Compound-specific nitrogen stable isotope analysis provides an approach for estimating animal trophic position that may overcome key issues associated with stable isotope analysis of bulk tissue. Yet compound-specific trophic discrimination factors have not been estimated for a broad range of habitats, taxa, and diets. We conducted a controlled-feeding experiment to characterize the variation in compound-specific (TDFAA) and bulk (TDFBulk) trophic discrimination factors of four freshwater fish species fed on three distinct diets. We also compared TDFAA of fish muscle and scale to evaluate the viability of scales for making food web inferences. Mean ±1 SDTDFBulk was 2.2‰ ± 0.9‰, and there were significant effects of species and diet trophic position on TDFBulk. Mean ± 1 SD TDFAA was 6.9‰ ± 0.8‰. Although there was no effect of species on TDFAA, there were significant differences in TDFAA across the three diets. TDFAA from fish scales were not significantly different from those of muscle. Our study illustrates the advantages of estimating trophic position using compound-specific stable isotopes and the need for continued investigation of factors resulting in variation in TDF values.
|Original language||English (US)|
|Number of pages||7|
|Journal||Canadian Journal of Fisheries and Aquatic Sciences|
|State||Published - 2017|
Bibliographical noteFunding Information:
We thank S. Long, M. Messing, T. Barry, and M. Freitas for assisting in the maintenance and cleaning of the aquarium system and feeding of the experimental fishes. M. Freitas and M. Wolman respectively provided the fathead minnows and zebrafish used in the feeding study, and J. Walsh and Z. DeQuatro assisted in initial aquarium system construction. P. Ostrom, N. Ostrom, and K. Morra shared their knowledge and expertise in the planning stages of this work. J. Pauli, S. Larson, T. Tunney, E. Pedersen, J. Walsh, A. Mikulyuk, C. Smith, M. Perales, and D. Goto provided helpful suggestions on earlier versions of the manuscript. This work was funded by the University of Wisconsin Sea Grant (Federal Grants Nos. HCE-7 and HCE-24, Projects PRJ57MH and PRJ87XV awarded to M. Jake Vander Zanden).
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