Following the people and events that make up the research community at Duke

Category: Climate/Global Change Page 1 of 8

Traveling With Friends Helps Even Mixed-Up Migrators Find Their Way

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North American monarch butterflies migrate each winter to just a few mountaintops in central Mexico, with help from an internal compass that guides them home. New computer modeling research offers clues to how migrating animals get to where they need to go, even when their magnetic compass leads them astray. Credit: Jesse Granger, Duke University

DURHAM, N.C. — Some of us live and die by our phone’s GPS. But if we can’t get a signal or lose battery power, we get lost on our way to the grocery store.

Yet animals can find their way across vast distances with amazing accuracy.

Take monarch butterflies, for example. Millions of them fly up to 2,500 miles across the eastern half of North America to the same overwintering grounds each year, using the Earth’s magnetic field to help them reach a small region in central Mexico that’s about the size of Disney World.

Or sockeye salmon: starting out in the open ocean they head home each year to spawn. Using geomagnetic cues they manage to identify their home stream from among thousands of possibilities, often returning to within feet of their birthplace.

Now, new research offers clues to how migrating animals get to where they need to go, even when they lose the signal or their inner compass leads them astray. The key, said Duke Ph.D. student Jesse Granger: “they can get there faster and more efficiently if they travel with a friend.”

When their internal compasses go bad, migrating animals like these sockeye salmon don’t stop to ask directions. But they succeed if they stay with their fellow travelers. Credit: Jonny Armstrong, USGS

Many animals can sense the Earth’s magnetic field and use it as a compass. What has puzzled scientists, Granger said, is the magnetic sense is not fail-safe. These signals coming from the planet’s molten core are subtle at the surface. Phenomena such as solar storms and man-made electromagnetic noise can disrupt them or drown them out.

It’s as if the ‘needle’ of their inner compass sometimes gets thrown off or points in random directions, making it hard to get a reliable reading. How do some animals manage to chart a course with such a noisy sensory system and still get it right?

“This is the question that keeps me up at night,” said Granger, who did the work with her adviser, Duke Biology Professor Sönke Johnsen.

Multiple hypotheses have been put forward to explain how they do it. Perhaps, some scientists say, migrating animals average multiple measurements taken over time to get more accurate information.

Or maybe they switch from consulting their magnetic compass to using other ways of navigating as they near the end of their journey — such as smell, or landmarks — to narrow in on their goal.

In a paper published Nov. 16 in the journal Proceedings of the Royal Society B, the Duke team wanted to pit these ideas against a third possibility: That some animals still manage to find their way, even when their compass readings are unreliable, simply by sticking  together.

To test the idea, they created a computer model to simulate virtual groups of migrating animals, and analyzed how different navigation tactics affected their performance.

The animals in the model begin their journey spread out over a wide area, encountering others along the route. The direction an animal takes at each step along the way is a balance between two competing impulses: to band together and stay with the group, or to head towards a specific destination, but with some degree of error in finding their bearings.

The scientists found that, even when the simulated animals started to make more mistakes in reading their magnetic map, the ones that stuck with their neighbors still reached their destination, whereas those that didn’t care about staying together didn’t make it.

“We showed that animals are better at navigating in a group than they are at navigating alone,” Granger said.

Even when their magnetic compass veered them off course, more than 70% of animals in the model still made it home, simply by joining with others and following their lead. Other ways of compensating didn’t measure up, or would need to guide them perfectly for most of the journey to accomplish the same feat.

But the strategy breaks down when species decline in number, the researchers found. The team showed that animals who need friends to find their way are more likely to get lost when their population shrinks below a certain density.

Prior to the 1950s, tens of thousands of Kemp’s ridley sea turtles could be seen nesting near Rancho Nuevo, Mexico on a single day. By the mid-1980s the number of nesting females had dropped to a few hundred.

“If the population density starts dropping, it takes them longer and longer along their migratory route before they find anyone else,” Granger said.

Previous studies have made similar predictions, but the Duke team’s model could help future researchers quantify the effect for different species. In some runs of the model, for example, they found that if a hypothetical population dropped by 50% — akin to what monarchs have experienced in the last decade, and some salmon in the last century — 37% fewer of the remaining individuals would make it to their destination.

“This may be an underappreciated aspect of concern when studying population loss,” Granger said.

This research was supported in part by the Air Force Office of Scientific Research (FA9550-20-1-0399) and by a National Defense Science & Engineering Graduate Fellowship to Jesse Granger.

CITATION: “Collective Movement as a Solution to Noisy Navigation and its Vulnerability to Population Loss,” Jesse Granger and Sönke Johnsen. Proceedings of the Royal Society B, Nov. 16, 2022. DOI: 10.1098/rspb.2022.1910

Robin Smith
By Robin Smith

A Peek Inside the Climate Situation (V)room

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As part of this year’s Energy Week at Duke, graduate and undergraduates were able to participate in a competitive “situation room” style event in which participants were split into five teams and given seventy-five minutes to create a plan for expanding EV (electric vehicle) access in Durham. 

For just over an hour in a Fuqua School of Business classroom, my fellow participants and I mulled over the complexities of an issue facing municipalities across the country and produced a variety of solutions, representative of the range of specialties within each group. One more CS-minded group proposed an app to both help residents locate charging stations and help the city collect data on the use of new EV infrastructure, while another group explored the technological and price saving perks of utility pole-mounted charging stations.

The resulting ideas were reviewed by a panel of judges who covered multiple areas of EV expertise: Jennifer Weiss, Senior Advisor for Climate Change Policy at the North Carolina Department of Transportation; Matt Abele, Director of Marketing and Communications at North Carolina Sustainable Energy Association; Sean Ackley, E-Mobility Segment Lead at Hitachi Americas, Ltd.; and Evian Patterson, Assistant Transportation Director in the Durham Department of Transportation.

The goal of Duke’s EnergyWeek is to “promote collaboration, knowledge-sharing, and professional networking” for students interested in the energy sector.  The situation room event was not strictly research oriented – our team rooms had windows and we were given free supper and lemonade – but it promoted the fundamentals of research: idea generation, collaboration, and outside-of-the-box thinking. 

The victors of the 2023 EnergyWeek Situation Room (photo: Michael Wood III)

The teams were tasked with crafting a strategy that combined technical, business, marketing, and policy considerations to increase EV penetration in Durham.  The teams operated under a hypothetical $10 million budget and strategies were to align with the Justice40 initiative, the federal plan to ensure that forty percent of the benefits of new clean transit jobs flow to “disadvantaged communities that are marginalized, underserved, and overburdened by pollution.”

Participants were encouraged to consider “potential barriers to EV adoption, the existing distribution of EV charging stations, and opportunities for community and business involvement” and to be creative.

My team was comprised of students from a range of scholarly backgrounds, from a freshman beginning a mechanical engineering track to a grad student at the Nicholas School with prior work and research in school bus electrification policy.  For our plan, we spent little time discussing electric cars and instead focused on expanding access to electric micro-mobility and electrified public transportation.  

Our team consulted this map from the Durham Bike+Walk Implementation plan in determining that electric cars are not a silver bullet
(map: durhamnc.gov)

We had many reasons for doing so.  Many Durham residents don’t own cars, so the likelihood of increasing the adoption of electric cars in a timely and affordable manner seems low.  Countries around the world are instead focusing on expanding e-bike access, citing, in addition to climate and affordability concerns, the desire to move away from the safety issues and traffic burden of car-centric urban design. 

We saw Durham, which is expected to double in population in just twenty-five years, as a city perfectly positioned to develop around micro-mobility and robust public transportation before it’s too late and set an example for growing urban centers across the country.  We used our $10 million to add bike lanes, fund electric buses, and subsidize electric bikes across income levels.

Our team placed second (no big deal!) and walked away with a full stomach and a rekindled spark to break the Duke bubble and get involved in the exciting development of the Bull City.

My winnings!
By Addie Geitner, Class of 2025

Do Snakes Have Tails? and Other Slithery Questions

Dhruv Rungta, a member of the Wild Ones club, with a ring-necked snake during a herpetology walk with Dr. Nicki Cagle in the Duke Forest.
Upper left: Dr. Nicki Cagle holding a ring-necked snake. Photo by Montana Lee, another Wild Ones member.

On a sunny Friday in September, Dr. Nicki Cagle led a herpetology walk in the Duke Forest with the Wild Ones. The Wild Ones is an undergraduate club focused on increasing appreciation for the natural world through professor-led outings. Herpetology is the study of reptiles and amphibians.

Dr. Cagle is a senior lecturer in the Nicholas School of the Environment at Duke and the Associate Dean of Diversity, Equity, and Inclusion. Along with teaching courses on environmental education and natural history, she is also the science advisor for a citizen science project focused on reptiles and amphibians, or herpetofauna, in the Duke Forest. Volunteers monitor predetermined sites in the Duke Forest and collect data on the reptiles and amphibians they find.

“We get a sense of abundance, seasonality… and how the landscape is affecting what we’re seeing,” Dr. Cagle says. There is evidence that herp populations in the Duke Forest and elsewhere are decreasing.

Dr. Nicki Cagle flipping over a cover board with members of the Wild Ones. The cover boards are used to monitor reptiles and amphibians for a citizen science project in the Duke Forest.

The project relies on transects, “a sampling design… where you have a sampling spot at various intervals” along a line of a predetermined length. In this case, the sampling spots are “traps” meant to attract reptiles and amphibians without harming them. Each site has a large board lying on the ground. “Different herps are more likely to be found under different objects,” Dr. Cagle explains, so the project uses both wooden and metal cover boards.

But why would snakes and other herps want to hide under cover boards, anyway? Reptiles and amphibians are “cold-blooded” animals, or ectotherms. They can’t regulate their own body temperature, so they have to rely on their environment for thermoregulation. Snakes might sun themselves on a rock on cold days, for instance, or hide under a conveniently placed wooden board to escape the heat.

Salamanders that use the cover boards might be attracted to the moist environment, while “snakes will tend to go under cover boards either to hide — like if they’re about to molt and they’re more vulnerable — to look for prey, or just to maintain the proper temperature,” Dr. Cagle says.

Citizen scientists typically check the boards once a week and not more than twice a week. Volunteers have to avoid checking the traps too often because of a phenomenon called “trap shyness,” where animals might start avoiding the traps because they’ve learned to associate them with pesky humans flipping the boards over and exposing their otherwise cozy resting places. By checking the traps less frequently, scientists can reduce the likelihood of that and minimize disturbance to the animals they’re studying.

The first snake we saw was a redbelly snake (Storeria occipitomaculata), dark above with a pink stomach.

Dr. Cagle gave the Wild Ones a behind-the-scenes tour of some of the cover boards. Using a special, hooked tool conveniently stashed in a PVC pipe next to the first cover board, we flipped each board over and looked carefully underneath it for slithery movements. We didn’t find any under the first several cover boards.

But then, under a large sheet of metal, we saw a tiny snake squirming around in the leaf litter. There was a collective intake of breath and exclamations of “snake!”

Dr. Cagle captured it and held it carefully in her hands. Snakes, especially snakes as young as this one, can be all too easily crushed. We gathered around to look more closely at the baby snake, a species with the adorable name “worm snake.” It was dark above with a strikingly pink underside. The pink belly is a key field mark of worm snakes. Earth snakes are also found around here and look similar, but they tend to have tan bellies.

After a minute or two, the worm snake made a successful bid for freedom and wriggled back under the board, disappearing from sight almost immediately.

Crossing over a dry “intermittent stream,” which Dr. Cagle describes as “the running-water equivalent of a vernal pool.” A vernal pool is a temporary wetland that is dry for much of the year.

Some of the cover boards revealed other animals as well. We found a caterpillar chrysalis attached to one and several holes — probably made by small mammals — under another.

Whatever made the holes, we can safely assume it wasn’t a snake. According to Dr. Cagle, the term “snakehole” is misleading. Most snakes don’t make their own holes, though some of them do use existing holes made by other animals. One exception is the bull snake, which is known for digging.

We found a young five-lined skink sunning itself on top of one of the metal cover boards. (Thermoregulation!) Juvenile five-lined skinks are colloquially known as blue-tailed skinks, but the name is somewhat misleading — the adults don’t have blue tails at all.

The snakes we were looking for, meanwhile, were often elusive. Some vanished under the leaf litter before we could catch them. Sometimes it was hard to tell whether we were even looking at a snake at all.

“What are you?” Dr. Cagle muttered at one point, crouching down to get a better look at what was either a stick-esque snake or a snake-esque stick. “Are you an animal? Or are you just a wet something?” (Just a wet something, it turned out.)

The Duke Forest is a valuable community resource with a complicated history. “We know that slavery was practiced on at least four properties” in the Duke Forest, Dr. Cagle says, and the forest is located on the traditional hunting grounds of several indigenous peoples. Today, the Duke Forest is used for research, recreation, timber management, and wildlife management and conservation.

Later on, we found at least three young ring-necked snakes (Diadophis punctatus) under different cover boards. One of them was particularly cooperative, so we passed it around the group. (“All snakes can bite,” Dr. Cagle reminded us, but “some have the tendency to bite less,” and this species “has the tendency not to bite.”) Its small, lithe body was surprisingly strong. The little snake wrapped tightly around one of my fingers and seemed content to chill there. A living, breathing, reptilian ring. That was definitely a highlight of my day.

The faint, dark line on this ring-necked snake’s underside (on the bottom of the loop) is the anal vent. Everything below that point (farther from the head) is considered the official tail of a snake.

If you’ve ever wondered if snakes have tails, the answer is yes. The official cut-off point, Dr. Cagle says, is the anal vent. Everything below that is tail. In between flipping over cover boards and admiring young snakes, we learned about other herps. Near the beginning of our walk, someone asked what the difference is between a newt and a salamander.

“A newt is a type of salamander,” Dr. Cagle says, “but newts have an unusual life cycle where they spend part of their life cycle on land… and that is called their eft phase.” As adults, they return to the water to breed.

We learned that copperheads “tend to be fatter-bodied for their length” and that spotted salamanders cross forest roads in large numbers on warm, rainy nights in early spring when they return to wetlands to breed.

Students holding a ring-necked snake. Above: Kelsey Goldwein (left), Gurnoor Majhail (one of the co-presidents of the Wild Ones), and Simran Sokhi (background on right). Below: Emily Courson (left) and Barron Brothers.

Perhaps the most interesting herp fact of the day came near the end of our walk when one of the students asked how you can tell the sex of a snake. Apparently there are two ways. You can measure a snake’s tail (males usually have longer tails), or you can insert a metal probe, blunted at the end, into a snake’s anal vent. Scientists can determine the sex of the snake by how deep the probe goes. It goes farther into the anal vent if the snake is a male. Why is that? Because male snakes have hemipenes — not two penises, exactly, but “an analogous structure that allows the probe to slide between the two and go farther” than it would in a female snake. The more you know…

Looking for snakes on a herpetology outing with Dr. Cagle and the Wild Ones. Photograph by Gurnoor Majhail.

Disclaimer: Handling wild snakes may result in snake bites. It can also be stressful to the snakes. Furthermore, some snakes in this area are venomous, and it’s probably best to familiarize yourself with those before getting close to snakes rather than afterward. Snakes are amazing, but please observe wildlife safely and responsibly.

Bonus snake! I saw this adorable fellow on the Duke Campus and thought it was an earthworm at first. Dr. Cagle thinks it might be a rough earth snake. I did not check to see if it had a tan belly.
Post by Sophie Cox, Class of 2025

What Are Lichens, and Why Does Duke Have 160,000 of Them?

Saxicolous lichens (lichens that grow on stones) from the Namib Desert, and finger lichen, Dactylina arctica (bottom left insert), common in the Arctic, on display in Dr. Jolanta Miadlikowska’s office. The orange color on some of the lichen comes from metabolites, or secondary chemicals produced by different lichen species. The finger lichen is hollow.

Lichens are everywhere—grayish-green patches on tree bark on the Duke campus, rough orange crusts on desert rocks, even in the Antarctic tundra. They are “pioneer species,” often the first living things to return to barren, desolate places after an extreme disturbance like a lava flow. They can withstand extreme conditions and survive where nearly nothing else can. But what exactly are lichens, and why does Duke have 160,000 of them in little envelopes? I reached out to Dr. Jolanta Miadlikowska and Dr. Scott LaGreca, two lichen researchers at Duke, to learn more.

Dr. Jolanta Miadlikowska looking at lichen specimens under a dissecting microscope. The pale, stringy lichen on the brown bag is whiteworm lichen (Thamnolia vermicularis), used to make “snow tea” in parts of China.

According to Miadlikowska, a senior researcher, lab manager, and lichenologist in the Lutzoni Lab (and one of the Instructors B for the Bio201 Gateway course) at Duke, lichens are “obligate symbiotic associations,” meaning they are composed of two or more organisms that need each other. All lichens represent a symbiotic relationship between a fungus (the “mycobiont”) and either an alga or a cyanobacterium or both (the “photobiont”). They aren’t just cohabiting; they rely on each other for survival. The mycobiont builds the thallus, which gives lichen its structure. The photobiont, on the other hand, isn’t visible—but it is important: it provides “food” for the lichen and can sometimes affect the lichen’s color. The name of a lichen species refers to its fungal partner, whereas the photobiont has its own name.

Lichen viewed through a dissecting microscope. The black speckles visible on some of the orange lichen lobes are a “lichenicolous” fungus that can grow on top of lichen. There are also “endolichenic fungi… very complex fungal communities that live inside lichen,” Miadlikowska says. “We don’t see them, but they are there. And they are very interesting.”

Unlike plants, fungi can’t perform photosynthesis, so they have to find other ways to feed themselves. Many fungi, like mushrooms and bread mold, are saprotrophs, meaning they get nutrients from organic matter in their environment. (The word “saprotroph” comes from Greek and literally means “rotten nourishment.”) But the fungi in lichens, Miadlikowska says, “found another way of getting the sugar—because it’s all about the sugar—by associating with an organism that can do photosynthesis.” More often than not, that organism is a type of green algae, but it can also be a photosynthetic bacterium (cyanobacteria, also called blue-green algae). It is still unclear how the mycobiont finds the matching photobiont if both partners are not dispersed together. Maybe the fungal spores (very small fungal reproductive unit) “will just sit and wait” until the right photobiont partner comes along. (How romantic.) Some mycobionts are specialists that “can only associate with a few or a single partner—a ‘species’ of Nostoc [a cyanobacterium; we still don’t know how many species of symbiotic and free-living Nostoc are out there and how to recognize them], for example,” but many are generalists with more flexible preferences. 

Two species of foliose (leaf-like) lichens from the genus Peltigera. In the species on the left (P. canina), the only photobiont is a cyanobacterium from the genus Nostoc, making it an example of bi-membered symbiosis. In the species on the right (P. aphthosa), on the other hand, the primary photobiont is a green alga (which is why the thallus is so green when wet). In this case, Nostoc is a secondary photobiont contained only in the cephalodia—the dark, wart-like structures on the surface. With two photobionts plus the mycobiont, this is an example of tri-membered symbiosis.

Lichens are classified based on their overall thallus shape. They can be foliose (leaf-like), fruticose (shrubby), or crustose (forming a crust on rocks or other surfaces). Lichens that grow on trees are epiphytic, while those that live on rocks are saxicolous; lichens that live on top of mosses are muscicolous, and ground-dwelling lichens are terricolous. Much of Miadlikowska’s research is on a group of cyanolichens (lichens with cyanobacteria partners) from the genus Peltigera. She works on the systematics and evolution of this group using morphology-, anatomy-, and chemistry-based methods and molecular phylogenetic tools. She is also part of a team exploring biodiversity, ecological rules, and biogeographical patterns in cryptic fungal communities associated with lichens and plants (endolichenic and endophytic fungi). She has been involved in multiple ongoing NSF-funded projects and also helping graduate students Ian, Carlos, Shannon, and Diego in their dissertation research. She spent last summer collecting lichens with Carlos and Shannon and collaborators in Alberta, Canada and Alaska. If you walk in the sub basement of the Bio Sciences building where Bio201 and Bio202 labs are located, check out the amazing photos of lichens (taken by Thomas Barlow, former Duke undergraduate) displayed along the walls! Notice Peltigera species, including some new to science, described by the Duke lichen team.

Lichens have value beyond the realm of research, too. “In traditional medicine, lichens have a lot of use,” Miadlikowska says. Aside from medicinal uses, they have also been used to dye fabric and kill wolves. Some are edible. Miadlikowska herself has eaten them several times. She had salad in China that was made with leafy lichens (the taste, she says, came mostly from soy sauce and rice vinegar, but “the texture was coming from the lichen.”). In Quebec, she drank tea made with native plants and lichens, and in Scandinavia, she tried candied Cetraria islandica lichen (she mostly tasted the sugar and a bit of bitterness, but once again, the lichen’s texture was apparent).

In today’s changing world, lichens have another use as well, as “bioindicators to monitor the quality of the air.” Most lichens can’t tolerate air pollution, which is why “in big cities… when you look at the trees, there are almost no lichens. The bark is just naked.” Lichen-covered trees, then, can be a very good sign, though the type of lichen matters, too. “The most sensitive lichens are the shrubby ones… like Usnea,” Miadlikowska says. Some lichens, on the other hand, “are able to survive in anthropogenic places, and they just take over.” Even on “artificial substrates like concrete, you often see lichens.” Along with being very sensitive to poor air quality, lichens also accumulate pollutants, which makes them useful for monitoring deposition of metals and radioactive materials in the environment.

Dr. Scott LaGreca with some of the 160,000 lichen specimens in Duke’s herbarium.

LaGreca, like Miadlikoska, is a lichenologist. His research primarily concerns systematics, evolution and chemistry of the genus Ramalina. He’s particularly interested in “species-level relationships.” While he specializes in lichens now, LaGreca was a botany major in college. He’d always been interested in plants, in part because they’re so different from animals—a whole different “way of being,” as he puts it. He used to take himself on botany walks in high school, and he never lost his passion for learning the names of different species. “Everything has a name,” he says. “Everything out there has a name.” Those names aren’t always well-known. “Some people are plant-blind, as they call it…. They don’t know maples from oaks.” In college he also became interested in other organisms traditionally studied by botanists—like fungi. When he took a class on fungi, he became intrigued by lichens he saw on field trips. His professor was more interested in mushrooms, but LaGreca wanted to learn more, so he specialized in lichens during grad school at Duke, and now lichens are central to his job. He researches them, offers help with identification to other scientists, and is the collections manager for the lichens in the W.L. and C.F. Culberson Lichen Herbarium—all 160,000 of them.

The Duke Herbarium was founded in 1921 by Dr. Hugo Blomquist. It contains more than 825,000 specimens of vascular and nonvascular plants, algae, fungi, and, of course, lichens. Some of those specimens are “type” specimens, meaning they represent species new to science. A type specimen essentially becomes the prototype for its species and “the ultimate arbiter of whether something is species X or not.” But how are lichens identified, anyway?

Lichenologists can consider morphology, habitat, and other traits, but thanks to Dr. Chicita Culberson, who was a chemist and adjunct professor at Duke before her retirement, they have another crucial tool available as well. Culbertson created a game-changing technique to identify lichens using their chemicals, or metabolites, which are often species-specific and thus diagnostic for identification purposes. That technique, still used over fifty years later, is a form of thin-layer chromatography. The process, as LaGreca explains, involves putting extracts from lichen specimens—both the specimens you’re trying to identify and “controls,” or known samples of probable species matches—on silica-backed glass plates. The plates are then immersed in solvents, and the chemicals in the lichens travel up the paper. After the plates have dried, you can look at them under UV light to see if any spots are fluorescing. Then you spray the plates with acid and “bake it for a couple hours.” By the end of the process, the spots of lichen chemicals should be visible even without UV light. If a lichen sample has traveled the same distance up the paper as the control specimen, and if it has a similar color, it’s a match. If not, you can repeat the process with other possible matches until you establish your specimen’s chemistry and, from there, its identity. Culberson’s method helped standardize lichen identification. Her husband also worked with lichens and was a director of the Duke Gardens.

Thin-layer chromatography plates in Dr. LaGreca’s office. The technique, created by Dr. Chicita Culberson, helps scientists identify lichens by comparing their chemical composition to samples of known identity. Each plate was spotted with extracts from different lichen specimens, and then each was immersed in a different solvent, after which the chemicals in the extracts travel up the plate . Each lichen chemical travels a characteristic distance (called the “Rf value”) in each solvent. Here, the sample in column 1 on the rightmost panel matches the control sample in column 2 in terms of distance traveled up the page, indicating that they’re the same species. The sample in column 4, on the other hand, didn’t travel as far as the one in column 5 and has a different color. Therefore, those chemicals (and species) do not match.

LaGreca shows me a workroom devoted to organisms that are cryptogamic, a word meaning “hidden gametes, or hidden sex.” It’s a catch-all term for non-flowering organisms that “zoologists didn’t want to study,” like non-flowering plants, algae, and fungi. It’s here that new lichen samples are processed. The walls of the workroom are adorned with brightly colored lichen posters, plus an ominous sign warning that “Unattended children will be given an espresso and a free puppy.” Tucked away on a shelf, hiding between binders of official-looking documents, is a thin science fiction novel called “Trouble with Lichen” by John Wyndham.

The Culberson Lichen Herbarium itself is a large room lined with rows of cabinets filled with stacks upon stacks of folders and boxes of meticulously organized lichen samples. A few shelves are devoted to lichen-themed books with titles like Lichens De France and Natural History of the Danish Lichens.

Each lichen specimen is stored in an archival (acid-free) paper packet, with a label that says who collected it, where, and on what date. (“They’re very forgiving,” says LaGreca. “You can put them in a paper bag in the field, and then prepare the specimen and its label years later.”) Each voucher is “a record of a particular species growing in a particular place at a particular time.” Information about each specimen is also uploaded to an online database, which makes Duke’s collection widely accessible. Sometimes, scientists from other institutions find themselves in need of physical specimens. They’re in luck, because Duke’s lichen collection is “like a library.” The herbarium fields loan requests and trades samples with herbaria at museums and universities across the globe. (“It’s kind of like exchanging Christmas presents,” says LaGreca. “The herbarium community is a very generous community.”)

Duke’s lichen collection functions like a library in some ways, loaning specimens to other scientists and trading specimens with institutions around the world.

Meticulous records of species, whether in databases of lichens or birds or “pickled fish,” are invaluable. They’re useful for investigating trends over time, like tracking the spread of invasive species or changes in species’ geographic distributions due to climate change. For example, some lichen species that were historically recorded on high peaks in North Carolina and elsewhere are “no longer there” thanks to global warming—mountain summits aren’t as cold as they used to be. Similarly, Henry David Thoreau collected flowering plants at Walden Pond more than 150 years ago, and his samples are still providing valuable information. By comparing them to present-day plants in the same location, scientists can see that flowering times have shifted earlier due to global warming. So why does Duke have tens of thousands of dried lichen samples? “It comes down to the reproducibility of science,” LaGreca says. “A big part of the scientific method is being able to reproduce another researcher’s results by following their methodology. By depositing voucher specimens generated from research projects in herbaria like ours, future workers can verify the results” of such research projects. For example, scientists at other institutions will sometimes borrow Duke’s herbarium specimens to verify that “the species identification is what the label says it is.” Online databases and physical species collections like the herbarium at Duke aren’t just useful for scientists today. They’re preserving data that will still be valuable hundreds of years from now.

Symposium Explores How People and Nature are Inextricably Entwined

The massive Keeler Oak, a white oak (Quercus alba) in New Jersey.

An April symposium at Grainger Hall, People and Nature, brought a diverse set of speakers, both from Duke and other U.S. institutions, to examine the relationship between human culture and land and to discuss pressing issues such as environmental justice. The session was organized by PhD students Nicholas School of the Environment and the biology department.

Paul Manos of Duke Biology

Professor Paul Manos of Duke Biology told us  how oaks, ubiquitous tree species in temperate regions, can make people think about nature. A walk in the woods looking at the different oaks can result in a fascinating journey of natural history. For those who are curious enough, an inquiry into the lives of oaks will take them deep into topics such as evolutionary history, leaky species boundaries, plant-animal interactions, among others, Manos said. Keeping true to the theme of the symposium, Manos explored some hypotheses about the first time that humans had contact with oaks, and how this relationship unfolded ever since.

Orue Gaoue of Tennessee-Knoxville

Associate Professor Orou G. Gaoue of the University of Tennessee, Knoxville,  took us through a detailed case study of human and plant interactions with long-term data from the country of Benin, in Africa. He showed how the harvest of the African mahogany (Khaya senegalensis) affects human demography and even the marriage dynamics of the Fulani people, with many other insights into the intertwined relationship of the locals and their harvest.

Andrew Curley of Arizona

Central to the morning sessions were the rights of nature and the granting of personhood to non-humans, which is common in the cosmology of many indigenous cultures. For instance, Andrew Curley, assistant professor at the University of Arizona, mentioned in his talk that the O’odham people in the Sonoran Desert confer the Saguaro cactus personhood status. His talk exposed how colonial dynamics have created climate catastrophes and drought around the Colorado River, how indigenous peoples have to navigate these foreign systems, and how they understand their relationship with the land and water.

Michelle Carter, a first-year Masters of Environmental Management (MEM) student at Duke, examined the feasibility of the rights of nature in the US legal system. These rights allow certain natural features (e.g. rivers) to stand as a sole party in litigation and recover damages on their behalf. However, effective application and the enforcement of policy have been lacking.

The second part of the symposium focused on environmental justice. Duke Ph.D. student Maggie Swift presented a land acknowledgement which was divided into three parts: recognition of the violent history of the past; an understanding of the present with a celebration of the lives and achievements of current indigenous peoples; and a call to action so that participants were encouraged to financially support native-led organizations.  Links for donations and more information can be found on the symposium website. The land acknowledgement was followed by a brief presentation on the project Unearthing Duke Forest  that explores the human history surrounding Duke Forest.

Why is it important to jointly consider people and nature in your work? What insights do you gain in your work by taking this approach?

People & NAture
Christine Folch of Duke Cultural Anthropology

Assistant professor Christine Folch, from Duke’s Department of Cultural Anthropology provided an analysis of the discourse around climate change. At the center was the question “do you believe in climate change?” which has ingrained the element of doubt and the ability of the speaker to say “no, I don’t.”  

Associate professor Louie Rivers III, from NC State University,  gave a talk on perceived environmental risks and their influence on social justice. He pointed out that these questions  could be dismissed by certain groups such as black farmers, who are concerned and disproportionally affected by environmental issues but might not relate to how the question is addressed.

Sherri White-Williamson, Environmental Justice Policy director at NC Conservation Network, explained the concept of environmental justice and provided concrete examples of how certain policies (e.g. federal housing/lending policies or interstate highway systems) can create inequalities that leave communities of color to bear the exposure of environmental degradation. She also made us aware that this year is the 40th anniversary of the birth of the US environmental justice movement that started when an African-American community  in Warren County, North Carolina organized to fight a hazardous waste landfill.

No exploration of people and nature would be complete without including the seas. A team of three students at the Duke University Marine Lab, undergrad Maddie Paris, second-year MEM Claire Huang, and Ph.D. student Rebecca Horan, presented two case studies of social and ecological outcomes linked to education and outreach interventions conducted in tropical marine environments.

Their first case study was on turtle education in Grenada, West Indies. Here a 10-week summer program for local children ages 9-12 created an improved understanding of marine turtle biology and its connection to the health of the ocean and their communities. The second case study was a 4-week training course for fisher people and fisheries officers in Mtwara, Tanzania. These participants increased their skills in monitoring the local reefs and were better equipped to educate their communities on marine environmental issues.

The symposium ended with two open questions for the audience, which should be considerations for anyone doing environmental research:  Why is it important to jointly consider people and nature in your work? What insights do you gain in your work by taking this approach?

Guest post by Rubén Darío Palacio, Ph.D. 2022 in Conservation Biology from the Nicholas School of the Environment, and science director of conservation non-profit Fundacion Ecotonos in Colombia.

Measuring What Climate Change Does, Not Just Whether It’s Happening

Duke has a goal of being a “climate university,” Nicholas School of Environment Dean Toddi Steelman said in introducing a panel discussion on Climate Change Science during Research Week. She said it’s a vision in which the university’s focus on climate informs every aspect of its mission, from education and operations to community partnerships – and, of course, research.

Five Duke climate scientists spoke on the Feb. 1 panel, all remotely. (View the Discussion.)

Jim Clark, professor of statistical science at the Nicholas School, described our planet’s climate as a “moving target” when it comes to understanding its impact on biodiversity. Complex connections exist between species, like a “system of interactions” between each other, that responds to climate change.

Our understanding of this system is limited by population data collection like the Breeding Bird Survey and the USDA Forest Inventory & Analysis — projects that lack “co-located monitoring of multiple species groups,” Clark said. Such measures fail to capture the relationships between species.

Professor James Clark

Instead, Clark advocates moving away from static models like these population measurements and towards the question of “How does change in the whole community respond to the environment and other species?” In order to understand our dynamic climate, we need an equally dynamic conception of biodiversity, he argued.

Marc Jeuland, associate professor of public policy and global health, and leader of the Sustainable Energy Researchers Initiative (SETI), talked about the “deep inequities” in energy access across rural parts of developing regions and the prospect of accomplishing “a just and sustainable energy transition” of their energy sources.

He thinks the transition can be accomplished with existing sustainable energy technologies like wind and solar.

The problem has two main parts, he said. First is the lack of clean cooking energy, with 2.6 billion humans dependent on solid fuels (wood and charcoal) and polluting stoves. The second is the lack of electricity and electrical services, with 760 million people going without and millions more lacking reliable service, he said.

Professor Marc Jeuland

Jeuland said there is an urgent need to reallocate resources to spread climate solution technologies in these parts of the world.

Jeuland and his SETI team tirelessly investigate how to overcome energy poverty and the populations they affect most – primarily in Africa and Southern Asia – to understand the feasibility and tradeoffs with the adoption of increased access to alternative fuels.

Emily Bernhardt, the James B. Duke distinguished professor of biogeochemistry in the Nicholas School and chair of Duke Biology, addressed the question of how climate change and sea level rise will impact coastal communities and ecosystems.

She said we don’t really have to wait to see what will happen: predominantly low-income communities along the coast are already suffering the consequences of sea water and extreme weather events. But she said the regions’ struggles remain unsolved and underrepresented because they lack the economic and political power to affect change.

Professor Emily Bernhardt

Whenever an event like a hurricane occurs, coastal plain communities are susceptible to storm surges that introduce salt into freshwater environment – leading to sometimes catastrophic, often long-lasting impacts on existing ecosystems, Bernhardt said.

Bernhardt and hundreds of other scientists along the United States coast are working together on something she called “convergence research” that seeks solutions for coastal and other vulnerable communities. It’s called the Saltwater Intrusion and Sea Level Rise (SWISLR) Research Coordinating Network. 

Betsy Albright, associate professor of environmental science and policy, and Brian McAdoo, associate professor of earth and climate science, shared their zoom-hosting duties.

They talked about social justice and social science in mitigating the impact of climate change. Their work examines the role of local communities and governments in disaster recovery and how they can work to create systems to manage aid and other resources as extreme weather events become more common.

As with most climate issues, marginalized communities are disproportionately impacted by these events, they said. Albright and McAdoo are searching for ways to help these regions create the capacity to respond and become more resilient to future events.

Professor Elizabeth Albright
Professor Brian McAdoo

The climate crisis is arguably the greatest challenge of this generation, but this esteemed panel brought much-needed attention to the obstacles facing every aspect of the world of climate science research and how their research is working to overcome them.

Post by Nhu Bui, Class of 2024

The Climate Crisis is Imminent. These Experts Offer Solutions.

In April of 2019, the first government declared climate change to be a national emergency. Since then, over 1,900 local governments and more than 23 national governments have expressed the same sentiment.

A 2021 report released by the IPCC labeled climate change a ‘code red’ for humanity, and every day more than 2 million people search the term ‘climate crisis’ on Google. So it’s apparent, the climate crisis is imminent. What’s the solution? Experts at Duke’s annual Research Week posed their research-based solutions during a virtual panel hosted on February 1st. (View the Session)

The panel, mediated by Biology professor Mohamed Noor, began with a solution posed by professors Mark Borsuk and Jonathan Wiener. Known as solar radiation modification, SRM is “an attempt to moderate global warming by intentionally increasing the amount of incoming sunlight that is reflected by the atmosphere back to space,” according to Borsuk. Its primary technique is stratospheric aerosol injection. Wiener explained that their research is “trying to understand the risk… And we’re working to study these multiple impacts because all too often, as we’re all familiar with human decision making at the individual level or the governmental public policy level tends to focus on one thing at a time.” However, even with possible governance challenges at play, their research poses an extremely cheap yet effective solution for avoiding some of the worst impacts of climate change.

Dalia Patino Echeverri’s presentation on GRACE, an energy solution.

Next up on the panel was Dalia Patino Echeverri, an associate professor at Duke’s Nicholas School of the Environment. She began by ruminating on the challenges faced in Texas after the snowstorm last year, and how climate change intensified those challenges. Her research focuses on how to address the electricity issues that climate change is producing in our nation, through a system called ‘GRACE’. ‘GRACE’ is a power grid that is risk-aware for clean, smart energy usage.

“It considers the forecast of electricity, the amount of load on the forecast of electricity generation from wind and sun of resources, and looks at the availability of conventional resources to schedule this commercial resources.” said Echeverri. Its operating system is extremely intelligent minimizing expected value and total cost of energy during times of climate crisis.

Brian Silliman’s presentation on Duke Restore.

Finally, a solution was presented from Brian Silliman, the Rachel Carson Distinguished Professor for marine biology. He introduced a more grassroots approach to climate restoration, called Duke Restore.

“A lot of our research and those of others have shown that the presence of restored marine environments greatly protects human societies on the coastline from increasing threat storm surge, and flooding generated in large part by climate change impacts, etc.” Silliman began.

Duke Restore aims to go out into ecosystems and restore the shorelines that have been lost, indirectly aiding in climate crisis alleviation. Silliman is currently collaborating with governments and other conservation organizations to help change the way they plan to restore these ecosystems from the bottom up. ““We’re doing this here in North Carolina with the US Marine Corps, changing the planting designs to switch the restoration trajectory from failure to success.”

Kay Jowers explaining her ideas for a more equitable approach to policy solutions.

Kay Jowers, a Senior Policy Associate at the Duke Nicholas Institute for Environmental Policy Solutions, closed out the panel event with some final thoughts.

“My charge is to give you some food for thought about creating a more supportive environment for environmental and climate justice at Duke,” she began. She explained the need for action as compared to documentation and explained that equitable approaches are needed to avoid a climate disaster.

“In the world of Environmental Justice Studies, the communities, and the scholars have been calling for less problematization and documenting of problems, and more orientation towards solutions.” Her sentiments resonated deeply with the theme of the panel, as solution-based research is of paramount importance in the 21st century.

The Duke Research Week panel on climate change solutions posed tangible explications for the ever imminent climate crisis happening around the world. Though climate change is apparent now more than ever, researchers like these hold the solutions for the future.

Post by Skylar Hughes, Class of 2025

Finding the Tipping Point for Coastal Wetlands

Cypress swamp, eastern North Carolina. Photo by Steve Anderson, Duke

DURHAM, N.C. — The Albemarle-Pamlico Peninsula covers more than 2,000 square miles on the North Carolina coastal plain, a vast expanse of forested swamps and tea-colored creeks. Many people would probably avoid this place, whose dense thickets of cane and shrubs and waterlogged soils can slow a hike to a crawl.

“It’s hard fieldwork,” says Duke researcher Steve Anderson. “It gets really dense and scratchy. That, plus the heat and humidity mixed with the smell of sulfur and the ticks and the poison ivy; it just kind of adds up.”

But to Anderson and colleagues from Duke and North Carolina State University, these bottomlands are more than impenetrable marsh and muck and mosquitoes. They’re also a barometer of change.

Researchers surveying plants in Alligator River National Wildlife Refuge in 2016. Photo by Mathew Stillwagon, North Carolina State University

Most of the area they study lies a mere two to three feet above sea level, which exposes it to surges of ocean water — 400 times saltier than freshwater — driven inland by storms and rising seas. The salt deposits left behind when these waters recede build up year after year, until eventually they become too much for some plants to cope with.

Trudging in hip waders through stunted shrubs and rotting tree stumps, Anderson snaps a picture with his phone of a carpet of partridge berry trailing along the forest floor. In some parts of the peninsula, he says, the soils are becoming so salty that plants like these can no longer reproduce or are dying off entirely.

Along the North Carolina coast, understory plants such as this partridge berry (left) are quickly ceding ground to species such as this bigleaf marsh-elder (right) as the soils become too salty for them to thrive. Credit: Steve Anderson

In a recent study the team, led by professors Justin Wright and Emily Bernhardt of Duke, and Marcelo Ardón of NC State, surveyed some 112 understory plants in the region, making note of where they were found and how abundant they were in relation to salt levels in the soil.

The researchers identified a ‘tipping point,’ around 265 parts per million sodium, where even tiny changes in salinity can set off disproportionately large changes in the plants that live there.

Above this critical threshold, the makeup of the marsh floor suddenly shifts, as plants such as wax myrtle, swamp bay and pennywort are taken over by rushes, reeds and other plants that can better tolerate salty soils.

Certain dwindling plants could be an early warning sign that salt is poisoning inland waters, researchers say. Credit: Steve Anderson

The hope is that monitoring indicator species like these could help researchers spot the early warning signs of salt stress, Anderson says.

This research was supported by grants from the National Science Foundation (DEB1713435, DEB 1713502, and Coastal SEES Collaborative Research Award Grant No. 1426802).

CITATION: “Salinity Thresholds for Understory Plants in Coastal Wetlands,” Anderson, S. M., E. A. Ury, P. J. Taillie, E. A. Ungberg, C. E. Moorman, B. Poulter, M. Ardón, E. S. Bernhardt, and J. P. Wright. Plant Ecology, Nov. 24, 2021. DOI: 10.1007/s11258-021-01209-2.

Salt is poisoning the soils past a point of no return for some marsh plants; one team is trying to pinpoint the early warning signs. By Steve Anderson.

Duke University Energy Week Part 1: The Energy Conference

Organized by students with support from the Duke University Energy Initiative and the Center for Energy, Development, and the Global Environment (EDGE) at The Fuqua School of Business, the 2021 Energy Week at Duke brought together business and technology leaders within the energy industry to provide audience members insight into the industry’s future.

The focal point of this article will be the Energy Conference, which occurred on November 10. If you’re curious about the future of clean energy within North Carolina, my colleague at the Duke Research Blog, Nhu Bui (Class of 2024), wrote a fascinating piece on the Energy Innovation Showcase.

Duke Energy Conference Organizing Team (photo by Jacob Hervey)

Over the course of eight hours, the Conference schedule alternated between a series of keynote addresses and fireside chats. The latter centered around a particular topical focus; each chat involved a faculty moderator and three industry experts whose organizations lie at the cutting edge of the climate transition within the private sector. In addition to the moderator’s questions, conference participants were invited to ask questions about the visions and innovations of their company.

The first fireside chat – Energy Transition Plans, Projects, and Pathways – broadly centered around the decarbonization of the energy industry. The speakers were Mallik Angalakudati, SVP of Strategy & Innovation at Washington Gas, Kirsten Knoepfle-Thorne, General Manager of Strategy at Chevron, and Jon Rodriguez, Energy Business Director of Engine Power Plants at Wartsila. All three acknowledged their companies’ traditional reliance on fossil fuels and stressed the need for emissions reduction moving into the future. The avenues each company was pursuing to reach this end varied considerably from green hydrogen to battery energy storage systems to carbon capture.

The second chat – Renewable Transportation – sought to highlight the latest innovations of firms within the burgeoning electric vehicle (EV) market. The panel consisted of Liz Finnegan (Fuqua ’17), Electric Vehicle Infrastructure and Energy at Rivian, Pei-Wen Hsu (Fuqua ’97), Global EV Marketing Director at Ford, and Kameale Terry, Co-Founder and CEO of ChargerHelp!. From launching new vehicles to servicing software breakdowns at charging stations across the nation, these speakers brought a wealth of perspectives to a high-growth market. They reinforced the certainty and necessity of mass consumer adoption of EV innovations, offering multiple roadmaps for the coming decades in transportation technologies.

Speakers from second fireside chat engaging with audience (photo by Jacob Hervey)

The third chat – Investing in Climate Tech Solutions – addressed the financial side of climate tech solutions. The speakers were Nneka Kibuule, SVP at Aligned Climate Capital, Lisa Krueger, President of US Operations at AES, and Sophie Purdom, co-founder of Climate Tech VC and an early-stage investor. Each speaker targeted climate solutions at different developmental stages, from early-stage ventures to companies ready for their IPOs. Taken as a whole, their firms reflected the robust nature of the financial ecosystem available to aspiring climate entrepreneurs and firms.

The three fireside chats engaged a number of angles through which the private sector can collectively curb climate change. As lab-developed technologies reach sufficient scale, the efficacy of climate solutions depend not solely on the quality of the innovation, but rather the quality of their implementation.

The conference conveniently coincided with the final few days of the COP26 Climate Summit in Glasgow, Scotland. As policy leaders half a world away wrangled over the minutiae of coal usage and climate financing, it became clear that a different sort of conversation was taking place on our campus. By engaging with the Energy Conference, even the most ardent skeptics of climate change progress would find it hard to deny the tangible shift in priorities that have occurred over the past few years. The prioritization of environmental concerns by the energy industry is now a given. The bigger question to consider is whether their plans and promises are sufficient to avert climate disaster.

Post by Vibhav Nandagiri, Class of 2025

Duke University Energy Week Part 2: The Energy Innovation Showcase

Organized by students with support from the Duke University Energy Initiative and the Center for Energy, Development, and the Global Environment (EDGE) at The Fuqua School of Business, Duke University Energy Week brought together business and technology leaders within the energy industry to provide audience members insight into the industry’s future. The focal point of this article will be the Energy Innovation Showcase, which occurred on November 11. If you want a glimpse into the eight hours of energy-focused conversation that happened on November 10, my colleague at the Duke Research Blog, Vibhav Nandagiri (Class of 2025), wrote a fascinating piece on the Energy Conference.

Welcome to the Energy Innovation Showcase (photo by Jacob Hervey)

The evening kicked off with a riveting conversation between Ajulo E. Othow, Esq. (Founder & CEO of EnerWealth Solutions and General Counsel at Carolina Solar Services) and Marshall Cherry (Chief Operating Officer at Roanoke Electric Cooperative), moderated by Duke’s own Dr. Brian Murray (Director of the Duke Energy Initiative and Nicholas Institute for Environmental Policy Solutions). Othow, Cherry, and Murray discussed the future of energy in North Carolina, from exciting prospects for renewable energy to access barriers in rural regions.

Othow, Cherry, and Murray in conversation (photo by Jacob Hervey)

At the conclusion of the keynote discussion, the evening segued into the tabling session, and the audience was released back into the Hub for two hours of mingling with energy representatives. There were spokespeople from every facet of the industry – development companies like Susteon and Good Solar, suppliers like Leyline Renewable Capital and Piedmont Lithium, and advocacy groups like the NC Sustainable Energy Association and the NC Business Council.

Grace Fernandez, Nicholas MEM/MBA student and co-chair of Energy Week, had her concerns about the whole affair at first. It was the first year that Energy Week was conducted through a hybrid of platforms, after being entirely online last year due to the pandemic. Fernandez said that it was hard to convince people – both Duke students and energy representatives – to come, but through determined calls and emails and targeted social media ads, Fernandez succeeded in her goal of getting a “new audience engaged in energy.”

Turns out, Fernandez had no need to worry about turnout. Some of the attendees included Joy and Tenzin (both Trinity ’22), who were not first-timers at the showcase; they came to enjoy the “interactive” aspect for another year and meet new people who had first-hand experience in the energy industry. Nicholas MEM student Anat is not necessarily studying energy, but still came for the “innovative” aspect – to see how new developments in energy might be more interdisciplinary and interconnected.

The attendees I spoke to took note of the fact that all the organizations present came from around North Carolina. Some, like Nicholas MEM student Chayan, would have preferred representation from further away. But others, like Pratt first-year Jack, from the Durham area, came to the showcase specifically to see what local energy companies are up to and what opportunities they may be offering.

Discussing Carolina Solar (photo by Jacob Hervey)

The spotlight on North Carolina was by design: the organizers of Energy Week had taken a different approach to this year’s showcase, specifically seeking to highlight groups from Durham and North Carolina at large. “I wanted Duke students to be able to see the incredible work happening in our own backyard,” said Trey Signorelli, an Energy Week Showcase co-chair. He commented that many Duke students aim to leave North Carolina and take their talents with them, so he wanted to put on display the many exciting opportunities they already had right on their doorstep.

Duke University Energy Week 2021 coincided with the final few days of the COP26 Climate Summit in Glasgow, Scotland. Three thousand miles away, world leaders debated coal usage and policy financing and the future of climate action. But if Thursday’s showcase taught us anything, it’s that if we want to see the future of energy, we don’t have too look far.

Post by Nhu Bui, class of 2024

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