Date of Award
8-2026
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Wildlife and Fisheries Biology
Committee Chair/Advisor
Dr. Amy E. Scaroni
Committee Member
Dr. Stefanie L. Whitmire
Committee Member
Dr. Daniel T. Pettay
Committee Member
Dr. James T. Anderson
Abstract
Anthropogenic pollution introduces contaminants, such as pathogenic bacteria and turbidity, into coastal watersheds. These contaminants are the major contributors to water quality impairments in the three sub-watersheds encompassing Edisto Island and the Town of Edisto Beach (hereafter referred to as the Edisto Island Watershed), located within the ACE Basin, South Carolina, USA. With 18 locations impaired for fecal bacteria and 19 for turbidity on the 2024 South Carolina 303(d) list of impaired waters, the Edisto Island Watershed offers valuable insights into the water quality challenges rural coastal communities face.
This study aimed to identify the sources of fecal bacteria and turbidity in the Edisto Island Watershed that contribute to restrictions on recreational use and shellfish harvesting. To determine the source of fecal bacteria pollution, water samples were routinely collected across various sites for host-specific qPCR microbial source tracking (MST) using genetic markers for human, canine, avian, ruminant, and equine hosts. Methods for the bacteria study also included the enumeration of fecal indicator bacteria (FIB) and nutrient analysis. Sample collection for bacteria lasted from September 2024 to August 2025, with an additional targeted sampling effort for qPCR and FIB enumeration from September 2025 to December 2025. Generalized additive mixed models and Wald t-tests were used to identify spatial and temporal trends in fecal indicator bacteria (Enterococcus and E. coli) and water quality parameters throughout the study. Spearman's rank correlation coefficients were used to identify relationships between water quality variables and to guide mixed modeling of turbidity drivers. Only 6% of the original samples exceeded the South Carolina state standard for Enterococcus in recreational waters, and host-specific qPCR detected the canine marker only once during the original study and five times during the additional, targeted sampling effort. These findings suggest that low bacteria concentrations in estuarine waters may limit qPCR's effectiveness and, therefore, this study's ability to identify the prominent drivers of fecal contamination in the Edisto Island Watershed.
To understand the drivers of turbidity, water samples were collected from June 2024 to August 2025. They were then analyzed for total suspended solids (TSS), chlorophyll a, phytoplankton community composition and nutrient concentrations. Results indicated that suspended sediment was the primary contributor to turbidity during the study period (p < 0.01), often driven by large tidal-range events (p < 0.001). While algae were not the primary driver of year-round turbidity, they contributed at times during the summer months (p < 0.001). This study highlights that coastal watersheds face complex water- quality challenges driven by dynamic environmental processes and anthropogenic pressures, and that solutions to these challenges may require multiple management strategies.
Recommended Citation
Sumner, Brynne, "Understanding the Potential Sources of Bacteria and Turbidity Pollution in the Edisto Island Watershed" (2026). All Theses. 4849.
https://open.clemson.edu/all_theses/4849
Author ORCID Identifier
0009-0000-9183-1245