Dietary Niche of Three Omnivorous Turtle Species in a Northern Florida River: Insights from Stable Isotope Analysis

Mathew J. Denton^1,*, Gerald R. Johnston², Travis M. Thomas³, J. Hardin Waddle¹, Susan C. Walls¹, and Kristen M. Hart⁴

¹US Geological Survey, Wetland and Aquatic Research Center, 7920 NW 71st Street, Gainesville, FL 32653. ²Department of Natural Sciences, Santa Fe College, Gainesville, FL 32606. ³Nature Coast Biological Station, University of Florida, Cedar Key, FL 32625. ⁴US Geological Survey, 3321 College Avenue, Davie, FL 33314. *Corresponding author.

Southeastern Naturalist,Volume 22, Special Issue 12 (2023): 359–377

Abstract
Macrochelys suwanniensis (Suwannee Alligator Snapping Turtle) coexists with 2 other native large omnivorous turtle species (Chelydra serpentina [Snapping Turtle] and Trachemys scripta scripta [Yellow-bellied Slider]) in a 9-km section of the Santa Fe River in northern Florida. A major shift in dominant submersed aquatic vegetation prompted us to quantify trophic position and niche overlap among these 3 species. Here, we examine carbon and nitrogen isotopic values of these turtles and their potential food resources within the changing riverine system. We provide evidence of low isotopic niche overlap between M. suwanniensis and C serpentina, whereas T. s. scripta occupied a discrete niche having lower carbon and nitrogen values.

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