title: Stable isotopes of C and N reveal habitat dependent dietary overlap between native and introduced turtles Pseudemys rubriventris and Trachemys scripta.
abstract: Habitat degradation and species introductions are two of the leading causes of species declines on a global scale. Invasive species negatively impact native species through predation and competition for limited resources. The impacts of invasive species may be increased in habitats where habitat degradation is higher due to reductions of prey abundance and distribution. Using stable isotope analyses and extensive measurements of resource availability we determined how resource availability impacts the long term carbon and nitrogen assimilation of the invasive red-eared slider turtle (Trachemys scripta elegans) and a native, threatened species, the red-bellied turtle (Pseudemys rubriventris) at two different freshwater wetland complexes in Pennsylvania, USA. At a larger wetland complex with greater vegetative species richness and diversity, our stable isotope analyses showed dietary niche partitioning between species, whereas analyses from a smaller wetland complex with lower vegetative species richness and diversity showed significant dietary niche overlap. Determining the potential for competition between these two turtle species is important to understanding the ecological impacts of red-eared slider turtles in wetland habitats. In smaller wetlands with increased potential for competition between native turtles and invasive red-eared slider turtles we expect that when shared resources become limited, red-eared slider turtles will negatively impact native turtle species leading to long term population declines. Protection of intact wetland complexes and the reduction of introduced species populations are paramount to preserving populations of native species.
authors.affiliation: Drexel University, Department of Biodiversity, Earth and Environmental Science, Philadelphia, Pennsylvania, United States of America. shp36@drexel.edu
authors.forename: Steven H
authors.initials: SH
authors.lastname: Pearson
authors.forename: Harold W
authors.initials: HW
authors.lastname: Avery
authors.forename: Susan S
authors.initials: SS
authors.lastname: Kilham
authors.forename: David J
authors.initials: DJ
authors.lastname: Velinsky
authors.forename: James R
authors.initials: JR
authors.lastname: Spotila
mesh_terms: D000818:Animals; D002247:Carbon Isotopes; D003247:Conservation of Natural Resources; D004032:Diet; D017753:Ecosystem; D005260:Female; D020387:Food Chain; D058865:Introduced Species / Q000639:trends; D019684:Magnoliopsida / Q000737:chemistry; D008297:Male; D009587:Nitrogen Isotopes; D010414:Pennsylvania; D006109:Poaceae / Q000737:chemistry; D013045:Species Specificity; D058009:Stramenopiles / Q000737:chemistry; D014426:Turtles / Q000502:physiology*; D053833:Wetlands
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes