Estuaries and Coasts

, Volume 42, Issue 4, pp 1138–1148 | Cite as

Comparisons of Population Structure and Morphology of a Saltmarsh Keystone Species (Malaclemys terrapin) Across Coastal Louisiana

  • Will SelmanEmail author
  • Steven H. Pearson
  • Jon J. Wiebe


Diamondback terrapins (Malaclemys terrapin) are an ecologically important species in salt marsh habitats, and they occur along the Gulf of Mexico and the Atlantic coastlines of the USA. Terrapins are subjected to a myriad of threats including loss of coastal marsh/nesting habitat and differential adult mortality in fisheries bycatch. In Louisiana, knowledge of terrapin populations is lacking even though they likely face these same threats. To address this knowledge gap, we sampled terrapins across coastal Louisiana from 2011 to 2015 using unbaited fyke nets at six study sites. We sexed all individuals and measured morphometric characters (including plastron length, PL and carapace height, CH). We captured 1111 individuals at all sites, and each site was represented by ≥ 96 individuals. Skewed sex ratios were found at five of the six sites, while three of the six populations were lacking individuals in the 13–15 cm PL size classes. Male and female PL varied, with Chenier Plain males being larger than Deltaic Plain males, while Deltaic Plain females were larger than Chenier Plain females. Similarly, CH also varied, with Deltaic Plain males and females being relatively deeper than individuals from the Chenier Plain. A number of biotic, abiotic, and anthropogenic factors likely interplay to influence population structure, shell morphology, and demographics. However, the latter, including bycatch in crab traps, is possibly influencing terrapin population structure at some study sites via selective mortality of males and juvenile females. We suggest that future studies research the effects of anthropogenic factors on terrapin populations.


Chenier Plain Deltaic Plain Fisheries bycatch Pet trade Salt marsh habitat Sexual-size dimorphism 



The support of this study by Louisiana Department of Wildlife and Fisheries (LDWF) administration was appreciated, especially B. Baker, T. Baker, and A. Bass. This project could not have been completed without public and private landowner permission granted by Jerome Carter, Conoco Phillips Corporation, Grand Isle Port Commission, Edward Wisner Donation, LDWF Office of Fisheries, Delacroix Corporation, Terre Aux Boeuf Land Company, Biloxi Marsh Lands Corporation, and Lake Eugenie Land & Development, Inc. Gerard Nunez, Adrian Savoie, and Terry Leopold (LDWF) provided airboat maintenance for the southwestern portion of the study. Many individuals also assisted with field data collection including Brett Baccigalopi, Chance Baccigalopi, Dane Cassidy, Todd Credeur, Ariel Dauzart, Rob Dobbs, Wade Hardy, Cody Haynes, James Ialeggio, Amy Magro, Sergio Merino, William Strong, Ben Stultz, Charlie Wahl, Ariel Kay, and Casey Wright. We would like to also thank colleagues within the LDWF’s Natural Heritage Program (Beau Gregory), Louisiana Department of Environmental Quality (David Greenwood, Eric Garner, Guy LeFleur), and Louisiana Coastal Protection and Restoration Authority (Todd Folse) for their continued support and collaboration. Ruth Elsey, Amity Bass, Joe Marty, and Keri Lejeune reviewed an earlier version of the manuscript, and their comments helped us improve the manuscript. LDWF approved this project, and we complied with all applicable animal care guidelines as outlined by Society for the Study of Amphibians and Reptiles.

Funding Information

Project support was provided by Rockefeller Wildlife Refuge Trust Fund of LDWF, U.S. Fish and Wildlife State Wildlife Grants (SWG T-094, T-107), and the LDWF Office of Fisheries.


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Copyright information

© Coastal and Estuarine Research Federation 2019

Authors and Affiliations

  • Will Selman
    • 1
    • 2
    Email author
  • Steven H. Pearson
    • 3
    • 4
  • Jon J. Wiebe
    • 3
  1. 1.Rockefeller Wildlife Refuge, Louisiana Department of Wildlife and FisheriesGrand ChenierUSA
  2. 2.Department of BiologyMillsaps CollegeJacksonUSA
  3. 3.Louisiana Department of Wildlife and FisheriesLafayetteUSA
  4. 4.New York Department of Environmental ConservationAlbanyUSA

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