Maciej T Krajcarz1, Magdalena Krajcarz2, Dorothée G Drucker3, Hervé Bocherens3,4. 1. Institute of Geological Sciences, Polish Academy of Sciences, Research Centre in Warszawa, Twarda 51/55, 00-818, Warszawa, Poland. 2. Institute of Archaeology, Nicolaus Copernicus University in Toruń, Szosa Bydgoska 44/48, 87-100, Toruń, Poland. 3. Senckenberg Centre for Human Evolution and Palaeoenvironment (HEP) at Tuebingen University, Hölderlinstr. 12, 72074, Tübingen, Germany. 4. Fachbereich Geowissenschaften, Paläobiologie (Biogeologie), Universität Tübingen, Hölderlinstr. 12, 72074, Tübingen, Germany.
Abstract
RATIONALE: The trophic enrichment factor (TEF) is a parameter reflecting the difference in isotopic ratio between a consumer's tissues and diet, used in isotopic ecology and paleoecology to track dietary habits. The TEF of sulfur is believed to be low, but was, until now, only documented in a limited number of taxa. In this study we use a subfossil accumulation of bones from a red fox (Vulpes vulpes) den to verify the TEF for sulfur in fox bone collagen. METHODS: Collagen was extracted from 30 samples of subfossil bones, including foxes and their prey. The δ34 S values of the bone collagen samples were measured with an elemental analyzer connected to an isotope ratio mass spectrometer. The TEF was calculated as [Δ34 S = (mean δ34 S in predator) - (mean δ34 S in prey)], using taphonomic indices to estimate the mean diet, and calculated separately for different age classes of the predator. RESULTS: We modeled 12 variants of TEF for different estimations of the diet composition and for three fox age classes (adult, subadult, and juvenile). The estimated TEF values range from -0.54 to +0.03‰ and are similar to TEFs known for other mammals. Absolute TEF values are nearly equal to or lower than the analytical error, which is ±0.4‰. CONCLUSIONS: For the first time, we present direct δ34 S data for the bone collagen of a free-living predator and its naturally selected prey. Our results indicate very low or even slightly negative TEF values for sulfur. Furthermore, according to our results, the δ34 S value should not be considered a reliable indicator of trophic position in terrestrial food webs but rather, it should be used to disentangle different food webs based on different primary producers.
RATIONALE: The trophic enrichment factor (TEF) is a parameter reflecting the difference in isotopic ratio between a consumer's tissues and diet, used in isotopic ecology and paleoecology to track dietary habits. The TEF of sulfur is believed to be low, but was, until now, only documented in a limited number of taxa. In this study we use a subfossil accumulation of bones from a red fox (Vulpes vulpes) den to verify the TEF for sulfur in fox bone collagen. METHODS: Collagen was extracted from 30 samples of subfossil bones, including foxes and their prey. The δ34 S values of the bone collagen samples were measured with an elemental analyzer connected to an isotope ratio mass spectrometer. The TEF was calculated as [Δ34 S = (mean δ34 S in predator) - (mean δ34 S in prey)], using taphonomic indices to estimate the mean diet, and calculated separately for different age classes of the predator. RESULTS: We modeled 12 variants of TEF for different estimations of the diet composition and for three fox age classes (adult, subadult, and juvenile). The estimated TEF values range from -0.54 to +0.03‰ and are similar to TEFs known for other mammals. Absolute TEF values are nearly equal to or lower than the analytical error, which is ±0.4‰. CONCLUSIONS: For the first time, we present direct δ34 S data for the bone collagen of a free-living predator and its naturally selected prey. Our results indicate very low or even slightly negative TEF values for sulfur. Furthermore, according to our results, the δ34 S value should not be considered a reliable indicator of trophic position in terrestrial food webs but rather, it should be used to disentangle different food webs based on different primary producers.
Authors: Zabibu Kabalika; Thomas A Morrison; Rona A R McGill; Linus K Munishi; Divine Ekwem; Wilson Leonidas Mahene; Alex L Lobora; Jason Newton; Juan M Morales; Daniel T Haydon; Grant G J C Hopcraft Journal: Mov Ecol Date: 2020-09-18 Impact factor: 3.600
Authors: Claire E Ebert; Asta J Rand; Kirsten Green-Mink; Julie A Hoggarth; Carolyn Freiwald; Jaime J Awe; Willa R Trask; Jason Yaeger; M Kathryn Brown; Christophe Helmke; Rafael A Guerra; Marie Danforth; Douglas J Kennett Journal: PLoS One Date: 2021-08-12 Impact factor: 3.240