Date of Award

8-28-2026

Document Type

Thesis

Degree Name

Master of Science in Coastal Marine and Wetland Studies

Department

Coastal and Marine Systems Science

College

College of Science

First Advisor

Angelos Hannides

Second Advisor

Cara Schildtknecht

Third Advisor

Chiara Gamberi

Additional Advisors

Danielle Viso

Abstract

Water quality monitoring crucially protects the health of beachgoers around the world. However, water-adjacent sediments, such as sandy beaches, are known to harbor harmful bacteria, yet are not monitored despite their intensive recreational use. This project monitored the abundance of fecal indicator bacteria (FIB), specifically Enterococci, in sandy beach sediments at beaches routinely monitored for water quality in Myrtle Beach and North Myrtle Beach, South Carolina. Surface sediment core sampling (0-5 cm) in the swash zone was conducted once per month for 4 months at 24 beaches in tandem with state-accredited surf-water FIB monitoring using IDEXX’s Enterolert test (Standard Method 9230 D-2013). A beach-face transect view of Enterococcal abundances was documented by low-tide sampling at three different intertidal-zone levels and sediment depths (0-60 cm) along with surf water. No significant difference was found between sediment and water abundances, which have a modest monotonic association. Generalized additive models (GAMs) with thin plate regression splines revealed nonlinear relationships between sediment Enterococci and environmental predictors, such as numbers of stormwater pipes within 500 m, precipitation during the previous 18 hours, dissolved oxygen, and water Enterococcal abundances, as well as linear effects with wind speed and water depth. Overall, the findings supply empirical evidence of nonlinear environmental drivers of sediment Enterococcus and constitute a preparatory dataset and modeling framework to inform future predictive model development.

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