Tissue‐ and diet‐dependent stable carbon and nitrogen isotope discrimination: a calibration study in a captive shorebird species

In ecology, stable‐isotope ratios are widely used to determine diets of organisms and reconstruct food webs. This is usually done by analyzing the stable‐isotope ratios of nitrogen (δ15N), which increase with increasing trophic level, and those of carbon (δ13C), which correlate with the δ13C value o...

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Main Authors: Tim Oortwijn, Luc G. G. de Monte, Daniel P. Varley, Marcel T. J. van der Meer, Jan A. van Gils
Format: Article
Language:English
Published: Wiley 2023-09-01
Series:Journal of Avian Biology
Online Access:https://doi.org/10.1111/jav.03094
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author Tim Oortwijn
Luc G. G. de Monte
Daniel P. Varley
Marcel T. J. van der Meer
Jan A. van Gils
author_facet Tim Oortwijn
Luc G. G. de Monte
Daniel P. Varley
Marcel T. J. van der Meer
Jan A. van Gils
author_sort Tim Oortwijn
collection DOAJ
description In ecology, stable‐isotope ratios are widely used to determine diets of organisms and reconstruct food webs. This is usually done by analyzing the stable‐isotope ratios of nitrogen (δ15N), which increase with increasing trophic level, and those of carbon (δ13C), which correlate with the δ13C value of food source(s) and generally differ between terrestrial and marine food sources. Assimilation of food changes stable‐isotope ratios, resulting in different values between the food source and its consumer. These differences are known as isotope trophic discrimination factors and, if known, can be used to determine from the stable‐isotope ratios in the consumer's tissue what the consumer has been eating. What is often ignored is that discrimination factors can differ between consumer's food sources and also between tissue types. Therefore, we performed a controlled feeding study in red knots Calidris canutus to determine discrimination factors between different food sources and red knot tissues. We kept two groups of red knots in captivity on a stable diet, one group feeding on mudsnails and the other on Trouvit pellets, for several months, during which the birds molted their feathers. We analyzed δ13C and δ15N in both food sources and in five red knot tissues (blood cells, blood plasma and three feather types) and subsequently calculated the isotope discrimination factors. We confirmed that the discrimination factors differed between tissues, and also between diets. Our values deviated from general averages reported in reviews on a wide range of animals/birds, but were very similar to values from previous red knot and dunlin studies. We therefore think that our discrimination factors can be used in future stable isotope studies, not only on red knots, but also on other marine shorebird species and plea for careful consideration of using the right discrimination factors. Keywords: δ13C, δ15N, discrimination factor, red knot, shorebird, stable isotope
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spelling doaj-art-ce4da5dcdc74493f9c51ec66d2daae8a2025-08-20T03:28:25ZengWileyJournal of Avian Biology0908-88571600-048X2023-09-0120239-10n/an/a10.1111/jav.03094Tissue‐ and diet‐dependent stable carbon and nitrogen isotope discrimination: a calibration study in a captive shorebird speciesTim Oortwijn0Luc G. G. de Monte1Daniel P. Varley2Marcel T. J. van der Meer3Jan A. van Gils4Dept Coastal Systems (COS), NIOZ Royal Netherlands Inst. for Sea Research Den Burg (Texel) the NetherlandsDept Coastal Systems (COS), NIOZ Royal Netherlands Inst. for Sea Research Den Burg (Texel) the NetherlandsDept Coastal Systems (COS), NIOZ Royal Netherlands Inst. for Sea Research Den Burg (Texel) the NetherlandsDept Marine Microbiology and Biochemistry (MMB), NIOZ Royal Netherlands Inst. for Sea Research Den Burg (Texel) the NetherlandsDept Coastal Systems (COS), NIOZ Royal Netherlands Inst. for Sea Research Den Burg (Texel) the NetherlandsIn ecology, stable‐isotope ratios are widely used to determine diets of organisms and reconstruct food webs. This is usually done by analyzing the stable‐isotope ratios of nitrogen (δ15N), which increase with increasing trophic level, and those of carbon (δ13C), which correlate with the δ13C value of food source(s) and generally differ between terrestrial and marine food sources. Assimilation of food changes stable‐isotope ratios, resulting in different values between the food source and its consumer. These differences are known as isotope trophic discrimination factors and, if known, can be used to determine from the stable‐isotope ratios in the consumer's tissue what the consumer has been eating. What is often ignored is that discrimination factors can differ between consumer's food sources and also between tissue types. Therefore, we performed a controlled feeding study in red knots Calidris canutus to determine discrimination factors between different food sources and red knot tissues. We kept two groups of red knots in captivity on a stable diet, one group feeding on mudsnails and the other on Trouvit pellets, for several months, during which the birds molted their feathers. We analyzed δ13C and δ15N in both food sources and in five red knot tissues (blood cells, blood plasma and three feather types) and subsequently calculated the isotope discrimination factors. We confirmed that the discrimination factors differed between tissues, and also between diets. Our values deviated from general averages reported in reviews on a wide range of animals/birds, but were very similar to values from previous red knot and dunlin studies. We therefore think that our discrimination factors can be used in future stable isotope studies, not only on red knots, but also on other marine shorebird species and plea for careful consideration of using the right discrimination factors. Keywords: δ13C, δ15N, discrimination factor, red knot, shorebird, stable isotopehttps://doi.org/10.1111/jav.03094
spellingShingle Tim Oortwijn
Luc G. G. de Monte
Daniel P. Varley
Marcel T. J. van der Meer
Jan A. van Gils
Tissue‐ and diet‐dependent stable carbon and nitrogen isotope discrimination: a calibration study in a captive shorebird species
Journal of Avian Biology
title Tissue‐ and diet‐dependent stable carbon and nitrogen isotope discrimination: a calibration study in a captive shorebird species
title_full Tissue‐ and diet‐dependent stable carbon and nitrogen isotope discrimination: a calibration study in a captive shorebird species
title_fullStr Tissue‐ and diet‐dependent stable carbon and nitrogen isotope discrimination: a calibration study in a captive shorebird species
title_full_unstemmed Tissue‐ and diet‐dependent stable carbon and nitrogen isotope discrimination: a calibration study in a captive shorebird species
title_short Tissue‐ and diet‐dependent stable carbon and nitrogen isotope discrimination: a calibration study in a captive shorebird species
title_sort tissue and diet dependent stable carbon and nitrogen isotope discrimination a calibration study in a captive shorebird species
url https://doi.org/10.1111/jav.03094
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