Category: News

By Tyjaha Steele

Heavy rain can change the way water moves through a wetland, sending more water through streams and carrying sediment along with it. For researchers studying contaminated wetlands, those changes can also affect how contaminants move through the environment.

Researchers from the University of Georgia’s Savannah River Ecology Laboratory (SREL), Savannah River National Laboratory and Argonne National Laboratory studied how rainfall affects uranium movement in the Tims Branch wetland at the Savannah River Site in South Carolina. The study was led by Daniel I. Kaplan, senior research scientist in Environmental Molecular Sciences at SREL and associate director of the University of Georgia Artificial Intelligence Research Institute (UGARI), along with Karah Greene, Wei Xing, Arelis Rivera-Giboyeaux, Kenneth Kemner and Peng Lin.

The Tims Branch wetland has held onto most of the uranium released into the area more than 55 years ago. Because much of that uranium is attached to sediment, researchers wanted to understand what happens when heavy rain causes those sediments to move.

“Most of the uranium has remained stored in the wetland, but heavy rainfall gives us a window into how some of that uranium can become mobile again,” Kaplan said. “By understanding that relationship between rainfall, sediment and uranium, we can better understand how contaminants may move through wetlands over time.”

To study this, researchers collected stream water samples every hour during six rainfall events between February and September 2024. The storms brought between 0.69 and 9.87 centimeters of rain and caused streamflow to increase by as much as 11 times its normal level. Researchers measured the amount of uranium in both the water and the suspended sediment carried by the stream.

The results showed that most of the uranium being moved during storms was associated with suspended sediment rather than being dissolved in the water. In some samples, as much as 94% of the uranium was associated with suspended solids. Researchers also found a strong relationship between the amount of sediment in the water and the amount of uranium being transported.

This means that changes in how much sediment a stream carries can provide a useful way to understand how much uranium is being moved during rainfall events. Turbidity, which is a measure of how cloudy the water is, was also closely related to uranium concentrations.

Using rainfall and uranium measurements from the study, researchers estimated that a relatively small portion of the uranium stored in the wetland was remobilized during rainy days in 2024. The three days with the most rainfall accounted for about 29% of the uranium estimated to have moved that year.

The researchers also used historical rainfall data to estimate how much uranium may have been remobilized since the original release. Their calculations suggest that only a small percentage, about 2.2%, of the uranium originally released had been remobilized over the 55 years following the release.

While most of the uranium remains in the wetland, the findings show that rainfall can play a role in moving some of it through the system. The researchers note that increases in total rainfall and extreme rainfall events could increase the rate at which contaminants are transported from wetlands.

The study also builds on previous research showing that wetland sediments can strongly bind uranium, helping keep it in place for decades. During heavy rain, however, some of those sediments can become suspended in the water and move downstream.

Understanding how rainfall affects that movement gives researchers another way to examine how contaminants behave in wetlands over time, particularly as rainfall patterns change.

The study, “Uranium remobilization from a riparian wetland: Implications on long-term stewardship and extreme rain events,” was published in Applied Geochemistry and was authored by Daniel I. Kaplan, Karah M. Greene, Wei Xing, Arelis M. Rivera-Giboyeaux, Kenneth M. Kemner and Peng Lin.

By Tyjaha Steele

A pile of wild boar feces might seem like an unlikely place to look for clues about an animal’s life, but it can contain something researchers are looking for: DNA. Because animals leave genetic material behind as they move through the landscape, researchers can sometimes use those traces to learn about wildlife without having to capture the animals themselves. The challenge is that not every sample contains enough usable DNA to provide the same information.

Noninvasive genetic sampling, which uses materials such as feces, hair, or urine instead of samples collected directly from an animal, allows researchers to study wildlife without having to capture or handle individual animals. These samples can contain DNA from the animal that leaves them behind, although the amount and quality of that DNA can vary depending on the sample and the conditions it experiences.

For wild boar, researchers are interested in using genetic information to understand how populations are connected and how they differ from one another. Researchers from the University of Georgia’s Savannah River Ecology Laboratory (SREL) and Warnell School of Forestry and Natural Resources, Iwate University, the National Institute for Environmental Studies, the Fukushima Prefectural Centre for Environmental Creation, and the Wildlife Symbiosis Centre tested whether DNA from wild boar feces could provide enough information to study those differences.

“Accurate estimates of wild boar population size are essential to optimizing management strategies. Because of their size, lack of distinguishing markings, and secretive nature, traditional mark-recapture techniques are not cost-effective for large-scale population assessments, and so non-invasive techniques like fecal based mark-recapture are a promising alternative for this species,” explains Beasley, a researcher and professor from the University of Georgia’s Savannah River Ecology Laboratory (SREL) and Warnell School of Forestry and Natural Resources.

The researchers were testing a method called multiplexed inter-simple sequence repeat genotyping by sequencing, or MIG-seq, which looks for small differences in an animal’s DNA. These differences, known as genetic markers, can be used to compare individual animals and examine how animals within a population are genetically connected. MIG-seq has been used to study wildlife genetics because it can work with relatively low-quality DNA.

“Previous studies have shown that fecal samples can be useful for studying genetic population structure using methods such as microsatellite and mitochondrial DNA analyses. In our previous study, we used MIG-seq on DNA extracted from muscle tissue and revealed the fine-scale population genetic structure of wild boar. So, we wanted to test whether fecal samples could also be used for MIG-seq and whether we could confirm the same genetic population structure,” shares Saito, an associate professor at Iwate University.

The researchers wanted to know whether feces could provide enough DNA for this type of analysis, and they also wanted to see how the quality of the sample affected the amount of genetic information they could recover. To test the method, researchers collected different types of samples from wild boar in Fukushima, Japan, including muscle tissue, feces collected directly from the animals, and feces left behind in traps.

 

Muscle tissue provided a reference point because it contained a larger amount of the animal’s DNA, allowing researchers to compare how much genetic information they could recover from each type of sample. The team then compared the genetic information found in the different samples to see how closely the fecal samples matched the information found in muscle tissue.

The results differed depending on where the fecal samples were collected. Feces collected directly from the animals contained substantially more usable genetic information than feces collected after being left in traps and exposed to the environment. On average, the samples collected directly from the animals contained 165 effective genetic markers, compared with 279 in the muscle samples, meaning they captured about 59% of the markers found in muscle. Trap-collected feces, however, contained an average of just 10 effective markers, or about 4% of those found in muscle.

That difference means the condition of a fecal sample can affect what researchers are able to learn from it. Feces contain cells from the animal, but once they are left in the environment, the DNA within those cells can degrade and become fragmented over time.

“One of the challenges we faced in this study was that, even when we obtained SNP data from fecal samples collected in the field, DNA from other organisms was amplified more than wild boar DNA. As a result, we could not obtain enough wild boar SNPs from the fecal samples collected in the field,” explains Saito.

The researchers found that the trap-collected samples also had higher error rates than the samples collected directly from the animals, and the amount of usable genetic information decreased as the quality of the DNA declined. Based on those results, the researchers concluded that the trap-collected samples did not provide enough genetic information to conduct population-level analysis using the MIG-seq method tested in this study.

“Feces collected directly from the rectum contained more sufficient DNA than feces collected from the field. Therefore, MIG-seq analysis of the rectal fecal samples detected, on average, 59% of the SNPs detected from muscle tissue. However, in fecal samples collected in the field, the amount of wild boar DNA may decrease and the DNA may become fragmented over time. This may have made it difficult to sufficiently amplify the relatively long DNA fragments targeted by MIG-seq,” shares Beasley.

The results were different for the samples collected directly from the animals. Those samples contained enough DNA to recover more than half of the genetic markers found in the muscle samples, while the field-exposed samples contained far fewer.

The researchers suggest that future work could focus on improving the method so it can better identify wild boar DNA and recover more genetic information from samples exposed to the environment. They also point to other approaches that could be tested, including higher-throughput sequencing and additional types of noninvasive samples.

“Due to their extensive use of wetland habitats where DNA degradation can be more severe, wild boar represent a particularly challenging species for genetic mark-recapture studies. These results, combined with prior studies examining field degradation of wild boar DNA in feces, suggest that further optimization of methods is needed to maximize the potential of molecular-based mark recapture techniques for this species,” states Beasley.

The study tested whether DNA from wild boar feces could provide the information needed for genetic analysis, and the results varied considerably depending on how the samples were collected. Feces collected directly from the animals produced substantially more genetic information than feces that had been exposed to the environment, providing researchers with a clearer picture of the conditions under which this method can and cannot recover genetic information.

The full study, Methodological Test of Genetic Population Structure Using MIG-Seq Analysis from Noninvasively Obtained Wild Boar (Sus scrofa) Feces DNA, was published in Mammal Study. Authors include Rie Saito, Natsuko Ito Kondo, Masanori Tamaoki, JaeIck Jo, Kenji Inami, and James C. Beasley.

September 3, 2026

Contact: Tyjaha Steele, (803) 508-0892

FOR IMMEDIATE RELEASE

Aiken, SC — The Savannah River Ecology Laboratory (SREL) celebrated the research and accomplishments of its graduate students during the laboratory’s 6th Annual Graduate Student Symposium on Sept. 3.

The full-day event provided an opportunity for SREL graduate students to share their research, connect with colleagues and highlight the range of ecological research being conducted at the laboratory. Students presented their work through poster presentations and oral presentations across three sessions.

SREL also welcomed Dr. Daniel Mead as the symposium’s keynote speaker. Drawing from more than two decades of work in vector-borne disease and wildlife health, Mead reflected on 26 years of arbovirus surveillance in Georgia, including the emergence of West Nile virus in the state.

Georgia’s first confirmed detection of West Nile virus came in 2001, when a dead crow from Lowndes County tested positive during statewide wildlife surveillance. Mead was part of the team documenting and responding to the virus as it emerged in Georgia, providing a firsthand perspective on the state’s early experience with West Nile virus and the importance of long-term wildlife disease surveillance.

The symposium also recognized students whose presentations stood out among this year’s research sessions. The 2026 award recipients were:

• Best Poster Presentation: Annie Beadle
• Session 1: Karin Ebey, A Sex Ratio by Incubation Temperature Reaction Norm for the American Alligator Based on Fluctuating Thermal Regimes
• Session 2: Abigail B. Bickle McKittrick, Exploring the Mode and Tempo of Epigenetic Aging Across Taxonomic Groups
• Session 3: Jackson S. Prosser, Influence of Wetland Hydroperiod on Mercury Bioaccumulation Among Watersnakes and Their Amphibian Prey

The symposium highlighted the breadth of research being conducted by SREL’s graduate students, from wildlife physiology and reproductive ecology to aging and contaminant dynamics. Their work contributes to a broader understanding of ecological systems and the challenges facing wildlife and their environments.

SREL is proud to support its graduate students as they develop their research and contribute to the scientific community. The laboratory looks forward to following their work and the research questions they pursue throughout their careers.

The Savannah River Ecology Laboratory, a research unit of the University of Georgia located near Aiken, South Carolina, studies a wide range of ecological research topics, including contaminant transport and ecotoxicology, wildlife ecology, conservation genetics, and ecosystem restoration. For further information, call SREL at 803-508-0892 or e-mail connect-srel@uga.edu.

 

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By Tyjaha Steele

Wildlife-vehicle collisions remain a persistent challenge for both public safety and wildlife conservation, causing billions of dollars in damage each year while injuring thousands of drivers and harming countless animals. Although wildlife crossings, roadside fencing, and warning systems can reduce collisions in some locations, these approaches are often expensive or limited to specific stretches of roadway. As a result, focus has turned towards onboard mitigation methods, such as vehicle lighting, which have the potential to influence wildlife behavior on roadways in which animals and vehicles intersect.   

Researchers from the University of Georgia’s Savannah River Ecology Laboratory (SREL) examined whether different vehicle lighting systems influence how wildlife responds to approaching vehicles at night. Given the rise in usage of LED headlights, researchers were interested in examining how animals responded to LED headlights compared to the older-style warm glowing halogen headlights. The team also tested a rear-facing lightbar mounted on the front of the vehicle, which increased frontal illumination and made more of the vehicle visible to animals at night. The study was led by Carson Pakula, who conducted the research as a doctoral student and is now a postdoctoral research associate at SREL. By studying white-tailed deer and wild pigs at the Savannah River Site (SRS) in South Carolina, the team investigated whether current and modified vehicle lighting could encourage animals to move sooner and create more time for both drivers and wildlife to avoid a collision. 

“Vehicle lighting is an interesting area to investigate because most damaging collisions occur at night. During this time, vehicle lighting is the main source of light on the roadways, which may influence how wildlife respond to approaching vehicles,” says Pakula. “Additionally, most new vehicles are being equipped with LED headlights, yet we currently don’t know if they have beneficial, detrimental, or neutral effect on animal behavior.”

To evaluate how animals responded to different lighting conditions, researchers conducted 95 nighttime driving surveys over a two-year period and documented 612 encounters with white-tailed deer and 176 encounters with wild pigs. Using a specially equipped vehicle outfitted with infrared cameras and multiple lighting configurations, the team compared traditional halogen headlights with modern LED headlights while also testing a lightbar designed to increase frontal illumination around the vehicle. By making more of the vehicle visible at night, the lightbar may provide deer and wild pigs with a more recognizable signal of an approaching threat, potentially increasing the likelihood of an avoidance response. 

Rather than simply recording whether animals were present, researchers focused on how they reacted to approaching vehicles, measuring when they moved, how far away they were when they responded, and whether their reactions occurred early enough to provide adequate stopping distance. 

The study suggests that deer and wild pigs do not respond to approaching vehicles in the same way, and those differences may influence collision risk. 

For white-tailed deer, the type of headlight appeared to have little effect on when animals initiated flight. However, researchers observed that additional illumination provided by the lightbar reduced the tendency for deer to remain stationary as vehicle speed increased, a behavior commonly referred to as “freezing” that can leave both animals and drivers with little time to react. This suggests that the lightbar may help mitigate the increase in collision risk typically associated with faster-moving vehicles. 

However, wild pigs responded differently. The study suggests that pigs exposed to LED headlights initiated flight substantially earlier than those exposed to halogen headlights, and on average they began moving approximately 88.5 meters farther away from approaching vehicles. The rear-facing lightbar also had a beneficial effect, although in a different way than it did for deer. Unlike deer, where the lightbar reduced freezing behavior, wild pigs responded by fleeing at greater distances when vehicles approached at higher speeds. These earlier responses may provide additional time for animals to leave the roadway and for drivers to react, potentially reducing collision risk.  

“Even though our results for deer and pigs were different, we found that overall, LED headlights and frontal vehicle illumination provided by the lightbar both tended to enhance their avoidance responses to the vehicle and increase safety,” explains Travis DeVault, associate director for research and senior research scientist at SREL.

The authors suggest that making more of the vehicle visible at night may help animals better recognize and respond to an approaching threat, helping explain the beneficial effects observed with the lightbar. The differing responses to LED headlights observed in deer and wild pigs may instead reflect differences in behavior and risk perception between the two species.  

These findings are particularly relevant as vehicle technology continues to evolve. Most new vehicles now come equipped with LED headlights, and wildlife across North America is increasingly encountering lighting systems that differ substantially from those used only a few decades ago. 

While no single solution is likely to eliminate wildlife-vehicle collisions, the study suggests that vehicle lighting may influence how animals perceive and respond to approaching vehicles. Specifically, increased frontal illumination of a vehicle appears to provide a low-cost modification that can result in more beneficial wildlife responses. Researchers have tested a variety of mitigation strategies over the years, yet vehicle lighting offers a unique advantage because it travels wherever drivers go and has the potential to influence wildlife behavior during every nighttime encounter on the road. 

“This study demonstrated that both standard vehicle lighting such as headlights and modified lighting that increases vehicle illumination can influence wildlife behavior,” Pakula notes. “These results present exciting opportunities for further research on how exactly lighting affects animal behavior and how vehicle lighting can be tailored to encourage more beneficial wildlife responses.”

By examining how wildlife responds to different lighting conditions, the research provides insight into the complex interactions between animals and vehicles while highlighting practical opportunities to improve safety for both people and wildlife. 

The full study, Modified Vehicle Lighting Reduces Wildlife Collision Risk by Enhancing Deer and Wild Pig Avoidance Responses at Night, was published in the Journal of Applied Ecology. Authors include Carson J. Pakula, Shane Guenin, Jonathon Skaggs, Olin E. Rhodes Jr., and Travis L. DeVault.  

By Tyjaha Steele

Across the southeastern United States, conservationists are working to restore longleaf pine ecosystems, landscapes once common across the region but now greatly reduced from their historic extent. Many plants and animals depend on these fire-maintained habitats, including the Carolina gopher frog, a species that spends much of its life hidden underground and is rarely seen outside a brief breeding season.

At the Savannah River Site (SRS) in South Carolina, researchers from the University of Georgia’s Savannah River Ecology Laboratory (SREL), the USDA Forest Service–Savannah River, and other conservation partners are working together to better understand and protect the species. Led by senior research scientist Stacey Lance, the effort combines habitat restoration, population monitoring, and conservation research to support one of South Carolina’s remaining Carolina gopher frog populations.

The need for that work has become increasingly urgent. Historically, Carolina gopher frogs occurred in three distinct metapopulations at the Savannah River Site and used at least 17 wetlands for breeding. Today, only one of those metapopulations remains, and breeding activity has been documented in just a handful of wetlands in recent years. Researchers have also observed declining genetic diversity within the remaining population, raising concerns about the species’ long-term persistence.

At the same time, restoration efforts are continuing to expand across the landscape. The USDA Forest Service–Savannah River has developed a comprehensive habitat restoration plan aimed at improving more than 3,000 acres of gopher frog habitat through prescribed fire, forest thinning, wetland restoration, and improvements to habitat connectivity.

Together, these efforts are designed to restore the open-canopy wetlands and longleaf pine habitats that gopher frogs depend upon. Yet one challenge remains: understanding how frogs use the landscape beyond the breeding season.

Finding What The Naked Eye Can’t See

Carolina gopher frogs breed in isolated seasonal wetlands, but adults spend most of the year in surrounding upland habitats where they shelter in underground refuges and dense vegetation. Because they are so difficult to detect, researchers often know far more about where frogs breed than where they spend the majority of their lives.

To help address that challenge, Lance partnered with wildlife biologist Dr. Karen DeMatteo and her conservation detection dog, DJ. Unlike traditional surveys that rely on visual observations or breeding-season activity, DJ is trained to locate gopher frogs using scent. Working through upland habitats, he searches for frogs hidden beneath vegetation or occupying underground refuges that would otherwise be difficult, and sometimes impossible, for researchers to locate.

The partnership began in 2023, when DeMatteo and DJ traveled to the Savannah River Site to help researchers locate recently metamorphosed gopher frogs released as part of a headstarting program. Those early efforts helped expose DJ to the scent of the species under a variety of conditions and demonstrated that conservation detection dogs could play an important role in amphibian monitoring.

A follow-up effort expanded the work to adult frogs, focusing on upland habitats and winter refuges, one of the least understood portions of the species’ life cycle. Trained using positive reinforcement, DJ performs a passive alert when he detects the scent of a gopher frog, stopping and staring at DeMatteo until he receives his reward. For researchers, each alert provides valuable information about where frogs are living across the landscape.

A Common Goal

While DJ’s role often draws attention, the project represents something much larger than a single dog or survey effort. It reflects years of collaboration among researchers, wildlife specialists, conservation agencies such as The Longleaf Alliance, and land managers working toward the same goal: ensuring the long-term survival of the Carolina gopher frog. Early support from Lisa Lord and The Longleaf Alliance helped bring many of these partners together and played an important role in launching the broader conservation effort.

That collaboration has helped support monitoring efforts, including the use of conservation detection dogs to better understand how Carolina gopher frogs use the landscape. Information gathered through detection dog surveys helps researchers better understand how far frogs travel from breeding wetlands, which habitat features they rely upon, and whether restored areas are being used. Those findings can then inform future management decisions, helping partners refine restoration efforts and prioritize areas most important to the species.

Each frog located provides another piece of a much larger puzzle. Together, those pieces help researchers evaluate habitat restoration, improve conservation planning, and build a clearer picture of what Carolina gopher frogs need to survive.

By combining ecological research, habitat restoration, and innovative monitoring tools, partners across the Savannah River Site are working to ensure that Carolina gopher frogs remain part of the longleaf pine ecosystem for generations to come.