Touring Duke’s Biggest Laboratory

Sari Palmroth

Sari Palmroth and the 130-foot research tower in the Blackwood Division of Duke Forest.

By Karl Leif Bates

You may think of Duke Forest as a nice place to run or walk your dog, but it’s actually the largest research laboratory on campus, and probably the oldest too.

Last week, Duke Forest director Sara Childs and operations manager Jenna Schreiber took about a dozen interested stakeholders on a whirlwind tour to see three active research installations tucked away in areas of Duke Forest the public often doesn’t see.

 

We had to hunt a little to find UNC Biology grad student Jes Coyle in the Korstian division off Whitfield Road, but at least she wasn’t 30 feet up in an oak tree like she usually is. Jes showed the group some of her cool climbing gear while explaining her work on figuring out which part of a lichen, the fungus or the algae, is more responsible for the lichen’s adaptation to microclimates.

She does this by climbing way the heck up into trees to affix little data loggers that track temperature and sunlight at various places on the trunk.

Coyle is looking at 67 lichen species in 54 sampling locations, which is a lot of climbing and a lot of little $50 loggers.

The whole time Jes was talking, we were eyeing her six-foot-tall slingshot and waiting for it to come into play.

Jes Coyle

UNC grad student Jes Coyle shows off her climbing gear.

Indeed it did, as she let three participants, including Sara Childs, have a go at shooting a ball on a fine string over a likely-looking branch to start a climbing rope. (None succeeded.)

 

Abundant data was the theme at our second stop too, where Sari Palmroth, an associate research professor in the Nicholas School of the Environment, explained how she measures how much water goes into and out of a tree.  Her installation is in the Blackwood Division off Eubanks Road, tucked behind the old FACE experiment.

Standing next to an imposing 130-foot scaffolding tower studded with active and abandoned instruments of all sorts, Palmroth said a square meter of Duke Forest exhales about 700 mm of rainfall a year, which is about half of what falls on it. “How do I know these numbers? Because it’s my job.”

In addition to being a lovely place to get away from the world and sway with the treetops, the tower measures CO2 levels at different heights throughout the canopy.

Sari Palmroth

Palmroth reveals where probes go into a tree trunk.

The tower also hosts a big white box stuffed with wires that capture data streaming in from sensors embedded in the tree trunks all around the tower.

Palmroth and her colleagues are seeing the trees breathe. During the day, when the tiny pores on the underside of their leaves – called stomata — are open and exhaling water and oxygen, roots in the top 40 centimeters of soil are pulling in more water. When the sun sets and the stomata close, then the tree’s deeper roots pull water up to the top level for tomorrow’s drinking.  Unless it doesn’t get cool at night and the stomata don’t completely close, which is the prediction for some climate change scenarios. What then?

 

Aaron Berdanier

Back in the vans and even deeper into the Blackwood division, we come upon an intrepid young man in a flannel shirt sitting in a sunny spot by the side of the two-track. He’s Aaron Berdanier, a doctoral candidate at Duke who is also looking at water use by taking  automated measurements of 75 trees every minute for four straight years.

His work is part of a larger research project established by Nicholas School professor Jim Clark 15 years ago. Every one of the 14,000 trees in this sloping 20-acre stand of the forest — from spindly saplings to giants —  is labeled and has its data regularly collected by a platoon of undergrads armed with computer tablets.

Other data flows automatically on webs of wiring leading to data loggers situated every few yards. Some of the trees wear a stainless steel collar with a spring that measures their circumference constantly and precisely. They change noticeably both seasonally and by the year, Berdanier says.

The forest is alive and its trees are breathing and pulsing. Berdanier likens his detailed measurement of water consumption to taking a human patient’s pulse. “We’re trying to determine winners and losers under future climate conditions.”

Duke Forest Q&A

Aaron handled a wide-ranging Q&A with the curious visitors as the sun set and the temperature fell.

Joining the Team: Duncan Dodson

duncandodsonHello world! My name is Duncan Dodson. I am a senior from Tulsa, Oklahoma, pursuing a BS in Environmental Science with a focus on Energy and Sustainability. Though my interests and academic pursuits at Duke have shifted over the course of my undergraduate career (I spent over half of it pursuing a mechanical engineering degree), a constant passion has been conservation of the environment. From age six I was involved in the Boy Scouts of America, received my Eagle Scout Award at sixteen, and have been an avid backpacker for five years. I recently co-directed Duke’s experiential education and backpacking based pre-orientation trip, Project WILD, and have been involved with various outdoor and environmental organizations the past three years.

Two things draw me towards exploring environmental issues: the impetus to think selflessly – environmental justice – and the necessity to approach problems on a larger scale – global climate change. Duke and my selective living group Ubuntu have challenged me to explore how we interact with the world around us in both wonderful and destructive ways.

My other budding passion at Duke is education. Challenging knowledge and ideas by informing and listening is a key part of learning. Transitioning from a more homogeneous community in Oklahoma to the vibrant and varied Triangle Area has framed my education in this respect. This is why I applied to write for the Duke Research Blog. Informing others of energy and sustainability research at Duke excites me; having an open forum where exposure to contrary opinions is expected impassions me.

Hopefully my exploration is as intriguing for readers as it is for me!

Four Things You May Not Know about Ecologist E.O. Wilson

By Erin Weeks

Edward O Wilson Red Hills, Aalabama  2010 by Beth Maynor Young 6x9_0

(Photo: Beth Maynor Young)

Edward O. Wilson is one of the most renowned living biologists, the world’s foremost authority on ants, and for a little while at least, a member of the Duke faculty.

Wilson is on campus teaching the first of an annual course, part of a recent partnership between the E.O. Wilson Biodiversity Foundation and Duke’s Nicholas School of the Environment. Feb. 11, he spoke to a sold-out auditorium about “The Diversity of Life,” a lecture that was equal parts awe-inspiring facts, humorous anecdotes from a life in science and call to arms for future generations.

Here are four things the audience learned last night about E.O. Wilson.

1. He’s dabbled in dreams of Jurassic Park. When asked what he thought of de-extinction, the plan to resurrect vanished species using their DNA, Wilson enumerated all the reasons why the efforts may be futile: we have only genetic shreds; the appropriate habitat may be gone; we can’t produce breeding populations from limited DNA.

But then he paused. “I’ll tell you frankly,” he said, “I’d like to see a mammoth.”

2. He made his first scientific discovery as an adolescent. An eye permanently damaged in a fishing accident led the young Wilson to his interest in ants, which he could view up close. One day in his native Alabama, he discovered a ferocious mound-building species he’d never seen before. He didn’t recognize it then, but those were among the first of the destructive red fire ants that would soon invade the entire Southeast, causing billions of dollars of economic and medical damage.

3. The man is 84 and still going strong. Professor Wilson closed his talk with a passage from his newest book, arriving in April, called “A Window on Eternity: A Biologist’s Walk Through Gorongosa National Park.” He’s written two dozen other books, including a foray into fiction at age 80 (the novel, called Anthill, won him the 2010 Heartland Prize for fiction).

4. The future is in nematodes. Or fungi. Or Archaea. Throughout the talk, Wilson reiterated his hopes for young scientists to become the cataloguers and guardians of Earth’s immense biological diversity. Only a fraction of the planet’s estimated species of nematodes, fungi and Archaea are known to science, and “these little things run the world,” he said.

The need for “-ologists” has never been greater, he said.

(Photo: Jared Lazarus)

(Photo: Jared Lazarus)

VIEW THE ENTIRE TALK (YouTube, 1:10 with introductions)

Turtle Sexes are Temperamental

Guest post by Lauren Burianek, doctoral candidate in cell biology

A pair of one-week-old red-eared sliders. The one on the right looks a little cranky. (Tadpole667 via Wikimedia Commons)

A pair of one-week-old red-eared sliders. (Tadpole667 via Wikimedia Commons)

When humans are developing, they snuggle in a warm environment and everything is provided by the mother. The sex of this developing fetus is determined by its individual genetic makeup, particularly the presence of the X and Y chromosomes.

But laid as an egg in a hole on a riverbank, the sex of a red-eared slider turtle is determined by the temperature at which the egg is developed.

At temperatures above 84.6°F, the hatchling will develop into a female, but at lower temperatures, the hatchling will develop into a male. However, at exactly this temperature (called the pivotal temperature), half of the hatchlings will be female and the other half will be male.

Scientists have no idea how temperature affects the sex of the turtle hatchlings, but researchers in Blanche Capel’s lab at Duke are trying to find out.

Red-eared sliders breed in late spring near riverbanks in Louisiana. Researchers carefully collect the eggs from common nesting spots and send the eggs to Duke University. In the Capel lab, graduate student Mike Czerwinski then buries the eggs in sand and places them into incubators at different temperatures. From here, he will analyze the gonads, or sexual organs, of the turtle embryos incubated at the different temperatures.

Grad student Mike Czerwinski in the Capel lab.

Grad student Mike Czerwinski in the Capel lab.

Czerwinski and his colleague Lindsey Mork discovered that when the turtle embryos were incubated at the pivotal temperature, both gonads developed into either testes or ovaries, but rarely did the two gonads develop into one of each.

Then, they incubated the turtle embryos at the pivotal temperature, dissected the two gonads and incubated each of them at different temperatures, either male-developing or female-developing temperatures. Surprisingly, the separated pairs of gonads still attempted to develop into the same sex regardless of the incubation temperature.

Tyrannosaurus Rex may have had temperature-sensitive eggs too. (tlcoles via Wikimedia Commons)

Tyrannosaurus Rex may have had temperature-sensitive eggs too. (tlcoles via Wikimedia Commons)

For example, if one of the gonads incubated in the male-developing temperature readily turned into a testis, the other gonad of the embryo, even though it was incubated in female-developing temperatures, is slower to develop into an ovary than expected, suggesting that it was genetically predisposed to be a testis.

“The results are exciting because it shows that there is a global mechanism beyond temperature dependence that allows for sex determination,” said Czerwinski. “All we’ve known up until now is that temperature is important for these turtles, but now we know that there also has to be a genetic component. Sex determination is so varied between different species, but this might give us insight into how we’re all connected.”

Climate change could definitely be a factor in the survival of these turtles and other temperature-dependent species. After all, the dinosaurs are thought to have exhibited temperature-dependent sex determination.

With increasing temperatures, a higher proportion of hatchlings will be females. Snapping turtles, however, have found a way to combat this – by moving north. The same species of snapping turtles exhibit different pivotal temperatures at different latitudes.

Evolution truly is an amazing process.

Pretty pictures show lemurs responding to changing climate

Guest Post by Sheena Faherty, Biology Graduate Student 

Madagascar’s much-adored and fuzzy lemurs might be “sweated out” of habitats by warming environments under global climate change. Or will they?

A team of researchers at the Duke Lemur Center is employing high-tech heat cameras used in  fire fighting, sports medicine and cancer diagnostics to take “glowing” rainbow pictures of lemurs and their forest surroundings. The results look similar to a child’s coloring project gone rogue.

A mother and baby Coquerel's Sifaka at the Lemur Center in thermograph and visible light. (Leslie Digby)

A mother and baby Coquerel’s Sifaka at the Lemur Center in thermograph and visible light. (Leslie Digby)

This technology, known as infrared thermography, is a camera that allows researchers to detect surface temperatures of lemurs and their hang-outs in the forest—at different depths and heights—and on varying surfaces such as the ground, leaves, and tree trunks.

Combining these data with records of where an animal prefers to spend time, the researchers can begin to determine what temperatures make lemurs most happy.

Leslie Digby, an associate professor in the Department of Evolutionary Anthropology, and her students want to see  how the lemurs are changing their behavior to warm-up on cool days, and cool-down on warm days without having to shiver or sweat.

This sounds rather like a lizard basking on a rock during a sunny day to warm his cold-blooded body up, but lemurs aren’t cold-blooded. They shouldn’t have to do this.

It turns out that even though lemurs are warm-blooded, they can conserve precious energy by channeling their inner Buddha — using sunning behaviors, just like lizards, to fine-tune core body temperatures.

Digby’s team is trying to understand why some species have seemingly restricted territories, even without obvious geographical barriers like mountain ranges or rivers. They suspect temperature plays a part.

“We know that primate species ranges have been very different in the past, so understanding how flexible these animals are, or [are] not, to temperatures can help us understand these larger scale impacts [of changing climate]”, says Digby.

Figuring out how animals respond to alterations in their environment, like rising temperatures, can help scientists anticipate species’ survival in the face of globally changing climates. And knowing which areas of the forest are preferred by lemurs, could help direct conservation efforts, like reforesting parts that have been cut down, or preserving those areas that have not.

Changing temperatures will undoubtedly have major impacts on lemur home ranges in the future, potentially altering them until the animals  are forced into an area outside their thermal limits. By gearing her research toward understanding the thermal tolerances of lemurs, Digby is doing her part to protect the vulnerable lemurs.

A ringtailed lemur striking the classic belly-warming Buddha pose in one of the natural enclosures at Duke Lemur Center. (David Haring)

A ringtailed lemur striking the classic belly-warming Buddha pose in one of the natural enclosures at Duke Lemur Center. (David Haring)

Humans, Whales and Taylor Swift

by Ashley Mooney

The similarities between chromium workers and whales are greater than one might think.

Environmental toxicology researcher John Wise has been studying the connection between exposure to pollutants and the onset of cancer in humans. To understand the link, he said one must take into account all species, especially whales. Wise spoke at Duke Oct. 25 at the Inaugural Duke Distinguished Lecture in Cancer and the Environment.

800px-Chromium_crystals_and_1cm3_cube

Chromium crystals. Courtesy of Wikimedia Commons.

“For environmental health for me, [the Earth] is the big picture,” Wise said. “This is home and we only have one, so we have to think pretty hard about environmental health.”

Wise studies the effect of pollutants—specifically forms of chromium—on genetic material in humans, marine mammals, and birds and other marine species.  While the standard approach to environmental toxicology research is to conduct epidemiology studies on highly exposed populations and then expose animals to high doses of the toxin, Wise has adopted a new method of study.

“We don’t really know what high-dose exposures mean on a day-to-day basis,” he said.

To understand the relationship between chromium exposure and the onset of cancer, Wise looks at the personal factors that affect one’s health, such as an individual’s body and genome, lifestyle, daily exposures and what kind of environment one lives in.

“We need to know mechanism: how does a normal cell become a tumor cell?” he said. “For a long time that is where the field has been hung up, trying to identify the ultimate carcinogen.”

Most forms of naturally occurring chromium are not toxic. Man-made hexavalent chromium, however, has been shown to cause lung cancer in those who are regularly or heavily exposed to it. Prolonged exposure induces an altered chromosome number and structure, as well as DNA double strand breaks.

Chronic exposure to chromium also causes a shift from more a protective form of DNA repair called homologous recombination to a less stable and error-prone pathway called non-homologous end joining. This means that cells will have permanently deficient repair mechanisms.

Wise applies his research in the context of ocean health, namely how chromium exposure might harm whale DNA.

Most ocean pollutants, including the toxic form of chromium, are in the ocean sediment. As the ocean becomes increasingly more acidic, the sediment breaks off and poses a growing threat to marine species.

Wise measured chromium levels in baleen whale skin, and found that Atlantic seaboard species—the northern right whale, fin whale and humpback whale—have 16- to 41-fold higher levels than other baleen whales.  Toothed whales living in the Gulf of Mexico exhibited levels that resembled those found in chromium workers who died of lung cancer.

A humpback whale surfacing for air. Courtesy of: Protected Resouces Division, Southwest Fisheries Science Center, La Jolla, California. swfsc.nmfs.noaa.gov/PRD/.

A humpback whale surfacing for air. Courtesy of: Protected Resouces Division, Southwest Fisheries Science Center, La Jolla, California. swfsc.nmfs.noaa.gov/PRD/.

In whales, chromium can lead to DNA damage and reproductive suppression.

“There’s only 400 [northern right whales] left in existence,” Wise said. “If you only have 400 animals, you need every single one of them [to be able to reproduce].”

Wise said he hopes his research will encourage people to think more about habitat degradation and climate change, and how they affect all species.

taylor-conor-sailing-team, courtesy of popdust.com

Wise (back right) photographed with his lab and Conor Kennedy (back left). Courtesy of popdust.com.

His lab, however, has recently gained publicity not for its research, but for the public figures that have worked with it. Conor Kennedy, a member of the influential Kennedy family, worked with Wise’s team and Ocean Alliance last year. At the time he was dating pop-star Taylor Swift.

“[He was], like any other high school student, constantly texting on his phone and I would do what I did with my kids and the other students, and say ‘put the girl down, we have to go to work,’ not knowing the girl was Taylor Swift,” Wise said. “It really hit home that we were traveling in very different circles.”