However, body temperature did not affect 15 N turnover in muscle tissue. Despite suggesting that the relationships between turnover and body mass might differ between these two tissue types, the magnitude of the difference in the intercepts appeared relatively small and may have arisen as an artefact of the considerably lower replication in the 15 N muscle model than in the 13 C model.
percasttreadrighde.tk As such, we chose to investigate the utility of combining data from these two tissue types, as for 13 C. However, the allometric relationships between turnover and body temperature in these tissues appeared almost identical see 3. For these combined models, 13 C turnover can be predicted via the equation: eqn 6. Similarly, 15 N turnover rates of whole organism or muscle can be estimated using the equation: eqn 7. Symbols are as for carbon model. Data exploration revealed that these were all ectothermic taxa Alligator mississippiensis , Elaphe guttata guttata , Paralichthys dentatus and Onisimus litoralis with relatively slow turnover rates.
Individual models were, therefore, constructed to explore this relationship separately in ectothermic and endothermic consumers. In smaller animals, tissues were generally not differentiated, and as with muscle, the turnover rates of whole organisms were related to an organism's body mass and temperature. We believe these findings can substantially improve both the design and interpretation of stable isotope studies. However, across a broad suite of animal taxa, thermoregulation type generally served as the strongest predictor of turnover rates in splanchnic tissues, being consistently greater in endotherms than ectotherms.
The limited predictive capacity of our models may result from the oversimplified nature of turnover estimates in the past two decades.
The incorporation of carbon and nitrogen was correlated across the range of consumer animals, but elemental turnover rates were not equivalent in all species. Although this specific mechanism cannot explain the differences observed between endotherms and ectotherms in all tissue types, the rapid respiratory exchanges of C might explain the relatively short retention times of 13 C in a wide range of ectotherm tissues. The physiological processes driving the differential isotopic replacement of C and N in ectothermic consumers warrant further investigation, and the potentially divergent time frames over which these elements integrate dietary information should be explicitly considered in future mixing models considering these taxa.
The nature of the allometric relationship was, however, highly variable between tissue types, with predictable effects of body mass and temperature in muscle tissues and whole organisms, and smaller or negligible effects in blood, plasma and liver.
Future turnover studies on individual species should, therefore, seek to establish the mechanisms behind turnover in more metabolically active tissues in order to improve the predictive capability over shorter timescales. The strength of the relationship in muscle and whole organism combined enabled us to provide a predictive tool with the capacity to improve future interpretations of stable isotope data.
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Share full text access. Please review our Terms and Conditions of Use and check box below to share full-text version of article. Summary The stable isotopes of carbon 12 C, 13 C and nitrogen 14 N, 15 N represent powerful tools in food web ecology, providing a wide range of dietary information in animal consumers. Figure 1 Open in figure viewer PowerPoint. Figure 2 Open in figure viewer PowerPoint. Figure 3 Open in figure viewer PowerPoint.
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The stable isotopic studies have become thus one of the most important tools in to delineate the anthropogenic forcing to create viable models of future climate scenarios. . Forest Ecosystem Analysis at Multiple Time and Space Scales spectrometers have allowed detection of isotopic ratios that previously could not be. Read chapter 2 ENRICHED STABLE ISOTOPES: Radioactive isotopes and in this field, the country is rapidly becoming more dependent on sources in the former Soviet Union for many necessary isotopes. But since there is no radiation to detect, specialized analytical methods for . Large-scale uptake studies in plants.
Volume 84 , Issue 3 May Pages Figures References Related Information. Close Figure Viewer. Therefore, changes in the isotopic signature over time have proven to be a tremendously powerful and sensitive means of detecting and measuring changes in steady-state systems. The article was received on 01 Oct , accepted on 21 Nov and first published on 22 Nov This article is licensed under a Creative Commons Attribution 3.
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