FERTILIZERS AND GREENHOUSE GAS

A Growing Summer Squash Plant

FROM:  NATIONAL SCIENCE FOUNDATION  

How much fertilizer is too much for Earth's climate?

Helping farmers around the globe combat greenhouse gas emissions and climate change

Helping farmers around the globe apply more precise amounts of fertilizer nitrogen can combat climate change.

That's the conclusion of a study published this week in the journal Proceedings of the National Academy of Sciences. In the paper, researchers at Michigan State University (MSU) provide an improved prediction of nitrogen fertilizer's contribution to greenhouse gas emissions from agricultural fields.

The study uses data from around the world to show that emissions of nitrous oxide (N2O), a greenhouse gas produced in soil following nitrogen addition, rise faster than previously expected when fertilizer rates exceed crop needs.

Nitrogen-based fertilizers spur greenhouse gas emissions by stimulating microbes in the soil to produce more nitrous oxide.

Nitrous oxide is the third most important greenhouse gas, behind carbon dioxide and methane.

Agriculture accounts for about 80 percent of human-caused nitrous oxide emissions worldwide, which have increased substantially in recent years due to increased nitrogen fertilizer use.

"Our motivation is to learn where to best target agricultural efforts to slow global warming," says MSU scientist Phil Robertson. Robertson is also director of the National Science Foundation (NSF) Kellogg Biological Station Long-term Ecological Research (LTER) site, one of 25 such NSF LTER sites around the globe, and senior author of the paper.

"Agriculture accounts for 8 to 14 percent of all greenhouse gas production globally. We're showing how farmers can help reduce this number by applying nitrogen fertilizer more precisely."

The production of nitrous oxide can be greatly reduced if the amount of fertilizer needed by crops is exactly the amount that's applied to farmers' fields.

When plants' nitrogen needs are matched with the nitrogen that's supplied, fertilizer has substantially less effect on greenhouse gas emissions, Robertson says.

"These results vastly improve the ability of research to inform climate change, food security and the economic health of the world's farmers," says Saran Twombly, a program director in NSF's Division of Environmental Biology, which funded the research through the LTER Program.

Lead author and MSU researcher Iurii Shcherbak notes that the research is especially applicable to fertilizer practices in under-fertilized areas such as sub-Saharan Africa.

"Because nitrous oxide emissions won't be accelerated by fertilizers until crops' nitrogen needs are met, more nitrogen fertilizer can be added to under-fertilized crops without much affecting emissions," says Shcherbak.

Adding less nitrogen to over-fertilized crops elsewhere, however, would deliver major reductions to greenhouse gas emissions in those regions.

The study provides support for expanding the use of carbon credits to pay farmers for better fertilizer management and offers a framework for using this credit system around the world.

Carbon credits for fertilizer management are now available to U.S. corn farmers, says Robertson.

The research was also funded by MSU, the U.S. Department of Energy's Great Lakes Bioenergy Research Center and the Electric Power Research Institute.

-- Cheryl Dybas, NSF
-- Layne Cameron, MSU
Investigators
Douglas Landis
Thomas Schmidt
Katherine Gross
Stephen Hamilton
G. Philip Robertson

WASTE METHANE MADE INTO BIODEGRADABLE PLASTIC BY SCIENTISTS

FROM:  NATIONAL SCIENCE FOUNDATION 

A biodegradable plastic made from waste methane

Scientists are making PHA (a biodegradable polymer similar to the polypropylene used in yogurt containers) from waste methane

What if we could make the Great Pacific Garbage Patch just disappear? What if plastics didn't accumulate in our landfills? What if we could reduce greenhouse gas emissions while replacing up to 30 percent of the world's plastics with a biodegradable substitute?

Researchers have tried for decades to achieve these goals. One approach being taken is the development of an efficient production process for poly-hydroxyalkanoate (PHA)--a biodegradable polymer similar to the polypropylene used to make yogurt containers.

Scientists at Stanford University and a Palo Alto, Calif.-based start-up company called Mango Materials have come up with a new way to make PHA from waste methane gas. And, with funding from the National Science Foundation (NSF), Mango Materials is advancing the process toward commercialization.

PHA is a biodegradable polyester that is produced naturally inside some bacteria under conditions of excess carbon and limited nutrient availability. Processes being developed to make PHA at a commercial scale typically involve bacteria strains that have been genetically modified to boost production and corn-based sugar as the carbon source.

The microorganisms feed on plant-derived sugars and produce PHA. The PHA is then separated from the bacteria and made into pellets that can be molded into plastic products. This approach has several shortcomings: It requires use of agricultural land and other inputs to produce feedstock, and it competes with the food supply.

Mango Materials' process uses bacteria grown in fermenters to transform methane and oxygen, along with added nutrients (to supply excess carbon), into PHA. Eventually, the PHA-rich bacteria--now literally swollen with PHA granules--are removed from the fermenters, and the valuable polymer is separated via proprietary techniques from the rest of the cell mass. The PHA is then rinsed, cleaned, and dried as needed.

After the products made of the PHA have reached the end of their useful life, the plastic can be degraded anaerobically (without air)--to produce methane gas. This closes the loop and provides a fresh feedstock for PHA production.  Because PHA's properties can be tweaked by varying the copolymer content or with additives, Mango Materials has identified a range of applications.

"We are currently focused on applications where biodegradability is key," says Molly Morse, CEO at Mango Materials. "However, we're open to all sorts of applications and are eager to bring PHA bioplastics to market."

This unique approach addresses challenges that have derailed previous attempts at PHA commercialization. Other processes use sugar as a carbon feedstock, whereas Mango Materials uses waste methane--which is considerably less expensive than sugar.

"By using methane gas as the feedstock, we can significantly drive down costs of production," Morse says.

In addition, the process relies on a mixed community of wild bacteria that are obtained through natural selection rather than genetic engineering. Using wild bacteria that are not genetically altered alleviates concerns of some toward genetically modified organisms. And, the use of a mixed community of wild bacteria reduces production costs because it eliminates the need to sterilize equipment.

"This stands in contrast to the processes many biotech companies use that require high-purity, genetically engineered cultures," says Allison Pieja, director of technology at Mango Materials.

As an added environmental benefit, the process sequesters methane, a potent greenhouse gas, and provides an economic incentive for methane capture at facilities such as landfills, wastewater treatment plants and dairy farms. The unused, vented methane from California landfills (based on 2010 data from the Methane to Markets Partnership)--if used as PHA feedstock--would yield more than 100 million pounds per year of plastic. (This estimate is based on Mango Materials' internal calculations using its own rates and yields).

Mango Materials has vetted this technology and achieved excellent yields at the lab scale. Field studies have shown that the methane-consuming cultures grow just as well on waste biogas, which includes contaminants such as sulfides, as on pure methane. Now, the company is setting out to achieve the same yields at a commercial scale. Mango Materials standard commercial plants will be sized to handle the methane produced at an average wastewater treatment plant--enough to produce more than 2 million pounds per year of PHA.

This technology was funded through the NSF Small Business Innovation Research Program.

This article was prepared by NSF for the American Institute of Chemical Engineers and appeared in the February 2014 issue of Chemical Engineering Progress.

Investigators
Molly Morse
Related Institutions/Organizations
Mango Materials

LINKING POLLEN PARTICLES TO CLIMATE CHANGE

FROM:  NATIONAL SCIENCE FOUNDATION

Estimating how pollen particles in the atmosphere influence climate

Researchers study water cycle and cloud formation and design computer algorithm models to understand impact

In the past, many atmospheric scientists believed that pollen particles probably had a negligible effect on climate because they were so big. In recent years, however, as they began to realize that pollen particles were not as sturdy as they once thought, they have been rethinking their old assumptions.

"Pollen can rupture and generate a lot of small, tiny particles," says Allison Steiner, an associate professor of atmospheric, oceanic and space sciences at the University of Michigan. "They can break pretty easily."

Moreover, pollen, the same airborne material that wreaks misery during certain seasons in the form of drippy noses and itchy eyes, apparently can have an influence on weather. When big pollen particles break into fine ones, they can take up water vapor in the air to promote the formation of clouds, potentially altering weather systems as a result. Unlike greenhouse gases, which contribute to warming, these fine particles can have a cooling effect.

This is a process that Steiner wants to learn more about, particularly now, when much of the scientific community is devoting considerable attention to the anthropogenic--or human--causes of climate change.

"The impact of pollen in the atmosphere may change weather and it could change our understanding of the climate system," says the National Science Foundation (NSF)-funded scientist.

"How much is nature contributing?" she adds. "How important will that be in understanding what we will see in the absence of human influences? It's easier to understand the human causes, but these natural aerosols like pollen are something we don't understand very well."

Prior research indicates that when pollen becomes wet, it easily ruptures into very small particles. She wondered whether these small, pollen fragments could, "seed" the creation of clouds.

"If you have water vapor in the atmosphere, it's hard to form droplets all by itself," she explains. "But if you have a little particle already there, it's easy for water to condense on it and grow into a droplet, which enables the formation of cloud droplets.

"Most people think of pollen as being pretty inert in the atmosphere, and it's not," she adds. "It's interacting with the water cycle, and can influence clouds in ways that people hadn't realized before."

She and her team are using ground based observation data obtained from across the nation to design a computer algorithm emissions model. The model includes the different types of pollen, and takes into account various conditions that can have an effect on pollen when it enters the atmosphere, for example, rain.

Furthermore, tiny pollen particles can react with radiation. "The models simulate the ability of pollen particles to interact with incoming solar radiation to understand how these particles will affect climate," she says. By using computer models, she can estimate the effect these particles have on regional climate.

She also has been working in the laboratory of Sarah Brooks, a professor of atmospheric sciences at Texas A&M University, to demonstrate pollen's effect on cloud formation. Using a cloud condensation nuclei chamber, an instrument that can reproduce the atmospheric conditions that form clouds, they were able to demonstrate that pollen can in fact grow and act as cloud droplets.

"This means that pollen could have an impact on climate," says Steiner, who conducted the experiments at Texas A & M in the spring. "One thing we are still trying to figure out is how big that effect actually is."

Steiner is conducting her research under an NSF Faculty Early Career Development (CAREER) award, which she received in 2010. The award supports junior faculty who exemplify the role of teacher-scholars through outstanding research, excellent education, and the integration of education and research within the context of the mission of their organization. NSF is funding her work with $599,940 over five years.

As part of the grant's educational component, she has worked with middle schools and high schools in Detroit and Ypsilanti. Using the sites and numerous hands-on activities will introduce students to hypothesis development, data collection and analysis, and interpretation, and also will help the pollen emissions model development.

She also plans to integrate elements of the pollen project with University of Michigan undergraduate and graduate programs, as well as form a partnership with the International Centre for Theoretical Physics in Trieste, Italy to train scientists from developing nations on the role of biosphere-atmosphere interactions.

Steiner says she is especially gratified by the response of the young middle school students "who find it a real change to have a college professor come into their classroom on a regular basis," she says, adding: "It can be a real challenge to make our research relevant for middle-school students. But the students have asked great questions, and we've developed some novel hands-on activities that have really helped the students to see how fun and exciting scientific research can be."

-- Marlene Cimons, National Science Foundation
Investigators
Allison Steiner
Related Institutions/Organizations
University of Michigan Ann Arbor

STUDY LOOKS AT POSITIVE AFFECTS OF INVASIVE SPECIES ON THE ENDANGERED

FROM:  NATIONAL SCIENCE FOUNDATION 

Eradicating invasive species sometimes threatens endangered ones

Study of California Clapper Rail and salt marsh cordgrass Spartina offers new insights

What should resource managers do when the eradication of an invasive species threatens an endangered one?

In results of a study published this week in the journal Science, researchers at the University of California, Davis, examine one such conundrum now taking place in San Francisco Bay.

The study was led by UC Davis researcher Adam Lampert.

"This work advances a framework for cost-effective management solutions to the conflict between removing invasive species and conserving biodiversity," said Alan Tessier, acting deputy division director in the National Science Foundation's (NSF) Directorate for Biological Sciences, which supported the research through NSF's Dynamics of Coupled Natural and Human Systems (CNH) Program.

CNH is also co-funded by NSF's Directorates for Geosciences and Social, Behavioral & Economic Sciences.

"The project exemplifies the goals of the CNH program," says Tessier, "which are to advance the understanding of complex systems involving humans and nature."

The California Clapper Rail--a bird found only in San Francisco Bay--depends on an invasive salt marsh cordgrass, hybrid Spartina, as nesting habitat.

Its native habitat has slowly vanished over recent decades, largely due to urban development and invasion by Spartina.

Study results show that, rather than moving as fast as possible with eradication and restoration plans, the best approach is to slow down the eradication of the invasive species until restoration or natural recovery of the system provides appropriate habitat for the endangered species.

"Just thinking from a single-species standpoint doesn't work," said paper co-author and UC-Davis environmental scientist Alan Hastings.

"The whole management system needs to take longer, and you need to have much more flexibility in the timing of budget expenditures over a longer time-frame."

The scientists combined biological and economic data on Spartina and on the Clapper Rail to develop a modeling framework to balance conflicting management goals, including endangered species recovery and invasive species restoration, given fiscal limitations.

While more threatened and endangered species are becoming dependent on invasive species for habitat and food, examples of the study's specific conflict are relatively rare--for now.

Another case where the eradication of an invasive species threatened to compromise the recovery of an endangered plant or animal is in the southwestern United States, where an effort to eradicate Tamarisk was cancelled because the invasive tree provides nesting habitat for the endangered Southwestern Willow Flycatcher.

"As eradication programs increase in number, we expect this will be a more common conflict in the future," said paper co-author and UC Davis scientist Ted Grosholz.

Other co-authors include scientists James Sanchirico of UC Davis and Sunny Jardine of the University of Delaware.

-NSF-

Media Contacts
Cheryl Dybas, NSF

SCIENTISTS FIND GOOD NEWS REGARDING MIDWESTERN LAKES

FROM:  NATIONAL SCIENCE FOUNDATION 

Clarity for lake researchers' water quality questions

Studies of trends in Midwestern lakes benefit from help of local residents
Scientists engaged in a study of long-term water quality trends in Midwestern lakes found some good news: little change in water clarity in more than 3,000 lakes.

Look deeper, and the research becomes something more: a chronicle of a new source of data for scientists, data from residents of towns and villages surrounding the lakes.

The results are published in a paper in the journal PLOS ONE.

The paper co-authors analyzed almost a quarter of a million observations taken over seven decades on 3,251 lakes in eight Midwestern states.

Enter local residents

But the researchers didn't collect those data. The observations came from lakefront homeowners, boaters, anglers and other interested members of the public wanting to know more about what's going on in "their" lakes.

Noah Lottig, a co-author of the paper and a scientist at the University of Wisconsin-Madison's Center for Limnology, says that ecologists are looking at big-picture issues--such as how changes in land use or climate affect ecosystems--at state, national and continental scales.

This time, the help of local residents was key to the findings.

"This study highlights research opportunities using data collected by citizens making important environmental measurements," says Elizabeth Blood, program director in the National Science Foundation's (NSF) Directorate for Biological Sciences, which funded the work through its MacroSystems Biology Program. "Their efforts provide scientists with data at space and time scales often not available by other means."

Water clarity from a Secchi disk reading--or tens of thousands of them

Lottig and freshwater scientists from across the United States combed through state agency records and online databases. The water clarity measurements they sought were taken by non-scientists using a circular, plate-sized instrument called a Secchi disk.

Used in the aquatic sciences since the mid-1800s, Secchi disks hang from a rope and are lowered into the water until their distinct black-and-white pattern disappears from view, a distance that marks the "Secchi depth."

Lake associations and other groups have used the disks for decades to document conditions in their respective waters.

Previous studies have shown that local residents' Secchi readings are nearly as accurate as scientists' measurements, says Lottig.

With a dataset covering more than 3,000 lakes and stretching back to the late 1930s, the team decided to ask questions about long-term change.

Before and after the Clean Water Act

The Clean Water Act provided a useful frame of reference. Signed into law in 1972, the act set water quality goals for all U.S. waters.

Thanks to the data collected by residents, Lottig's team had access to water clarity measurements for decades before and after the act came into effect.

Somewhere in that data, the researchers reasoned, they might detect a landscape-scale shift over time to clearer (often an indicator of cleaner) water.

While there was a slight one percent yearly increase in water clarity for the lakes, Lottig says, "most of the lakes are just chugging along, not changing much through time."

While some lakes improved, others did not. Taken as a whole, there was no major change in clarity at the landscape scale.

Lottig is part of the "Cross-Scale Interaction" or "CSI Limnology" project, an effort to collect global data on water chemistry and aquatic biology that will add needed context.

Townspeople weigh in

For Ken Fiske, collecting data has been well worth the effort.

In 1985, Fiske saw an announcement for volunteers for a new Wisconsin lake monitoring program. Fiske had been coming to northern Wisconsin from his home in Illinois for years and had recently bought property on the shoreline of Lake Adelaide.

"My interest was in finding out what the quality of water in Lake Adelaide was and seeing what we could do to maintain it," he says.

For the next several years, Fiske went on a monthly five-hour drive to Lake Adelaide to take measurements. Eventually, he found some neighbors to help. Some 30 years later, the group is still going strong.

"We've been doing it long enough that it makes the results meaningful," Fiske says.

Scientists are harnessing efforts like Fiske's to try to answer questions about not just one lake, but 3,251--or more--of them.

-- Cheryl Dybas, NSF
Investigators
Noah Lottig
Emily Stanley
Related Institutions/Organizations
University of Wisconsin-Madison

SECRETARY KERRY'S REMARKS AT SUMMIT REGARDING OCEANS AND FOOD SECURITY

FROM:  U.S. STATE DEPARTMENT 

Opening Remarks to the Global Oceans Action Summit for Food Security and Blue Growth

Remarks

John Kerry

Secretary of State

The Hague, Netherlands

April 24, 2014

---

Good morning. I’m sorry I can’t be with you in the Netherlands this week, but I’m very pleased to offer a few thoughts from Washington as the Global Oceans Action Summit continues. To start, let me thank all of the Summit’s sponsors for bringing together so many influential people – from so many different sectors – to discuss one of the most complex global challenges we face today: how we sustainably manage our ocean. 

It’s certainly an appropriate week for the Summit to take place. This past Tuesday marked the 45th annual Earth Day. I still remember the very first Earth Day back in 1970, when more than 20 million Americans gathered in parks and schools and auditoriums to demand better care for our natural resources. I actually helped organize the efforts in my homes state of Massachusetts. Well the fact is, it’s impossible to care for our Earth without caring for the ocean that covers nearly three-quarters of it. And if you look at a map, you’ll see that no single country can claim the ocean as its own. It is very clearly our ocean to share and that also means we share the responsibility to act as its steward. 

I know that every one of you at the Summit understands this. And you know how much the ocean means to our economies, our well-being, and our entire way of life on Earth – and that’s true whether you’re talking about a community on the coast or one hundreds of miles from the nearest beach. 

But you also know the extent to which our ocean is in trouble. First, we have record pollution that’s contributing to hundreds of dead zones around the globe where life simply can’t exist. 

Second – yet another deeply troubling part of climate change – our ocean is absorbing enormous amounts of carbon dioxide, which is changing the chemical makeup of the ocean and causing it to acidify and eat away at coral reefs, shellfish, and more. 

And third, today too much money is chasing far too few fish. I spent a lot of time examining this issue as Chairman of the U.S. Senate’s Oceans and Fisheries Subcommittee. To a lot of people, the supply of fish seems endless. But that’s simply not the case at all. Almost one third of the world’s fish stocks are currently overexploited, and most of the others are fished at the absolute maximum levels. That’s the definition of unsustainable. Obviously, this is bad news for the hundreds of millions of families around the world who depend on income from fisheries to feed their children and pay their bills. But it’s also major threat to global food security: More than one billion people rely on fish as their primary source of protein – most of whom live in the poorest, least developed countries, where other protein options are either too limited or too expensive for the average family to buy. 

Addressing all of these challenges won’t be easy. But the good news is, we know what kinds of steps we need to take if we want to honor our responsibility to leave behind a healthy and vibrant ocean for future generations. 

With overfishing, for example, part of the problem is that a huge chunk of seafood caught around the world is obtained in ways that are illegal, unreported, or unregulated. So, one solution would be government policies that only allow seafood into markets if there’s proof that the seafood was captured legally and in a way that you can trace. This would help us to level the playing field for honest fishermen – while at the same time protecting fish stocks around the world. 

Ultimately, what we need is a new global ocean policy agenda. And the kind of clear and comprehensive agenda I’m talking about cannot be developed without the input of governments, the private sector, civil society leaders, and other stakeholders around the world. 

That’s why I’m so grateful that the Global Oceans Action Summit is taking place. And that’s also why on June 16th and 17th, I’m convening a conference here at the State Department. I’m inviting international leaders from all different sectors to help build consensus around ways to better protect our ocean. And we really want as many people as possible to be involved in that effort – we’re going to stream the conference online and include a number of ways for folks to participate via social media. 

Protecting our ocean isn’t only an environmental issue. It’s an economic issue. It’s a global health issue. It’s a food security issue. And above all, it’s a moral responsibility. So I look forward to hearing what comes out of the Global Action Summit and to carrying your ideas forward here at the State Department in June. Thank you very much.

SCIENTIST STUDY GENETIC DIVERSITY IN OCEAN MICROBES

FROM:  NATIONAL SCIENCE FOUNDATION
Octillions of microbes in the seas: Ocean microbes show incredible genetic diversity

In a few drops of seawater, one species, hundreds of subpopulations
The smallest, most abundant marine microbe, Prochlorococcus, is a photosynthetic bacterial species essential to the marine ecosystem.

It's estimated that billions of the single-celled creatures live in the oceans, forming the center of the marine food web.

They occupy a range of ecological niches based on temperature, light, water chemistry and interactions with other species.

But the diversity within this single species remains a puzzle.

To probe this question, scientists at the Massachusetts Institute of Technology (MIT) recently performed a cell-by-cell genomic analysis of a wild population of Prochlorococcus living in a milliliter of ocean water--less than a quarter of a teaspoon--and found hundreds of distinct genetic subpopulations.

Each subpopulation in those few drops of water is characterized by a set of core gene alleles linked to a few associated flexible genes--a combination the scientists call the "genomic backbone."

This backbone gives the subpopulation a finely tuned ability to fill a particular ecological niche.

Diversity also exists within backbone subpopulations; most individual cells in the samples carried at least one set of flexible genes not found in any other cell in its subpopulation.

A report on the research by Sallie Chisholm and Nadav Kashtan at MIT, along with co-authors, appears in this week's issue of the journal Science.

The National Science Foundation (NSF), through its Divisions of Environmental Biology and Ocean Sciences, supported the research.

"In this extraordinary finding on the power of natural selection, the scientists have discovered a mosaic of genetically distinct populations of one of the most abundant organisms on Earth," says George Gilchrist, program director in NSF's Division of Environmental Biology.

"In spite of the constant mixing of the oceans," Gilchrist says, "variations in light, temperature and chemistry create unique habitats that evolution has filled with an enormous diversity of populations over millions of years."

Adds David Garrison, program director in NSF's Division of Ocean Sciences, "The results will change the way marine ecologists think about how planktonic microbes and, in turn, planktonic communities may respond to climate and environmental change."

The scientists estimate that the subpopulations diverged at least a few million years ago.

The backbone is an older, more slowly evolving, component of the genome, while the flexible genes reside in areas of the genome where gene exchange is relatively frequent, facilitating more rapid evolution.

The study also revealed that the relative abundance of the backbone subpopulations changes with the seasons at the study site near Bermuda, adding strength to the argument that each subpopulation is finely tuned for optimal growth under different conditions.

"The sheer enormity of diversity that must be in the octillion Prochlorococcus cells living in the seas is daunting to consider," Chisholm says. "It creates a robust and stable population in the face of environmental instability."

Ocean turbulence also plays a role in the evolution and diversity of Prochlorococcus.

A fluid mechanics model predicts that in typical ocean flow, just-divided daughter cells drift rapidly, placing them centimeters apart from one another in minutes, tens of meters apart in an hour, and kilometers apart in a week's time.

"The interesting question is, 'Why does such a diverse set of subpopulations exist?'" Kashtan says.

"The huge population size of Prochlorococcus suggests that this remarkable diversity and the way it is organized is not random, but is a masterpiece product of natural selection."

Chisholm and Kashtan say the evolutionary and ecological distinction among the subpopulations is probably common in other wild, free-living (not attached to particles or other organisms) bacteria species with large populations and highly mixed habitats.

Other co-authors of the paper are Sara Roggensack, Sébastien Rodrigue, Jessie Thompson, Steven Biller, Allison Coe, Huiming Ding, Roman Stocker and Michael Follows of MIT; Pekka Marttinen of the Helsinki Institute for Information Technology; Rex Malmstrom of the U.S. Department of Energy Joint Genome Institute and Ramunas Stepanauskas of the Bigelow Laboratory for Ocean Sciences.

The NSF Center for Microbial Oceanography, U.S. Department of Energy Genomics Science Program and the Gordon and Betty Moore Foundation Marine Microbiology Initiative also supported the work.

-NSF-

ECOLOGISTS LOOK AT RELATIONSHIP BETWEEN YELLOWSTONE'S WILLOWS AND STREAMS

Photo:  Yellowstone Stream.  From: Wikimedia.

FROM:  NATIONAL SCIENCE FOUNDATION 
Earth Week: Whither Yellowstone's willows and the streams they shade?

Yellowstone's water table dropping below riverbank willow trees
Willows and streams. In Yellowstone, where there's one, the other isn't far behind.

On Earth Week, scientists are asking: How far do such connections reach?

New research on water-dependent willows shows that streams and willows may be conducting the music on Yellowstone's ecological dance floor.

Ecologists Tom Hobbs, Kristin Marshall and David Cooper published the results in a recent issue of the Journal of Ecology. Hobbs and Cooper are with Colorado State University (CSU) in Fort Collins, Marshall is at NOAA.

After wolves were extirpated from Yellowstone almost 100 years ago, elk multiplied, says Hobbs. The herbivores roamed across the landscape, nibbling willows to nubbins.

But the story doesn't end there.

With fewer willows to gnaw on, beavers began to decline. Crucially for willows, without the dams beavers build, which slow the flow of water, streams ran faster. Brooks soon became deeply carved into their banks from the force of rapidly-moving water.

Before long, the water table fell below the reach of streamside willows' roots.

Wolves and elk, beavers and willows: carefully choreographed parts

"All the possible interactions among plants and animals in nature are impossible to separately identify and measure," says Henry Gholz, program director in the National Science Foundation's (NSF) Division of Environmental Biology, which funds the Yellowstone willow research through its Long Term Research in Environmental Biology (LTREB) Program.

"Yet scientists know these links are critical to the maintenance of functional ecosystems."

Over a 30-year-period, Hobbs and colleagues studied riparian willow (Salix spp.) establishment and stem growth. In Yellowstone's northern range, the scientists reconstructed willows' history from tree rings. The three-decade time-frame covered the reintroduction of wolves in 1995.

"What happens to willows is shaped more by how high the water table is," says Hobbs, "than by any other factor."

The finding shows how complicated ecosystem links can be, says Gholz. "The effects of elk browsing on streamside willows in Yellowstone over the past 30 years are related more to variations in year-to-year climate, age of the willow trees, and changes in streams due to declining numbers of beavers."

The scientists used climate variables such as annual precipitation, stream flow and growing season length; the abundance of herbivores (elk); and landscape elevation and an index of "topographic wetness" (how soggy the ground is) to predict willow growth before and after the reintroduction of wolves.

"Explaining variability in [willow] establishment required models with stream flow, annual precipitation and elk abundance," write the ecologists in their paper.

"The results show that changes in the growth of willows after the reintroduction of wolves," says Marshall, "can't be understood without considering all the variables."

Life as a willow: water required

Picture a willow as it leans over a river or stream. Willows, sallows and osiers form the genus Salix, made up of some 400 species of deciduous trees and shrubs. All are found on moist soils in cold and temperate regions of the Northern Hemisphere.

Most are known as willows, but some narrow-leaved shrub species are called osiers, and broader-leaved species are referred to as sallows, from an Old English word derived from the Latin term salix.

Willows are the dominant riparian, or riverside, woody vegetation in Yellowstone and across the Rocky Mountains, according to Hobbs.

In Yellowstone, willows are found along rivers and streams, as well as near springs, seeps and anywhere water is available.

"As long as willows' roots can reach groundwater," says Hobbs, "the trees can survive--and withstand very high levels of browsing by elk. It all comes down to water."

On Earth Week and every week, the dance of life needs all the partners

Restoring an ecologically complete ecosystem in Yellowstone requires the return of willows--and with them, beavers, says Hobbs.

Once willows have returned, beavers will gnaw down a certain number of the trees to build dams. The dams will slow stream flow, allowing yet more willows to grow.

Willows, streams and beavers; wolves and elk. Willows and streams may have the first dance. But without them all, Yellowstone's ecological music will eventually fade away.

-- Cheryl Dybas
Investigators
Fred Watson
David Cooper
Jennifer Hoeting
Matthew Kauffman
N. Thompson Hobbs
Related Institutions/Organizations
Colorado State University

NSF ON ROCKY MOUNTAIN BARK BEETLES AND WATER QUALITY

Photo:  Rocky Mountains. Credit:  Wikimedia, Williams Jim, U.S. Fish and Wildlife Service. 

FROM:  NATIONAL SCIENCE FOUNDATION 

Earth Week: Bark beetles change Rocky Mountain stream flows, affect water quality

What happens when millions of dead trees, killed by beetles, no longer need water?

On Earth Week--and in fact, every week now--trees in mountains across the western United States are dying, thanks to an infestation of bark beetles that reproduce in the trees' inner bark.

Some species of the beetles, such as the mountain pine beetle, attack and kill live trees. Others live in dead, weakened or dying hosts.

In Colorado alone, the mountain pine beetle has caused the deaths of more than 3.4 million acres of pine trees.

What effect do all these dead trees have on stream flow and water quality? Plenty, according to new research findings reported this week.

Dead trees don't drink water

"The unprecedented tree deaths caused by these beetles provided a new approach to estimating the interaction of trees with the water cycle in mountain headwaters like those of the Colorado and Platte Rivers," says hydrologist Reed Maxwell of the Colorado School of Mines.

Maxwell and colleagues have published results of their study of beetle effects on stream flows in this week's issue of the journal Nature Climate Change.

As the trees die, they stop taking up water from the soil, known as transpiration. Transpiration is the process of water movement through a plant and its evaporation from leaves, stems and flowers.

The "unused" water then becomes part of the local groundwater and leads to increased water flows in nearby streams.

The research is funded by the National Science Foundation's (NSF) Water, Sustainability and Climate (WSC) Program. WSC is part of NSF's Science, Engineering and Education for Sustainability initiative.

"Large-scale tree death due to pine beetles has many negative effects," says Tom Torgersen of NSF's Directorate for Geosciences and lead WSC program director.

"This loss of trees increases groundwater flow and water availability, seemingly a positive," Torgersen says.

"The total effect, however, of the extensive tree death and increased water flow has to be evaluated for how much of an increase, when does such an increase occur, and what's the water quality of the resulting flow?"

The answers aren't always good ones.

Green means go, red means stop, even for trees

Under normal circumstances, green trees use shallow groundwater in late summer for transpiration.

Red- and gray-phase trees--those affected by beetle infestations--stop transpiring, leading to higher water tables and greater water availability for groundwater flow to streams.

The new results show that the fraction of late-summer groundwater flows from affected watersheds is about 30 percent higher after beetles have infested an area, compared with watersheds with less severe beetle attacks.

"Water budget analysis confirms that transpiration loss resulting from beetle kill can account for the increase in groundwater contributions to streams," write Maxwell and scientists Lindsay Bearup and John McCray of the Colorado School of Mines, and David Clow of the U.S. Geological Survey, in their paper.

Dead trees create changes in water quality

"Using 'fingerprints' of different water sources, defined by the sources' water chemistry, we found that a higher fraction of late-summer streamflow in affected watersheds comes from groundwater rather than surface flows," says Bearup.

"Increases in stream flow and groundwater levels are very hard to detect because of fluctuations from changes in climate and in topography. Our approach using water chemistry allows us to 'dissect' the water in streams and better understand its source."

With millions of dead trees, adds Maxwell, "we asked: What's the potential effect if the trees stop using water? Our findings not only identify this change, but quantify how much water trees use."

An important implication of the research, Bearup says, is that the change can alter water quality.

The new results, she says, help explain earlier work by Colorado School of Mines scientists. "That research found an unexpected spike in carcinogenic disinfection by-products in late summer in water treatment plants."

Where were those water treatment plants located? In bark beetle-infested watersheds.

-- Cheryl Dybas, NSF
Investigators
Reed Maxwell
Eric Dickenson
Jonathan Sharp
Alexis Navarre-Sitchler
Related Institutions/Organizations
Colorado School of Mines

HERBEVORES AND FERTILIZER CAN INCREASE PLANT BIODIVERSITY

FROM:  NATIONAL SCIENCE FOUNDATION 
Herbivores + light = more plant biodiversity in fertilized grasslands
Research on six continents shows that it all comes down to the light
It all comes down to the light. At least in plant species diversity in fertilized grasslands.

Fertilizing by humans and plant-eating by herbivores can combine to benefit plant biodiversity--if enough light still reaches the ground, according to results of a study by ecologists Elizabeth Borer and Eric Seabloom of the University of Minnesota and colleagues.

The findings, published this week in the online edition of the journal Nature, are important in a world where humans are changing both where herbivores are found and the supply of plant nutrients such as nitrogen, phosphorus and potassium.

Enter the Nutrient Network

To conduct the study, Borer and Seabloom enlisted the help of the Nutrient Network, or NutNet, an experiment they and other researchers began as a way to understand how grasslands around the world respond to changing environments.

NutNet scientists at 40 sites set up plots with and without added fertilizer and with and without fences to keep out local herbivores such as deer, kangaroos, sheep or zebras.

The research took place in the United States, Canada, China, Australia, Switzerland, United Kingdom, South Africa, Tanzania, Germany and Argentina.

The scientists' hypothesis was that grassland plant species losses caused by eutrophication (overfertilization) could be offset by the increased light availability that results when taller plants are munched down by herbivores like deer and sheep.

This "trimming" by herbivores ultimately lets in more light, fueling increased plant growth.

The experiment, replicated in 40 grasslands on six continents, demonstrated that the researchers had it right.

New explanation for grassland plant biodiversity

"Global patterns of biodiversity have largely defied explanation due to many interacting, local driving forces," says Henry Gholz, a program director in the National Science Foundation's (NSF) Division of Environmental Biology, which funded coordination of the research, along with the many institutions involved.

"These results show that grassland biodiversity is likely largely determined by the offsetting influences of nutrition and grazing on light capture by plants," Gholz says.

In the study, the ecologists measured the amount of plant material, the light reaching the ground and the number of species of plants in the plots.

When the scientists compared results across the sites, they found that fertilizer both reduced the number of plant species in the plots and favored those that were faster-growing. Species less able to tolerate a lack of light in shady conditions were literally overshadowed by their faster-growing neighbors.

So there were fewer kinds of plants, but taller-growing ones.

An herbivore is an herbivore is an herbivore?

In both fertilized and unfertilized plots, removal of vegetation by herbivores increased the amount of light reaching the ground. The taller plants were eaten by the herbivores. Then plant species diversity increased.

The results were the case whether the grassland was in Minnesota, the United Kingdom or Tanzania, and whether the herbivores were rabbits, sheep or elephants.

"This suggests that these effects dovetail with changes in light availability at the ground level," says Borer. "That appears to be a big factor in maintaining or losing biodiversity in grasslands."

Light a key piece of the puzzle

In short, Borer says, "where we see a change in light, we see a change in biodiversity" for the better.

The findings offer important insights into how humans are affecting prairies, savannas, alpine meadows and other grasslands by adding fertilizers.

In showing how fertilization, grazing, light availability and biodiversity are linked, scientists are closer to understanding grassland ecosystems in a changing world.

-- Cheryl Dybas
Investigators
Elizabeth Borer
Related Institutions/Organizations
University of Minnesota-Twin Cities

SCIENTISTS STUDY SEED DISPERSAL

FROM:  NATIONAL SCIENCE FOUNDATION 
Seed dispersal study shows value of conservation corridors

Ecologists study how wind moves seeds through longleaf pines
Field ecologists go to great lengths to get data. Radio collars and automatic video cameras are among their tools for documenting the natural world.

So when a group of ecologists set out to see how wind moves seeds through isolated patches of habitat carved into a longleaf pine plantation, they came up with a novel way of addressing this question. They twisted colored yarn to create mock seeds that would drift with the wind much like native seeds.

The scientists discovered that both wind and the corridors between the patches of habitat matter to seed dispersal in the longleaf pine forest.

Their experimental "seeds" were dusted with fluorescent powder and inserted into custom-made boxes mounted on poles, then released as the scientists monitored local wind conditions.

That night, the field crew returned for a black-light treasure hunt, locating more than 80 percent of the fake seeds, which glowed under the ultraviolet light.

The paths of these glowing seeds were matched with output from a computer model to produce the first accurate picture of how wind moves seeds through corridors linking two patches of habitat.

The study results are published in a paper in this week's issue of the journal Proceedings of the National Academy of Sciences (PNAS).

Conservation biologists have long discussed building conservation corridors to link isolated patches of protected land.

"Understanding the conservation impact of corridors is at the cutting edge of conservation," says lead paper author Ellen Damschen, a zoologist at the University of Wisconsin-Madison.

Corridors are designed to improve conditions for uncommon native species living in separated habitats.

Small populations in these "islands" of habitat may be killed by storms or disease. They may lack genetic diversity and be prone to inbreeding. And they may be unable to reach new habitat.

"It makes intuitive sense that these connections could foster genetic and biological diversity," says Damschen. "But there has been little scientific evidence for if and how they work."

Most of the studies have involved animals, she adds, even though plants provide the basic energy and structure to land ecosystems.

Wind matters for the movement of seeds and whole organisms, Damschen says. "In many open habitats, more than one-third of plants are wind dispersed, but there are also insects, spiders, pathogens and fungi that move on the wind."

The experiment, supported by the National Science Foundation (NSF) and the U.S. Forest Service, began in 2000 with the creation of eight groups of patches at the Savannah River Site, a large holding of the U.S. Department of Energy. Each set of patches was built at a different orientation to prevailing winds.

"Relatively few researchers have investigated the effects of habitat configuration on wind-dispersed species," says Betsy Von Holle, a program director in NSF's Division of Environmental Biology, which funded the research. "This study demonstrates that influences on wind-dispersed species are more complex than previously thought."

A research group of meteorologists and ecologists found that corridors increased the movement of wind and of their glowing artificial seeds, echoing the results of a computer model developed by Gil Bohrer at The Ohio State University, a paper co-author.

And when Damschen and colleagues counted newly dispersed plants over the 12-year experiment, they found that a corridor linking two patches of land indeed promotes the diversity of plants dispersed by wind - especially if the corridor is oriented roughly parallel to the prevailing winds.

Both the data and the model showed that wind speeds up in certain areas of the patches, and that a strong vertical air movement is present.

"Uplift is important because the wind tends to be faster higher above the ground," Damschen says, "and uplift can lead to long-distance dispersal, which is significant for moving plants around the landscape."

That's why the study matters for conservation biology, Damschen says.

"We predicted that corridors in line with the dominant winds would move more species, and this is what we found. Wind alignment matters for species diversity in conservation areas."

The results are especially relevant to threatened Midwestern ecosystems like grasslands, prairies and savannas, where big bluestem and milkweed are two of many native plants that loft their seeds on the wind.

"In conservation science, it is often assumed that wind-dispersed seeds can go everywhere, but that's not true," Damschen says.

"Wind direction, and the shape of the habitat, control where these seeds go.

"While this adds another factor to consider in management of natural areas, the information is on the table so we can make better decisions about how to achieve management goals."

Other co-authors of the paper are: Dirk Baker of the University of Wisconsin-Madison; Ran Nathan of The Hebrew University of Jerusalem; John Orrock of the University of Wisconsin-Madison; Jay Turner of Washington University in St. Louis; Lars Brudvig of Michigan State University; Nick Haddad of North Carolina State University; Doug Levey of the University of Florida, Gainesville; and Joshua Tewksbury of the University of Washington.

-NSF-

OVERFISHING AND CORAL KILLING-SPONGES

FROM:  NATIONAL SCIENCE FOUNDATION 
Overfishing of Caribbean coral reefs favors coral-killing sponges
Caribbean-wide study shows protected coral reefs dominated by sponges with chemical defenses

Scientists had already demonstrated that overfishing removes angelfish and parrotfish that feed on sponges growing on coral reefs--sponges that sometimes smother the reefs. That research was conducted off Key Largo, Fla.

Now, new research by the same team of ecologists suggests that removing these predators by overfishing alters sponge communities across the Caribbean.

Results of the research, by Joseph Pawlik and Tse-Lynn Loh of the University of North Carolina Wilmington, are published this week in the journal Proceedings of the National Academy of Sciences (PNAS).

"In fact," says Pawlik, "healthy coral reefs need predatory fish--they keep sponge growth down."

The biologists studied 109 species of sponges at 69 Caribbean sites; the 10 most common species made up 51 percent of the sponge cover on the reefs.

"Sponges are now the main habitat-forming organisms on Caribbean coral reefs," says Pawlik.

Reefs in the Cayman Islands and Bonaire--designated as off-limits to fishing--mostly have slow-growing sponges that manufacture chemicals that taste bad to predatory fish.

Fish numbers are higher near these reefs. Predatory fish there feast on fast-growing, "chemically undefended" sponges. What's left? Only bad-tasting, but slow-growing, sponges.

Overfished reefs, such as those off Jamaica and Martinique, are dominated by fast-growing, better-tasting sponges. "The problem," says Pawlik, "is that there are too few fish around to eat them." So the sponges quickly take over the reefs.

"It's been a challenge for marine ecologists to show how chemical defenses influence the structure of ocean communities," says David Garrison, a program director in the National Science Foundation's (NSF) Division of Ocean Sciences, which funded the research.

"With this clever study, Pawlik and Loh demonstrate that having--or not having--chemical defenses structures sponge communities on Caribbean coral reefs."

The results support the need for marine protected areas to aid in coral reef recovery, believes Pawlik.

"Overfishing of Caribbean coral reefs, particularly by fish trapping, removes sponge predators," write Loh and Pawlik in their paper. "It's likely to result in greater competition for space between faster-growing palatable sponges and endangered reef-building corals."

The researchers also identified "the bad-tasting molecule used by the most common chemically-defended sponge species," says Pawlik. "It's a compound named fistularin 3."

Similar chemical compounds defend some plants from insects or grazers (deer, for example) in onshore ecosystems, "but the complexity of those ecosystems makes it difficult to detect the advantage of chemical defenses across large areas," says Pawlik.

When it comes to sponges, the view of what's happening is more direct, he says. "The possibility of being eaten by a fish may be the only thing a reef sponge has to worry about."

And what happens to reef sponges may be critical to the future of the Caribbean's corals.

-NSF-

MACROSYSTEMS BIOLOGY DATA REQUIREMENTS

FROM:  NATIONAL SCIENCE FOUNDATION 

Data-intensive ecology needed to understand what makes the biosphere tick
Journal special issue reports new findings on macrosystems biology: biological sciences writ large.

Have you looked closely at a local pond, meadow or forest--or at nature in your suburb or city--and observed changes in it over time? That's exactly what scientists are trying to do on a larger, regional to continental scale--a macrosystems biology scale.

Macrosystems biology might be called "biological sciences writ large."

Scientists funded by the National Science Foundation's (NSF) MacroSystems Biology Program are working to better detect, understand and predict the effects of climate and land-use change on organisms and ecosystems at regional to continental scales.

The researchers have published new results in this month's special issue of the journal Frontiers in Ecology and the Environment, published by the Ecological Society of America.

The ecologists are asking questions such as: How are regional-scale processes in plant and animal invasions, and in disease transmission, shaped by continent-wide environmental and land-use patterns? How can continent-wide data lead to better forecasts of disease outbreaks? How do invasive species and infectious diseases arrive at new locations, sometimes across great distances?

"Scientists conducting macrosystems biology research are working to find answers to these complex questions," says John Wingfield, NSF assistant director for Biological Sciences.

"Current knowledge of the biosphere is largely based on research in small plots of land and on satellite-scale remote sensing," says Wingfield. "But the insights needed to answer critically important questions about the biosphere's future can't always be extrapolated from such studies. They require new approaches."

Now macrosystems biologists are entering a new realm: that of big data.

"Ecologists can no longer sample and study just one or even a handful of ecosystems," says Patricia Soranno, a scientist at Michigan State University and co-editor of the special issue with David Schimel of the California Institute of Technology's Jet Propulsion Lab.

"We also need to study lots of ecosystems and use lots of data to tackle many environmental problems--such as climate change, land-use change and invasive species--because such problems exist at larger scales than other problems we have faced in the past."

Soranno and Schimel worked with many researchers, all funded by NSF's MacroSystems Biology Program, to produce the special issue.

"Data-intensive science is being touted as a new way to do science of any kind, and we think it has a lot to offer ecology," says Soranno.

"Traditionally, ecologists are trained to study and take samples from the field in places like forests, grasslands or wetlands, and measure things in the lab.

"In the future, many ecologists will also need to be trained in advanced computational methods that will allow them to study complex systems using big datasets."

Researchers have accumulated decades and decades of data. The sources include small, individual projects by university biologists; government agency scientists monitoring natural resources; terabytes of data from new or existing field sensors and observation networks; and millions of high-definition satellite images.

Easier access to supercomputers is paired with a near-endless deluge of data. Analyses that once took months or years can now be conducted in hours or days. Scientists also have access to the latest statistical modeling and geographic information system tools, says Soranno.

"Ten years ago, it would have been much harder to take this approach," she says. "We didn't have the intersection we have today of great tools, volumes of data, sufficient computing power and a growing understanding of natural systems at broad scales."

The makeup of macrosystems biology research teams should reflect the demands of data-intensive ecology, these researchers believe. Groups should include database managers, data-mining experts, GIS professionals and others, they say.

"An important question we're facing is how ecologists can best solve many of today's top environmental problems, challenges that need a broad-scale approach," Soranno says.

"From the research that has already been conducted by macrosystems biologists, evidenced by the papers in this special issue, we think we're on the right path."

It's where science needs to go, say these papers' authors, to understand what makes Earth's biosphere tick.

The research papers in the special issue can be accessed online at the Frontiers in Ecology and the Environment website.

-NSF-

NSF ARTICLE ON PHYSICS OF MOVEMENT FOR DESERT DWELLERS AND ROBOTS

FROM:  NATIONAL SCIENCE FOUNDATION 

Desert dwellers and 'bots reveal physics of movement
The Georgia-Tech based 'CRAB' lab investigates how organisms navigate tricky terrain

Physicist Daniel Goldman and his fellow researchers at the Georgia Institute of Technology shed light on a relatively unexplored subject--how organisms such as sea turtles and lizards move on (or within) sand.

If you've ever struggled to walk with even a modicum of grace on a soft, sandy beach, you may appreciate the question. The answers that Goldman's CRAB lab (Complex Rheology and Biomechanics Laboratory) uncovers--with the help of living animals and biologically inspired robots--deepen our understanding not only of animal survival, evolution and ecology, but also, potentially, the evolution of complex life forms on Earth. The lab's research also assists the design and engineering of robots that must traverse unstable, uneven terrain--those used in search and rescue operations at disaster sites, for example.

Goldman first investigated the properties of sand, which can act like a solid, fluid or even a gas, when he was a doctoral student of physics at University of Texas at Austin. Later, as a postdoc in the University of California-Berkeley lab of biologist Robert J. Full (a leader in the field of nature-inspired robots), he helped investigate locomotion on complex terrain--cockroaches' climbing of vertical surfaces, for example, or spiders running over surfaces with few footholds. A fellow researcher, Wyatt Korrf, was interested in movement on a different kind of complex terrain--granular, shifting media. Goldman became hooked, and the two men started working together.

"Some of the insights and tools we developed then were incredibly helpful in my early and current research, in particular, air fluidized beds as a way to control ground properties," Goldman says.

To a student or lover of critters, Goldman's job might seem like a dream. He has worked with a large variety of desert dwellers and other animals, including geckos, zebra-tailed lizards, sidewinders , ghost crabs, sandfish, wind scorpions, funnel weaver spiders and hatchling loggerhead sea turtles.

In the lab and in the field, he and his colleagues observe these animals as they creep, crawl, walk, run, slither and otherwise transport themselves over or in granular matter. The researchers pin down precise details--the flexible spines on a spider's legs that appear to facilitate movement over a wire mesh, for example, or the way a snake flattens itself when climbing a slope. Then they design robots with the physical elements and movement patterns they want to know more about. With these tests as well as computer simulations and analyses, the team can develop, challenge and refine hypotheses related to physics principles inspired by the animals' movements.

The CRAB lab's cast of robot characters to date includes a robot modeled after baby sea turtles, as well as a sandfish robot.

Flipperbot

Recently, the team studied newly hatched sea turtles hurrying across the beach to the sea--a treacherous journey many of us have seen in nature TV shows.

"The best robots people design and build can't out-compete a hatchling sea turtle whose life consists of swimming all the time and using these appendages on land only for half an hour, running from the nest. If a female makes it to adulthood she will use flippers again, of course, to lay eggs," Goldman said.

For this study, CRAB lab researcher Nicole Mazouchova and research technician Andrei Savu traveled with a mobile lab to Jekyll Island in Georgia. They video-recorded hatchlings' movements on the beach and in a portable test bed. Analyzing the videos back at the lab, they saw that on more packed sand, the baby turtles used their flippers as rigid struts and to pivot. On looser sand, however, the turtles dug in deeper and bent their wrists.

With the help of Flipperbot (you guessed it, a robot with flippers), a poppy-seed-filled test bed, plus theoretical modeling by mechanical engineer Paul Umbanhowar of Northwestern University (who also helped make the 'bot), the team confirmed that the turtles' wrist bending helped them avoid slipping and kept their bodies above the sand, minimizing friction and drag. The model revealed how digging in deeper to more sand provided greater efficacy, keeping the substrate from yielding underfoot.

"We found [the turtle] extremely sensitive to how deep it puts its flippers into the ground and that it did better when it bends its wrists," Goldman said.

They also found the turtles (and Flipperbot) were seriously hindered when trying to navigate sand that had already been disturbed by movement.

Flipperbot--whose movements are surprisingly graceful--is the first robot modeled on sea turtles and tested on granular materials. Its work may someday help engineers make more agile robots as well as advance our understanding of evolution on Earth--especially those first walkers to emerge from the sea.

"There is a lot of speculation about the mechanics which allowed early animals to walk on land," says Goldman. "They had hand-like fins or finlike feet and nobody knows in detail how they would have interacted with flowable substrates (like mud and sand)

"We have an eye on biological questions of existing organisms but also those who could have lived in the past. If you look at gazelles, cheetahs--these animals are incredibly agile over terrestrial ground, and they came from things that had no concept of terrestrial ground."

The Flipperbot findings may be useful in other ways as well, such as informing sea turtle conservation strategies.

Sandfish robot

In various studies, Goldman's team has uncovered patterns that can help the engineering of search and rescue robots designed to move over and into debris piles and wreckage. It confirmed, for example, something scientists long suspected--that the chiseled head of the sandfish--a lizard found in north Africa--helps it dive underground. Robot tests showed that the angular head shape not only reduces drag but also generates greater lift forces.

Using x-ray imaging to reveal how the sandfish moves under the surface, the researchers found that to escape predators the little lizard tucks its limbs close to its body and undulates through the sand--looking like a true swimmer. The sandfish uses a consistent wave pattern from head to tail that pushes its body against the sand and generates forward motion. This wave pattern optimizes speed and energy use.

In a more recent study involving a six-legged robot, the team used 3-D printing technology to make legs of different shapes and physical orientations, and learned that convex robot legs made in the shape of the letter "C" worked out best.

Developing 'terradynamics'

It may be tempting to regard the CRAB lab's unique robots as the end rather than the means of research. But the machines are first a way to develop and confirm hypotheses, Goldman says. The lab, which is funded in part by National Science Foundation's (NSF) Physics of Living Systems and Dynamical Systems programs, is steadily identifying basic principles that will significantly advance understanding of how objects move on or in granular media.

"The idea is to begin to develop a terradynamics--equivalent to aero- and hydrodynamics--which will allow us to predict mobility of devices in these complex environments," Goldman says.

The lab has had recent success in terradynamics, publishing a paper in Science that describes a new approach to predicting how small-legged robots move on sand or other flowing materials. The approach uses the forces (such as drag) applied to independent elements of the robot legs to get a measure of the net force on a moving robot (or animal).

"The lizard swimming in sand gives us a broad understanding behind all animals swimming in true fluids," Goldman says. "Analyzing sandfish turns out sufficiently simple we can use as a baseline to understand other swimmers."

What specific studies are up ahead for the busy Georgia Tech lab? In the near future, the team will test and refine theoretical models as they apply to legs and wheels thrusting into flowing material. They also will be conducting experiments to learn more about wet sand versus dry. And thirdly, they will be looking at the physics involved when teams of organisms, such as fire ants, move and dig within complex terrain.

STUDY LOOKS AT TOMATOES ON THE WILDSIDE TO EXAMINE BIODIVERSITY

Supermarket Tomatoes.  Credit:  USDA-Wikimedia.

FROM:  NATIONAL SCIENCE FOUNDATION 
Staple of recipe favorites--the tomato--reveals processes that maintain biodiversity

No hothouse plants: Study examines supermarket tomatoes' wild relatives, which live in Earth's most extreme environments
Tomatoes are in almost everything we eat, from salad and soup to chili and pizza. For some, tomato-based dishes are featured during the holiday season.

Most people don't realize, however, that there are more than a dozen wild tomato species, or that wild tomatoes grow in the deserts, rainforests and highlands of South America and on the Galapagos Islands.

These wild species don't have the big, bold fruits we're used to seeing in the supermarket, though. Wild tomato fruits are smaller, from the size of a pea to that of a large marble and are sometimes green and bitter when they're ripe.

But compared with their domesticated relatives, wild tomatoes are more diverse in many hidden and not-so-hidden ways.

Now scientists are using the genomes of wild tomatoes to study the processes that drive Earth's biodiversity.

Their goal is to learn how species cope with differences in climate and natural enemies, and what might happen in this time of environmental change.

Wild tomato genomes as a framework for understanding biodiversity

To study natural trait and genome diversity in wild tomatoes, scientists Leonie Moyle, David Haak and Matthew Hahn of Indiana University Bloomington received a grant from the National Science Foundation's (NSF) Dimensions of Biodiversity program.

Dimensions of Biodiversity is part of NSF's Science, Engineering and Education for Sustainability investment and is supported by NSF's Directorates for Biological Sciences and Geosciences.

Scientists funded through Dimensions of Biodiversity integrate genetic, taxonomic and functional approaches in their research.

"The resulting discoveries go beyond expanding our knowledge of the depth and breadth of life on Earth," says John Wingfield, NSF assistant director for Biological Sciences.

"They have the potential to revolutionize the way we manage agriculture, practice medicine, address global climate change and develop new technologies."

The award to Moyle's team funds sequencing of the complete set of all expressed genes (the transcriptome) in populations of wild tomato species.

"Variations within and between these wild tomato genomes can be compared by using the genome sequence of the domesticated tomato as a 'backbone,'"says Moyle.

By linking this genome-wide sequence data with information on wild tomato trait variation, the biologists hope to identify the genes responsible for adaptation to environmental change.

The research focuses on the role of drought and of defense against herbivores, or plant-eaters, in the diversity of wild tomatoes.

"These factors," says Haak, "capture two of the most important aspects of any plant's environment: climate and natural enemies."

Wild tomatoes: From hothouse to deep freeze

While domesticated tomatoes thrive only in agricultural irrigation, wild tomatoes live in some of the planet's most extreme environments.

They're among the few plants found in the driest place on Earth--the Atacama Desert in Chile. Other wild tomatoes blossom along the rocky, salty shores of the Galapagos Islands, and in the daily rains of Ecuador's rainforests.

But it's not just the climate in which they grow that varies among wild tomatoes.

The plants bristle with an array of natural defenses, from dense coverings of plant hairs to toxins deadly against insect attackers.

Measuring biodiversity in plant defenses

In a forthcoming paper in the journal Ecology, Haak, Moyle and colleagues document large differences in defenses among wild tomatoes.

They used bioassays--experiments in which living organisms are used to reveal the potency or concentration of a substance.

In this case, they fed leaf samples of different wild tomato species to tobacco hornworms.

The tobacco hornworm--also known as the tomato hornworm--is an enemy of both domesticated and wild tomatoes. It rapidly eats its way through the plants' leaves.

Each hornworm caterpillar was weighed before and after feeding to determine how much it had gained on a diet of wild tomato leaves.

Those tomatoes on which caterpillars gained little or no weight, says Haak, have more natural defenses than those on which the caterpillars gained weight.

In one wild tomato species, caterpillars lost significant weight; they refused to consume the plant's toxic leaves.

The researchers showed that the level of natural defense varies widely among wild tomato species.

"Although all wild tomatoes are closely related, these patterns of defense variation don't simply follow historical, evolutionary relationships," says Moyle. "The defense level of each wild tomato population is likely shaped by responses to local herbivores."

Linking biodiversity to genomics to understand environmental responses

Moyle and Haak are using DNA sequencing to look at the genes that are expressed differently in wild tomatoes with varying levels of natural defenses, and with differences in responses to drought.

Genes that are consistently up- or down-regulated in these conditions, says Moyle, can reveal the changes important for responding to and coping with environmental stresses.

"By linking data on DNA sequence variation, and on variation in gene expression, with wild tomatoes' responses to drought and natural enemies," she says, "we may find a powerful model for understanding the genetics of responses to environmental change."

The study could also uncover genetic variations helpful in improving domesticated tomatoes and their cultivated relatives, including potatoes and peppers.

"This research on tomatoes' wild relatives offers insights into the huge reservoir of genetic information available to ensure our future food security," says Simon Malcomber, lead NSF program director for Dimensions of Biodiversity.

"Tomatoes are one of the most widely consumed foods around the world," he says. "Studies such as this provide important information that could be used to improve herbivore resistance in crop cultivars."

Next time you're in the supermarket, tomatoes are worth a closer look. These common plants may offer a glimpse of our global food security, and of Earth's environmental future.

-- Cheryl Dybas, NSF
Investigators
David Haak
Leonie Moyle
Matthew Hahn
Related Institutions/Organizations
Indiana University
Related Programs
Dimensions of Biodiversity

NSF: RISING SEAS THREATEN WETLANDS

Credit:  Wikimedia

FROM:  NATIONAL SCIENCE FOUNDATION 
Wetlands' ability to overcome sea level rise threatened

When do wetlands reach their limit, and how are we lowering that point?
Left to themselves, coastal wetlands can resist rapid sea level rise.

But humans could be sabotaging some of wetlands' best defenses, according to results published in this week's issue of the journal Nature.

Thanks to an intricate system of feedbacks, wetlands are remarkably good at building up soils to outpace sea level rise. The questions are: When do they reach their limit, and how have we lowered that point?

Without human-caused climate change, "we wouldn't be worried about wetlands surviving the rates of sea level rise we're seeing today," says lead paper author Matthew Kirwan of the Virginia Institute of Marine Science and the National Science Foundation (NSF) Virginia Coast Reserve Long-Term Ecological Research (LTER) site.

Virginia Coast Reserve is one of 26 such NSF LTER sites around the globe in ecosystems from deserts to mountains and marshes to grasslands.

In an unchanged world, "wetlands would build vertically at faster rates," says Kirwan, "or move inland to higher elevations."

The paper's co-author is Patrick Megonigal of the Smithsonian Environmental Research Center.

A wetland is land that's saturated with water, whether permanently or seasonally. The water found in wetlands can be saltwater, freshwater or brackish water. Main wetland types include swamps, marshes, bogs and fens.

Wetlands have developed several ways to build elevation to keep from drowning.

Aboveground, tidal flooding provides one of the biggest assists. When marshes flood during high tides, sediment settles out of the water, adding new soil. As sea level rises and flooding occurs more often, marshes react by building soil faster.

Belowground, the growth and decay of plant roots add organic matter.

Even erosion can work in wetlands' favor, as sediment lost at one marsh may be deposited in another. While a particular wetland may lose ground, the total wetland area may remain unchanged.

But, if a wetland becomes so submerged that its vegetation dies off, these "positive feedback loops" are lost. Similarly, if sediment delivery to a wetland is cut off, that wetland can no longer build soil to outpace rising seas.

"This study reveals the complex, long-term interplay among processes that maintain coastal wetlands in the face of sea level rise," says Saran Twombly, program director in NSF's Division of Environmental Biology, which funds the NSF Virginia Coast Reserve LTER site.

"Humans are newcomers to this delicate balance. The future of a habitat so essential to human well-being depends on how severely we alter it."

For example, groundwater withdrawal and artificial drainage can cause the land to sink, as is happening in Chesapeake Bay.

Because of this subsidence, eight of the world's 20 largest coastal cities have relative sea level rise greater than climate change projections.

Dams and reservoirs also prevent 20 percent of the global sediment load from reaching the coast.

Marshes on the Yangtze River Delta, for example, have survived a relative sea level rise of more than 50 millimeters per year since the 7th century--until the recent building of more than 50,000 dams cut off the supply of sediment and accelerated erosion.

"Tidal marshes are amazing ecosystem engineers that can raise themselves upward if they remain healthy, especially if there is sediment in the water," says Megonigal.

"We know there are limits, however. Those limits are changing as people alter the environment."

-NSF-

IS TASMANIAN DEVIL HEADED FOR EXTINCTION?

Tasmanian Devil.  Credit:  Wikimedia Commons.

FROM:  NATIONAL SCIENCE FOUNDATION 
Tasmanian devils: Will rare infectious cancer lead to their extinction?

Taz, was his name, the Tasmanian devil of Warner Bros. cartoon fame. A scrappy omnivore who ate anything and everything, he spun in a vortex and bit through everything in his path.

The devil was short-lived, however, making television appearances for a few years in the late 1950s and early 1960s before disappearing from view. In 1991, Taz got a reprieve: His own show, "Taz-Mania," which ran for three seasons. Then he was gone for good.

From the screen to the wild

Tasmanian devils in the wild are no less imperiled. Carnivorous marsupials, they're found only on the Australian island of Tasmania. With a stocky build, black fur, keen sense of smell and ferocity when feeding, "real-life" Tasmanian devils and their cartoon namesake have much in common.

The size of small dogs, Tasmanian devils became the largest carnivorous marsupials in the world following the 1936 extinction of thylacines (Thylacinus cynocephalus), known as Tasmanian tigers or Tasmanian wolves. Thylacines lived on continental Australia, Tasmania and New Guinea.

Will the fate of Sarcophilus harrisii, the scientific name for the Tasmanian devil, mimic that of the thylacine?

"If a way isn't found to stop devil facial tumor disease, or DFTD," says disease ecologist Andrew Storfer of Washington State University, "models predict that Tasmanian devils could be extinct in as few as10 years."

And vanishing with them, valuable clues to diseases in other species, including humans.

DFTD is an aggressive, non-viral, transmissible parasitic cancer that is 100 percent lethal, says Storfer. "In short," he says, "it's bad news."

Can we save the Tasmanian devil?

To study DFTD and find ways of understanding its emergence and spread, Storfer has received a grant from the National Science Foundation (NSF)- National Institutes of Health (NIH) Ecology and Evolution of Infectious Diseases (EEID) Program.

Collaborators include Paul Hohenlohe of the University of Idaho, Hamish McCallum of Griffith University, Menna Jones of the University of Tasmania and Elizabeth Murchison of the Wellcome Trust Sanger Institute.

The NSF-NIH EEID Program supports efforts to understand the ecological and biological mechanisms that link environmental changes and the emergence and transmission of infectious diseases.

Projects funded through the program allow scientists to study how large-scale environmental events--such as habitat destruction, invasions of nonnative species and pollution--alter the risks of emergence of viral, parasitic and bacterial diseases.

Storfer's research may lead to new insights about the spread of flu in humans. It also may help scientists understand other infectious diseases in animals such as bats, and how certain cancers progress.

"This study provides an excellent test-bed for understanding the spread of infectious diseases," says Sam Scheiner, EEID program director at NSF. "The results may help us control the spread of seasonal flu in people, West Nile virus in birds and white-nose syndrome in bats, among many other diseases."

Tasmanian devils: extinction on the horizon

The first official case of devil tumor facial disease was reported in 1996. Since then, Tasmania's devil population has declined by 70 percent. Findings reported in 2010 show that 80 percent of the remaining devils are affected.

"Tasmanian devils that live in high-density populations may suffer drastic reductions a few years after emergence of the disease," Storfer says.

DFTD has been slowly moving from east to west across Tasmania for the last 17 years; it's now approaching the west coast. "Soon there may be no known uninfected devils," says Storfer.

The disease is spread when Tasmanian devils bite each other's heads while fighting over food, during territorial interactions and when they spar during mating season.

Devils that contract the disease develop lesions around their mouths that become cancerous tumors. The tumors may spread from their faces to their entire bodies. Devils almost always die within six to nine months.

Devil facial tumor disease likely began in what are called Schwann cells. Schwann cells are found in the peripheral nervous system; they produce myelin and other proteins essential for the functions of nerve cells.

In response to DFTD, Tasmanian devils have changed their reproductive habits. Before the outbreak, females started breeding at two years old. Now they breed by the end of their first year--and often die of DFTD soon afterward.

There's a ray of light, however, in this dark day for devils. Some devils have been found with partial immunity to the disease. Breeding in captivity is underway to try to save the species.

"Emerging infectious diseases like DFTD are one of the great scientific challenges of the 21st century," says Storfer. "Infectious diseases are now the sixth leading cause of species extinctions."

Answers in Tasmanian devils' genomes?

Extensive research by Storfer and others, including thousands of samples taken before and after devil die-offs, has given scientists a rare opportunity to study the genomic interactions of an infectious disease and its host--the devils--across an entire species' range.

"The research will tell us about the genetic basis of Tasmanian devils' susceptibility to the tumors," says Storfer, "providing environmental managers with information about which particular devils would be best suited for captive breeding programs."

Knowledge of the rates and direction of past tumor spread will enable scientists to uncover the likely locations of future infections.

Although only a few infectious cancers have been documented, Storfer says, "this disease shares properties with human cancers.

"Our research, especially genetic studies, may reveal the underlying reasons why DTFD is so prevalent and can hold on for so long in a population, perhaps providing information on cancer recurrence in humans."

To test predictions of the course of the epidemic, he and colleagues plan to meld what they call "devil contact network modeling" with genomic studies of Tasmanian devil populations expected to become infected.

"The answers will help in developing responses to this and other disease outbreaks in Tasmanian devils--and potentially in people," says Storfer.

Taz may be gone, but, says Storfer, "Hopefully it's not too late for the real Tasmanian devil."

-- Cheryl Dybas, NSF

NANOGRID TECHNOLOGY MAY BE USEFUL IN BREAKING DOWN WATER POLLUTANTS

FROM:  NATIONAL SCIENCE FOUNDATION 
Nanogrid, activated by sunlight, breaks down pollutants in water, leaving biodegradable compounds
November 8, 2013

Oil spills do untold damage to the environment--to the waters they pollute and to marine and other wildlife. The Deepwater Horizon spill in the Gulf of Mexico in 2010, for example, the largest accidental marine oil spill in the history of the petroleum industry, flowed unabated for three months.

Typically, such oil spills are extraordinarily difficult to clean up.

Soon, however, the process may become infinitely easier and ecologically friendly, the result of a new invention by a National Science Foundation- (NSF) supported scientist.

Pelagia-Irene (Perena) Gouma, a professor in the Department of Materials Science and Engineering at the State University of New York (SUNY) Stony Brook, created a novel "nanogrid," a large net consisting of metal grids made of a copper tungsten oxide, that, when activated by sunlight, can break down oil from a spill, leaving only biodegradable compounds behind.

"We have made a new catalyst that can break down hydrocarbons in water, and it does not contaminate the water," says Gouma, who also directs SUNY's Center for Nanomaterials and Sensor Development. "It utilizes the whole solar spectrum and can work in water for a long time, which no existing photocatalyst can do now. Ours is a unique technology. When you shine light on these grids, they begin to work and can be used over and over again.

"Something like this would work fine for any oil spill," Gouma adds. "Any ship can carry them, so if they have even a small amount of spill, they can take care of it."

Initially, the grids, which resemble non-woven mats of miniaturized ceramic fishing nets, probably will be used for oil spills, although they potentially could prove valuable in other applications, such as cleaning contaminated water produced by "fracking," the process of hydraulic fracturing to extract natural gas from shale, and as well as from other industrial processes.

"Fracking is a reality," she says. "It is happening. If the science and engineering we produce in the lab can help alleviate environmental problems, we will be happy about that."

Because they work well both in water and air, they also could be a chemical-free, possibly even water-free, method of cleaning clothes in the future. "The dry cleaning process that we now use involves a lot of contaminants that have to be remediated and treated, such as benzene," she says. "This could be a dry cleaning substitute that would be more environmentally friendly than current dry cleaning approaches."

Moreover, "imagine you lay this over your clothes, and expose them to light. You won't need a washing machine, or chemicals, or even water," she adds.

The photocatalytic nanogrids™ invented in her lab are made by a unique self-assembly process that occurs "during the nanomanufacturing on non-woven nanofibrous mats deposited on metal meshes," according to Gouma. "Upon heating, metal clusters diffuse inside polymeric nanofibers, then turn into single crystal nanowires, then oxidize to form metal oxide--ceramic--nanoparticles that are interconnected, like links in a chain," she says.

These form an unusual and "robust third architecture that allows for the highest surface area, providing maximum exposure to the contaminant to be remediated, while the nanoscale particle sizes enable fast catalytic action," she adds. "The result is a self-supported water remediation targeted photocatalytic technology that has no precedent."

In the fall of 2011, Gouma was the first scientist to receive a $50,000 NSF Innovation Corps (I-Corps) award, which supports a set of activities and programs that prepare scientists and engineers to extend their focus beyond the laboratory into the commercial world.

Such results may be translated through I-Corps into technologies with near-term benefits for the economy and society. It is a public-private partnership program that teaches grantees to identify valuable product opportunities that can emerge from academic research, and offers entrepreneurship training to faculty and student participants.

"The I-Corps program was very useful for the students," she says. "It got them involved, and got them to realize that there is a practical application to what they do. It was extremely useful for them to see how something developed in the lab could be used in the field, and that you actually can start a business from something started in the lab."

She and her team are in the process of creating a startup business--they have two patents pending on the process--with the hope of scaling up production and carrying out pilot studies.

"We want to demonstrate feasibility in the real world, and then produce them in large quantities," she says. "We have proof of principle that our technology can be useful. Our technique works in the lab. We now need to make sure that it works in the field."

-- Marlene Cimons, National Science Foundation
Investigators
Jusang Lee
Clive Clayton
Pelagia Gouma