2006-2008 Research Projects: Ecosystem Dynamics
Project: Using Diamondback Terrapins As Sentinel Species For Monitoring Mercury Contamination In Estuarine Systems
David Owens, College of Charleston
Diamondback terrapins (Malaclemys terrapin) are the subject of this continuing project which will test the hypothesis that the diamondback can prove to be a powerful sentinel species to help track the accumulation and degradation of contaminants in estuarine and coastal environments.
Objectives of this study are to (1) Complete the long-term mercury feeding study and determine if bioaccumulation is occurring and finalize assessment of the validity of non-lethal blood and keratin sampling techniques, (2) Test the relationship of health endpoints to long-term mercury exposure, including reproductive, behavioral, and endocrine and (3) Determine if terrapins can be useful as a sentinel species for estuarine settings by linking terrapin sampling locations to existing projects investigating local mercury contamination, water quality parameters, and land-use criteria. To-date there has been several interesting findings. The larger females do have significantly higher Hg levels than the males which most likely relates to their prey items since females eat larger periwinkles (Littorina) than males do and larger periwinkles also have significantly higher Hg (121 ppb vs. 19 ppb). There is also a clear and significant seasonal drop in blood Hg in terrapins (both sexes) during August when they are maximally active metabolically. Our sampling in Georgia at the Purvis Creek super fund site (location of a former chlorine manufacturing plant) showed significantly elevated blood (746 ppb) and scute (3810 ppb) Hg at 10X or more higher levels than our sites in South Carolina. The female terrapins at Purvis Creek were also significantly smaller and showed indications of immunological deficiencies so they may have been directly impacted by the mercury.
The results will, in addition to being useful to terrapin conservation, also establish basic toxicity thresholds that may be relevant for other threatened reptilian taxa, such as sea turtles, that utilize estuaries. In addition, the biomonitoring tool to be developed should prove useful for resource management agencies, public health officials, and environmental impact assessment and remediation.
Contact for Questions
David Owen (firstname.lastname@example.org)
Project: Potential Impacts of Upstream Land Use Change On Phytoplankton Community Dynamics In Winyah Bay, S.C.
Tammi Richardson, University of South Carolina
The role of changing land use on estuarine quality depends in large part on a clear understanding of the potentially interactive effects of light quality, light quantity, and nutrient availability on phytoplankton community composition and the development of algal blooms.
This work will examine and characterize the phytoplankton community of Winyah Bay, South Carolina, a heavily impacted riverine estuary located about 50 miles north of Charleston. Characterization of phytoplankton community composition is critical because the taxonomic composition and relative abundance of different algal groups in a phytoplankton community are fundamental determinants of aquatic ecosystem structure and function. Significant alterations in phytoplankton community composition could have major negative ecological and economic impacts on the entire estuarine ecosystem. Harmful and nuisance algal blooms, decreases in water quality, alterations of trophic structure, and collapse of fisheries are all potential consequences of major shifts in community structure either at the algal group or species level. Bulk measures of community response (as measured by chlorophyll a) fail to show such shifts.
During the first year of the project, the researchers will (1) Characterize the spatial and temporal variability in underwater light quality and quantity, nutrient form and concentration, and phytoplankton community composition at nine stations along the Winyah Bay estuary, (2) Establish and run a continuous water quality monitoring station that will allow characterization of the fine scale temporal variability in water chemistry and biology, including CDOM concentrations and phytoplankton community composition, at an upstream (blackwater-influenced) site in Winyah Bay and (3) Quantify the degree of interference of high CDOM with estimates of chlorophyll a by fluorescence.
Contact for Questions
Tammi Richardson (email@example.com)
Project: An integrated hydrologic and ecological study of salt marsh dynamics
Alicia Wilson, University of South Carolina and James Morris, University of South Carolina
Coastal salt marshes are an important interface between the land and ocean. The researchers will conduct studies to further examine the root causes of salt marsh dieback, a phenomenon that results in the loss of key economic and ecological services normally provided by the state’s critically important salt marsh ecosystem. The exact cause of marsh dieback is yet unknown, although drought appears to play a major role. The proposed study will provide a critical first step for understanding marsh dieback by determining how drought affects soil moisture and salinity in marsh systems and how hydrologic changes propagate to marsh plants.
The first phase of the study will include the instrumentation of two adjacent marsh transects to monitor groundwater levels, salinity, evapotranspiration, and ecological productivity for a minimum of 18 months. In the next phase, the investigators will create numerical groundwater flow and transport models to simulate drought conditions. These will be developed using SUTRA, which is a well-established groundwater flow and transport software developed by the U.S. Geological Survey.
Project: Effects of Sublethal Concentrations of Agricultural Herbicides on the Structure and Function of Estuarine Phytoplankton Communities
James Pinckney, University of South Carolina
This research project is based on the notion that habitat alteration and loss of biodiversity due to pesticide contamination is rapidly emerging as a major ecological threat in wetland and estuarine ecosystems. Initial evidence shows that the common herbicide, atrazine, may be having significant effects on South Carolina’s wetlands and saltmarshes. In aquatic ecosystems, phytoplankton are usually the most atrazine-sensitive biotic components.
As such, the investigator will determine the short-term sublethal effects of environmentally-relevant concentrations of atrazine (under high and low nutrient concentrations) on estuarine phytoplankton community structure and function. Short-term phytoplankton bioassays will be used to measure initial phytoplankton responses to different levels of atrazine and nutrient exposure. The purpose of these experiments is to determine the effects of a range of atrazine and nutrient concentrations on phytoplankton primary productivity and biomass of specific algal groups (i.e., diatoms, cyanobacteria, dinoflagellates, cryptophytes, etc.) in natural estuarine phytoplankton assemblages. These data will be used to assess “who” responds to the different levels of atrazine treatments under ambient (light, nutrient, temperature, etc.) conditions. This experimental approach is critical for understanding the mechanisms underlying phytoplankton community responses and dynamics in estuarine ecosystems.
Contact for Questions
James Pinckney (firstname.lastname@example.org)
Project: Patterns and Processes Of Establishment Success Of Beach Vitex (Vitex Rotundifolia) Populations and Potential for Eradication
Allan Strand, College of Charleston and Courtney Murren, College of Charleston
The investigators will employ a multifaceted research approach to eventually test management strategies for dealing with a relatively new, non-native (possibly invasive) taxon, the dune plant commonly know as beach vitex (Vitex rotundifolia). There is concern that the plant will out-compete native species, negatively affect dune communities, and may also interfere with sea turtle nesting. In order to guide management efforts, knowledge of its reproductive and dispersal ecology are critical. In South Carolina, little is known about ecological or genetic factors that contribute to the establishment success or potential for exponential spread. Such data could serve as the basis for the development of successful control, eradication and restoration efforts.
The investigators will (1) Describe pollinator visitation patterns in North Carolina and South Carolina, (2) Conduct fieldwork for demographic modeling to assess changes on population dynamics both spatially and temporally, and (3) Assess genetic diversity, track local spread, and evaluate several alternative hypotheses of spread. In the first year, the research team will also monitor sand accumulation and beach erosion sites to determine if Vitex rotundifolia protects dunes from erosion; monitor and establish replicated trials of Vitex rotundifolia eradication methods and restoration efforts with native replacement species; and conduct greenhouse studies to determine the importance of above and below-ground competition between Vitex rotundifolia and local taxa (Uniola paniculata; Panicum amarum, and Iva imbicata). Similar studies will be conducted in the second year, and the focus will become the development of management protocols based on the field research. The investigator will conduct his work in cooperation with the South Carolina Beach Vitex Task Force, a non-profit organization. In addition, the Consortium is joining forces with North Carolina Sea Grant (where beach vitex is also becoming a problem) in a coordinated outreach/education initiative.
Project: An Assessment of Stormwater Best Management Practices for Coastal South Carolina: The Oak Terrace Preserve Monitoring Project
Dwayne Porter, University of South Carolina
The investigators have noted that best stormwater management practices (BMPs) developed at the national level may not be effective in certain regional and local situations. Recent regional research suggests that may not be efficiently treating and removing pollutants in stormwater. Therefore, the ultimate goal of this project is to test innovative BMPs at a local development site (Oak Terrace Preserve), where before-and-after data will be collected and made available to determine if the design BMPs are efficient at maintaining pre-development flow rates and effectively filtering/removing NPS pollutants at the small watershed scale. The Noisette Company, Inc., a partner in the project, has created plans for Oak Terrace Preserve as a way to redevelop land surrounding the former Charleston Naval Base in an effort to revitalize the community and promote sustainable development. Oak Terrace Preserve is a 55-acre tract of land, which will be developed to include over 370 parcels (mixture of 303 single-family homes and 74 town homes). Noisette is planning to use Low Impact Development (LID) practices that disperse stormwater throughout the developed area and allow increased infiltration to occur, which in effect should minimize changes to the existing hydrodynamics of the site. These plans also include innovative BMPs that presumably will promote stormwater infiltration and the retention of pollutants.
The results of the research will provide insight into the hydrologic transformations that occur throughout the development of Oak Terrace Preserve and how this may affect post-construction hydrodynamics and stormwater management. The investigators will monitor two sites: (1) A control (with no BMPs), which will be located in a suburban setting, and 2) A treatment (BMP) watershed in the Oak Terrace Preserve. Resultant data should provide further knowledge of regional hydrodynamics in coastal South Carolina that is pertinent to both understanding stormwater management in the southeast and improving stormwater BMP methodologies.
Contact for Questions
Dwayne Porter (email@example.com)