Literaturdatenbank
Literaturdatenbank |
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Hofmeister, N. R., Welk, M., & Freedberg, S. (2013). Elevated levels of ∂15n in riverine painted turtles (chrysemys picta): Trophic enrichment or anthropogenic input? Canadian Journal of Zoology, (online early).
Added by: Admin (06 Jan 2014 18:24:34 UTC) |
| Resource type: Journal Article DOI: 10.1139/cjz-2013-0121 BibTeX citation key: Hofmeister2013 View all bibliographic details  |
Categories: General Keywords: Chrysemys picta, Emydidae, Ernährung - nutrition, Habitat - habitat, Nordamerika - North America, Schildkröten - turtles + tortoises Creators: Freedberg, Hofmeister, Welk Collection: Canadian Journal of Zoology |
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| Abstract |
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The natural abundance of stable isotopes of elements in animal tissue is influenced by both biotic and abiotic factors. Biotically, animals feeding at higher trophic levels are enriched in the ratio of 15N:14N (δ15N) relative to their food resources due to the preferential excretion of 14N. Abiotically, increases in δ15N may also reflect different sources of biologically available nitrogen, including nitrogen resulting from denitrification of inorganic fertilizer. We studied variation in δ15N among freshwater turtle populations to assess spatial variation in δ15N and to determine whether this variation can be attributed to differences in nitrogen source or trophic enrichment. We examined nitrogen and carbon stable isotope ratios in duckweed (Lemna sp., L., 1753) and in painted turtles (Chrysemys picta, Schneider, 1783) in aquatic ecosystems expected to be differentially affected by agricultural activity and denitrification of inorganic fertilizer. Across sites, C. picta δ15N was strongly correlated with Lemna δ15N and was elevated in sites influenced by agricultural activity. Furthermore, trophic position of turtles was not associated with δ15N but was consistent with expected values for primary consumers in freshwater systems, indicating that differences in tissue δ15N could be attributed to differences in initial sources of nitrogen in each ecosystem. Our results suggest that care must be taken when attributing differences in isotopic values of animal populations to trophic factors.
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