The Kennedy Center conducts original applied and basic research on waterfowl, wetlands, and other wetland-dependent wildlife. Our research addresses the issues managers face, and we provide solutions to improve the management of wetlands and waterfowl on public and private lands.
Mapping climate vulnerability: Per- and polyfluoroalkyl substances (PFAS) in the South Carolina coastal plain.
Coastal wetlands serve as transitional systems that filter contaminated stormwater runoff and industrial discharges, often sequestering and transforming harmful pollutants. However, contaminants of emerging concern that resist degradation, such as per- and polyfluoroalkyl substances (PFAS), persist and accumulate in wetland systems. To address heightened climate influence on these low elevation systems, this study will synthesize contaminant concentrations with meteorological and landscape drivers of PFAS presence in South Carolina’s coastal plain surface waters, to map watershed vulnerability. To do this, we compiled publicly available contaminant datasets with collected surface water samples to create an interpolated layer of surface water concentrations in Arc GIS Pro. PFAS were isolated from water using solid phase extraction and analyzed using liquid chromatography tandem mass spectrometry (LC-MS/MS). We selected statistically downscaled meteorological projections within categories of hydrology, precipitation, and sea level rise under two greenhouse gas emission scenarios. We will integrate these normalized values with landscape metrics that influence the deposition of PFAS into natural surface waters, such as landcover change, soil types, stormwater pond density, and percent impervious surfaces. The resulting vulnerability indices (0-1) will reveal which coastal watersheds are most susceptible to contaminant exposure, and how that vulnerability varies under multiple greenhouse gas emission scenarios. By integrating climate and landscape variables, this approach translates complex environmental dynamics into interpretable vulnerability maps.
A spatiotemporal comparison of per- and polyfluoroalkyl substances (PFAS) in dated estuary sediments.
Per- and polyfluoroalkyl substances (PFAS) are a group of over 20,000 synthetic molecules characterized by a carbon chain bound to fluorine atoms. The molecular structure and composition of these molecules result in hydrophobic, or water-repellant, and lipophobic, or fat-repellant, properties desirable in many consumer and industrial products. The combined effect of widespread production and use with environmental persistence has resulted in the detection of PFAS across environmental and biotic matrices. The type and concentration of PFAS are conventionally analyzed using liquid chromatography tandem mass spectrometry (LC-MS/MS) to quantitate a fixed number of PFAS. Alternative methods use a measurement of total fluorine as a nontargeted proxy for total estimated PFAS concentration within a sample. Although this method is constrained to concentration estimations and cannot identify individual molecule identities, it can provide a more comprehensive picture of the total legacy and emergent PFAS present in a sample. The objective of this study is to identify spatial and temporal trends in total fluorine and PFAS profiles within estuarine sediments. Sediment cores were collected in areas of high sediment accretion in Winyah bay, Georgetown, South Carolina and at the estuary’s four tributaries, the PeeDee, Waccamaw, Sampit, and Black rivers (n=10). Cores were separated into 5cm vertical increments and will be analyzed using both targeted and nontargeted methods. Dated sediment cores will be analyzed to construct the depositional history of accreted sediment layers. This analysis will allow us to make inferences about PFAS sources to Winyah Bay and trends of emergent and legacy PFAS compounds.
Per- and polyfluoroalkyl substances (PFAS) in the habitat and blood of diamondback terrapins (Malaclemys terrapin).
Per- and polyfluoroalkyl substances (PFAS) are highly persistent environmental contaminants known to accumulate in wetlands and associated wildlife. Diamondback terrapins (Malaclemys terrapin) are aquatic turtles endemic to salt marshes, coastal areas, and tidal creeks along the Atlantic and Gulf Coasts of the United States. Terrapins exhibit relatively high trophic status, strong site fidelity, and long life spans, characteristics that make them especially suited as bio monitors for contaminants in saltmarsh ecosystems. The objective of this ongoing study is to examine the types and concentrations of PFAS in free ranging terrapins and their habitat. We collected sediment (n=29), surface water (n=3), and M. terrapin blood samples (n=20) from a tidal marsh associated with the Tom Yawkey Wildlife Center, Georgetown, South Carolina. Samples were extracted in the laboratory and analyzed using liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine the presence and concentration of 21 different PFAS. In a preliminary analysis of five blood samples, we identified six PFAS above the limit of quantitation (PFOS, PFUnDA, PFOA, PFDA, PFHxS, PFNA). These concentrations will be examined for sex- and size- related differences among turtles and compared to concentrations in associated water and sediment. This project is expanding to include data collection at three additional estuarine sampling sites on the Atlantic coastal plain, Dauphin Island, Alabama, Jekyll Island, Georgia, and coastal Connecticut. This research will define regional species-specific baseline PFAS levels, so that deviations from reference levels can be identified and monitored.
Promoting Food Security and Environmental Literacy Through Community Gardens and Pollinator Education in a Rural, Underserved Community
Rural underserved communities often experience limited access to fresh food alongside fewer opportunities for environmental education. This study examines whether a community garden and pollinator education initiative can improve food security, environmental literacy, gardening self-efficacy, and social cohesion within a historically African American community near Hampton Plantation State Historic Site in McClellanville, South Carolina. An initial community survey assesses barriers to gardening and healthy food access, interest in garden participation, knowledge of pollinators and pollinator-friendly practices, and culturally significant plants. Survey findings will guide the development of a community garden, educational materials, and public interpretive displays. Follow-up surveys will evaluate changes in participant knowledge, confidence, community engagement, and pro-environmental behavior. The project will also assess the feasibility of adapting this collaborative model for other underserved rural communities facing similar food-access and environmental-literacy challenges.
Temporal and Environmental Drivers of Pollinator Community Structure in Coastal South Carolina Wetlands
Pollinator communities in coastal wetlands remain poorly documented despite their importance to plant reproduction, biodiversity, and ecosystem resilience. This study examines temporal and environmental variation in butterfly and bumblebee abundance, richness, diversity, evenness, dominance, and community composition at Hampton Plantation State Historic Site in coastal South Carolina. Weekly surveys conducted within fixed plots from May 2025 through April 2027 will record pollinators, floral resources, plant associations, behavior, and environmental conditions, including temperature, humidity, wind, rainfall, drought, and proximity to saline water. Special attention will be given to rare and conservation-priority species, while year-round monarch monitoring will assess migratory and potentially resident populations. Diversity metrics, mixed-effects models, temporal turnover analyses, and multivariate methods will be used to evaluate how environmental conditions and floral resources shape pollinator communities through time. Findings will improve understanding of pollinator ecology in tidally influenced wetlands and help guide conservation and habitat-management strategies under increasing climatic variability and coastal change.
Tracking Climate, Resources, and Phenology: Projected Mismatch Between Coastal Plain Pollinators and Their Plant Resources
Climate change may alter pollinator distributions independently of the plant resources required for adult foraging and larval development, creating spatial and seasonal ecological mismatches. This study will evaluate future climate suitability and resource overlap for selected pollinators across the three-state Coastal Plain. Focal taxa will include common generalists, larval-host specialists, species of conservation concern, and species with distinctive seasonal activity. Species distribution models will be developed separately for each pollinator and its associated larval-host or nectar-resource plants under current and projected mid- and late-century climates. Spatial overlap, range retention, range displacement, and seasonal resource alignment will then be compared among ecological groups. We anticipate that generalists will retain greater climate and resource overlap, whereas host specialists, conservation-concern species, and seasonally constrained pollinators will experience greater losses or displacement of suitable habitat. Results will identify potential climate refugia, emerging resource gaps, and priority areas for host-plant restoration, seasonal nectar enhancement, monitoring, and climate-adaptive pollinator conservation.
Forecasting Changes in Carolina Bay Biotic Communities Under Multiple Future Land Use Scenarios
Rapid population growth and development across South Carolina’s Coastal Plain continue to place pressure on Carolina Bays, geographically isolated wetlands that may receive limited regulatory protection and have historically experienced drainage and other anthropogenic disturbances. Intact Carolina Bays provide important habitat for Wood Ducks (Aix sponsa) and diverse wetland-dependent communities. This study evaluates relationships between past and current land use and Carolina Bay biodiversity to predict how biotic communities may respond to land-use change through 2100. Biotic and abiotic data from 68 Carolina Bays are being integrated with National Land Cover Database information. Each wetland is assigned a disturbance score based on its distance from developed land-cover types and the Land Development Index within 250 m of its boundary. Relationships between disturbance and bird, frog, invertebrate, and plant communities will be analyzed and projected under four USGS FORE-SCE scenarios representing alternative patterns of population growth and resource use. Preliminary results indicate that disturbance is positively associated with overall bird richness but negatively associated with some facultative wetland species, including Blue-gray Gnatcatcher (Polioptila caerulea) and Eastern Towhee (Pipilo erythrophthalmus). Frog richness did not vary significantly with disturbance, although Pine Woods Treefrog (Dryophytes femoralis) and Southern Leopard Frog (Lithobates sphenocephalus) exhibited species-specific responses. We anticipate that increasing development will shift community composition toward disturbance-tolerant taxa while reducing wetland-associated birds and functional diversity across taxonomic groups. Scenarios with limited development are expected to produce smaller and less intense ecological changes than scenarios characterized by widespread development. These projections will identify vulnerable wetlands, potential biodiversity refugia, and priority areas for conservation and restoration while clarifying the long-term implications of development for statewide biodiversity and waterfowl distribution.
Baseline Ecological Conditions of an Abandoned Shrimp Farm in Coastal South Carolina, USA
Wetlands provide essential ecosystem services, including nutrient cycling, shoreline stabilization, water-quality improvement, and habitat for diverse fish and wildlife communities. Historical conversion of coastal wetlands to aquaculture has altered hydrologic connectivity and ecological processes, yet relatively little is known about the ecological conditions of abandoned aquaculture sites before restoration. This study established baseline ecological conditions within a former shrimp aquaculture facility located on Little Edisto Island, South Carolina, by characterizing water quality, fish communities, and vegetation across six impounded salt marshes. Water quality monitoring included monthly measurements of dissolved oxygen, temperature, salinity, conductivity, pH, and nutrients. Fish communities were sampled quarterly using passive and active sampling gears, while vegetation surveys were conducted seasonally to quantify species composition, percent cover, canopy height, and stem density. Statistical analyses were performed using generalized and linear mixed-effects models to evaluate temporal patterns in water quality and biological communities and to examine relationships between environmental variables and fish assemblages. This study provides a comprehensive ecological assessment of a historically modified coastal wetland and establishes a quantitative baseline for evaluating future restoration success. The findings contribute to understanding how legacy aquaculture infrastructure influences environmental conditions and biological communities within impounded salt marshes and provide information to guide restoration planning and long-term ecosystem management in coastal South Carolina.
Decomposition Rates of Black Needlerush (Juncus roemerianus) and Saltmarsh Cordgrass (Sporobolus alterniflorus) Leaf Litter in an Impounded Salt Marsh
Leaf litter decomposition is a fundamental ecological process that regulates nutrient cycling, carbon storage, and energy flow within coastal wetlands. Despite its ecological importance, decomposition dynamics within impounded salt marshes formerly used for aquaculture remain poorly understood. This study compared decomposition rates of black needlerush (Juncus roemerianus) and saltmarsh cordgrass (Sporobolus alterniflorus) across six impounded marshes on Little Edisto Island, South Carolina. It evaluated the influence of environmental conditions and litter chemistry on decomposition. A total of 252 litterbags containing standardized 10-g samples of each species were deployed and retrieved individually per species and stake over 1 year. Remaining dry weight, percent mass remaining, and litter chemistry (acid detergent fiber, neutral detergent fiber, and total nitrogen) were quantified, while dissolved oxygen, temperature, salinity, and pH were measured during each collection. Linear mixed-effects models were used to evaluate the effects of plant species, decomposition time, environmental variables, and litter chemistry on remaining litter dry weight. Sporobolus alterniflorus decomposed significantly faster than Juncus roemerianus, with decomposition strongly influenced by time and dissolved oxygen availability. Temperature also significantly affected decomposition, whereas pH did not. Total nitrogen was negatively associated with remaining litter dry weight, indicating that litter with higher nitrogen content decomposed more rapidly, while acid detergent fiber and neutral detergent fiber exhibited marginal relationships with decomposition. These findings improve understanding of nutrient cycling within impounded salt marsh ecosystems and provide an ecological baseline for evaluating ecosystem recovery following restoration of historically modified coastal wetlands.
Aquatic Macroinvertebrate management in MSMI: a review
Moist soil management is a wetland management type that is used to support primary sources of sustenance for migratory birds and wildlife such as submerged aquatic vegetation (SAV) and macroinvertebrates. Although MSMI are common within South Carolina (SC) and macroinvertebrates are key part of these ecosystems, the types and quantities of macroinvertebrates that reside within MSMI in SC are widely understudied. The goal of this review is to give a basis of knowledge of the various types of macroinvertebrates that typically live within these systems and management techniques that have been found to be effective in supporting these crucial organisms. A full literature review will be conducted on the importance of managing for macroinvertebrates in MSMI using the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) formatting method. With this, we will be searching reliable databases (Google Scholar, Web of Science, EBSCOhost, etc.) using a select group of key phrases (“Moist-Soil Management Techniques,” “Macroinvertebrates,” etc.) to find key literature. This review intends to explore publications on management types commonly used in moist soil units and see what has been seen to best support macroinvertebrate communities.
Herbicide application impacting aquatic macroinvertebrate genus counts in MSMI
Specific management techniques differ between MSMI; however, herbicide application is commonly used in preventing unwanted vegetation within the impoundment. Herbicides and pesticides have been seen to be toxic to aquatic macroinvertebrates. This study will be conducted in two parts. The first part is a field-based study that focuses on herbicide application timing and how that can impact macroinvertebrate genus counts in MSMI. This portion of the study will be conducted on various MSMI around the state. During the first portion of this study, macroinvertebrate genus counts are cataloged, and the topmost prevalent genus will be selected for the latter part of the study. The latter portion is a wet-lab based study focused on what levels of herbicide are considered toxic to this genus and how the exposure to a stressful amount of herbicide can impact physiological mechanisms of the organism. Specifically, metabolic stress from herbicide exposure will be measured via an enzyme transport system (ETS) assay. Based on previous studies, we predict that the best time to apply herbicide will be X. Additionally, based on previous studies, we expect to find that the organisms will be able to tolerate X amount of herbicides without it negatively impacting their metabolic respiration.
Red Swamp Crayfish invasion affecting macroinvertebrate genus counts and submerged aquatic vegetation (SAV)
Red swamp crayfish are one of the most invasive macroinvertebrates in the world. In the 1970s, there were zero known populations of P. clarkii in South Carolina. As of 2022, there are almost 5,000 recorded captured individuals between 85 known populations in the Little Pee Dee, Winyah, and Waccamaw watersheds. Red swamp crayfish are considered habitat engineers and have been shown to decrease both SAV and macroinvertebrate genus counts in wetlands around the world. Red swamp crayfish absence, presence, or invasion will be monitored with the MSMI alongside sampling for macroinvertebrates and SAV. Expected results of this study are that invasion of red swamp crayfish is going to significantly decrease the number of macroinvertebrates and SAV found in MSMI. This significant decrease in SAV and macroinvertebrates will directly impact the sustenance that migratory waterfowl and other wildlife gain from these taxa.
Simulation model for macroinvertebrate communities affected by environmental factors and management techniques.
The effect of different management techniques on macroinvertebrates in MSMI in South Carolina is widely understudied. In this study, I plan to create a comprehensive simulation model using Simulink software. The basics of this model will be based on a Clemson University dissertation titled “A Simulation Model of Dynamics of Aquatic Macroinvertebrate Communities” by Dr. Vladlena V. Gertseva (2002). The goal of this model is to be a tool that is accessible to land managers to help better understand how different management techniques can directly impact macroinvertebrate communities and carrying capacities of the MSMI. To validate the model, there will be continuous sampling throughout the project of macroinvertebrate genus counts alongside collecting data from the land managers about what management techniques were performed.
Assessing Survival and Movement of Wild and Game-farm Mallards in South Carolina
Atlantic Flyway Mallard (Anas platyrhynchos) populations have generally declined since the late 1990s, raising concern about the effects of released game-farm Mallards and their hybridization with wild birds. Game-farm and hybrid Mallards may exhibit reduced survival and reproductive performance, altered migration, and lower foraging efficiency. We are evaluating differences in dispersal, migration, survival, harvest susceptibility, and reproductive behavior between game-farm and wild Mallards in South Carolina using band recoveries, VHF and GPS telemetry, genetics, morphometrics, and photography. Beginning in summer 2025, we fitted 187 game-farm Mallards with field-readable bands. From November 2025 through February 2026, we banded and equipped 98 additional game-farm Mallards with Lotek NanoTag VHF transmitters. Following the hunting season, four presumed wild Mallards received GPS transmitters, and 19 surviving game-farm birds were fitted with recovered NanoTags. Blood and tissue samples are being analyzed to verify ancestry, evaluate population genetics, and assess harvest susceptibility relative to game-farm ancestry. During the hunting season, 18 band-only and 28 transmitter-equipped game-farm Mallards were reported harvested. Thirty additional transmitters were recovered from predated birds, while at least 20 of 117 transmitter-equipped game-farm Mallards survived through July 2026. Game-farm birds remained near release sites: harvest recoveries occurred within a few miles, and no birds were detected by Motus towers beyond the newly established local receiver. In contrast, three of four GPS-tagged presumed wild Mallards migrated north, while one remained near its Lake Marion capture site. Preliminary results indicate that some released game-farm Mallards survive beyond the hunting season but exhibit limited dispersal compared with presumed wild birds. Continued monitoring and genetic verification will clarify how releases affect Mallard population dynamics and inform evaluation of future management strategies.
Community Structure Comparison of Former Shrimp Farm Impoundments and Reference Saltmarshes
Saltmarshes have many ecosystem services that support both humans and wildlife, such as water filtration and nutrient removal, protection of shorelines against erosion and wind, sequestration of carbon and supporting populations of sportfish and commercially harvested crustaceans. Many areas of saltmarsh in South Carolina have undergone significant changes through both natural and anthropogenic means. One way in which humans have caused disturbance to saltmarshes is by creating saltwater impoundments, blocking or regulating the flow of water into and out of the area using water control structures. This has the potential to alter what organisms can persist in and which species become dominant.
The goal of this research is to determine how the hydrologic alteration of six saltwater impoundments, located on Little Edisto Island, South Carolina (32.611126, -80.319256), have changed biotic community assemblages of the site (birds, fish, invertebrates, plants) from what would be expected of unimpeded saltmarsh ecosystems . We are also examining how the six impoundments differ based on indicators of water quality, such as total suspended solids, nutrient concentration (nitrate, phosphate, ammonia), Escherichia coli concentration, temperature and dissolved oxygen.
So far, observations of birds have indicated a large amount of songbird usage of the berms surrounding the impoundments, which is potentially caused by the high amount of woody vegetation present on the berms.
Impact of Seasonality on Surveys of Vegetation in Saltmarsh Habitats
Saltmarsh plant communities are restricted by the high concentration of salt and frequent tidal inundation. This limited plant community may respond differently to seasonal changes than terrestrial systems or freshwater wetland systems. Conducting plant surveys during different seasons may not produce the same patterns that we see in freshwater wetlands. Plant surveys during the non-growing season may be sufficient to provide a good sense of plant community structure in saltmarshes due to the persistent presence of the dominant plant species in these ecosystems, such as saltmarsh cordgrass (Sporobolus alterniflorus) and black needle rush (Juncus roemerianus).
We are conducting this experiment to determine how season of sampling impacts the recorded percent cover of different plant species during our surveys, as well as whether season has a significant effect on the recorded plant species richness and total percent plant cover. So far, we have been observing most of the change in percent cover among plant species that are more strongly associated with high marsh habitat.
Saltmarsh plant community composition differences driven by sampling method: Do drone-based and ground-based surveys offer unique or similar plant cover patterns?
There are many ways that plant community surveys can be conducted. Traditional ground-based surveys using PVC quadrats (often one-square-meter in size) have been conducted for decades Unmanned aerial vehicles (UAV) offer a less invasive method of determining plant community structure that limits disturbance to the environment and potential risks to personnel. We are investigating the effectiveness of using images derived from a low-cost UAV flown in a line transect pattern with the results obtained from quadrat ground-based surveys conducted by the same observer. By sampling both impoundment sites (32.611126, -80.319256) and multiple saltmarsh sites on Edisto Island, South Carolina, we will see how the two methods of plant surveys differ when used in a wide range of saltwater wetland types.
In addition to the use of UAVs, we are also investigating the effectiveness of an artificial intelligence model to automatically classify UAV images and quantify plant cover of each species within the aerial photo. This would make the process of determining fine-scale community composition of saltmarshes easier. We will be comparing the ability of the model and the human observer at determining the percent plant cover of each species. The use of such a model could have widespread applications as a means of monitoring plant communities in wetlands of different types, based on the training image data provided, in a manner that limits exposure of personnel to hazardous conditions and reduces overall disturbance to the environment.
Using a novel method of fine-scale habitat classification to assess suitability of saltwater wetlands for wading birds
Unmanned aerial vehicles (UAVs) are rapidly becoming a prominent means classifying habitats based on features in the landscape. These capabilities can be combined with observations of an organism of interest, such as a bird, to develop a means of predicting the distribution of that organism within a landscape, such as a saltmarsh. I am constructing an artificial intelligence model that will classify habitat images of saltmarshes captured by UAVs automatically, placing them into categories based on the percent coverage of different habitat features visible in aerial images taken at low altitudes during low tide (saltmarsh cordgrass, pluff mud, oyster beds, woody vegetation, emergent vegetation, etc.). The habitat data from these images will be combined with the observational data I collect on great egrets (Ardea alba) to predict locations where they are most likely to appear in the saltmarsh landscape. This will act as a demonstration of the model’s effectiveness at determining organism distribution based on percent cover of key habitat features.
Bridging Heritage, Hydrology, Restoration, and Decision Support in South Carolina’s Historic Tidal Rice Fields
Historical tidal rice fields in South Carolina are culturally significant coastal wetlands, whose patchy evidence severely limits integrated restoration and adaptive management. This systematic review has linked the fragmented socio-ecological, hydrological, geospatial, historical and decision-support knowledge on breached and intact rice-field systems. Following the PRISMA guidelines, six databases were searched to retrieve 872 records, of which 317 full-text articles were reviewed after screening and duplicate removal. The number of publications surged from the mid-2000s onward; journal articles accounted for the largest share of papers. Authorship was centered within the region; co-authorship showed 7 communities and a dynamic network of 636 unique authors split across three periods. Biodiversity and other ecological factors featured the largest share of keyword networks (96.6%); few studies integrated the rich historical/archeological aspects (25.4%). Decision support readiness was weighed between the moderate and high bands (107 articles each), while hydrology & heritage evidence of past rice fields remained strongly under-integrated (81.7). To carry out equitable coastal stewardship planning, future studies should seamlessly integrate monitoring, cultural knowledge, hydrological model outputs and spatial decision-support tools.
An Integrated Decision-support Tool and Risk-Benefit Matrix for Sustainable Waterfowl Management in Historic Rice Fields.
South Carolina's historic rice fields are critical Atlantic Flyway wetlands that provide waterfowl habitat and are facing sea-level rise, increased salinity, disrupted hydrologic connectivity and wetland habitat degradation. We developed an integrated Hydro-Habitat Decision Framework to support conservation and restoration across heterogeneous rice-field networks. Habitat and biodiversity value were assessed using five indicators: wetland composition, waterfowl richness, at-risk species, habitat patch condition, and rare ecosystem value. Hydrologic functionality embraced six indicators: proximity to flowline/waterbody, catchment position, stream density, water coverage and waterbody/wetland hydraulic connectivity. We standardized, combined and mapped these indicators to produce a Hydro-Habitat Conservation Priority Index, which was examined by basin, county, field type and through weighting scenarios. Pee Dee had the highest mean priority score (56.24), followed by Salkehatchie (52.06). Georgetown County had the highest mean priority score (57.35), with 35.33% of fields ranking in the top two priority categories. Tidal functional had the highest mean priority score (57.41), followed by Tidal broken (54.75) and Inland (47.78). Hydrological functionality consistently exceeded habitat/biodiversity value across group and weighting scenarios, making habitat enhancement the dominant management need. These differences between basins, counties, and field types demonstrate the need for a spatially explicit decision framework. The framework translates ecological and hydrological patterns into explicit conservation priorities, helping stakeholders target protection, habitat enhancement, and hydrologic restoration under changing environmental conditions and competing management goals.
Understanding Stakeholder Perspectives on Waterfowl and Rice Field Conservation Through Mixed-methods Engagement.
Coming Soon!
Measuring Restoration Success: Comparative Analyses of Historic Rice Fields Based on Spatial and Field-based Assessments.
Coming Soon!
Guiding Adaptive Management of Historical Rice-Field Wetlands in Coastal South Carolina: Drone-Based Assessment of Waterbird Abundance and Habitat Associations
Coastal South Carolina’s antebellum rice-field impoundments are legacy wetlands whose ecological value depends on water-control infrastructure that regulates hydrology, salinity, and vegetation. We evaluated waterbird abundance and habitat associations across functional tidal, broken tidal, and inland impoundments using repeated drone-based aerial strip-transect surveys. Color and thermal imagery collected with a DJI Mavic 3T Enterprise drone was used to identify and count waterbirds. Repeated surveys supported Bayesian N-mixture models that estimated species-specific abundance while accounting for imperfect detection. High-resolution orthomosaics were also classified using a deep-learning model to quantify open water, submerged aquatic vegetation (SAV), and emergent aquatic vegetation (EAV). Functional tidal impoundments supported the greatest estimated abundance for 12 of 13 focal species, whereas broken tidal impoundments generally supported the lowest abundance, frequently approaching zero. Wood Duck (*Aix sponsa*) was the principal exception, occurring most abundantly in inland impoundments. Habitat relationships varied among ecological guilds. Dabbling ducks were generally associated with shallow water, while diving ducks responded positively to greater water depth. Open water and SAV positively influenced several duck species, whereas responses to EAV and salinity were species-specific. Hydrology and vegetation were generally stronger predictors of abundance than impoundment size. These findings demonstrate that intact tidal infrastructure and active water management sustain heterogeneous habitat mosaics that support diverse wintering waterbird communities. Integrating drone surveys, high-resolution habitat classification, and hierarchical abundance models provides an efficient, repeatable framework for prioritizing rice-field restoration, establishing water-level and vegetation targets, and evaluating adaptive wetland-management outcomes.
Development and Field Testing of a Drone-Deployable Floating Autonomous Recording Units Platform for Secretive Marsh Birds Monitoring in Inaccessible Wetlands.
Autonomous Recording Units (ARUs) support passive acoustic monitoring, but deployment in flooded, remote, or inaccessible wetlands can be difficult, hazardous, and biased toward habitat edges. To improve sampling within wetland interiors, we developed and field-tested a low-cost, lightweight floating ARU platform designed for drone-assisted deployment and retrieval. Constructed from commercially available materials, the platform cost approximately US$21, weighed about 560 g with an AudioMoth recorder installed, and positioned the recorder approximately 1.2 m above the water. A multirotor drone equipped with a payload-release device transported the platform to predetermined locations, while a suspended treble hook engaged dual wire loops for retrieval. We evaluated the system during 50 paired deployment–retrieval trials across inland, tidal-broken, and tidal-functional historical rice-field impoundments along the South Carolina coast. All 50 deployments and retrievals were successful, producing a 100% operational success rate. Median deployment and retrieval times were 6 and 9 min, respectively, with retrieval requiring significantly more time because of the precision needed for hook engagement. Operation time increased with distance from the launch point. No platform damage, overturning, or displacement occurred. This platform provides an affordable, stable, and field-ready method for extending passive acoustic monitoring into wetland interiors that are difficult or unsafe to access manually. Improved interior coverage may reduce edge-related sampling bias and strengthen monitoring of secretive marsh birds and broader wetland biodiversity. The design may also be adapted to deploy other lightweight environmental sensors and sampling devices.
A History of Per- and Polyfluoroalkyl Substances (PFAS) and a Review of Their Impact on Waterfowl
Per- and polyfluoroalkyl substances (PFAS) are manufactured chemicals that were found to be
beneficial for many industrial and commercial applications (Buck et al. 2011). This led to the
mass production of PFAS in the 1950s, which, in turn, resulted in mass amounts of runoff
entering natural environments. Further studies into PFAS have shown highly detrimental
consequences to habitats, fish, wildlife, and humans. Despite this, only six PFAS are actively
monitored by the United States Environmental Protection Agency. A grossly understudied
species with regards to impacts of PFAS, especially in the United States, are waterfowl.
Waterfowl represents a unique study system for investigating both the spread and impacts of
PFAS, primarily due to their communal and migratory nature, but with so few studies focused on
waterfowl, it can be difficult to understand any true effects. To understand what is currently
known on this topic, I will be performing an in-depth literature review from notable databases
(e.g., Scopus, Web of Science, etc.) using key terms (e.g., “PFAS AND *fowl”; “PFAS AND
waterfowl”) to provide a narrative describing the history and development of PFAS, and what is
currently known about its long-term impacts on waterfowl. We will then use this vital
background information to help answer important biological questions regarding the impacts of
PFAS on waterfowl in South Carolina, as well as other Atlantic coast states. Additionally, we
plan to use this to develop new questions that can continue to shed light on this important, and
yet understudied, topic within ecotoxicology and waterfowl ecology.
Impact of Legacy and Emerging PFAS on Wood Duck (Aix sponsa) Tissues, Blood Cell Structure and Immune Response: Implications for Waterfowl and Human Health
Based on previous literature, PFAS have been described as ubiquitous in the environment,
especially aquatic ecosystems. Many industrial locations (e.g., military
installations, airports, etc.) are often found near or within these aquatic ecosystems and are often
the primary culprits for the release of PFAS. Because
many avian species, including waterfowl, can accumulate and hold PFAS in their blood and
tissues, it can result in an immune response in the host and potentially act as a
novel exposure route into a new host (e.g., duck hunters). This is particularly concerning, given
the popularity of waterfowl hunting across the state of South Carolina. Contaminants like heavy
metals and pollutants like PFAS are known to have genotoxic effects on avian species, leading to
cellular and genetic mutations, decreased reproductive success, and cancer.
Visible effects of these contaminants can be seen in avian red blood cells through erythrocytic
nuclear abnormalities (ENAs), which can serve as a biomarker for the cellular response to
contamination. To better understand the genotoxic effects of PFAS in Atlantic coast
waterfowl, we will be completing the following objectives: 1) assess exposure to PFAS across
age and sex classes of South Carolina wood ducks, 2) investigate the presence and
concentrations of PFAS in wood duck breast tissue and plasma, 3) determine any potential
relationships between concentrations of PFAS and health parameters of sampled wood ducks, 4)
examine the viability of using ENAs in blood smears as a measure of PFAS contamination, and
5) assess exposure risk of PFAS to sport and sustenance hunters via ingestion of contaminated
waterfowl tissues. The results of this study will document effects of PFAS on a cellular level in
waterfowl and additionally provide clarity to the likelihood of hunted waterfowl acting as a novel
route of exposure of PFAS to duck hunters.
Quantifying Historic and Present Concentrations of Legacy and Emerging PFAS Using Atlantic Coast Common Eider (Somateria mollisima dresseri) Feathers
Wild birds are known as an effective biomonitor for a suite of contaminants, including PFAS, although there are limited peer-reviewed studies using them as models for PFAS monitoring. The process of capturing and collecting requisite samples from birds can result in excessive stress, leading to capture myopathy. To combat this, researchers have been investigating the usefulness of feathers for studying contaminants in avian systems, starting in the late 2010s for PFAS. Preliminary studies over the last 15 years seem to indicate that feathers are indeed a successful matrix for PFAS analysis. This is primarily due to feathers being directly connected to blood flow during their genesis and growth. While some studies have examined PFAS concentrations in body, wing, and tail feathers, less is known about the bioaccumulation of PFAS within each feather type. It is possible that PFAS may exhibit different concentrations and bioaccumulation abilities depending on the feather type, as well as the species. North American sea duck species have been in decline for over a decade; however, the full reasons for these long-term declines are poorly understood. Despite this, few studies have investigated historic trends in exposure to PFAS and fewer still have attempted to quantify historic and current trends of PFAS exposure using less invasive sampling methods, like feathers. We will complete the following objectives: 1) compare PFAS concentrations in primary wing and tail feathers from sea duck populations, 2) compare PFAS concentrations between feathers and plasma collected from sampled birds, 3) determine the efficacy of using feathers to quantify trends of PFAS concentrations in sea ducks, and 4) establish trends of historic PFRAS concentrations in common eiders using archived feathers.
Risks of Maternal Transfer of Legacy and Emerging PFAS to Eggs and Ducklings of Atlantic Coast Waterfowl
PFAS have a variety of exposure routes for both humans and wildlife, with the primary route being through consumption of contaminated food and water. Many animal species have shown the potential to transfer PFAS burdens and concentrations from mother to offspring (maternal transfer). In birds, studies have shown that birds can transfer many pollutants, including PFAS, to their young through the development of the egg, beginning first with ingestion of PFAS by the hen. It has been reported that the efficiency of transfer is directly tied to the carbon-chain length of PFAS. The full effects of PFAS on both the embryo and the chick are not fully understood and have been examined primarily in domestic chickens, where it has been suggested that embryonic exposure to PFAS results in developmental issues. Very few studies have been performed using waterfowl, as such, we will be completing the following objectives: 1) understand any possible maternal transfer of PFAS in wild wood ducks from South Carolina, 2) describe the concentrations and composition of emerging and legacy PFAS found in the eggs of wild wood ducks, 3) investigate any potential relationships between emerging and legacy PFAS found in eggs with those found in the plasma of the corresponding female, 4) determine any biological effects on material transfer of PFAS, and 5) provide baseline data for maternal transfer of six key PFAS analytes in ducks through a controlled captive study.
Microplastic Accumulation in Green-winged Teal (Anas c. carolinensis) Across Historic Rice Field Wetlands in Georgetown County, South Carolina
Microplastics are contaminants of emerging concern in aquatic ecosystems, where they may be ingested by wildlife and transport associated pollutants through food webs. Coastal South Carolina’s historic antebellum rice fields provide important wintering habitat for dabbling ducks but may receive microplastic inputs from surrounding development and other anthropogenic sources. We quantified and characterized anthropogenic particles in the gizzards of Green-winged Teal (Anas crecca) harvested from these wetlands. Gizzard contents were chemically digested using potassium hydroxide and hydrogen peroxide, and particles were analyzed with an Agilent 8700 Laser Direct Infrared chemical imaging system to determine abundance, size, shape, and material composition. Particles occurred in 70.9% of samples, with counts ranging from 0 to 907 and averaging 185 particles per sample. Particle abundance did not differ significantly between male and female teal. Rounded particles were significantly more abundant than coarse or thin fibers, while particles smaller than 30 µm dominated the size distribution. Rubber was the most abundant and frequently detected material, followed by polyamide, magnesium stearate, chlorinated polyethylene, and polyethylene. Although rubber is an elastomer rather than a plastic, it may behave similarly by interacting with environmental contaminants and producing adverse biological effects. Particle occurrence and abundance exceeded values reported in previous Atlantic Flyway waterfowl studies, likely reflecting the improved detection of particles smaller than 100 µm through infrared imaging. The predominance of small, rounded particles raises questions about particle retention, physical alteration within the gizzard, and potential movement into tissues. These findings document substantial exposure to anthropogenic microparticles and support further investigation of contaminant sources, tissue translocation, toxicological effects, and mitigation strategies in coastal wetland systems.
Biotic and Spatial Factors Associated with Microplastic Accumulation in Green-winged Teal (Anas c. carolinensis) in Functional Historic Antebellum Rice Fields in Georgetown County, South Carolina
Microplastics are widespread in aquatic environments, yet their distribution and bioaccumulation remain understudied in coastal wetlands relative to open-ocean systems. Estuaries and tidal wetlands may retain substantial quantities of land-derived microplastics, with accumulation influenced by hydrodynamics, polymer properties, urbanization, population density, and wastewater inputs. These knowledge gaps are especially relevant along coastal South Carolina, where historic antebellum rice fields provide important wintering habitat for Green-winged Teal (Anas crecca) and other dabbling ducks in the Atlantic Flyway. This study will evaluate how biological and landscape variables are associated with microplastic abundance, concentration, size, shape, polymer composition, and polymer diversity in Green-winged Teal gizzards collected from these wetlands. Microplastic-response data will be integrated with biological variables, including sex, body mass, and predominant prey, and spatial variables describing watershed boundaries, urban land cover, human population density, wastewater-treatment-plant abundance, and hydrologic distance from wastewater facilities. Statistical models will account for multicollinearity among landscape predictors and variation among collection locations. We hypothesize that microplastic burdens will increase with urbanization, population density, and proximity to wastewater-treatment infrastructure and will vary with sex and dietary composition, whereas body mass will have comparatively little explanatory power. We further predict that particle morphology and polymer diversity will reflect surrounding land use and wastewater influence. By linking microplastic exposure in a migratory waterfowl species to biological characteristics and landscape conditions, this study will identify potential predictors of contaminant accumulation, guide future source-tracking efforts, and inform wetland management and pollution-mitigation priorities across the South Atlantic region.
