Date of Award

Spring 5-11-2026

Document Type

Thesis

Degree Name

Bachelor of Science (BS)

Department

Marine Science

College

College of Science

First Advisor

Ryan Rezek

Abstract/Description

Estuarine food webs are driven by multiple basal resource pathways, yet the relative importance of estuarine primary production to higher trophic level consumers remains unclear. We compared the trophic ecology of juvenile Carcharhinus plumbeus (sandbar shark; n = 19, 66–120 cm fork length) and Rhizoprionodon terraenovae (Atlantic sharpnose shark; n = 7, 73–81 cm fork length) within Winyah Bay, South Carolina. Fin tissues were analyzed for stable isotope ratios of carbon (δ¹³C), nitrogen (δ¹⁵N), and sulfur (δ³⁴S). Bayesian mixing models and nonparametric statistical analyses were used to estimate source contributions and compare trophic patterns between species. Posterior distributions indicated that both species were primarily supported by Spartina-derived production and estuarine phytoplankton, with minimal contributions from benthic or terrestrial sources. Mean trophic levels were similar between species (C. plumbeus: mean = 3.56; R. terraenovae: mean = 3.51), indicating that both species function at comparable trophic positions within the estuarine food web and may utilize similar prey resources. Differences in δ¹³C and δ³⁴S values between species suggested variation in basal resource use and energy pathways. A significant positive relationship between body size and trophic level was detected in R. terraenovae but not in C. plumbeus, indicating potential ontogenetic shifts in feeding ecology. Overall, these findings suggest that estuarine primary production, particularly Spartina-derived production and phytoplankton, plays an important role in supporting juvenile sharks within Winyah Bay. This study highlights the ecological importance of estuarine productivity in supporting coastal shark populations and food web dynamics.

Download

Available for download on Sunday, May 06, 2029

Share

COinS