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.
Akshit R. Suthar
Doctoral Student, Clemson University
James C. Kennedy Waterfowl and Wetlands Conservation Center
Secretive marsh birds, such as rails, bitterns, and gallinules, are notoriously elusive and well-camouflaged, presenting significant challenges for study using traditional methods. These birds inhabit dense vegetation in wetland habitats, making observation and study difficult. Antebellum (pre-U.S. Civil War) rice field impoundments provide essential habitat for many species of secretive marsh birds in coastal South Carolina. These rice fields, developed between the 1600s and 1800s, were primarily managed by the labor of enslaved people during the colonial era. Rice culture declined post-Civil War, and recent mapping efforts show it spans about 95,000 hectares. Currently, many of these fields are primarily managed for wintering waterfowl. Recent studies suggest constant water level management creates higher sites within an impoundment and can develop patches of saltgrass, clump cordgrass, and salt meadow cordgrass (Distichlis spicata, Sporobolus bakeri, and Sporobolus pumilus), providing suitable cover and nesting habitat for secretive marsh birds.
Our research aims to 1) quantify habitat use by these birds within the antebellum rice fields of coastal South Carolina and 2) Design innovative techniques for monitoring them. We employed Autonomous Recording Units (ARUs) for Passive Acoustic Monitoring (PAM) to capture the call activities of secretive marsh birds. ARUs are less invasive and reduce time and labor costs. We used Audiomoth recorders to monitor king rail (Rallus elegans), clapper rail (Rallus crepitans), Virginia rail (Rallus limicola), sora (Porzana carolina), black rail (Laterallus jamaicensis), American bittern (Botaurus lentiginosus) and least bittern (Ixobrychus exilis) during their breeding season from March to mid-June when they are notably more vocal. Our recording schedule involved capturing audio for one minute every three minutes from 5:45 PM to 9 AM for three days, aligning with the peak activity periods of the focal species.
We developed a low-cost methodology using drones to deploy and retrieve ARUs mounted on lightweight, multi-terrain floating platforms from inaccessible areas. This approach aimed to overcome the limitations of traditional deployment methods, such as data bias from unapproachable large managed and unmanaged rice field impoundments. We maintain a 200-meter distance between each ARU, effectively covering entire habitats with less time, effort, and human resources. This method allowed us to deploy ARUs in the center of impoundments and far, inaccessible and less disturbed areas, which are crucial for monitoring potential habitats of species like the black rail.
For data analysis, we utilized the open-source Artificial Intelligence model called BirdNet, developed by Cornell Lab. Data recorded in .wav format was fed into the model, which analyzed each three-second spectrogram against eBird checklists and BirdNet algorithms, providing species identification with confidence intervals. Last season, we deployed 130 ARUs, surveyed 29 rice field impoundments, recorded approximately 119,000 files, and logged around 2,000 hours of recordings. Moving forward, we plan to expand our survey efforts, double the number of impoundments surveyed, and analyze the collected data to understand better the habitat use and preferences of secretive marsh birds in these historically significant landscapes.
This research underscores the importance of integrating advanced technologies, like drones and ARUs, in secretive marsh bird monitoring and conservation. The innovative methodologies developed here enhance our understanding of secretive marsh bird populations and offer scalable habitat monitoring solutions in challenging environments.
Akshit R. Suthar
Doctoral Student, Clemson University
James C. Kennedy Waterfowl and Wetlands Conservation Center
Coastal South Carolina’s antebellum (Pre-Civil War) rice field impoundments play a crucial role in waterfowl conservation. The cultivation of rice began in the 1600s, deeply intertwined with the history of enslavement and the transatlantic enslaved laborer trade. Enslaved Africans brought their knowledge and technologies of rice cultivation from West Africa to colonial South Carolina, constructing extensive dikes and canal systems by hand to create rice field impoundments. These transformations converted tidal swamps and hardwood bottomland forests into highly managed agricultural systems. Although rice cultivation declined post-Civil War, the loss of labor as former enslaved persons were freed, and subsequent hurricanes and tropical storms caused extensive damage to the agricultural rice areas. Attempts to rebuild were unsuccessful due to costs, other factors, and increasing market competition from rice produced in Texas, Louisiana, and Arkansas. Today, approximately 95,000 hectares of antebellum rice fields are mapped and categorized as Tidal Functional, Tidal Broken, and Inland (Figure 1), with many managed for waterfowl. This habitat faces significant threats from sea level rise and climate change, exacerbating the degradation of rice field infrastructure through increased tidal amplitudes and more frequent tropical storms (Figure 2). There is ongoing debate about the impact of impoundments on wetlands and waterfowl habitats. Some argue that managed impoundments are more beneficial, while others believe that tidal wetlands would suffice if impoundments didn't exist. This highlights the complexity of conservation planning. Recent research underscores the high value of antebellum rice field impoundments for waterfowl. Accurate quantification of waterfowl utilization, along with understanding the biological and environmental factors driving high abundance, is essential for efficient conservation, management, and restoration of these habitats.
Drones are increasingly utilized in wildlife surveys, providing an aerial perspective of the landscape and overcoming accessibility and visibility challenges, which can be particularly limiting in waterfowl surveys. Our objectives were to 1) estimate waterfowl abundance by species and guilds within these rice fields using drone 2) investigate the relationships between waterfowl and impoundment characteristics, such as average water depth and vegetation types, to understand habitat preferences 3) evaluate the efficacy of drones for future waterfowl research. We conducted preliminary surveys at the Tom Yawkey Wildlife Center, Georgetown, during February and December 2023, utilizing a DJI Mavic 3T enterprise drone (Figure 3). We conducted aerial surveys of Tidal Functional rice field impoundments (N=2) (Blackout and Penfold) to estimate waterfowl abundance and species richness and collected high-resolution images of impoundments for modeling habitat characteristics using an ArcGIS Deep Machine Learning model. We conducted a traditional ground-based survey to compare both methodologies to count waterbirds.
Our findings reveal that the total average waterbird counts obtained from drone surveys were significantly higher, with an average of 2,202 birds counted. This is 347.21% higher compared to the average of 492 birds counted during ground surveys (Figure 4). Additionally, drone surveys were able to identify an average of 12 species, which is 8.7% higher than the 11 species identified through ground surveys (Figure 5). Our study demonstrates the effectiveness of drones for accurately identifying and quantifying waterbirds compared to ground surveys, especially in areas with large bird populations. Using ArcGIS Deep Machine Learning model, we classified and categorized impoundments in emergent and submerged vegetation, open water, and dikes. Kernel density estimation was used to analyze waterbird habitat selection, while Poisson regression models determined the impact of impoundment’s hydrological variables on waterfowl abundance (Figure 6). We found % submerged vegetation has a strong positive impact on waterfowl abundance across all species. % open water has positive impact with varying significance, average water level (cm) has positive impact with varying significance, % emergent vegetation has small or non-significant impact and, impoundment size (ha) has less clear impact, with some species showing negative or non-significant effects (Figure 7)). Integrating thermal and RGB images improved detection probabilities (Figure 8), demonstrating the added benefits of thermal imaging for waterfowl surveys. Our study underscores the importance of antebellum rice field impoundments in maintaining waterbird habitats and provides essential insights for conserving, managing, and restoring antebellum rice fields by focusing on key habitat features crucial for supporting waterbird populations. emphasize the need for advanced management strategies to conserve these critical waterfowl habitats amidst ongoing environmental changes.
Aruã Yaym de Castro Ferreira
M.S. Student, Clemson University
James C. Kennedy Waterfowl and Wetlands Conservation Center
South America's Pantanal is one of the world's most extensive contiguous freshwater wetlands, spanning 160,000 km2 (39.5 million acres). Consequently, its ecosystem services significantly contribute to climate regulation on a local and global scale and are dependent on the biodiversity that is a result of this biome's unique flood pulses. The Pantanal intersects Brazil, Bolivia and Paraguay, with Brazil's share (Fig. 1) accounting for approximately 80% or 140,000 km2 (35.5 million acres). Since the colonialists arrived in the Pantanal approximately 250 years ago, numerous threats, including deforestation, pollution, wildfires, and poaching, have impacted it. However, the consequences of historic gold mining have been ignored over the past 25 years. In the 1990s, researchers identified high levels of mercury in the Pantanal at different trophic levels (Lacerda et al., 1991a; Lacerda et al., 1991b; von Tümpling Jr et al., 1995; Alho & Vieira, 1997; Filho & Maddock, 1997). In recent decades, studies such as May et al. 2018 found high levels of mercury accumulation in the fur of jaguars (Panthera onca) in the Pantanal. The studies in the 1900s led to policies that outlawed the use of mercury in gold mining, but as May et al. (2018) displayed, mercury still lingers in the landscape. Thus, it is of utmost importance to investigate the mercury concentrations in the Pantanal.
The largest concentration of gold mining takes place within the Bento Gomes River watershed (Fig. 1.1), where 7,463 hectares (18,441 acres) are impacted according to the latest estimate by the MapBiomas Brazil. Sitting on the northernmost edge of the Pantanal, the Bento Gomes River watershed is the best representative for evaluating mercury bioaccumulation in the Pantanal. Our goal is to determine the degree of mercury accumulation in wetland-dependent birds in the northern Pantanal, trace its geographic source, pinpoint its position in the trophic level and food web, and correlate mercury concentrations in water, sediment, and birds. We will use birds as bioindicators because they are found higher in the trophic levels, are exposed to a wide range of chemicals, are susceptible to bioaccumulation, and are geographically widespread. To achieve our goal, we will capture wetland-dependent birds of the Anseriformes, Charadriiformes, Gruiformes, Pelecaniformes, Podicipediformes, and Suliformes clades in properties that are along the Bento Gomes River watershed mainstream; collect and estimate mercury accumulation in the water and soil/sediment of habitats where birds were captured; define prey items consumed by the species of interest via literature review, direct observations, and DNA fecal analysis; collect and estimate mercury accumulation in the prey items consumed by the species of interest; utilize spatial analysis and the project's data set to determined potential sources of mercury accumulation and model Hg concentrations throughout the watershed. The study area and our species of interest, combined with the other variables collected in this project, can provide us with great insight into the current state of mercury bioaccumulation in the Pantanal.
We expect Hg bioaccumulation in birds, water, soil/sediment, and prey items to exceed the accepted thresholds. Specifically, piscivorous bird species, which occupy higher trophic levels, are anticipated to exhibit significantly higher Hg concentrations than herbivorous and omnivorous species. Birds showcasing elevated Hg levels in their feathers will show signs of compromised health. Finally, Hg levels in birds are expected to correlate highly with Hg concentrations in the surrounding soil/sediment and water.
Bobby Greco
Doctoral Student, Clemson University
James C. Kennedy Waterfowl and Wetlands Conservation Center
Crocodilians suffered global declines due to overhunting and habitat loss throughout the 20th century. Legal protections and conservation management plans were implemented for many crocodilian species, with some, such as American alligators (Alligator mississippiensis) and the Indo-Pacific crocodile (Crocodylus porosus), experiencing successful recovery. Various conservation management methods have been used on crocodilians to increase population numbers. Head-start has been used with many species of crocodilians worldwide.
Though there have been many different crocodilian head-start programs globally, little information is available in the literature. In most of the literature, the methods of head-starting are not detailed and, therefore, hard to replicate. Additionally, only a few accounts in the literature assess the head-start's success quantitatively. Furthermore, head-starting is rarely the central theme of the papers available. However, recovery and management programs for C. acutus in the Caribbean could provide valuable information to fill knowledge gaps on head-starting crocodilians.
The American crocodile (Crocodylus acutus) is a sizeable neotropical crocodile that occurs from the southern tip of Florida down into the Greater Antilles and the Caribbean and Pacific coasts of Mexico, Central America, and northern South America. Crocodylus acutus is predominately a coastal species that inhabits a variety of freshwater, brackish, and marine habitats, including estuarine sections of rivers, freshwater lakes, and reservoirs, mangrove swamps, coastal lagoons, offshore islands, and atolls. The IUCN lists C. acutus as "Vulnerable," and the Convention on Trade in Endangered Species of Flora and Fauna (CITES) lists them under Appendix I (Rainwater et al., 2021). Though IUCN reports that the overall population trend is increasing, many populations throughout the range are still declining and threatened with extirpation due to overhunting, pollution, and habitat loss and degradation (Rainwater et al., 2021). In the Caribbean, multiple species recovery projects have been implemented using head-starts or captive breeding in their recovery plans for C. acutus.
One population of C. acutus that is declining and threatened with extirpation is in Lago Enriquillo, Dominican Republic. Population surveys conducted by Greco et al. (2023) found that there were likely only 40–60 breeding adults left in a population that used to have 300–600 breeding adults in the 1970s and 1980s (Schubert and Santana, 1996). These findings made key stakeholders reconsider the long-term management plan for C. acutus in Lago Enriquillo. The Dominican Ministry of Environment and Natural Resources (MENR) and its collaborators decided that a head-start program would be beneficial for increased recruitment and population recovery. The implementation of a head-start program in Lago Enriquillo has provided us with a unique opportunity to research head-start individuals, their Ex-situ environments, and the natural system into which they will be released.
We are investigating the various methods that have been used for crocodilian head-start programs, different methods of quantifying success, some of the challenges that come with head-start and set some general research recommendations for managers to consider before deciding if head-starting is the proper method for population recovery. Specifically, the goals of our project are to: 1) do a literature review on crocodilian head-start programs to provide the various methods of head-start, methods of quantifying success pre- and post-release, and general management recommendations; 2) identify and quantify Ex-situ techniques that prove successful on head-start individuals with C. acutus from Lago Enriquillo; 3) conduct In-situ research on resource selection, home range selection, ecotoxicology, and community dynamics with wild C. acutus in Lago Enriquillo (with an emphasis on individuals from the same cohort as head-start individuals) to provide critical life history information, prioritize areas best suited for releasing head-started individuals, and optimize captive conditions for head-start crocodiles; 4) and analyze data to elucidate which techniques work best for head-start, quantify head-start success, and reveal In-situ patterns of crocodiles in Lago Enriquillo with consideration for long-term management.
We recently finished our first field season in June 2024. We collected Head-start crocodile hatchlings, administered an initial health assessment, placed them in enclosures, and monitored them daily. Simultaneously, we conducted two nocturnal eyeshine surveys by boat (one in May and one in June), captured four crocodiles and performed gastric lavage to analyze diet, collected blood and scute samples for mercury analysis, and conducted bird and aquatic biodiversity surveys. Currently, we are analyzing our data with plans to have preliminary results by the Fall 2024 semester.
Christopher Pettengill
Doctoral Student, Clemson University
James C. Kennedy Waterfowl and Wetlands Conservation Center
Oysters are one of the most prevalent sessile organisms on the eastern seaboard of the United States. Oyster beds can be deployed in areas experiencing rapid shoreline erosion, but they are not a permanent fixture of coastal mitigation banks. Stakeholders are interested in the contributions of oysters to meeting restoration goals in coastal habitats, such as improvements in water quality and providing habitat structure for wildlife. Research is needed to understand better the impacts of incorporating oysters into salt marsh restoration. Christopher is investigating how the addition of oyster structures (wooden stakes, wireframes) to salt marsh restoration sites can enhance habitat quality and provide economic benefits to the site. Examples of these ecosystem services include providing habitat for fish and invertebrates (which provides food for aquatic birds) and biofiltration (for which they are interested in nitrate and phosphate reduction).
Christopher’s primary research objectives are:
Christopher’s hypotheses for each research objective are:
The restoration site where the study is being conducted is located at Little Edisto Island, South Carolina. Southeast Mitigation LLC (funding source and partner) is restoring natural tidal flux to a set of six saltwater impoundments at this location by removing sections of the surrounding berms.
Christopher is comparing the habitat conditions present at the restoration site currently with multiple reference sites also found on Little Edisto Island and Edisto Island, which he places into categories depending on the density of oysters and oyster beds present at the sites.
Methods:
Each month, Christopher records water quality parameters (water temperature, salinity, conductivity, pH, dissolved oxygen concentration). He takes water samples, which he filters using a Millex brand 45-um filter unit, and processes in the lab to record concentrations of phosphate and nitrate. Christopher monitors bird activity at each of the impoundments during monthly surveys. For fish sampling, Christopher uses minnow traps (six per impoundment), crab traps (one per impoundment), a fifty-foot seine net (five sweeps per impoundment), and throwing an eight-foot diameter cast net (ten cast net throws per impoundment). Invertebrate surveys involve taking sediment core samples using a PVC pipe sediment trap, as well as a D-net. Christopher samples invertebrates along a transect from the most upland position in the impoundment (that is covered by water at high tide) to the deepest point (that is accessible) of the impoundment. The same survey methods are also used at each reference site where surveys of that type are possible. In a separate experiment taking place at the restoration site, Christopher will be comparing the growth and colonization rates of oysters on wireframes and wooden stakes. The goal is to determine which of the oyster structure types provides the greatest oyster growth and recruitment relative to the cost of deploying the structures. Stakeholders from Southeast Mitigation will be using the more efficient of these two methods to deploy oysters at a much larger restoration site, where they plan on creating one hundred acres of oyster habitat.
Preliminary results – Prior to restoration actions
Pre-restoration conditions at the site show that wading birds, shorebirds, and wetland-associated songbirds use the impoundments at the Little Edisto Restoration site, mainly when large numbers of birds descend onto exposed mudflat habitat at low tide. Impoundments (and portions of impoundments) that have been unconnected to any tidal influence show few signs of bird activity outside of grassland songbirds. Waterfowl are currently essentially absent from the restoration site, outside of one male-female pair of hooded mergansers present in one of the impoundments with permanent water during a winter survey. Plant communities at the restoration site reflect what are traditionally considered salt marsh plant community assemblages, with Sporobolus alterniflorus, Salicornia depressa, and Distichlis spicata being the three dominant species. Water quality at the restoration site varies slightly across impoundments. Still, we are expecting to see a more significant effect of season on nitrate and phosphate concentrations, with higher concentrations being detected during summer than in winter.
Cindy L. Von Haugg
M.S. Student, Clemson University
James C. Kennedy Waterfowl and Wetlands Conservation Center
Wood ducks (Aix sponsa) are common year-round residents of wetlands throughout the Southeastern United States. Evidence suggests that >90% of the North American wood duck population nests in tree cavities rather than in artificial nest boxes. However, few studies exist on the occurrence of natural tree cavities, particularly across their southern breeding range. We aimed to determine forest and tree characteristics indicative of cavities suitable for nesting wood duck hens to direct future studies to areas most likely to have cavities. We surveyed 20-m radius plots within the five dominant forest types of South Carolina (n = 166) on private and federally managed land and measured and inspected 4,633 trees >22 cm diameter at breast height (DBH) for cavity presence and suitability. We identified 225 potential cavities, 156 cavities, and 31 cavities suitable for nesting wood ducks. We found total cavity and suitable cavity densities (no./ha) at our study sites were greatest in oak (Quercus spp.), gum (Nyssa spp.), and cypress (Taxodium spp.) (19.35 ± 20.27, 4.20 ± 5.12) stands, followed by oak and hickory (Carya spp.) (8.37 ± 11.42, 1.36 ± 2.98), oak and pine (Pinus spp.) (4.90 ± 7.15, 1.17 ± 2.80), loblolly pine (P. taeda) (2.10 ± 4.42, 0.23 ± 1.34), and longleaf pine (P. palustris) (1.40 ± 3.57, 0.23 ± 1.34), which was consistent with densities at both sites individually. The best-fit model for cavity presence showed a significant positive effect for site index, DBH, and stand age and a minor negative effect for tree density. Results for suitability cavity presence also showed a significant positive effect for DBH and stand age, a significant negative effect for tree density, and no effect for basal area. We used an optimized hot spot analysis in ArcGIS to narrow down our total sample area using our findings to areas with 90% (73 ha), 95% (56 ha), and 99% (732 ha) confidence for suitable cavity occurrence, which amounted to 0.001% (73 ha), 0.001% (56 ha), and 0.008% of our total sample area (89,559 ha), respectively. This understanding of the relative abundance of cavities and cavities suitable for wood duck nesting and the identification of tree and stand forest metrics that influence the occurrence of cavities and suitable cavities promotes efficient management of nesting wood ducks, forest, and timber harvest practices.
Figure 1. Densities of cavities (F4, 4624 = 22.83; P < 0.0001) and suitable cavities (F4, 4624 = 4.29; P = 0.0018) for wood ducks in 166 randomly selected 20-m plots by forest type (n = 5). Plot surveys were conducted in stands >50 years old at Hobcaw Barony and Francis Marion National Forest, South Carolina, USA. Error bars indicate 95% confidence intervals, and significant differences are represented with different letters.
Figure 2. Heat map using estimates of relative abundance to develop optimized hot spots for areas with >95% and >99% confidence intervals for highest and lowest cavity occurrence probabilities. The abundance estimates were derived from forest surveys at randomly selected 20-m plots, stratified by forest type, at Francis Marion National Forest (left) in Berkeley and Charleston Counties, and Hobcaw Barony (right) in Georgetown County, South Carolina, USA, from February through July 2022.
Cindy L. Von Haugg
M.S Student, Clemson University
James C. Kennedy Waterfowl and Wetlands Conservation Center
The reproductive ecology of cavity-nesting Aix sponsa (Wood Duck) has long gone understudied due to the secretive nature of this species and the inability to estimate the vital rates of the population. Trapping and monitoring individual activity has been successfully used to uncover the behavior and habitat selection of numerous species. However, migratory species add additional difficulty to diagnosing the proper timing of trapping efforts. Uncovering successful trapping techniques is required to maximize research efforts and increase our understanding of cavity-nesting Wood Ducks. Moreover, timing trapping effort is fundamental to successfully trapping locally nesting Wood Duck hens. Between 11 January and 30 June 2023, we monitored trap sites (n = 41). We collected trail camera images with Wood Ducks (n = 2,271 frames) to evaluate seasonal and diel activity patterns of hen, drake, and hatch-year Wood Ducks in coastal South Carolina. Our analysis of images of hen (n = 1,641), drake (n = 2,358), and hatch-year (n = 341) Wood Ducks showed that the occurrence of each differed among months, and the highest densities of hens occurred in January, February, and May. Our results suggest setting traps no earlier than 1 March to increase the chance of trapping a locally nesting hen. Our estimates also suggest the pre-breeding phase occurred from mid-January to late March; the first nesting attempts occurred from early March to late April, and the second nesting attempts began around late April. Wood Duck (96.5%) and hen-specific (96.3%) activity were highest during diurnal periods, suggesting trap site visits should be avoided at this time to minimize disturbance. Using these results as guidelines for future trapping efforts could greatly improve the trapping success of Wood Duck hens during the breeding season, thus increasing our understanding of the reproductive ecology of cavity-nesting Wood Ducks and best-informing management decisions.
Figure 1. The four trap phases, one week per phase, were used to accustom the wood duck (Aix sponsa) to the trap site over 28 days: 1) bait only; 2) the wire was positioned linear across the trap site between the observed avenue of approach and the bait; 3) the wire was positioned in a circle or rectangle, if it was a rectangular trap, with the bait placed inside; and 4) the trap was set. The trap entrance was configured into a funnel 20 cm at the narrowest point and 1.9 cm, heavy-duty nylon mesh, poultry netting, or top panels, if it was a rectangular trap, were zip-tied across the top (North and Hicks 2017). The set trap was approximately 2.5 m in diameter or length. Trapping efforts were conducted from 11 January to 30 June 2023 at Ernest F. Hollings ACE Basin National Wildlife Refuge in Colleton, Charleston, and Beaufort Counties, Waccamaw National Wildlife Refuge in Georgetown, Horry, and Marion counties, Santee National Wildlife Refuge in Clarendon County, Clemson University’s Pee Dee Research and Education Center in Darlington and Florence counties, and privately-owned Witherspoon Island in Darlington County, South Carolina, USA.
Cindy L. Von Haugg
M.S Student, Clemson University
James C. Kennedy Waterfowl and Wetlands Conservation Center
The challenges associated with climbing trees to measure cavity dimensions have limited the accumulation of knowledge regarding wood duck (Aix sponsa) nesting habitat and ecology. To overcome this issue, we developed a 2-person method to measure external and internal tree-cavity dimensions from the ground. Our approach uses a telescopic pole, wireless cavity inspection camera with a monitor, and reference scale, allowing an object of known length to be viewed and recorded inside the cavity. We tested our method using simulated cavities (n = 20), assessed accuracy by comparing the estimated and actual measurements, and evaluated precision between 2 observers. The average difference (±1 SE) between estimated and actual measurements (n = 40) for entrance width (0.9 ± 0.9 cm), entrance height (0.8 ± 1.1 cm), platform width (0.1 ± 3.7 cm), and platform length (1.0 ± 3.2 cm) were ≤1 cm. There was no significant difference between observer measurements for entrance width, entrance height, platform width, or platform length. Observers overestimated cavity depth by an average of 0.1 ± 1.6 cm and there was a significant difference (1.3 ± 2.2 cm) between observers for mean cavity depth. We applied the technique to naturally occurring cavities. The time to complete a natural-cavity survey in the field (n = 37) averaged 12.2 ± 6.9 min. Our method increases the practicality, accessibility, and safety of researchers conducting cavity surveys for wood ducks and other cavity-dependent wildlife using a cost-effective, cavity-measuring tool.
Figure 1. The assembled wireless cavity monitoring system capable of measuring internal dimensions of wood duck nesting cavities using a reference scale that can be 1) stored; 2) attached to the camera; and 3) lowered into a cavity.
Figure 2. Two-person operation of a wireless cavity monitoring system capable of measuring external and internal dimensions of wood duck nesting cavities.
Crystal Anderson
Doctoral Student, Clemson University
James C. Kennedy Waterfowl and Wetlands Conservation Center
Wetlands and the surrounding landscapes provide habitat for at-risk and endangered pollinator species such as the monarch butterfly (Danaus plexippus), southern plains pine bumble bee (Bombus fraternus), the rusty patch bumblebee (Bombus affinis), and a plethora of pollinators critical for ensuring sustainable gardens, agriculture, and ecological diversity in South Carolina. Among the 31 historical populations of monarch butterflies, 15 are facing the threat of extinction due to rising sea levels and excessively high temperatures caused by climate change. South Carolina is a critical stopover area for migrating monarchs, but a population of monarchs also overwinter in our area. The southern plains pine bumble bee, frequently found in the South Carolina coastal region, has experienced a significant loss in range, with a resulting 24% population decline since 2010. The rusty patch bumble bee has seen similar declines, especially with increased development and community HOA regulations that require frequent mowing during the critical emergence of this species. Community education and participation in pollinator gardens may increase pollinator abundance and diversity.
Hampton Plantation is a historical site located in the community of Germanville, South Carolina, inhabited primarily by descendants of those enslaved to work the historic rice fields. Many of the families surrounding Hampton Plantation have lived in this region for hundreds of years and continue to bury their family members within an active cemetery located on the property. The community surrounding Hampton Plantation faces food scarcity and high poverty rates due to its remote rural setting. In the US, 12.8% of households faced food insecurity in 2014, with higher rates among Black, Latino, and low-income families. Limited access to healthy food leads to health issues like depressive symptoms, diabetes, and heart disease. Food-insecure populations struggle to afford fresh food due to poor food environments. Alternative programs like community gardens may address these challenges, especially where traditional supermarkets are lacking. With nearly 75% of agricultural plants relying on pollinators to produce, understanding community needs and using pollinator plants and associated pollinators provides not only ecological benefit, but can play a pivotal role in empowering underserved communities to take charge of their dietary needs.
Social surveys will be conducted to establish a baseline understanding of historically preferred foods, as well as the economic and physical barriers to gardening and the ecological knowledge of Germanville community members concerning the benefits of pollinators. Pollinator gardens will be established at both Hampton Plantation and within the Germanville community for educational purposes. Additionally, multiple food gardens will be installed in the Germanville community to facilitate agricultural education and community empowerment. Throughout the three-year study period, community education events will be organized to promote gardening concepts and actively solicit feedback on any challenges to gardening progress, enabling project adjustments to enhance the likelihood of success. A final survey will be used in year three to determine the knowledge gained, the number of participants still active in the program. If the program is deemed a success, we will work with other SC State Parks to create additional community projects around historical rice fields.
Crystal Anderson
Doctoral Student, Clemson University
James C. Kennedy Waterfowl and Wetlands Conservation Center
Historical antebellum rice fields in the low country of South Carolina have been deeply ingrained in the culture since the early 1700s. Through the installation of rice trunks, a large wooden apparatus that allowed the control of water levels through the rise and fall of tides, large-scale rice production was possible. Sprawling plantations brought immense prosperity to the southeast and ultimately changed our coastal geography. We understand today that tidal wetlands deliver a multitude of ecosystem services crucial for ecological well-being, as well as for the cultural and emotional well-being of residents. They offer services including the provisioning of food, fiber, fuel, and biochemical materials; climate regulation via hydrological flows, water purification, and erosion control; cultural protection and recreational opportunities; and essential ecological functions such as soil formation and nutrient cycling. Since the early 1900s, many of the 236,000 acres of antebellum rice fields across South Carolina’s coast have been left to nature, reverting to natural marsh. However, many are still actively managed for a different sort of production – waterfowl populations.
Antebellum rice fields provide a critical stopover wintering habitat for many waterfowl and waterbird species. The restoration and protection of antebellum rice fields may be an essential factor in slowing the onslaught of climate change and associated ecosystem service losses, as well as ensuring adequate waterfowl habitat for future populations. However, restoration can be cost-prohibitive, and with rising sea levels, we must assess at what point the restoration and protection of these historical relics are viable.
Management decisions that fail to consider the history, knowledge, and perceptions of the community can create resistance in community support, underscoring the need to understand human knowledge and perceptions to effectively address both environmental and social dimensions of resilience. Stakeholder surveys play an instrumental part in bridging the gap between policy and people. We are addressing the human dimensions of waterfowl management in antebellum rice fields by creating an in-depth survey that evaluates stakeholder knowledge of historic rice fields, cultural influence, and perceptions of associated infrastructure, and restoration. Out stakeholders are defined as state and private waterfowl managers, area residents, and culturally significant populations.
We anticipate that state and private waterfowl managers will have a strong knowledge of the ecological significance of waterfowl management. Area residents and culturally sensitive populations will have little understanding of ecological significance. State and private waterfowl managers and culturally significant stakeholders will have a strong desire to continue current rice field management strategies for waterfowl populations. However, we anticipate those with cultural ties to the area wishing to maintain traditional irrigation management through historical rice trunk technology. In contrast, state and private waterfowl managers and area residents may seek less cost-prohibitive methods for irrigation control.
Surveys will run from October 2024 through December 2024. The analysis will begin in January, with anticipated results by May 2025. These results will then be used in conjunction with aerial drone and acoustic surveys to help develop a decision support tool for future antebellum rice field management to promote coastal resiliency and future waterfowl populations.
Hallie E. Cowan Barrera
M.S. Student, Clemson University
James C. Kennedy Waterfowl and Wetlands Conservation Center
Three species of caiman currently range in Suriname: spectacled caiman (Caiman crocodilus), smooth-fronted caiman or Schielder’s dwarf caiman (Paleosuchus trigonatus), and Cuvier’s dwarf caiman (Paleosuchus palpebrosus). Very little work has been done with their populations in Suriname. The only published papers on caimans in Suriname look at population ecology of Caiman crocodilus (Ouboter & Nanhoe, 1987, 1988, 1989).
In recent years, ecotoxicology has been delved into more and more when it comes to crocodilians. Crocodilians have been found to be great bioindicators when it comes to heavy metal contaminants because of their longer lifespan, varied diet, and trophic level (Marrugo-Negrete et al., 2019; Nilsen et al., 2019; Schneider et al., 2013). They move through trophic levels throughout their lives, being eaten by many other animals when young, including birds and other crocodilians, to apex predators as adults. This allows for studies looking at ecotoxicology to see how heavy metal concentrations change through trophic level changes.
Small-scale gold mining using mercury amalgamation is popular in the eastern part of Suriname. As the mercury gets used to separate the gold from the sediment, it gets released into the environment. The disruption of soil through this process can also release mercury, which is a natural component of the soil (Ouboter, 2015). Studies focusing on mercury accumulation have been on the rise, with most of the focus on the southwest region of the Amazon and lacking in the northern region (Guiana Shield) (Martoredjo et al., 2024).
This project investigates the effects and amounts of heavy metals in three species of caiman in Suriname (Caiman crocodilus, Paleosuchus trigonatus, and Paleosuchus palpebrosus). Specifically, we want to look at mercury, lead, and selenium. Also, we will look at what each species is eating in these populations and correlate this to the amounts of metals they are accumulating.
We will look at all three species of caiman at two sites, one where there is a lot of anthropogenic impacts and one with relatively low impact. The first site is located in a remote area in west Suriname. It is a newly opened research station, and we will be some of the first to use it. The second location will be in Peperpot Nature Park. This is across the Suriname River (less than 1 kilometer away) from Paramaribo, the capital of Suriname.
For each caiman, we will take 5mm clippings from three scutes towards the tip of the tail, three nail clippings from the three longest nails, and a blood sample. Clippings will be cut with sharp claw clippers and put into plastic tubes labeled with the PIT tag number of the individual. They will be put in a freezer immediately after returning to the place of stay in the field until sent for analysis (Lemaire, Bustamante, Marquis, et al., 2021).
To learn more about the diets of these caimans and better understand how these caimans are accumulating all these metals, we will be looking at their stomach contents using stomach flushing. This is commonly used in crocodilians to see what exactly individuals in a population are eating without dissection. There are multiple techniques for stomach flush. We chose to use a hose with Heimlich maneuvers as it was found to be the most efficient at removing all stomach contents (Fitzgerald, 1989).
We predict that there will be a difference in total mercury accumulation between the sites, with the caimans at the more remote western site having lower overall concentrations. We are looking to see a correlation between continents and diet, especially caimans that eat more fish, which accumulate mercury in high concentrations (Da Silva et al., 2005). With this, caimans that eat more terrestrial vertebrates and less fish may have lower total mercury accumulation.
This study could help push for healthier waterways not only for caimans but also for humans. In many of these areas where caimans live and eat, humans are doing the same things, with a large part of their diet being fish caught from rivers. Caimans can be used as bioindicators of mercury contamination, helping give the people who live in these areas an idea of the health effects of the fish they are eating.
Jordan McCall
M.S. Student, Clemson University
James C. Kennedy Waterfowl and Wetlands Conservation Center
Wetland habitats are ecologically valuable due to their high biological diversity and productivity, with many avian species depending on them. Understanding how waterfowl select habitats for use is essential to successful wetland management. The southeastern coastal plain of the United States contains 27% of the wetlands within the lower 48 states. However, only about 9% of these wetlands are of high or moderate value to waterfowl and other waterbirds. The region is comprised of 7 main wetland type classifications: (1) estuarine deepwater, (2) estuarine wetland, (3) freshwater emergent, (4) freshwater forested and shrub, (5) freshwater ponds, (6) lakes, and (7) riverine wetlands. Despite the significance of the Hobcaw Barony in a region historically known as a waterfowl hunting paradise, the long history of the Belle W. Baruch Institute of Coastal Ecology and Forest Science on Hobcaw Barony and the establishment of the James C. Kennedy Waterfowl and Wetlands Conservation Center at the Baruch Institute in 2014, no comprehensive study of waterbirds has occurred on site. Thus, this study aims to form a fundamental baseline of wetland and waterbird data as the beginning of a long-term dataset. Our specific objectives were to 1) determine which wetland type is hosting the most waterbirds in terms of species diversity and abundance and 2) determine what environmental factor(s) are contributing to the most productive wetland type at Hobcaw Barony and DeBordieu Colony.
This study along the South Carolina coast began in January of 2022, encompassing extensive, conserved lands and highly developed and altered landscapes. Two field seasons have since been completed from February-July of 2022 and January-July of 2023. Research sites were at the Hobcaw Barony (~7,000 ha) and the DeBordieu Colony (~1,000 ha).
In 2022, we performed point count surveys at 95 randomly selected wetlands, varying by type, and secretive marshbird surveys at 10 emergent wetlands to estimate occupancy rates, species diversity, species abundance, and migration chronology. In 2023, we performed point counts in 98 randomly selected wetlands and secretive marshbird surveys in 8 emergent wetlands. In year 2, we readjusted and maximized sampling effort on wetland types where waterbirds were most abundant and decreased on the remaining types (based on the availability of time to survey) where few birds were observed, surveying in 98 wetlands. Wetland-level data (e.g., water quality, water regimes, vegetation, macroinvertebrates) were also collected to model waterbird use and selection of wetlands. To determine which environmental factor(s) were driving waterbird attraction, we will perform a generalized linear mixed model with a Poisson distribution for each species guild and our top 12 detected species.
We detected 4,099 waterbirds over our two field seasons. We observed 56 species, with 34 of those species seen in both field seasons, 8 species unique to 2022 and 13 species unique to 2023. We observed 1,518 wading birds (10 species), 744 shorebirds (16 species), 844 waterfowl (13 species), 347 marshbirds (6 species), 161 gulls-terns (6 species), 445 anhingas-cormorants-pelicans (4 species), and 40 grebes (1 species). Preliminary results from the generalized linear model for waterfowl reveal that the following environmental factors have a significant effect on their presence: location, wetland classification, vegetation distribution pattern, water regime, wind direction, distance to nearest wetland, wetland area, macroinvertebrate species richness, and percent vegetation cover. Waterfowl had a significant positive relationship with DeBordieu, specifically, lacustrine limnetic unconsolidated bottom wetlands (i.e., lakes) and permanently flooded open-water wetlands. These results are no surprise as DeBordieu contains primarily this wetland type, and historically, this wetland type highly supports waterfowl species.
This study would not have been possible without funding support from the DeBordieu Colony and the James C. Kennedy Waterfowl and Wetlands Conservation Center, and logistical support from the Nemours Wildlife Foundation, Belle W. Baruch Foundation, and Clemson’s Department of Forestry and Environmental Conservation. We also appreciate Jack Corbin, Anna Koon, Carly Sprott, and Blair Abernathy for their assistance in the field.
Jordan McCall
M.S. Student, Clemson University
James C. Kennedy Waterfowl and Wetlands Conservation Center
The South Coastal Plain of South Carolina is essential for migrating, wintering, and breeding waterfowl and other waterbirds. Historically, 30 to 50% of Atlantic Flyway green-winged teal (Anas crecca), northern shoveler (Spatula clypeatea), mallard (A. platyrhynchos), northern pintail (A. acuta), American wigeon (Mareca americana), and gadwall (M. strepera) wintered in the region. However, recently, waterfowl have been wintering further north, possibly due to climate change and warming temperatures. Waterfowl often migrate due to changes in habitat conditions, resource availability, nesting location, breeding season, and other factors. Spring migration for waterfowl, specifically, is an essential phase of their annual cycle and can provide critical information when it comes to wetland management. Despite the significance of the Hobcaw Barony in a region historically known as a waterfowl hunting paradise, the long history of the Belle W. Baruch Institute of Coastal Ecology and Forest Science on Hobcaw Barony and the establishment of the James C. Kennedy Waterfowl and Wetlands Conservation Center at the Baruch Institute in 2014, no comprehensive study of waterfowl or waterbirds has occurred on site. Thus, this study aims to form a fundamental baseline of wetland and waterbird data as the beginning of a long-term dataset. Our primary objectives were to 1) document winter and spring temporal trends and spring migration chronology of waterbirds using wetlands on Hobcaw Barony and DeBordieu Colony (an adjacent development) and 2) determine which species have similar migration patterns.
This study along the South Carolina coast began in January of 2022, encompassing extensive, conserved lands and highly developed and altered landscapes. Two field seasons have since been completed from February-July of 2022 and January-July of 2023. Research sites were at the Hobcaw Barony (~7,000 ha) and the DeBordieu Colony (~1,000 ha).
In 2022, we performed point count surveys at 95 randomly selected wetlands, varying by type, and secretive marshbird surveys at 10 emergent wetlands to estimate occupancy rates, species diversity, species abundance, and migration chronology. In 2023, we performed point counts in 98 randomly selected wetlands and secretive marshbird surveys in 8 emergent wetlands. In year 2, we readjusted and maximized sampling effort on wetland types where waterbirds were most abundant and decreased on the remaining types (based on the availability of time to survey) where few birds were observed. To document temporal trends, we averaged species densities in each wetland and graphed them over two-week periods. We also performed a complete linkage hierarchical cluster analysis to identify which species had similar migration patterns.
We detected 4,099 waterbirds over our two field seasons. We observed 56 species, with 34 of those species seen in both field seasons, 8 species unique to 2022 and 13 species unique to 2023. We observed 1,518 wading birds (10 species), 744 shorebirds (16 species), 844 waterfowl (13 species), 347 marshbirds (6 species), 161 gulls-terns (6 species), 445 anhingas-cormorants-pelicans (4 species), and 40 grebes (1 species). On average, wading birds peaked in late March at 2.92 ± 1.09 birds/ha; shorebirds peaked in mid-May at 3.37 ± 1.35 birds/ha; waterfowl peaked in late March at 1.91 ± 1.42 birds/ha; secretive marshbirds peaked in late April at 0.83 ± 0.29 birds/ha; pelicans, anhingas, and cormorants peaked in late March at 0.89 ± 0.31 birds/ha, as well as gulls and terns at 0.43 ± 0.27 birds/ha. The cluster analysis revealed two large species clusters, cluster A, more frequently occurring from April to July, and cluster B, more regularly occurring from January to March, including almost all waterfowl species.
Of the 56 species detected, 14.3% occurred throughout our survey period, with most being herons, egrets, and anhingas. The remaining 85.7% exhibited patterns of increasing or decreasing in the study area due to rainfall, tide levels, and simply using the property as a stopover site during migration. Our study identified a very low overall density for most species, which could have been due to weather during our field seasons, such as a lack of rainfall or overall low habitat quality. When Hurricane Hugo hit these properties in 1989, it caused a decline in the total number of vegetation species present at Hobcaw, with Phragmites rapidly colonizing these areas. Further vegetation declines occurred between 2013 and 2015, likely due to rising sea levels and an increase in water salinity, possibly contributing to the low species densities. We recommend that future managers of these and surrounding properties use these data to know when and how to manipulate their wetlands. Future research could include performing point-count surveys during low or high tide only to standardize conditions, using drone technology to increase counts further than just the eye can see, and collecting macroinvertebrate data more often (e.g., monthly) to analyze how their population densities align with waterfowl.
This study would not have been possible without funding support from the DeBordieu Colony and the James C. Kennedy Waterfowl and Wetlands Conservation Center, and logistical support from the Nemours Wildlife Foundation, Belle W. Baruch Foundation, and Clemson’s Department of Forestry and Environmental Conservation. We also appreciate Jack Corbin, Anna Koon, Carly Sprott, and Blair Abernathy for their assistance in the field.
Maiya Duncan
Ph.D. Wildlife and Fisheries Biology, Clemson University
James C. Kennedy Waterfowl and Wetlands Conservation Center
Mallards (Anas platyrhynchos) are a widely distributed dabbling duck species that have served as a vital food source for humans for thousands of years. Historically, these ducks nested west of the Mississippi River, with the highest nesting densities found in the Prairie Pothole regions. Due to significant human interaction, including hunting, observation, protection, domestication, and introduction to new habitats, mallards have been extensively studied and managed, particularly in Eurasia.
The introduction of mallards to eastern North America occurred through two primary mechanisms: natural breeding range expansion and game farm release. Wild mallards from western North America expanded their range eastward, while domesticated game-farm mallards, originally from Eurasia, were released starting in the 1920s. Estimates suggest that annual releases ranged from 200,000 to 500,000 individuals. While these efforts have bolstered mallard populations globally, they have also resulted in genetic hybridization due to human-induced disturbances. Increased contact between wild and domestic forms has led to a loss of genetic integrity, posing significant threats to the long-term survival of these species. The introduction of domestic genes into wild populations can diminish their adaptation to natural environments, increasing vulnerability to extinction.
Humans have been domesticating mallards since 500 BC, beginning in central China. The practice of domestic mallard supplementation has been widespread, with intensive release programs commencing in the early 20th century. Game-farm mallards are bred explicitly for release on private hunting grounds and training duck dogs. These domesticated individuals have significantly altered the genetic composition of wild mallard populations in both Eurasia and North America. The intentional or accidental release of domestic mallards has resulted in widespread introgression, threatening the genetic integrity of wild populations.
This study aims to investigate the differences between hybrid/game-farm mallards and wild-born mallards through genetic analysis, tracking migratory behavior across the Atlantic Flyway, and observing predator-prey interactions using camera traps. By analyzing the genetic differences, migration patterns, and responses to predation, we seek to understand the implications of hybridization on local adaptation and the ecological integrity of wild mallard populations. The research will employ a mixed-methods approach by conducting genetic analysis. Blood samples will be collected from both hybrid/game-farm and wild-born mallards, followed by DNA sequencing to identify genetic differences. GPS devices will be fitted to a subset of mallards to monitor their migration patterns over two years. Camera traps will be deployed at nesting sites to observe nesting success and predator interactions, focusing on behavioral differences between hybrid and wild mallards. The findings from this study will provide critical insights into the genetic, behavioral, and ecological differences between hybrid/game-farm mallards and wild-born mallards. Understanding these differences is essential for conservation efforts aimed at preserving the genetic integrity of wild mallard populations and mitigating the impacts of hybridization.
Miriam Boucher
Doctoral Student, Clemson University
James C. Kennedy Waterfowl and Wetlands Conservation Center
Human activity is the largest contributor of environmental contaminants at the global level. In many areas, legacy contaminants like mercury and contaminants of emerging concern, including per- and polyfluorinated substances (PFAS) and microplastics, enter the environment through surface waters. These contaminants pose risks to natural resources, including water and wildlife, mainly where wildlife is consumed as part of recreational or commercial harvest. As contaminants of emerging concern, research on PFAS and microplastics is critical to addressing data gaps to quantify and understand potential impacts on wildlife; one management strategy to assess and monitor water quality is using indicator species that reflect the biotic or abiotic state of the environment.
American alligators (Alligator mississippiensis) are ubiquitous in freshwater and brackish wetlands throughout the southeastern United States, including the coastal plain of South Carolina. Alligators are currently used as indicators of exposure to contaminants, particularly metals and persistent organic pollutants. Moreover, they are a highly managed species, captured annually for research and management programs and harvested legally through public and private hunting. As such, there is potential to explore alligators as candidate indicator species for PFAS and microplastics in South Carolina and across their range. In addition to contaminants, there is a lack of data regarding alligator diet throughout much of the range. As the primary exposure pathway for contaminants, determining trends in the alligator diet is vital to elucidating patterns of contaminant exposure in alligators.
This project leverages an 8-state collaborative network to collect alligator stomach contents, blood, and tail muscle from wild alligators through live capture and stomach flushing, as well as from hunter-harvest. We have collected over 400 samples in the first two years from North Carolina, South Carolina, Georgia, Florida, Alabama, Mississippi, Louisiana, and Texas. We have analyzed preliminary data of diet for 300 alligators, finding notable differences in prey prevalence between tidal and non-tidal habitats. Although waterfowl and waterbirds are present in some stomachs, we found little evidence of duck depredation, with one blue-win teal recovered from east Texas. However, we recovered four wood duck web tags from one adult alligator on Lake Moultrie, SC, and one web tag from Apalachee WMA, FL. These tags were deployed as part of the large wood-duck project supported by the Kennedy Center and Nemours Wildlife Foundation. We are working with B. Bauer of Nemours Wildlife Foundation to publish these results.
In conjunction with our diet data, we analyzed 100 blood, 100 muscle, 100 water, and 100 sediment samples from South Carolina for PFAS in collaboration with Dr. John Bowden at the University of Florida. Data analysis and peak integration are in progress, and this work may expand in 2025. In partnership with Dr. Kylie Rock at Clemson University, we are also analyzing the largest multistate dataset of alligator blood and muscle samples for mercury. We also engaged 12 undergraduate students on the project through a Clemson Creative Inquiry course, and three of these students completed 2024 summer internships with the Kennedy Center. The results of our diet, PFAS, and Mercury analyses will contribute to the first regional datasets of this scale for American alligators.
Oluwatobi Emmanuel OLANIYI
Doctoral Student, Clemson University
James C. Kennedy Waterfowl and Wetlands Conservation Center
Antebellum rice fields along South Carolina's coast, once key for rice farming, today provide critical habitat for bird species like warblers, shorebirds, and waterfowl. Planters used to maintain these fields for economic advantage, but they are now prized for their more comprehensive environmental benefits. With increasing sea levels threatening these places, there is an urgent need for novel management solutions that fulfill both ecological preservation and community needs. This study aims to develop a decision-support tool for managing these historic rice fields. It will involve collecting and integrating data on environmental and social aspects, assessing restoration methods, and creating a risk-benefit matrix profile to evaluate the impacts of various management actions.
This research uses a mixed-methods strategy that combines quantitative and qualitative methodologies to assess the restoration of antebellum rice fields. It uses geospatial analysis, field assessments, and socioeconomic evaluations to understand restoration results comprehensively. The Analytical Hierarchy Process (AHP) is used in the study to make multi-criteria decisions, which will aid in assessing numerous success variables and prioritizing restoration activities. The study engages a diverse group of stakeholders, including Gulla Geechee, the public, and plantation managers, focusing on ten restoration sites across key river basins. Data collection methods include GIS and remote sensing for tracking land use and cover changes, field-based ecological assessments, and socioeconomic surveys through questionnaires and focus group discussions. For data analysis, AHP will assist in evaluating and prioritizing success criteria, while geospatial analysis, machine learning models, generalized linear modeling, Bayesian Belief Networks, and Python libraries will be employed to conduct scenario analysis and develop risk-benefit matrix profiles and decision support tools.
The findings are expected to reveal the effectiveness of restoration efforts, focusing on key indicators such as ecological dominance, diversity, hydrological connectivity, and socioeconomic impacts. The study will also provide insights into the risks and benefits associated with ecological and societal factors. Also, the development of a decision support tool will facilitate informed management decisions by integrating various data and analysis scenarios. Results will be summarized in tables showing restoration success and socioeconomic impacts, and figures illustrating risk-benefit analyses and the decision support tool's interface.
Rene Brown
M.S Student, Clemson University
James C. Kennedy Waterfowl and Wetlands Conservations Center
One of the most prevalent substances on Earth is water, which is made up of hydrogen and oxygen and is essential to all living things. It is the main component of the majority of living things, including people. Water availability is a major limiting factor for plant productivity in terrestrial ecosystems globally, even though it is abundant on Earth's surface. This emphasizes how vital water is to the survival of ecosystems in general and wetlands in particular.
Wetlands are ecosystems distinguished by soil, vegetation, and hydrological characteristics. These include certain soil types, plants that do well in damp environments, and the existence of standing water for a portion of the growth season. Another noteworthy quality of wetlands is their capacity to filter metals out of surface and groundwater, improving the quality of the environment. These characteristics highlight their significance as natural filtration systems that preserve water quality as well as biodiversity hotspots.
The Eastern oyster, or Crassostrea virginica, is a keystone species that offers a multitude of ecological functions and is one of the species that are essential to wetland and estuary environments. As a commercial product, oysters support coastal economies and provide food and building materials. Oysters have a significant ecological impact in addition to being economically valuable since they filter water, enhance its quality, and provide habitat for other species. Particularly in regions where anthropogenic activities have an influence, their existence increases the resilience of the ecosystem.
Plant litter decomposition in estuarine wetlands is crucial for short-term carbon storage, nutrient cycling, and coastal trophodynamics. Aquatic ecosystems depend on the decomposition of organic matter to recycle nutrients and other chemical elements, maintain vital food chains, and support primary production. Although the coastal ecosystem of Little Edisto Island is still mostly intact, problems with water quality could endanger the oyster habitats, plant communities, and fish populations. One method for developing living shorelines and stabilizing coastal systems is the restoration of native oyster populations. Oysters are essential to these habitats because they grow in unique formations like "oyster flats" along creeks and rivers or on the edges of marshes. The former shrimp farm site S-161 on Little Edisto Island offers a chance for oyster farming and wetland restoration. Impoundments will be converted into oyster beds, new buildings will be erected, and water filtration will be improved to promote oyster development at this site.
The goal of this study is to clarify the relationships between environmental variables and the condition of these essential ecosystems. The research will improve conservation and restoration methods targeted at strengthening the resilience and sustainability of these ecosystems in the face of anthropogenic and climatic stressors by gaining an understanding of the factors that affect oyster and plant populations.
The breakdown of plant litter, an essential process for the nutrient cycle and overall health of salt marsh ecosystems, is a major area of attention for this research. In an impounded salt marsh, the decomposition rates of leaf litter from Juncus roemerianus and Sporobolus virginicus are investigated in this study. The study quantifies the decomposition process and determines the environmental conditions causing these changes by tracking mass loss over time using litter bags. When compared to natural marshes, the peculiarities of impounded marshes may change the dynamics of decomposition, affecting the availability of nutrients and the general health of the ecosystem. These results will help create better management strategies to preserve the ecological balance and productivity of reclaimed salt marshes. By integrating these different aspects of wetland ecosystems, the research aims to provide insights into ecosystem functioning and restoration, contributing to the broader goals of wetland conservation
Scott Binger
Doctoral Student, Clemson University
James C. Kennedy Waterfowl and Wetlands Conservation Center
Wetlands are highly impactful ecosystems, providing ecosystem services including water quality and flooding regulation, carbon sequestration, and harvestable resource provisioning (Mitsch et al. 2015). However, wetlands are also some of the least protected ecosystems in many areas (Barbier 2011). Additionally, wetlands that are isolated (lacking direct connections to rivers, streams, estuaries, or the ocean) face increased vulnerability to loss and extensive disturbance (McCauley et al. 2013). Carolina Bays are unique isolated wetlands found throughout coastal South Carolina that provide important habitat for rare species but have faced extensive loss due to urbanization and agriculture (Sharitz 2003). Conservation efforts in these areas require the ability to quickly assess the biotic and abiotic conditions of these sites, and the ability to gauge how these conditions respond to human disturbance and environmental change. Indices of Biotic Integrity (hereafter referred to as IBIs) are useful tools that allow these assessments to be made using data on biological communities (Veselka and Anderson 2013). Anuran, avian, macroinvertebrate, and vegetative community compositions each respond to changes in conditions differently, and data on these compositions can be used to derive a variety of metrics that can be included in IBIs, allowing for indices that capture a range of important biotic responses to disturbance that can be easily applied across sites and used to inform wetland management decisions. This study seeks to create IBIs for Carolina Bay wetlands, with the goal of assessing how their biotic communities respond to human disturbance and creating actionable, easily interpreted research tools to assist management efforts.
This study will use a mixed-method approach, sampling 60 Carolina Bay wetlands over 2 years from 13 counties in South Carolina. For the biotic data in each wetland, we will quantify the abundance and biomass of macroinvertebrates by family or finer resolution, collect quantitative and qualitative measures of plant species presence and cover, determine relative abundances of anuran species via call surveys, and determine the abundance of avian species via point count surveys. These sampling efforts will occur seasonally throughout the year, repeated as necessary. We will develop a disturbance gradient based on land use, hydrological alteration, and habitat alteration/development. This gradient will be used to score each site. In addition, we will measure soil and water chemistry and hydroperiod to determine abiotic variables influencing community composition. Sites will be divided into reference and stressed sites by degree of disturbance, and we will conduct comparisons of potential IBI metrics between reference and stressed sites. We will test and grade metrics by the level of overlap in the interquartile ranges of values for reference and stressed sites, and the highest-graded metrics for each taxon will be kept. We will use generalized linear models to evaluate the response of these metrics to human impairment, which will inform which metrics are combined to create IBIs for each taxonomic group and cumulatively across taxonomic groups.
We anticipate that the best performing IBIs, with regard to their response to human impairment, will use combinations of metrics that respond to a wide range of stressors, and that these IBIs will help to identify 1). high-risk taxonomic groups 2). sites of high vulnerability and 3). highly impactful stressors. We hope that, by identifying these, we can create tools that will streamline the assessment of sites and improve potential management outcomes in isolated wetlands.
