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Academic literature on the topic 'Facteurs de discrimination (∆δ13C, ∆δ15N)'
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Journal articles on the topic "Facteurs de discrimination (∆δ13C, ∆δ15N)"
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Therrien, J. F., G. Fitzgerald, G. Gauthier, and J. Bêty. "Diet–tissue discrimination factors of carbon and nitrogen stable isotopes in blood of Snowy Owl (Bubo scandiacus)." Canadian Journal of Zoology 89, no. 4 (April 2011): 343–47. http://dx.doi.org/10.1139/z11-008.
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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.
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Franssen, Nathan R., Eliza I. Gilbert, Angela P. James, and Jason E. Davis. "Isotopic tissue turnover and discrimination factors following a laboratory diet switch in Colorado pikeminnow (Ptychocheilus lucius)." Canadian Journal of Fisheries and Aquatic Sciences 74, no. 2 (February 2017): 265–72. http://dx.doi.org/10.1139/cjfas-2015-0531.
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Stable isotope ecology has made great strides in quantifying energy transfer through food webs. However, trophic inferences gleaned from field-collected data can be limited when isotopic turnover and isotopic discrimination factors (Δ13C or Δ15N) are unknown. We quantified isotopic turnover and discrimination factors using an isotopic diet switch in the endangered Colorado pikeminnow (Ptychocheilus lucius). The estimated half-life for δ13C was 62 days or a 33% increase in mass and δ15N averaged 133 days or a 52% increase in mass. Growth and metabolic processes both contributed to rates of turnover, but metabolic processes had a stronger effect in δ13C than in δ15N. Lipid-corrected δ13C values resulted in discrimination factors of Δ13C between 0.67 and 0.82 and Δ15N between 2.31 and 2.93, values similar to other fishes. These results suggest sampling fin tissue may be a useful, nonlethal tool for isotopic studies. Fins also demonstrated enrichment in 13C that was not linked to the diet switch, highlighting the importance of controls in isotopic diet switch studies to verify species- and diet-specific estimates of isotopic turnover rates.
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Carolan, J. Veliscek, D. Mazumder, C. Dimovski, R. Diocares, and J. Twining. "Biokinetics and discrimination factors for δ13C and δ15N in the omnivorous freshwater crustacean, Cherax destructor." Marine and Freshwater Research 63, no. 10 (2012): 878. http://dx.doi.org/10.1071/mf11240.
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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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Hobbie, Erik A., Janet Chen, Paul J. Hanson, Colleen M. Iversen, Karis J. McFarlane, Nathan R. Thorp, and Kirsten S. Hofmockel. "Long-term carbon and nitrogen dynamics at SPRUCE revealed through stable isotopes in peat profiles." Biogeosciences 14, no. 9 (May 17, 2017): 2481–94. http://dx.doi.org/10.5194/bg-14-2481-2017.
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Abstract. Peatlands encode information about past vegetation dynamics, climate, and microbial processes. Here, we used δ15N and δ13C patterns from 16 peat profiles to deduce how the biogeochemistry of the Marcell S1 forested bog in northern Minnesota responded to environmental and vegetation change over the past ∼ 10 000 years. In multiple regression analyses, δ15N and δ13C correlated strongly with depth, plot location, C ∕ N, %N, and each other. Correlations with %N, %C, C ∕ N, and the other isotope accounted for 80 % of variance for δ15N and 38 % of variance for δ13C, reflecting N and C losses. In contrast, correlations with depth and topography (hummock or hollow) reflected peatland successional history and climate. Higher δ15N in plots closer to uplands may reflect upland-derived DON inputs and accompanying shifts in N dynamics in the lagg drainage area surrounding the bog. The Suess effect (declining δ13CO2 since the Industrial Revolution) lowered δ13C in recent surficial samples. High δ15N from −35 to −55 cm probably indicated the depth of ectomycorrhizal activity after tree colonization of the peatland over the last 400 years, as confirmed by the occasional presence of wood down to −35 cm depth. High δ13C at ∼ 4000 years BP (−65 to −105 cm) could reflect a transition at that time to slower rates of peat accumulation, when 13C discrimination during peat decomposition may increase in importance. Low δ13C and high δ15N at −213 and −225 cm ( ∼ 8500 years BP) corresponded to a warm period during a sedge-dominated rich fen stage. The above processes appear to be the primary drivers of the observed isotopic patterns, whereas there was no clear evidence for methane dynamics influencing δ13C patterns.
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Huneau, Jean-François, Olivier L. Mantha, Dominique Hermier, Véronique Mathé, Guillaume Galmiche, François Mariotti, and Hélène Fouillet. "Natural Isotope Abundances of Carbon and Nitrogen in Tissue Proteins and Amino Acids as Biomarkers of the Decreased Carbohydrate Oxidation and Increased Amino Acid Oxidation Induced by Caloric Restriction under a Maintained Protein Intake in Obese Rats." Nutrients 11, no. 5 (May 16, 2019): 1087. http://dx.doi.org/10.3390/nu11051087.
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A growing body of evidence supports a role for tissue-to-diet 15N and 13C discrimination factors (Δ15N and Δ13C), as biomarkers of metabolic adaptations to nutritional stress, but the underlying mechanisms remain poorly understood. In obese rats fed ad libitum or subjected to gradual caloric restriction (CR), under a maintained protein intake, we measured Δ15N and Δ13C levels in tissue proteins and their constitutive amino acids (AA) and the expression of enzymes involved in the AA metabolism. CR was found to lower protein mass in the intestine, liver, heart and, to a lesser extent, some skeletal muscles. This was accompanied by Δ15N increases in urine and the protein of the liver and plasma, but Δ15N decreases in the proteins of the heart and the skeletal muscles, alongside Δ13C decreases in all tissue proteins. In Lys, Δ15N levels rose in the plasma, intestine, and some muscles, but fell in the heart, while in Ala, and to a lesser extent Glx and Asx, Δ13C levels fell in all these tissues. In the liver, CR was associated with an increase in the expression of genes involved in AA oxidation. During CR, the parallel rises of Δ15N in urine, liver, and plasma proteins reflected an increased AA catabolism occurring at the level of the liver metabolic branch point, while Δ15N decreases in cardiac and skeletal muscle proteins indicated increased protein and AA catabolism in these tissues. Thus, an increased protein and AA catabolism results in opposite Δ15N effects in splanchnic and muscular tissues. In addition, the Δ13C decrease in all tissue proteins, reflects a reduction in carbohydrate (CHO) oxidation and routing towards non-indispensable AA, to achieve fuel economy.
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Villegas, Mariana, Catherine Soos, Gustavo Jiménez-Uzcátegui, Shukri Matan, and Keith A. Hobson. "Isotopic Niche Segregation among Darwin’s Finches on Santa Cruz Island, Galápagos." Diversity 13, no. 4 (March 30, 2021): 147. http://dx.doi.org/10.3390/d13040147.
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Darwin’s finches are a classic example of adaptive radiation involving differential use of dietary resources among sympatric species. Here, we apply stable isotope (δ13C, δ15N, and δ2H) analyses of feathers to examine ecological segregation among eight Darwin’s finch species in Santa Cruz Island, Galápagos collected from live birds and museum specimens (1962–2019). We found that δ13C values were higher for the granivorous and herbivorous foraging guilds, and lower for the insectivorous finches. Values of δ15N were similar among foraging guilds but values of δ2H were higher for insectivores, followed by granivores, and lowest for herbivores. The herbivorous guild generally occupied the largest isotopic standard ellipse areas for all isotopic combinations and the insectivorous guild the smallest. Values of δ2H provided better trophic discrimination than those of δ15N possibly due to confounding influences of agricultural inputs of nitrogen. Segregation among guilds was enhanced by portraying guilds in three-dimensional isotope (δ13C, δ15N, and δ2H) space. Values of δ13C and δ15N were higher for feathers of museum specimens than for live birds. We provide evidence that Darwin’s finches on Santa Cruz Island tend to be generalists with overlapping isotopic niches and suggest that dietary overlap may also be more considerable than previously thought.
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Robb, G. N., S. Woodborne, P. R. de Bruin, K. Medger, and N. C. Bennett. "The influence of food quantity on carbon and nitrogen stable isotope values in southern African spiny mice (Acomys spinosissimus)." Canadian Journal of Zoology 93, no. 5 (May 2015): 345–51. http://dx.doi.org/10.1139/cjz-2014-0134.
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Stable isotope analysis is frequently applied as a tool to examine dietary patterns in animals. However, some of the underlying assumptions associated with using this approach are increasingly being questioned. We carried out a controlled diet experiment on the southern African spiny mouse (Acomys spinosissimus Peters, 1852) to test a number of aspects relating to these assumptions and also examine the hypothesis that stable isotopes, especially δ15N, can be used to provide evidence of nutritional stress. We compared the δ13C and δ15N values of livers and blood from animals that were fed ad libitum with animals undergoing a 10% reduction in food supply. Food-restricted animals showed no significant difference in δ15N; however, δ13C values of both liver and blood were depleted. Restricted animals also had a significantly lower C:N ratio. We examined the role of lipids and found following lipid extraction that both livers and lipids still showed the same separation in carbon values. Tissue–diet discrimination values were also calculated and found to be higher for both Δ13C and Δ15N compared with other mice species. Empirical values for discrimination rates were then compared with values calculated using an alternative method based on employing generic values and were found to be dissimilar, suggesting the use of generic values are not always appropriate. Our results highlight the need for greater understanding of the assumptions associated with using stable isotope analysis to examine diet and we suggest that studying a single species under captive conditions presents an ideal method to begin to test these hypotheses.
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McAllister, LT, TE Van Leeuwen, JM Hanlon, CJ Morris, J. Potter, J. Wells, and M. Abrahams. "Sea cage aquaculture may provide an energetic subsidy to wild juvenile cod in coastal bays of southern Newfoundland, Canada." Marine Ecology Progress Series 674 (September 16, 2021): 241–55. http://dx.doi.org/10.3354/meps13832.
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Sea cage aquaculture can alter the spatial distribution of wild fish populations; however, little is known about the dietary habits of wild fish frequenting sea cages. We used wild juvenile cod Gadus morhua reared in the laboratory and fed either an aquafeed pellet or marine-based diet to determine trophic discrimination factors (TDFs) of stable carbon (δ13C) and nitrogen (δ15N) isotope values in white muscle tissue and baseline liver proportions of vegetable-oil based (VOB) fatty acids. We then used δ13C and δ15N and proportions of VOB fatty acids to investigate the dietary habits of wild cage-associated juvenile and adult Atlantic cod and adult Atlantic redfish Sebastes fasciatus. Cod and redfish were collected in the immediate area of sea cages and reference areas of no aquaculture production. Juvenile cod captured around sea cages had both elevated δ13C and δ15N values and proportions of VOB fatty acids, and isotopic fractionation comparable to laboratory cod fed an aquafeed diet. However, differences in δ13C and δ15N and proportions of VOB fatty acids between cage-associated and reference site adult cod and redfish were predominately absent. Results suggest that sea cages may provide an energetic subsidy to juvenile cod but perhaps not at the level to sustain adult cod or redfish. Therefore, the lack of differences suggests that both adult groups may be using cage sites opportunistically and only for short duration, as isotopic values and fatty acid proportions were not consistent with waste feed consumption despite individuals being collected in close proximity to sea cages.
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Beckett, Nicola M., Darren I. Grice, James F. Carter, and Sarah L. Cresswell. "Precursor discrimination of designer drug benzylpiperazine using δ13C and δ15N stable isotopes." Science & Justice 55, no. 1 (January 2015): 57–62. http://dx.doi.org/10.1016/j.scijus.2014.09.001.
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Lopes, Marta S., Salvador Nogués, and José L. Araus. "Nitrogen source and water regime effects on barley photosynthesis and isotope signature." Functional Plant Biology 31, no. 10 (2004): 995. http://dx.doi.org/10.1071/fp04031.
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Water stress and nitrogen (N) availability are the main constraints on barley (Hordeum vulgare L.) yield in Mediterranean conditions. Here we studied the combined effects of N source and water regime (WR) on plant growth, photosynthesis and carbon isotope discrimination (Δ13C) in barley grown under controlled conditions. The effects of these conditions on plant N isotope discrimination against the fertiliser (Δ15N) was also examined to assess whether the natural variation in plant N isotope composition is a reliable indicator of N nutrition. Six experimental treatments were established with three nutrient solutions containing ammonium (NH4+), nitrate (NO3–) or a mixture of the two (NH4+ : NO3–), each either well watered or moderately water stressed. The NH4+ : NO3– treatment resulted in the greatest biomass accumulation and photosynthetic capacity in both WRs. The NH4+ plants showed accelerated phenology and depressed growth. They also had the lowest photosynthetic rates in both WRs. This effect was mainly due to stomatal closure, while electron transport and carboxylation capacity of leaves were less affected. Consistent with lower stomatal conductance, leaf Δ13C was lower in plants that received NH4+, indicating higher water use efficiency (WUE) not only when irrigated, but also under water stress. In addition, leaf Δ13C and photosynthetic N use efficiency (PNUE) correlated positively with each other and with shoot biomass in both WRs. However, NO3– treatment produced the greatest Δ15N, which was higher in leaves than in roots. Leaf Δ15N was decreased by water stress only in plants in the NO3– treatment. We conclude that leaf Δ13C is an adequate trait to assess the differences in growth, photosynthetic activity and WUE caused by distinct N sources. However, the usefulness of natural abundance of 15N in plant tissue as a nitrogen source marker is restricted by the effect of WR and internal plant fractionation, at least for plants that received NO3–.
Dissertations / Theses on the topic "Facteurs de discrimination (∆δ13C, ∆δ15N)"
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Blanchet-Aurigny, Aline. "Les populations d'ophiures épigées Ophiothrix fragilis et Ophiocomina nigra à la pointe de Bretagne : évolution et écologie trophique." Phd thesis, Université de Bretagne occidentale - Brest, 2012. http://tel.archives-ouvertes.fr/tel-00863260.
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L'évolution spatio-temporelle des populations d'Ophiocomina nigra et d'Ophiothrix fragilis (Ophiuridés, Echinodermes) a été étudiée dans deux écosystèmes contrastés de la pointe de Bretagne (France); la rade de Brest et la baie de Douarnenez. Entre la fin des années 80 et 2011, la population d'O. nigra s'est très largement étendue sur l'ensemble des zones d'études et a vu sa densité augmenter d'un facteur 5 en rade de Brest. Dans ce site, l'expansion d'O. nigra a généré de profonds changements qui se sont progressivement traduits entre autre par une exclusion spatiale d'O. fragilis du bassin central vers la partie sud de la zone d'étude où l'espèce colonise des coquilles vides de crépidules; Crepidula fornicata. L'expansion d'O. nigra a été mise en relation avec la combinaison de possible changements globaux du milieu et les traits biologiques de l'espèce. Les isotopes stables naturels (δ13C & δ15N) et les marqueurs d'acides gras ont été utilisés pour décrire l'écologie trophique des deux ophiures par un suivi in situ, sur des stations sélectionnées en raison de leurs situations contrastées (influence continentale vs influence océanique). Les facteurs de discrimination (∆δ13C et ∆δ15N) ont été calculés en expérimentation pour les deux espèces avec trois types de sources et ont montré principalement un effet de la qualité de la nourriture et de l'état reproducteur des espèces sur ces facteurs et des différences interspécifiques. Le suivi in situ a principalement révélé des différences interspécifiques dans l'alimentation des espèces. Le phytoplancton (diatomées) apparait en été comme une source majeure pour les deux espèces et plus importante pour O. fragilis. Des valeurs en δ15N plus élevées chez O. nigra par rapport à O. fragilis associées à une plus forte contribution de bactéries, de détritus et de matériel d'origine animal, indiquent que l'espèce exploite une grande diversité de sources de nourriture expliquant en partie son succès. Les macroalgues (Ulva sp) et les apports terrigènes semblent jouer un rôle trophique mineur pour les deux espèces, malgré une augmentation significative dans les sites plus confinés en fin d'étude.