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The Diamondback Terrapin Working Group was formed in 2004 by individuals from academic, scientific, regulatory and private institutions/organizations working to promote the conservation of the diamondback terrapin, the preservation of intact, wild terrapin populations and their associated ecosystems throughout their range. The Diamondback Terrapin Working Group is committed to and supports research, management, conservation, and education efforts with the above goals in mind.
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Stable Isotope Analysis Enhances Our Understanding of Diamondback
Terrapin (Malaclemys terrapin) Foraging Ecology
Mathew J. Denton1,2
& Amanda W. J. Demopoulos1 & John D. Baldwin2 & Brian J. Smith3 & Kristen M. Hart1
Received: 29 November 2017 /Revised: 15 October 2018 /Accepted: 15 October 2018
# The Author(s) 2018
Abstract
Dietary studies on generalist predators may provide valuable information on spatial or temporal changes in the structure of
ecological communities. We initiated this study to provide baseline data and determine the utility of stable isotope analysis (SIA)
to evaluate the foraging strategies of an opportunistic reptilian predator, the diamondback terrapin (Malaclemys terrapin), which
specializes in salt marshes and mangrove estuaries along the Atlantic and Gulf coasts. We evaluated stable carbon (13C) and
nitrogen (15N) isotope values of multiple tissues from terrapins inhabiting mainland and island mangrove habitats in south
Florida and potential food sources to examine spatial and temporal variations in terrapin resource use. We fit linear regression
models to determine the best predictors of isotopic values for both terrapins and their prey, and Stable Isotope Bayesian Ellipses in
R (SIBER) analysis to examine terrapin isotopic niche space and overlap between groups. We identified differences in terrapin
isotopic 13C and 15N values among all sites. Blood and scute tissues revealed different isotopic compositions and niche overlap
between sites, suggesting diets or foraging locations may change over time, and amount of variation is site specific. Niche overlap
between size classes was larger for blood (short term) versus scute (long term), suggesting greater variability in food habits or
resource isotopes over the long term versus short term. These results demonstrate the usefulness of SIA in examining the spatial
and temporal variability in diamondback terrapin resource use within estuary systems and further define their niche within these
dynamic food webs.
Keywords Testudines . Everglades