1. Scavenging ecology: Dr. James Beasley (Assistant Professor, SREL)
Scavenging ecology is an understudied aspect of basic ecosystem services, especially as it pertains to contaminant flow through food webs in diverse ecosystems. In particular, heavy metals and radionuclide transport via scavenging of vertebrate remains is a direct pathway for contaminant uptake and, as data generated by our research group has demonstrated, is a much larger link for energy transfer in trophic networks than has previously been thought. Research experiences for undergraduates will involve experimental camera-trap trials for the study of vertebrate, invertebrate, and microbial utilization of natural and human-mediated vertebrate carrion. Data from camera-trap trials will be used to parameterize risk assessment models for contaminant uptake. Specifically, undergraduates will design and implement individual experiments focused on vertebrate utilization of carrion and will participate as members of the broader team of faculty, graduate students, and postdocs working on contaminant transfer via invertebrate and microbial pathways. It is expected that data collected by the REU participants will be used in part or in whole as the basis for development of a publication in the primary literature on which they will participate as an author. The student involved in this research also will have the opportunity to work on numerous ongoing related studies within the PIís lab and more broadly within SREL.
2. Bioaccumulation of radionuclides in terrestrial and aquatic ecosystems: Dr. James Beasley (Assistant Professor, SREL)
Although bioaccumulation of radionuclides has been documented in aquatic ecosystems, radionuclide transport among trophic levels remains an understudied area of research, especially in terrestrial environments. In particular, few data are available regarding contaminant burdens in mammals or the effects of chronic, low-dose exposure to radiation in free-ranging wildlife. This project will involve live capture and handling of various wildlife species across multiple control (non-contaminated) and experimental (areas with known radiocesium legacy in sediments) sites throughout the Savannah River Site to quantify the relationship between trophic position and radionuclide burden, as well as whether accumulation of radiocesium varies among landscapes with disparate levels of legacy contamination. This research also may involve assessment of various sub-lethal health effects (e.g., blood biochemistry, physiological stress, blood parasite loads, etc.) as a function of chronic, low-dose exposure to radiation. Specifically, undergraduate students involved in this research will assist in the design and implementation of field experiments focused on quantifying radionuclide accumulations and the sub-lethal health impacts of elevated radiation exposure in wild animals. Students will participate as members of a broader team of faculty, graduate students, and post-docs working in this area of research at SREL. Undergraduates participating in this research will be involved in hands on collection of data including capture and handling of various species, collection and analysis of biological samples, and measurement of radiocesium burdens. It also is expected that the data undergraduates collect will be used in part or in whole as the basis for the development of a publication in the primary literature on which they will participate as an author. Students could be co-mentored under related programs.
3. Radiocesium in biota associated with an abandoned reactor effluent canal and settling basin: Larry Bryan (Research Professional, SREL)
Legacy radiocesium contamination has been documented in sediments associated with various aquatic systems associated with historical production of defense materials, including canals, streams, ponds and impoundments. Bioaccumulation of radiocesium has been documented by some species in selected aquatic systems. Students participating in this program would conduct independent research projects examining radiocesium uptake in aquatic and/or terrestrial biota within these aquatic systems, and possibly their prey (e.g.; biofilms, seeds, plants, insects, etc.), as time/funding allows. The student(s) will work to finalize project design and learn sampling equipment assembly. Working within protocols established for the contaminated systems, students will be involved in sample collection, sample preparation for analysis, and actual analysis for radiocesium. Depending on the study organisms, students may also examine the influence of external (e.g., on skin or in fur) and internal (e.g., in gut tube) sediments on overall radiocesium concentrations of individuals, and how the differences in concentrations may influence assessment of risk. Students may also be able to assess potential trophic effects of the cesium uptake (e.g.; variation in radiocesium in plants relative to herbivorous insects, etc.). Participation in development and production of subsequent publications resulting from research results is possibly, but depends on study results. This project, particularly the prey base sampling and analyses, will create opportunities to collaborate with and potentially provide supportive information for other programs.
4. Effects of contaminants on mosquito immunity and vector competence: Dr. Guha Dharmarajan (Assistant Research Scientist, SREL)
Mosquitoes transmit many diseases to humans and animals all over the world. Even today over a million people die from mosquito-borne diseases every year. The factors affecting the ability of mosquitoes to transmit diseases to humans and animals remains one of the most important challenges in controlling mosquito-borne disease. One specific area of interest in our lab is to understand how exposure to heavy metals and/or radionuclides during the aquatic larval stage of the mosquito lifecycle affects the ability of adult mosquitoes to fight parasite infection (immunity), survive the negative effects of being infected with parasites (tolerance) and transmit parasites to the next vertebrate host (vector competence). Research experiences for undergrads in this project will involve field sampling of mosquitoes, as well as lab-based experiments on mosquito immunity, tolerance and vector competence. Our lab utilizes an interdisciplinary approach to addressing research questions. Thus, undergraduates will be encouraged to design their own specific experiments utilizing a broad range of tools Ė ecological, entomological, molecular and computational Ė under the guidance of the faculty member, postdocs and/or graduate students. It is expected that data collected by the REU participants will be used in part or in whole as the basis for development of a publication in the primary literature on which they will participate as an author.
5. Contaminant distribution in sediments of a complex stream system: Dean Fletcher (Research Professional, SREL)
Industrial areas on the Savannah River Site potentially impact stream systems via numerous outfalls and runoff routes. Evaluating environmental contamination is an essential component of assessing stream condition. Insects and crustaceans, critical components of aquatic communities, are essential for movement of primary production into aquatic food webs and its transfer to higher trophic levels such as fishes, amphibians, reptiles and birds. Consequently macroinvertebrates are known to be instrumental in the movement of bioavailable contaminants into and through a food web. In addition to stream sediments, analyzing contaminant accumulation in macroinvertebrates enhances environmental assessments by verifying which contaminants are bioavailable and actually entering biotic communities. Because adults of many stream aquatic insects are flying terrestrial organisms, aquatic insects also represent a potential vector of transport of contaminants from aquatic to terrestrial food webs. Comparison of different functional feeding groups allows discernment of potential vectors of contaminant uptake and trophic transfers. Habitat specificity, even within closely related taxa such as dragonfly nymphs provide an exceptional opportunity to compare contaminant accumulation in syntopic macroinvertebrates that are all predators within the same order (Odonata) and suborder (Anisoptera), but differ vastly in their habitat use and body form. The project will assess contaminant dynamics in these critical components of aquatic communities. The student will participate in sample collection and laboratory preparation for chemical analyses that will include mercury employing a direct mercury analyzer and radiocesium using a gamma-counter. Analyses may also include assessing trace elements on an ICP-MS. Overall, the project will provide opportunity for the student to learn an array of field and laboratory techniques while establishing levels of contaminants entering aquatic communities.
6. Amphibian ecotoxicology and disease susceptibility: Dr. Stacey Lance (Associate Research Scientist, SREL)
Environmental contaminants and emerging diseases have been implicated as a contributing factor to the global decline of amphibian populations. Amphibians are susceptible to exposure from a wide variety of contaminants including organics such as pesticides and phenols, and inorganics such as metals/metalloids and fertilizers. Numerous studies have examined the lethal or sub-lethal effects of organic contaminants on amphibians; these effects can include increased mortality, decreased growth rates, malformations, endocrine disruption, and immunosuppression. However, substantially less is known concerning the effects of metals and radionuclides on amphibian populations. In addition, almost nothing is known concerning the interaction of contaminant and disease stressors. Working with Dr. Lance and in collaboration with co-PI David Scott, the REU student associated would be directly involved in studies designed to examine the impacts of radionuclides, metals, and mixed contaminants on amphibians. Impacts examined may include survival, time to metamorphosis, size at metamorphosis, susceptibility to disease, behavioral endpoints, metal body burdens, and gene expression. Several species (including eastern narrowmouth toads, southern toads, and spadefoot toads) can breed in late May/early June and have rapid development (30-60 days). Our typical studies involve a factorial design with multiple source populations, clutches, treatments and replicates and therefore can get very largeówith over 400 tadpoles per experiment. We can run highly controlled experiments in SRELís Animal Care Facility and also less controlled experiments in situ in a variety of contaminated wetlands/streams on the SRS. Thus students would get hands on experience in all aspects of running a large experiment with live organisms in the lab and in the field. Students would be involved in all aspects of design, data collection, and analysis and could collaborate with other related programs.
7. Interaction between radiation exposure and heavy metals on the incidence of antibiotic resistance in aquatic bacteria: Dr. J Vaun McArthur (Senior Research Scientist, SREL)
One of the legacies left by mankind during their rapid colonization of the earth has been heavy metal pollution. Heavy metals, like lead, mercury, arsenic, and cadmium, have been used in a wide variety of industrial, energy and technological processes. The direct effects of heavy metals on organisms are severe and can often be lethal. Another legacy created by man over the last 50+ years is the increase in antibiotic resistance in disease-causing or pathogenic bacteria of bacteria. This phenomenon is thought to be the direct result of the misuse and over-prescription of antibiotic containing drugs. The problem is getting more acute with fewer antibiotic drugs being effective and more bacteria showing resistance to multiple drugs. A final legacy is radioactive contamination, which has been acutely accentuated with recent releases from reactors in Japan. Bacteria can become resistant to the effects of both heavy metals and to antibiotics. We have demonstrated that bacteria exposed to heavy metals have increased incidences of antibiotic resistance to a variety of clinically relevant drugs. There are several unanswered questions regarding the mechanisms of acquisition of antibiotic resistance traits and nothing is known about the effects of mixed wastes (rads and metals) on the incidence of resistance. REU students will work on projects to determine how exposure to radiation affects the acquisition of resistance traits under controlled and replicated factorial experiments using metals and radiation. Others could study the lateral transfer of resistance genes in various environmental matrices among stressed bacteria using GFP-labeled bacteria that fluoresce when receiving a plasmid or have plasmids that fluoresce after being transferred. Students could be co-mentored under related programs.
8. Identifying the influence of environmental quality on fundamental aging processes: Dr. Ben Parrott (Assistant Professor, SREL)
The underlying etiology of many complex disease phenotypes is intimately associated with age-associated processes. Epigenetic mechanisms integrate environmental signals into biological responses, and the epigenome undergoes stereotypical age-associated changes over the course of the vertebrate lifespan. Accelerated epigenetic aging (epigenetic age vs. chronological age) is linked to disease risk and mortality in humans. Recently, we observed that mercury exposure is correlated to accelerated epigenetic aging in the American alligator, suggesting that epigenetic aging might have environmental determinants. This project will examine the interaction between environmental exposures and epigenetic aging in several fish species located on the Savannah River Site.
9. Contaminant uptake in aquatic species: Dr. Gene Rhodes (Director and Professor, SREL)
Contaminant uptake subsequent to disturbance is an important area of ecotoxicology, especially as it pertains to resurgence of contaminant flow through food webs in diverse aquatic ecosystems. In particular, heavy metals and radionuclide transport into game species (e.g.,largemouth bass) that may potentially be consumed by humans is an important area of research. Research experiences for undergraduates in this project will involve capture, marking, and sampling of largemouth bass in the Par Pond Reservoir on the Savannah River Site. The Par Pond Reservoir has been the focus of much past research on contaminant concentrations in soil, water, and biota and has a legacy of contamination with both heavy metals and radionuclides. The focus of this research is to evaluate metal and radionuclide contamination in largemouth bass subsequent to a major perturbation of this reservoir, which occurred in the 1990ís. Data on population size, movement behavior and contaminant loads of largemouth bass will be used to parameterize risk assessment models for contaminant uptake of this species. Specifically, undergraduates will conduct experiments focused on estimation of population size, movement, and contaminant concentrations in largemouth bass as members of the broader team of faculty, graduate students, and postdocs working on contaminant transfer in aquatic systems. It is expected that data collected by the REU participants will be used in part or in whole as the basis for development of a publication in the primary literature on which they will participate as an author. The student involved in this research also will have the opportunity to work on numerous ongoing related studies within the PIís lab and more broadly within SREL.
10. In situ immobilization of radionuclides and metals: Dr. John Seaman (Senior Research Scientist, SREL)
The disposition of radioactive waste is a major environmental concern facing both the federal government and the nuclear industry. While the disposition of high level waste remains an issue, especially for the nuclear industry, the development of methods for remediating large areas that are marginally contaminated with radionuclides and other contaminants remains a major challenge at sites within the US and abroad. Less expensive in situ contaminant immobilization strategies typically rely on the introduction of chemical additives chosen to alter target contaminant speciation in a manner that enhances solid-phase partitioning in order to reduce migration, bioavailability and ultimately the associated exposure hazard. However, the use of in situ remediation techniques requires a fundamental understanding of the underlying geochemical processes, as the contaminant remains in place with the potential to become a hazard at a later date. REU students will participate in research that focuses on improving our understanding of the chemical speciation, and fate and transport of radionuclides (e.g., U, 137Cs, 99Tc, etc.) in the environment, and the development and testing of both short- and long-term radioactive waste containment strategies.
11. Long-lived reptiles as ecological receptors: Drs. Tracey Tuberville (Associate Research Scientist, SREL) & Melissa Pilgrim (Director of Research and Associate Professor, University of South Carolina Upstate)
Fifty-eight reptile species occur on the SRS, and many are susceptible to accumulating significant body burdens of a variety of contaminants due to their relatively long life spans, physiology, high trophic status, and use of both aquatic and terrestrial habitats. Thus, reptiles can serve as ecological receptors for assessing risks associated with long-term contaminant exposure. We will use a variety of field and laboratory approaches to study the biological effects of exposure to radiological and metal contaminants in long-lived reptiles at the individual, population and community levels. Specifically, students working with us will develop and conduct independent research projects conceptually centered on (1) factors affecting the assimilation and transfer of contaminants among biota, (2) the physiological consequences and sublethal effects associated with exposure to or bioaccumulation of contaminants, or (3) integration of archived samples and historical mark -recapture data into studies of contaminant dispersion among biota and contaminant persistence through time. We will help our students formalize project goals and a research plan within these three study areas. Our students will also assist other lab members in related ongoing research projects. Exposure to and participation in ongoing projects will increase student interactions with other lab members and broaden the scope of research techniques they experience while at SREL, including live-trapping techniques, animal handling (e.g., body measurements and collection of biological samples), and a suite of laboratory procedures, such as respirometry, bacteria killing assays, corticosterone assays, the preparation of samples for isotope and heavy metal analysis and wildlife health diagnostic profiles. Students may be co-mentored through collaborations with other programs.