, which co-funded the research with NSF's Division of Earth Sciences.

"This finding shows that bacteria can produce superoxide in the absence of light."

The bacteria are found "miles beneath the seafloor, in hot fluids coming from underwater volcanoes, in every type of underground soil and throughout deep lake and ocean waters," Hansel says.

The number of these bacteria in a thimble of seawater or soil is greater than the human population of San Francisco. And they're all releasing large amounts of superoxide.

On Earth's surface, "superoxide can kill corals, turning them white," says Hansel. "It can also produce huge fish kills during red tides. But it's not always bad."

It also helps ocean microorganisms acquire the nutrients they need to survive. And superoxide may remove the neurotoxin mercury from the sea, keeping it out of fish and off dinner plates.

The bacteria that produce superoxide could account for the total amount of the chemical in the oceans, Hansel and colleagues say, and are likely the main source in dark environments.

"That's a paradigm shift that will transform our understanding of the chemistry of the oceans, as well as of lakes and underground soils," says Hansel, "and of the life forms that live in and depend on them."

Co-authors of the paper are Julia Diaz and Chantal Mendes of Harvard University, Peter Andeer and Tong Zhang of Woods Hole Oceanographic Institution and Bettina Voelker of the Colorado School of Mines.

-NSF-

SCIENTISTS FIND THE DESTINATION OF CHARCOAL

At NSF's Florida Coastal Everglades LTER site, charcoal is part of the dissolved organic carbon. Credit: Wikimedia Commons

 

FROM: NATIONAL SCIENCE FOUNDATION
Where Does Charcoal, or Black Carbon, in Soils Go?
Scientists have uncovered one of nature's long-kept secrets--the true fate of charcoal in the world's soils.

The ability to determine the fate of charcoal is critical to knowledge of the global carbon budget, which in turn can help understand and mitigate climate change.

However, until now, researchers only had scientific guesses about what happens to charcoal once it's incorporated into soil. They believed it stayed there.

Surprisingly, most of these researchers were wrong.

The findings of a new study that examines the result of charcoal once it is deposited into the soil are outlined in a paper published this week in the journal Science.

The international team of researchers was led by scientists Rudolf Jaffe of Florida International University and Thorsten Dittmar of the German Max Planck Society.

"Most scientists thought charcoal was resistant," says Jaffe. "They believed that once it was incorporated into soils, it stayed there. But if that were the case, soils would be black."

Charcoal, or black carbon, is a residue generated by combustion including wildfires and the burning of fossil fuels.

When charcoal forms, it is usually deposited into the soil.

"From a chemical perspective, no one really thought it dissolved, but it does," Jaffe says.

"It doesn't accumulate for a long time. It's exported into wetlands and rivers, eventually making its way to the oceans."

It all started with a strange finding in the Everglades.

At the National Science Foundation (NSF) Florida Coastal Everglades Long-Term Ecological Research (LTER) site--one of 26 such NSF LTER sites in ecosystems around the world--Jaffe studied the glades' environmental chemistry.

Dissolved organic carbon is known to be abundant in wetlands such as the Everglades and plays a critical role in the ecology of these systems.

Jaffe wanted to learn more about what comprised the organic carbon in the Everglades.

He and colleagues discovered that as much as 20 percent of the total dissolved organic carbon in the Everglades is charcoal.

Surprised by the finding, the researchers shifted their focus to the origin of the dissolved charcoal.

In an almost serendipitous scientific journey, Dittmar, head of the Max Planck Research Group for Marine Geochemistry at the University Oldenburg in Germany, was also tracing the paths of charcoal, but from an oceanographic perspective.

To map out a more comprehensive picture, the researchers joined forces. Their conclusion is that charcoal in soils is making its way into the world's waters.

"This study affirms the power of large-scale analyses made possible through international collaborations," says Saran Twombly, program director in NSF's Division of Environmental Biology, which funded the research along with NSF's Directorate for Geosciences.

"What started out as a puzzling result from the Florida Everglades engaged scientists at other LTER sites in the U.S., and eventually expanded worldwide," says Twombly. "The result is a major contribution to our understanding of the carbon cycle."

Fire is probably an integral part of the global carbon cycle, says Dittmar, its effects seen from land to sea.

The discovery carries significant implications for bioengineering, the scientists believe.

The global carbon budget is a balancing act between sources that produce carbon and sources that remove it.

The new findings show that the amount of dissolved charcoal transported to the oceans is keeping pace with the total charcoal generated by fires annually on a global scale.

While the environmental consequences of the accumulation of black carbon in surface and ocean waters are currently unknown, Jaffe said the findings mean that greater consideration should be given to carbon sequestration techniques.

Biochar addition to soils is one such technique.

Biochar technology is based on vegetation-derived charcoal that is added to agricultural soils as a means of sequestering carbon.

As more people implement biochar technology, says Jaffe, they should take into consideration the potential dissolution of the charcoal to ensure that these techniques are environmentally friendly.

Jaffe and Dittmar agree that there are still many unknowns when it comes to the environmental fate of charcoal, and both plan to move on to the next phase of the research.

They've proved where charcoal goes.

Now they'd like to answer how that happens, and what the environmental consequences are.

The more scientists can understand the process and the environmental factors controlling it, says Jaffe, the better the chances of developing strategies for carbon sequestration and mitigating climate change.

The research was also conducted at NSF's Bonanza Creek; Konza Prairie; Hubbard Brook; Coweeta; and Georgia Coastal Ecosystems LTER sites, and at other locations around the world.

Other authors of the paper are: Yan Ding of Florida International University; Jutta Niggemann of the Max Planck Research Group for Marine Geochemistry; Anssi Vahatalo of the University of Helsinki; Aron Stubbins of the Skidaway Institute of Oceanography in Savannah, Georgia; Robert Spencer of the Woods Hole Research Center in Massachusetts; and John Campbell of the USDA Forest Service.

-NSF-

SCIENTISTS LOOK FOR LIFE'S "WHITE GOLD"

 

Tracking high-elevation snowfall at NSF's Niwot Ridge LTER site in Colorado. Credit: NSF Niwot Ridge LTER Site

FROM: NATIONAL SCIENCE FOUNDATION

An American exodus, it's been called, the largest "migration" of people in modern U.S. history.

It happened during the 1930s Dust Bowl, when severe drought conditions coupled with erosion brought about an environmental catastrophe. Choking dust storms caused major economic, ecological and agricultural damage in Texas, Oklahoma and parts of New Mexico, Kansas and Colorado.

Ill winds blew across fields, plucking deep-rooted grasses and carrying them hundreds of miles. Farmlands disappeared and homes were destroyed. These "black blizzards" swirled all the way to East Coast cities such as New York and Washington.

On April 14, 1935--"Black Sunday"--20 of the worst of the storms turned day into night. More than 500,000 people were left homeless. Most headed due west in search of work. Some, victims of dust pneumonia or malnutrition, never made it.

For today's residents of states like Colorado, that scene is long ago and far away. Or is it? On Earth Week, with much of the Mountain West in an extreme drought, people in the Four Corners are wondering.

　

The search for white gold
The answer lies in white gold: snowmelt.

"Snow and its meltwaters are indeed white gold, and they're getting harder and harder to find," says Mark Williams, an ecologist at the University of Colorado-Boulder and principal investigator of the National Science Foundation's (NSF) Niwot Ridge Long-Term Ecological Research (LTER) site in Colorado.

In western North America, snow typically begins to fall in November. It piles up, reaching its peak in April. In the Rocky Mountains region, 85 percent of the water resources come from snow as it eventually melts.

At Niwot Ridge, ecologists are prospecting for white gold, no easy task at 9,800 feet up.

Niwot Ridge is one of 26 NSF LTER sites in mountain, prairie, coastal and other ecosystems around the world. The sites are primarily supported by NSF's Directorate for Biological Sciences, with major additional funding from its Directorate for Geosciences.

Niwot Ridge is part of the Boulder Creek, Colorado, watershed, where scientists at NSF's Boulder Creek Critical Zone Observatory (CZO) are also looking for white gold.

Their search takes them into Earth's critical zone--the region between the top of the forest canopy and the base of unweathered rock. Boulder Creek is one of six such NSF CZOs in watersheds across the country.

"The depth of winter's snowpack and timing of spring snowmelt determine how much water we will have the following summer," says Williams, who is also affiliated with the Boulder Creek CZO, "and the extent of a drought that's the most severe since the Dust Bowl."

It's 2013, not 1935. But farmers are again asking whether there will be enough water for their fields.

Water well running dry

At Niwot Ridge and Boulder Creek, scientists face howling winter winds to measure snow depth.

Without deep snows, the researchers are discovering, our water well is running dry.

"Water is critical for recharging soil moisture, keeping plants alive and replenishing stream networks," says Williams. "Those streams and rivers are what feed our reservoirs."

Water in all its forms--vapor, liquid and solid--distinguishes our planet, says John Wingfield, NSF assistant director for Biological Sciences.

"Much remains to be learned about the complex biological processes, and interactions of the biosphere and geosphere, in snow and ice cover," Wingfield says. "Large-scale shifts of snow and ice fields will have major downstream effects. The implications for ecosystems even far removed from high altitude and latitude snow and ice are unknown."

To find answers, Williams, Suzanne Anderson, principal investigator of the Boulder Creek CZO, and colleagues recently conducted a study of water flow on hillslopes of the Colorado Front Range. They published the results in the journal Hydrological Processes.

Other authors of the paper are Eve-Lyn Hinckley and Robert Anderson of the University of Colorado-Boulder, Brian Ebel of the U.S. Geological Survey and Rebecca Barnes of Bard College. Hinckley is the lead author.

"The interaction of climate and ecosystems is an example of the critical questions that lie at the interface between scientific disciplines," says Roger Wakimoto, NSF assistant director for Geosciences. "The results from this study will greatly improve our understanding of the hydrologic cycle."

The research, conducted in the headwaters of the Rockies, shows that higher temperatures are shifting the timing of maximum snow accumulation ever-earlier and decreasing the ratio of snow-to-rain.

"It's raining a heck of a lot more than it used to," says Williams. "In times past, it did nothing but snow."

A flash-in-the-pan, rain is gone more quickly than snow. Within hours of falling, it evaporates or seeps into the ground, and doesn't have snow's longer residence time on mountainsides.

"The slow melt of mountain snow is what keeps streams and rivers running like spigots turned on," says Williams. "Eventually, they lead right to the taps in our kitchens, bathrooms and yards."

Where, exactly, does the white gold come from?

As scientists at Niwot Ridge and Boulder Creek have discovered, the mother lode is hidden in snow "water towers."

"Water towers" for the Mountain West--and beyond

Mountain ecosystems serve as "water towers" that store winter snow until it's released during spring runoff.

The water towers, however, have sprung leaks.

Subalpine forests are becoming warmer and drier during all seasons. At higher elevations, alpine tundra has longer growing seasons, warmer summers and cool and wet versus cold and snowy winters.

How long a snowpack lasts is affected by what scientists call aspect: whether a hillslope faces north or south.

In the Rockies, lodgepole pines, which prefer colder, wetter climes, dot north-facing slopes; Ponderosa pines cover south-facing, drier slopes.

"You can pretty well guess how much snow a slope will have by which way it faces," says Williams, "and by which tree species grows there."

A tale of two trees

Lodgepole pine-covered, north-facing slopes are usually laden with snow straight through the winter. South-facing slopes, with their Ponderosa pines, have only intermittent snow.

"North- and south-facing slopes at the Boulder Creek CZO are an excellent natural laboratory for studying the effects of climate change on water availability and soil geochemistry," says Enriqueta Barrera, NSF program director for the CZO network, supported by the agency's Directorate for Geosciences.

Williams agrees. "North-facing slopes store more water in the 'near-surface' than south-facing slopes," he says. "On south-facing slopes, water sinks quickly into the deep bedrock."

Earlier snowmelt may be changing those patterns, "which could have consequences for the health and composition of the forest," Williams says, and for water resources.

"Research at sites such as the Niwot Ridge LTER shows how catastrophic large-scale shifts in snowmelt will be," says Saran Twombly, NSF program director for the LTER network.

Lack of snow, for example, led to forest fires like Colorado's High Park Fire of June, 2012, and Waldo Canyon Fire less than a month later. The Waldo Canyon Fire was the most expensive wildfire in Colorado history. It was also the most destructive.

"White blizzard" falling

It's April 8, 2013: date of the average peak snowpack in the Colorado mountains. Despite this winter's snow drought, the day, perhaps, of a good omen.

"Heavy snow will blanket much of the west," intoned weather forecasters. Blizzard watches went up. Snowplows, fallow too long, once again geared down.

When all was said and done, more than a foot of snow fell across high peaks and low prairies.

It sparkled across the land, until spring sunlight turned it into a precious commodity: white gold.

SCIENTISTS FIND REDUCTIONS IN FOUR POLLUTANTS CAN SLOW SEA LEVEL RISE

Black carbon, a short-lived pollutant (shown in purple), shrouds the globe.
Credit-NOAA

FROM: NATIONAL SCIENCE FOUNDATION
Cutting Specific Atmospheric Pollutants Would Slow Sea Level Rise
With coastal areas bracing for rising sea levels, new research indicates that cutting emissions of certain pollutants can greatly slow sea level rise this century.

Scientists found that reductions in four pollutants that cycle comparatively quickly through the atmosphere could temporarily forestall the rate of sea level rise by roughly 25 to 50 percent.

The researchers focused on emissions of four heat-trapping pollutants: methane, tropospheric ozone, hydrofluorocarbons and black carbon.

These gases and particles last anywhere from a week to a decade in the atmosphere and can influence climate more quickly than carbon dioxide, which persists in the atmosphere for centuries.

"To avoid potentially dangerous sea level rise, we could cut emissions of short-lived pollutants even if we cannot immediately cut carbon dioxide emissions," says Aixue Hu of the National Center for Atmospheric Research (NCAR) in Boulder, Colo., first author of a paper published today in the journal Nature Climate Change.

"Society can significantly reduce the threat to coastal cities if it moves quickly on a handful of pollutants."

The research was funded by the National Science Foundation (NSF) and the U.S. Department of Energy.

"Sea level rise and its consequences present enormous challenges to modern society," says Anjuli Bamzai, program director in NSF's Division of Atmospheric and Geospace Sciences, which supported the research.

"This study looks at projections of global sea level rise, unraveling the effects of mitigating short-lived greenhouse gases such as methane, tropospheric ozone, hydrofluorocarbons and black carbon, as well as long-lived greenhouse gases like carbon dioxide," says Bamzai.

It is still not too late, "by stabilizing carbon dioxide concentrations in the atmosphere and reducing emissions of shorter-lived pollutants, to lower the rate of warming and reduce sea level rise by 30 percent," says atmospheric scientist Veerabhadran Ramanathan of the Scripps Institution of Oceanography (SIO) in San Diego, a co-author of the paper. Ramanathan initiated and helped oversee the study.

"The large role of the shorter-lived pollutants is encouraging since technologies are available to drastically cut their emissions," says Ramanathan.

The potential effects of rising oceans on populated areas are of great concern, he says.

Many of the world's major cities, such as New York, Miami, Amsterdam, Mumbai, and Tokyo, are located in low-lying areas along coasts.

As glaciers and ice sheets melt, and warming oceans expand, sea levels have been rising by an average of about 3 millimeters annually in recent years (just over one-tenth of an inch).

If temperatures continue to warm, sea levels are projected to rise between 18 and 200 centimeters (between 7 inches and 6 feet) this century, according to reports by the Intergovernmental Panel on Climate Change and the U.S. National Research Council.

Such an increase could submerge coastal communities, especially when storm surges hit.

Previous research by Ramanathan and Yangyang Xu of SIO, a co-author of the paper, showed that a sharp reduction in emissions of shorter-lived pollutants beginning in 2015 could offset warming temperatures by up to 50 percent by 2050.

Applying those emission reductions to sea level rise, the researchers found that the cuts could dramatically slow rising sea levels.

The results showed that total sea level rise would be reduced by an estimated 22 to 42 percent by 2100, depending on the extent to which emissions were cut.

However, the study also found that delaying emissions cuts until 2040 would reduce the beneficial effect on year-2100 sea level rise by about a third.

If society were able to substantially reduce both emissions of carbon dioxide as well as the four other pollutants, total sea level rise would be lessened by at least 30 percent by 2100, the researchers conclude.

"We still have some control over the amount of sea level rise we are facing," Hu says.

Another paper co-author, Claudia Tebaldi of Climate Central, adds: "Without diminishing the importance of reducing carbon dioxide emissions in the long-term, this study shows that more immediate gains from shorter-lived pollutants are substantial.

"Cutting emissions of those gases could give coastal communities more time to prepare for rising sea levels," says Tebaldi. "As we have seen recently, storm surges in populated regions of the East Coast show the importance of making such preparations and cutting greenhouse gases."

To conduct the study, Hu and colleagues turned to the NCAR-based Community Climate System Model, as well as a second computer model that simulates climate, carbon and geochemistry.

They also drew on estimates of future emissions of heat-trapping gases under various social and economic scenarios and on computer models of melting ice and sea level rise.

The study assumes that society could reduce emissions of the four gases and particles by 30-60 percent over the next several decades.

That is the steepest reduction believed achievable by economists who have studied the issue at Austria's International Institute for Applied Systems Analysis, one of the world's leading research centers into the effects of economic activity on climate change.

"It must be remembered that carbon dioxide is still the most important factor in sea level rise over the long-term," says NCAR scientist Warren Washington, a paper co-author. "But we can make a real difference in the next several decades by reducing other emissions."

-NSF-

THE GREENING OF THE ARTIC

Photo:  Melting Artic Ice.  Credit:  NOAA

FROM: NATIONAL SCIENCE FOUNDATION
New Models Predict Dramatically Greener Arctic in the Coming Decades

Rising temperatures will lead to a massive "greening" of the Arctic by mid-century, as a result of marked increases in plant cover, according to research supported by the National Science Foundation (NSF) as part of its International Polar Year (IPY) portfolio.

The greening not only will have effects on plant life, the researchers noted, but also on the wildlife that depends on vegetation for cover. The greening could also have a multiplier effect on warming, as dark vegetation absorbs more solar radiation than ice, which reflects sunlight.

In a paper published March 31 in Nature Climate Change, scientists reveal new models projecting that wooded areas in the Arctic could increase by as much as 50 percent over the coming decades. The researchers also show that this dramatic greening will accelerate climate warming at a rate greater than previously expected.

"Such widespread redistribution of Arctic vegetation would have impacts that reverberate through the global ecosystem," said Richard Pearson, lead author on the paper and a research scientist at the American Museum of Natural History's Center for Biodiversity and Conservation.

In addition to Pearson, the research team includes other scientists from the museum, as well as from AT&T Labs-Research, Woods Hole Research Center, Colgate and Cornell universities, and the University of York.

The research was funded by two related, collaborative NSF IPY grants, one made to the museum and one to the Woods Hole Researc Center.

IPY was a two-year, global campaign of research in the Arctic and Antarctic that fielded scientists from more than 60 nations in the period 2007-2009. The IPY lasted two years to insure a full year of observations at both poles, where extreme cold and darkness preclude research for much of the year. NSF was the lead U.S. government agency for IPY.

Although the IPY fieldwork has been largely accomplished "in addition to the intensive field efforts undertaken during the IPY, projects such as this one work to understand IPY and other data in a longer-term context, broadening the impact of any given data set," said Hedy Edmonds, Arctic Natural Sciences program director in the Division of Polar Programs of NSF's Geosciences Directorate.

Plant growth in Arctic ecosystems has increased over the past few decades, a trend that coincides with increases in temperatures, which are rising at about twice the global rate.

The research team used climate scenarios for the 2050s to explore how the greening trend is likely to continue in the future. The scientists developed models that statistically predict the types of plants that could grow under certain temperatures and precipitation. Although it comes with some uncertainty, this type of modeling is a robust way to study the Arctic because the harsh climate limits the range of plants that can grow, making this system simpler to model compared to other regions, such as the tropics.

The models reveal the potential for massive redistribution of vegetation across the Arctic under future climate, with about half of all vegetation switching to a different class and a massive increase in tree cover. What might this look like? In Siberia, for instance, trees could grow hundreds of miles north of the present tree line.

These impacts would extend far beyond the Arctic region, according to Pearson.

For example, some species of birds migrate from lower latitudes seasonally, and rely on finding particular polar habitats, such as open space for ground-nesting.

The computer modeling for the project was supported by a separate NSF grant to Cornell by the Division of Computer and Network Systems in NSF's Directorate for Computer & Information Science & Engineering, as part of the directorate's Expeditions in Computing program.

"The Expeditions grant has enabled us to develop sophisticated probabilistic models that can scale up to continent-wide vegetation prediction and provide associated uncertainty estimates. This is a great example of the transformative research happening within the new field of Computational Sustainability," said Carla P. Gomes, principal investigator at Cornell.

In addition to the first-order impacts of changes in vegetation, the researchers investigated the multiple climate-change feedbacks that greening would produce.

They found that a phenomenon called the albedo effect, based on the reflectivity of the Earth's surface, would have the greatest impact on the Arctic's climate. When the sun hits snow, most of the radiation is reflected back to space. But when it hits an area that's "dark," or covered in trees or shrubs, more sunlight is absorbed in the area and temperature increases. This has a positive feedback to climate warming: the more vegetation there is, the more warming will occur.

"By incorporating observed relationships between plants and albedo, we show that vegetation distribution shifts will result in an overall positive feedback to climate that is likely to cause greater warming than has previously been predicted," said co-author and NSF grantee Scott Goetz, of the Woods Hole Research Center.

-NSF-

THE LAST "HOT SPELL" ON EARTH

Former dwellers in Pliocene seas: fossil coral found on modern-day Cyprus.

FROM: NATIONAL SCIENCE FOUNDATION

In Last Great Age of Warmth, Carbon Dioxide at Work...But Not Alone
Temperature patterns during Earth's last prolonged global "hot spell"--the Pliocene, some 5.3 to 2.6 million years ago--differed dramatically from those of modern times, according to results reported in this week's issue of the journal Nature.

Cloud feedbacks, ocean mixing and other factors must have played a greater role in Pliocene warming than previously recognized, and these must be accounted for to make meaningful predictions of Earth's future climate, the scientists said.

"This study shows that no one mechanism can explain all the observations," says Candace Major, a program director in the National Science Foundation's (NSF) Division of Ocean Sciences, which funded the research.

The data come from studies of the geochemistry of microfossils (microscopic shells of tiny plankton) preserved in deep-sea sediments.

The sediments were retrieved by researchers affiliated with the Deep Sea Drilling Project, the later Ocean Drilling Program and the current Integrated Ocean Drilling Program--all supported by NSF.

Yale University climate scientist Alexey Fedorov and colleagues compiled records of sea surface temperatures going back five million years, to the early Pliocene.

The records reveal a world with fairly uniform warm temperatures in the Tropics before four million years ago--a scenario that typical climate model simulations fail to show.

"If we want to understand our future climate, we have to be able to understand the climate of the past," said Fedorov, an author of this week's paper.

"The Pliocene Epoch attracts particular attention because of similar carbon dioxide levels to what we have had over the last few decades, but its climate was markedly different in several important ways," he said.

"If we're able to simulate early Pliocene climate, however, we will be more confident in our ability to predict future climate change."

Warm and temperate, the Pliocene is widely viewed as a potential analog for a future hot Earth.

Using chemical fingerprints in ocean sediments to estimate sea surface temperatures, the researchers describe long-term climate trends from the early Pliocene to the present, comparing that ancient climate with today's.

The Pliocene Earth had the same maximum temperature as today, and a similar concentration of atmospheric carbon dioxide, but waters in the Tropics--off the coast of Peru, for example--were much warmer than they are now, resembling modern El Niño conditions.

There was little to no east-to-west temperature variation along the equator. Temperature differences between high latitudes and the Tropics were also much smaller.

Kira Lawrence of Lafayette College, also an author of the paper, said that "we have been focused on changes in the global mean temperature. What our study demonstrates is the potential for climate patterns to be markedly different in a world that is not that much warmer than today's."

Previous attempts to explain Pliocene climate have emphasized tectonic changes in Indonesia and Central America.

But accounting for this in climate models still results in a conflict with actual temperature patterns.

The scientists have proposed several factors to explain warm temperatures during the Pliocene.

They include ocean mixing in subtropical waters, perhaps due to widespread hurricanes and diminished cloud reflectivity, maybe a result of a different aerosol composition. Both would tend to warm the ocean.

When combined in models with higher levels of carbon dioxide, they help replicate conditions of the warm Pliocene Earth.

But so far these factors have not been included in climate models used to make future projections, the researchers said.

A better understanding of what drove Pliocene climate, with its nearly uniform tropical ocean temperatures, will increase our confidence in the models, said Fedorov.

"We can't discount a possible future that has a vast pool of warm water covering the tropics, and the changes in atmospheric circulation and rainfall that would go along with that," said paper author Chris Brierley of the University College London.

Other authors include Zhonghui Liu of the University of Hong Kong, Petra Dekens of San Francisco State University and Christina Ravelo of University of California, Santa Cruz.

In addition to NSF, the research was supported by the U.S. Department of Energy, the David and Lucile Packard Foundation and Yale University.

-NSF-

THE ALGAE BLOOM OF DOOM

Lake Erie , Photo by Lynn Betts, USDA/Wikipedia Commons

FROM: NATIONAL SCIENCE FOUNDATION
Exxtreme Algae Blooms: The New Normal?
A 2011 record-breaking algae bloom in Lake Erie was triggered by long-term agricultural practices coupled with extreme precipitation, followed by weak lake circulation and warm temperatures, scientists have discovered.

The researchers also predict that, unless agricultural policies change, the lake will continue to experience extreme blooms.

"The factors that led to this explosion of algal blooms are all related to humans and our interaction with the environment," says Bruce Hamilton, program director at the National Science Foundation (NSF), which funded the research through its Water, Sustainability and Climate (WSC) Program.

WSC is part of NSF's Science, Engineering and Education for Sustainability (SEES) initiative.

"Population growth, changes in agricultural practices and climate change are all part of the equation," says Hamilton. "These findings show us where we need to focus our attention in the future."

Results of the research are published in this week's online early edition of the journal Proceedings of the National Academy of Sciences (PNAS).

Algae overtakes a lake in Iowa.  Credit:  Wikimedia Commons.

"The 'perfect storm' of weather events and agricultural practices that occurred in 2011 is unfortunately consistent with ongoing trends," says Anna Michalak, the paper's lead author and a scientist at the Carnegie Institution for Science's Department of Global Ecology, located at Stanford University.

"That means that more huge algal blooms can be expected in the future, unless a scientifically-guided management plan is implemented for the region."

Freshwater algal blooms may result when high amounts of phosphorus and nitrogen are added to the water, usually as runoff from fertilizer.

These excess nutrients encourage unusual growth of algae and aquatic plants.

When the plants and algae die, decomposers in the water that feed on them use up oxygen, which can drop to levels too low for aquatic life to thrive.

At first the Lake Erie algae were almost entirely Microcystis, an organism that produces a liver toxin and can cause skin irritation.

The scientists combined sampling and satellite-based observations of the lake with computer simulations to track the bloom.

It began in the lake's Western region in mid-July and covered an area of 230 square miles.

At its peak in October, the bloom had expanded to more than 1,930 square miles. Its peak intensity was more than three times greater than any other bloom on record.

The researchers looked at numerous factors that could have contributed to the bloom, including land-use, agricultural practices, runoff, wind, temperature, precipitation and circulation.

They found that three agriculture management practices in the area can lead to increased nutrient runoff: autumn fertilization, broadcast fertilization (uniform distribution of fertilizer over the whole cropped field), and reduced tillage.

These practices have increased in the region over the last decade.

Conditions in the fall of 2010 were ideal for harvesting and preparing fields and increasing fertilizer application for spring planting.

A series of strong storms the following spring caused large amounts of phosphorus to flow into the lake.

In May alone rainfall was more than 6.5 inches, a level more than 75 percent above the prior 20-year average for the month.

This onslaught resulted in one of the largest spring phosphorus loads since 1975, when intensive monitoring began.

Lake Erie was not unusually calm and warm before the bloom. But after the bloom began, warmer water and weaker currents encouraged a more productive bloom than in prior years.

The longer period of weak circulation and warmer temperatures helped incubate the bloom and allowed the Microcystis to remain near the top of the water column. That had the added effect of preventing the nutrients from being flushed out of the system.

The researchers' data did not support the idea that land-use and crop choices contributed to the increase in nutrient run-off that fueled the bloom.

To determine the likelihood of future mega-blooms, the scientists analyzed climate model simulations under both past and future climate conditions.

They found that severe storms become more likely in the future, with a 50 percent increase in the frequency of precipitation events of .80 inch or more of rain.

Stronger storms, with greater than 1.2 inch of rain, could be twice as frequent.

The researchers believe that future calm conditions with weak lake circulation after a bloom's onset are also likely to continue, since current trends show decreasing wind speeds across the United States.

That would result in longer-lasting blooms and decreased mixing in the water column.

"Although future strong storms may be part of the new normal," says Michalak, "better management practices could be implemented to provide some relief to the problem."

The research was also supported by the NOAA Center for Sponsored Coastal Ocean Research and the Lake Erie Protection Fund.

-NSF-

THE WHITE HOUSE PUSHES BRAIN RESEARCH WITH NATIONAL SCIENCE FOUNDATION

FROM: NATIONAL SCIENCE FOUNDATION
National Science Foundation Participates in White House Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative
April 2, 2013

President Obama today announced that the National Science Foundation (NSF) will participate in a White House initiative called Brain Research through Advancing Innovative Neurotechnologies (BRAIN), which is designed to revolutionize our understanding of the human brain. NSF Acting Director Cora Marrett took part in the announcement at the White House, which also included the National Institutes of Health and the Defense Advanced Research Projects Agency, as well as private sector representatives.

"NSF is ideally positioned to support the BRAIN Initiative because of the broad scope of science and engineering research funding we provide to the nation," Marrett said. "NSF's neuroscience and cognitive science research portfolio is expansive, and this initiative enhances efforts that are already underway to explore neurological connections from the cellular to human behavioral levels."

NSF intends to support approximately $20 million in research that will advance this $100 million, 10-year initiative. The Foundation's contributions will include research into the development of molecular-scale probes that can sense and record the activity of neural networks; advances in "Big Data" that are necessary to analyze the huge amounts of information that will be generated; and increased understanding of how thoughts, emotions, actions and memories are represented in the brain.

Some of NSF's current investments in neuroscience research include:
Studies employing species comparative approaches on how the nervous system develops and coordinates complex functions are generating the computational models of neuronal networks that are essential for understanding the emergent properties of the nervous system and how network plasticity influences behavior.
Research on the chemical and physical principles governing the activity of neural systems is leading to mechanistic and predictive models of cellular behavior and to new approaches for understanding system-wide effects of external stimuli such as pharmacological agents and anesthetics, genetic modifiers and the environment.
Principles underlying microelectronics, optics, optobiology and nanosystems provide key platforms for addressing the temporal and spatial characteristics of functional brain mapping.
Converging research in machine learning, big data, computational neuroscience, human-centered computing and informatics is essential for mapping and understanding brain activity on a large scale.
Frameworks that link brain activity patterns to a diverse range of cognitive and behavioral functions carried out in specific ecological, evolutionary, developmental and social contexts are being developed. At the same time social science theory, methods, and approaches are enabling patterns of brain activity be linked to individual behaviors making this knowledge relevant to the human experience.
For more information, go to www.whitehouse.gov/blog.

-NSF-

NSF REPORTS ON ENDANGERED LEMURS' GENOME SEQUENCING

Photo:  Aye-Aye Lemur.  Credit:  Wikimedia Commons.

FROM: NATIONAL SCIENCE FOUNDATION
Endangered Lemurs' Genomes Sequenced
 For the first time, the complete genomes of three populations of aye-ayes--a type of lemur--have been sequenced and analyzed.

The results of the genome-sequence analyses are published this week in the journal Proceedings of the National Academy of Sciences (PNAS).

The research was led by George Perry, an anthropologist and biologist at Penn State University; Webb Miller, a biologist and computer scientist and engineer at Penn State; and Edward Louis of the Henry Doorly Zoo and Aquarium in Omaha, Neb., and Director of the Madagascar Biodiversity Partnership.

The aye-aye--a lemur that is found only on the island of Madagascar in the Indian Ocean--was recently re-classified as "Endangered" by the International Union for the Conservation of Nature.

"The biodiversity of Madagascar is like nowhere else on Earth, with all 88 described lemur species restricted to the island, but with less than 3 percent of its original forest remaining," said Simon Malcomber, program director in the National Science Foundation's (NSF) Division of Environmental Biology, which in part funded the research.

"It's essential to preserve as much of this unique diversity as possible," Malcomber said.

Added Perry, "The aye-aye is one of the world's most unusual and fascinating animals."

"Aye-ayes use continuously growing incisors to gnaw through the bark of dead trees. They have long, thin, flexible middle fingers to extract insect larvae, filling the ecological niche of a woodpecker.

"Aye-ayes are nocturnal, solitary and have very low population densities, making them difficult to study and sample in the wild."

Perry and other scientists are concerned about the long-term viability of aye-ayes as a species, given the loss and fragmentation of forest habitats in Madagascar.

"Aye-aye population densities are very low, and individual aye-ayes have huge home-range requirements," said Perry.

"As forest patches become smaller, there's a risk that there won't be sufficient numbers of aye-ayes in an area to maintain a population over multiple generations.

"We were looking to make use of new genomic-sequencing technologies to characterize patterns of genetic diversity among some of the surviving aye-aye populations, with an eye toward the prioritization of conservation efforts."

The researchers located aye-ayes and collected DNA samples from the animals in three regions of Madagascar: the northern, eastern and western regions.

To discover the extent of the genetic diversity in present-day aye-ayes, the scientists generated the complete genome sequences of 12 individual aye-ayes.

They then analyzed and compared the genomes of the three populations.

They found that, while Eastern and Western aye-ayes are somewhat genetically distinct, aye-ayes in the northern part of the island and those in the east show a more significant genetic distance, suggesting an extensive period during which interbreeding has not occurred between the populations in these regions.

"Our next step was to compare aye-aye genetic diversity to present-day human genetic diversity," said Miller.

"This analysis can help us gauge how long the aye-aye populations have been geographically separated and unable to interbreed."

To make the comparison, the team gathered 12 complete human DNA sequences--the same number as the individually generated aye-aye sequences--from publicly available databases for three distinct human populations: African agriculturalists, individuals of European descent, and Southeast Asian individuals.

Using Galaxy--an open-source, web-based computer platform designed at Penn State for data-intensive biomedical and genetic research--the scientists developed software to compare the two species' genetic distances.

The researchers found that present-day African and European human populations have a smaller amount of genetic distance than that between northern and eastern aye-aye populations, suggesting that the aye-aye populations were separated for a lengthy period of time by geographic barriers.

"We believe that northern aye-ayes have not been able to interbreed with other populations for some time," said Miller. "Although they are separated by a distance of only about 160 miles, high plateaus and major rivers may have made intermingling relatively infrequent."

The results suggest that the separation of the aye-aye populations stretches back longer than 2,300 years, when human settlers first arrived on Madagascar and started burning the aye-ayes' forest habitat and hunting lemurs.

"This work highlights an important region of aye-aye biodiversity in northern Madagascar, and this unique biodiversity is not preserved anywhere except in the wild," said Louis.

"There is tremendous historical loss of habitat in northern Madagascar that's continuing at an unsustainable rate today."

In future research, the scientists would like to sequence the genomes of other lemur species--more than 70 percent of which are considered endangered or critically endangered--as well as aye-ayes from the southern reaches of Madagascar.

In addition to Perry, Miller and Louis, scientists who contributed to the research include Stephan Schuster, Aakrosh Ratan, Oscar Bedoya-Reina and Richard Burhans of Penn State; Runhua Lei of the Henry Doorly Zoo and Aquarium and Steig Johnson of the University of Calgary in Alberta, Canada.

Funding for aye-aye sample collection was provided by Conservation International, the Primate Action Fund and the Margot Marsh Biodiversity Foundation, along with logistical support from the Ahmanson Foundation and the Theodore F. and Claire M. Hubbard Family Foundation.

Additional support came from the National Institutes of Health, the Pennsylvania Department of Health and the College of the Liberal Arts at Penn State University.

-NSF-

NSF REPORTS TRIASSIC VOLCANIC ERUPTIONS CAUSED MASS EXTINCTION

Photo:  Volcanic Killer.  Credit:  NSF

FROM: NATIONAL SCIENCE FOUNDATION
Before Dinosaurs' Era, Volcanic Eruptions Triggered Mass Extinction

More than 200 million years ago, a massive extinction decimated 76 percent of marine and terrestrial species, marking the end of the Triassic period and the onset of the Jurassic.

The event cleared the way for dinosaurs to dominate Earth for the next 135 million years, taking over ecological niches formerly occupied by other marine and terrestrial species.

It's not clear what caused the end-Triassic extinction, although most scientists agree on a likely scenario.

Over a relatively short time period, massive volcanic eruptions from a large region known as the Central Atlantic Magmatic Province (CAMP) spewed forth huge amounts of lava and gas, including carbon dioxide, sulfur and methane.

This sudden release of gases into the atmosphere may have created intense global warming, and acidification of the oceans, which ultimately killed off thousands of plant and animal species.

Now, researchers at MIT, Columbia University and other institutions have determined that these eruptions occurred precisely when the extinction began, providing strong evidence that volcanic activity did indeed trigger the end-Triassic extinction.

Results of the research, funded by the National Science Foundation (NSF), are published this week in the journal Science.

"These scientists have come close to confirming something we had only guessed at: that the mass extinction of this ancient time was indeed related to a series of volcanic eruptions," says Lisa Boush, program director in NSF's Division of Earth Sciences.

"The effort is also the result of the EARTHTIME initiative, an NSF-sponsored project that's developing an improved geologic time scale for scientists to interpret Earth's history."

The scientists determined the age of basaltic lavas and other features found along the East Coast of the United States, as well as in Morocco--now-disparate regions that, 200 million years ago, were part of the supercontinent Pangaea.

The rift that ultimately separated these landmasses was also the site of CAMP's volcanic activity.

Today, the geology of both regions includes igneous rocks from the CAMP eruptions as well as sedimentary rocks that accumulated in an enormous lake. The researchers used a combination of techniques to date the rocks and to pinpoint CAMP's beginning and duration.

From its measurements, they reconstructed the region's volcanic activity 201 million years ago, discovering that the eruption of magma--along with carbon dioxide, sulfur and methane--occurred in repeated bursts over a period of 40,000 years, a short span in geologic time.

"This extinction happened at a geological instant in time," says Sam Bowring, a geologist at MIT. "There's no question the extinction occurred at the same time as the first eruption."

In addition to Bowring, the paper's co-authors are Terrence Blackburn and Noah McLean of MIT; Paul Olsen and Dennis Kent of Columbia; John Puffer of Rutgers University; Greg McHone, an independent researcher from New Brunswick, N.J.; E. Troy Rasbury of Stony Brook University; and Mohammed Et-Touhami of the Université Mohammed Premier (Mohammed Premier University) Oujda, Morocco.

Blackburn is the paper's lead author.

More than a coincidence

The end-Triassic extinction is one of five major mass extinctions in the last 540 million years of Earth's history.

For several of these events, scientists have noted that large igneous provinces, which provide evidence of widespread volcanic activity, arose at about the same time.

But, as Bowring points out, "just because they happen to approximately coincide doesn't mean there's cause and effect."

For example, while massive lava flows overlapped with the extinction that wiped out the dinosaurs, scientists have linked that extinction to an asteroid collision.

"If you want to make the case that an eruption caused an extinction, you have to be able to show at the highest possible precision that the eruption and the extinction occurred at exactly the same time," Bowring says.

For the time of the end-Triassic, Bowring says that researchers have dated volcanic activity to right around the time fossils disappear from the geologic record, providing evidence that CAMP may have triggered the extinction.

But these estimates have a margin of error of one to two million years. "A million years is forever when you're trying to make that link," Bowring says.

For example, it's thought that CAMP emitted a total of more than two million cubic kilometers of lava.

If that amount of lava were spewed over a period of one to two million years, it wouldn't have the same effect as if it were emitted over tens of thousands of years.

"The timescale over which the eruption occurred has a big effect," Bowring says.

Tilting toward extinction

To determine how long the volcanic eruptions lasted, the group combined two dating techniques: astrochronology and geochronology.

The former is a technique that links sedimentary layers in rocks to changes in the tilt of the Earth.

For decades, scientists have observed that the Earth's orientation changes in regular cycles as a result of gravitational forces exerted by neighboring planets.

The Earth's axis tilts at regular cycles, returning to its original tilt every 26,000 years. Such orbital variations change the amount of solar radiation reaching the Earth's surface, which in turn has an effect on the planet's climate, known as Milankovich cycles.

This cyclical change in climate can be seen in the types of sediments deposited in the Earth's crust.

Scientists can determine a rock's age by first identifying cyclical variations in deposition of sediments in quiet bodies of water, such as deep oceans or large lakes.

A cycle of sediment corresponds with a cycle of the Earth's tilt, established as a known period of years.

By seeing where a rock lies in those sedimentary layers, scientists can get a good idea of how old it is. To obtain precise estimates, researchers have developed mathematical models to determine the Earth's tilt over millions of years.

Bowring says the technique is good for directly dating rocks up to 35 million years old, but beyond that, it's unclear how reliable the technique is.

He and colleagues used astrochronology to estimate the age of the sedimentary rocks, then tested those estimates against high-precision dates from 200-million-year-old rocks in North America and Morocco.

The geologists broke apart rock samples to isolate tiny crystals known as zircons, which they analyzed to determine the ratio of uranium to lead.

The technique enabled the team to date the rocks to within approximately 30,000 years--a precise measurement in geologic terms.

Taken together, the geochronology and astrochronology techniques gave the geologists precise estimates for the onset of volcanism 200 million years ago.

The techniques revealed three bursts of magmatic activity over 40,000 years--a short period of time during which massive amounts of carbon dioxide and other gas emissions may have drastically altered Earth's climate.

While the evidence is the strongest thus far for linking volcanic activity with the end-Triassic extinction, Bowring says that more work can be done.

"The CAMP province extends from Nova Scotia all the way to Brazil and West Africa," he says. "I'm dying to know whether those are exactly the same age."

-NSF-

RESEARCHERS STUDY BLUE MUSSELS AND OCEAN ACIDIFICATION

Photo:  Mussel.  Credit:  Wikimedia Commons

FROM: NATIONAL SCIENCE FOUNDATION
Blue Mussels 'Hang On' Along Rocky Shores: For How Long?

Imagine trying to pitch a tent in a stiff wind. You just have it secured, when a gale lifts the tent--stakes and all--and carries it away.

That's exactly what's happening to a species that's ubiquitous along the rocky shores of both the U.S. West and East Coasts: the blue mussel.

Mussels make use of what are called byssal threads--strong, silky fibers--to attach to rocks, pilings and other hard substrates. They produce the threads using byssus glands in their feet.

Now, scientists have discovered, the effects of ocean acidification are turning byssal threads into flimsy shadows of their former selves, leaving mussels tossed about by wind and waves.

At high levels of atmospheric carbon dioxide--levels in line with expected concentrations over the next century--byssal threads become weaker, less able to stretch and less able to attach to rocks, found scientists Emily Carrington, Michael O'Donnell and Matthew George of the University of Washington.

The researchers recently published their results in the journal Nature Climate Change; O'Donnell is the lead author.

Oceans turning caustic

The pH of the seas in which these and other marine species dwell is declining. The waters are turning more acidic (pH dropping) as Earth's oceans change in response to increased carbon dioxide in the atmosphere.

As atmospheric carbon rises as a result of human-caused carbon dioxide emissions, carbon in the ocean goes up in tandem, ultimately resulting in ocean acidification, scientists have found.

To study the effects of ocean acidification on marine organisms, Carrington has been awarded an NSF SEES (Science, Engineering, and Education for Sustainability) Ocean Acidification grant.

"We need to understand the chemistry of ocean acidification and its interplay with other marine processes--while Earth's seas are still hospitable to life as we know it," says David Garrison, program director in NSF's Division of Ocean Sciences. "In the rocky intertidal zone, blue mussels are at the heart of those processes."

Land between the tides

Visit the land between the tides, and you'll see waves crashing on boulders tinged dusky blue by snapped-closed mussels.

"Their shells are a soft color, the misty blue of distant mountain ranges," wrote Rachel Carson more than 50 years ago in her best-selling book The Edge of the Sea.

For blue mussels trying to survive, the rocky intertidal zone indeed may be akin to scaling a mountain range.

The rocky intertidal is above the waterline at low tide and underwater at high tide--the area between tide marks.

It's home to such animals as starfish and sea urchins, and seaweed such as kelp. All make a living from what floats by rocky cliffs and boulders.

It can be a hard go. Rocky intertidal species must adapt to an environment of harsh extremes. Water is available when the tide washes in; otherwise residents of this no man's land between sea and shore are wide open to the elements.

Waves can dislodge them, and temperatures can run from scalding hot to freezing cold.

Hanging on for dear life

In the rocky intertidal, blue mussels hang on for dear life.

That may not always be the case.

Combining results from laboratory experiments with those from a mathematical model, Carrington and colleagues show that at high carbon dioxide concentrations, blue mussels can be dislodged by wind and wave forces 40 percent lower than what they are able to withstand today.

Mussels with this weakened ability, once dislodged from their homes, could cause ecological shifts in the rocky intertidal zone--and huge economic losses in a global blue mussel aquaculture industry valued at U.S. $1.5 billion each year.

"Mussels are among the most important species on rocky shores worldwide," says O'Donnell, "dominating ecosystems wherever they live. The properties in their byssal threads are also of interest to biochemists and have been studied as possible medical adhesives."

Blue mussels may make important contributions to the field of materials science, says Carrington.

"Some species of mussels are experts at gluing onto seagrass, some to other shells, some even adhere to rocks in the harsh conditions of deep-sea hydrothermal vents. Each may have different genes that code for different proteins, so the adhesives vary."

Will their potential be realized? Carrington, O'Donnell and George have found a disturbing answer.

The scientists allowed mussels to secrete byssal threads in a range of ocean water chemistries from present-day through predicted near-future conditions, then tested the threads to see how strong they were.

At levels considered reasonable for a near-future coastal ocean (given current rates of acidification), byssal threads were less able to stretch and therefore less able to adhere. Further testing revealed that the problem was caused by weakening of the glue where the threads attach to rocks and other hard surfaces.

Ocean acidification beyond shells and corals

"Much ocean acidification research has focused on the process of calcification," says Carrington, "through which animals and some plants make hard parts such as shells."

In acidifying oceans, marine species that depend on calcium carbonate have a more difficult time forming shells or, in the case of coral reefs, skeletons.

"But there's more to marine communities than calcified parts," says O'Donnell. Other species such as mussels and their byssal threads, he says, are equally important.

"Understanding the broader consequences of ocean acidification requires looking at a variety of biological processes in a range of species."

A need that didn't exist when Rachel Carson wrote The Edge of the Sea.

"When we go down to the low-tide line, we enter a world that is as old as the Earth itself--the primeval meeting place," mused Carson, "of the elements of earth and water."

And of mussels and rock. Fifty years hence, will the mussels still be here?