Ontogenetic dependence of Nile crocodile ( Crocodylus niloticus ) isotope diet‐to‐tissue discrimination factors

2021 ◽  
Author(s):  
Stephan Woodborne ◽  
Hannes Botha ◽  
David Huchzermeyer ◽  
Jan Myburgh ◽  
Grant Hall ◽  
...  
Keyword(s):  
Tissue Discrimination ◽  
Nile Crocodile ◽  
Discrimination Factors

The requirement for accurate diet-tissue discrimination factors for interpreting stable isotopes in sharks

Hydrobiologia ◽  
2010 ◽  
Vol 654 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Nigel E. Hussey ◽  
M. Aaron MacNeil ◽  
Aaron T. Fisk
Keyword(s):  
Stable Isotopes ◽  
Tissue Discrimination ◽  
Discrimination Factors

Diet–tissue discrimination factors of carbon and nitrogen stable isotopes in blood of Snowy Owl (Bubo scandiacus)

2011 ◽  
Vol 89 (4) ◽  
pp. 343-347 ◽  
Author(s):  
J.-F. Therrien ◽  
G. Fitzgerald ◽  
G. Gauthier ◽  
J. Bêty
Keyword(s):  
Stable Isotopes ◽  
Bird Species ◽  
Potential Effect ◽  
Mouse Muscle ◽  
Blood Samples ◽  
Web Studies ◽  
Tissue Discrimination ◽  
Discrimination Factors ◽  
Snowy Owl ◽  
Bubo Scandiacus

Analysis of carbon (13C/12C) and nitrogen (15N/14N) stable isotope ratios (hereafter δ13C and δ15N, respectively) in animal tissues is a powerful tool in food-web studies. However, isotopic ratios of prey are not transmitted directly to a consumer, as a diet–tissue discrimination factor (denoted Δ) occurs between sources and consumer’s tissues. An accurate assessment of the diet of a consumer with stable isotopes thus requires that the Δ13C and Δ15N of the studied species are known. Our aim was to establish Δ13C and Δ15N values in the Snowy Owl ( Bubo scandiacus (L., 1758)). Moreover, we assessed the potential effect of ethanol preservation of blood samples on δ13C and δ15N values. We kept four captive adult Snowy Owls on a pure diet of mice for ≥6 weeks. We then collected mouse muscle and blood samples from the owls and analyzed their δ13C and δ15N values. Δ13C and Δ15N values (mean ± SE) for owl blood were +0.3‰ ± 0.2‰ and +1.9‰ ± 0.1‰, respectively. These values are the first discrimination factors ever reported in Strigiformes and are lower, for Δ15N, than those obtained in terrestrial carnivores and other bird species, including falcons. Preservation in ethanol did not significantly affect δ13C and δ15N values.

δ15N and δ13C diet–tissue discrimination factors for large sharks under semi-controlled conditions

2010 ◽  
Vol 155 (4) ◽  
pp. 445-453 ◽  
Author(s):  
Nigel E. Hussey ◽  
Jaclyn Brush ◽  
Ian D. McCarthy ◽  
Aaron T. Fisk
Keyword(s):  
Controlled Conditions ◽  
Tissue Discrimination ◽  
Discrimination Factors ◽  
Δ15n And Δ13c

scholarly journals Variable δ15N Diet-Tissue Discrimination Factors among Sharks: Implications for Trophic Position, Diet and Food Web Models

PLoS ONE ◽  
2013 ◽  
Vol 8 (10) ◽  
pp. e77567 ◽  
Author(s):  
Jill A. Olin ◽  
Nigel E. Hussey ◽  
Alice Grgicak-Mannion ◽  
Mark W. Fritts ◽  
Sabine P. Wintner ◽  
...  
Keyword(s):  
Food Web ◽  
Trophic Position ◽  
Tissue Discrimination ◽  
Discrimination Factors

scholarly journals Diet to tissue discrimination factors for the blood and feathers of the monk parakeet (Myiopsitta monachus) and the ring–necked parakeet (Psittacula krameri)

2019 ◽  
pp. 389-395 ◽  
Author(s):  
D. Mazzoni ◽  
N. A. Borray-Escalante ◽  
A. Ortega–Segalerva ◽  
L. Arroyo ◽  
J. González–Solís ◽  
...  
Keyword(s):  
Nitrogen Isotopes ◽  
Single Species ◽  
Prey Type ◽  
Monk Parakeet ◽  
Carbon And Nitrogen ◽  
Myiopsitta Monachus ◽  
Psittacula Krameri ◽  
Tissue Discrimination ◽  
The Difference ◽  
Discrimination Factors

Stable isotope analyses (SIAs) have been widely used in recent years to infer the diet of many species. This isotopic approach requires using diet to tissue discrimination factors (DTDFs) for each prey type and predator tissue, i.e., to determine the difference between the isotopic composition of the predator tissues and the different prey that conform its diet. Information on DTDF values in Psittaciformes is scarce. The aim of this study was to assess DTDF values for the carbon and nitrogen isotopes of the monk parakeet (Myiopsitta monachus) and the ring–necked parakeet (Psittacula krameri), two invasive alien species of concern. We fed captive birds of the two parakeet species on a single–species diet based on sunflower seeds to establish the DTDFs for the blood and feathers. In the monk parakeet (N = 9) DTDFs were Δδ13C 2.14 ‰ ± 0.90 and Δδ15N 3.21 ‰ ± 0.75 for the blood, and Δδ13C 3.97 ‰ ± 0.90 and Δδ15N 3.67 ‰ ± 0.74 for the feathers. In the ring–necked parakeet (N = 9), the DTDFs were Δδ13C (‰) 2.58 ± 0.90 and Δδ15N (‰) 2.35 ± 0.78 for the blood, and Δδ13C 3.64 ‰ ± 0.98 and Δδ15N 4.10 ‰ ± 1.84 for the feathers. DTDF values for the ring–necked parakeet blood were significantly higher than those for the monk parakeet blood. No difference was found between the two species in the DTDF for feathers. Our findings provide the first values of DTDFs for blood and feathers in these parakeets, factors that are key to infer the diet of these species based on SIA.

scholarly journals Stable isotope turnover rates and fractionation in captive California yellowtail (Seriola dorsalis): insights for application to field studies

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Daniel J. Madigan ◽  
Owyn E. Snodgrass ◽  
John R. Hyde ◽  
Heidi Dewar
Keyword(s):  
Stable Isotope ◽  
Isotope Analysis ◽  
Field Studies ◽  
Individual Variability ◽  
Turnover Rates ◽  
Tissue Discrimination ◽  
Aquaculture Feed ◽  
Discrimination Factors ◽  
Seriola Dorsalis

AbstractStable isotope analysis (SIA) measurements from long-term captivity studies provide required parameters for interpretation of consumer SIA data. We raised young-of-the-year (14–19 cm) California yellowtail (Seriola dorsalis) on a low δ15N and δ13C diet (pellet aquaculture feed) for 525 days, then switched to a high δ15N and δ13C diet (mackerel and squid) for 753 days. Yellowtail muscle was sequentially sampled from each individual after the diet switch (0 to 753 days) and analyzed for δ15N and δ13C, allowing for calculation of diet-tissue discrimination factors (DTDFs) from two isotopically different diets (low δ15N and δ13C: pellets; high δ15N and δ13C: fish/squid) and turnover rates of 15N and 13C. DTDFs were diet dependent: Δ15N = 5.1‰, Δ13C = 3.6‰ for pellets and Δ15N = 2.6‰, Δ13C = 1.3‰ for fish/squid. Half-life estimates from 15N and 13C turnover rates for pooled yellowtail were 181 days and 341 days, respectively, but varied considerably by individual (15N: 99–239 d; 13C: 158–899 d). Quantifying DTDFs supports isotopic approaches to field data that assume isotopic steady-state conditions (e.g., mixing models for diet reconstruction). Characterizing and quantifying turnover rates allow for estimates of diet/habitat shifts and “isotopic clock” approaches, and observed inter-individual variability suggests the need for large datasets in field studies. We provide diet-dependent DTDFs and growth effects on turnover rates, and associated error around these parameters, for application to field-collected SIA data from other large teleosts.

Biokinetics and discrimination factors for δ13C and δ15N in the omnivorous freshwater crustacean, Cherax destructor

2012 ◽  
Vol 63 (10) ◽  
pp. 878 ◽  
Author(s):  
J. Veliscek Carolan ◽  
D. Mazumder ◽  
C. Dimovski ◽  
R. Diocares ◽  
J. Twining
Keyword(s):  
Food Web ◽  
Freshwater Ecosystems ◽  
Discrimination Factor ◽  
Δ13c And Δ15n ◽  
Web Studies ◽  
Cherax Destructor ◽  
Tissue Discrimination ◽  
Order Of Magnitude ◽  
Freshwater Crustacean ◽  
Discrimination Factors

Knowledge and understanding of biokinetics and discrimination factors for carbon-13 (δ13C) and nitrogen-15 (δ15N) are important when using stable isotopes for food-web studies. Therefore, we performed a controlled laboratory diet-switch experiment to examine diet–tissue and diet–faeces discrimination factors as well as the biokinetics of stable-isotope assimilation in the omnivorous freshwater crustacean, Cherax destructor. The biokinetics of δ13C could not be established; however, the δ15N value of C. destructor tissue reached equilibrium after 80 ± 35 days, with an estimated biological half-time for 15N of 19 ± 5 days. Metabolic activity contributed to the turnover of 15N by nearly an order of magnitude more than growth. The diet–tissue discrimination factors at the end of the exposure were estimated as –1.1 ± 0.5‰ for δ13C and +1.5 ± 1.0‰ for δ15N, indicating that a δ15N diet–tissue discrimination factor different from the typically assumed +3.4‰ may be required for freshwater macroinvertebrates such as C. destructor. The diet–faeces discrimination factor for δ15N after 120 days was estimated as +0.9 ± 0.5‰. The present study provides an increased understanding of the biokinetics and discrimination factors for a keystone freshwater macroinvertebrate that will be valuable for future food-web studies in freshwater ecosystems.

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