Source Partitioning Using Stable Isotopes: Coping with Too Much Variation

Parnell, Andrew C.; Inger, Richard; Bearhop, Stuart; Jackson, Andrew L.

doi:10.1371/journal.pone.0009672

Cited by 2,481 publications

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“…2010) to run a simulation study with juvenile Chinook Salmon that were collected off the west coast of Vancouver Island in British Columbia, Canada, from 2000 to 2009 (see Tucker et al. (2011) for sampling details).…”

Section: Methodsmentioning

confidence: 99%

“…Given isotopic separation between prey sources, the contribution of different diet sources to a consumer, thus where an organism fits into a food web, can also be determined using stable isotope analysis (Parnell et al. 2010). Different stable isotopes can elucidate different aspects of food web structure, with nitrogen ( δ 15 N) and carbon ( δ 13 C) generally being the most commonly used isotopes.…”

Section: Introductionmentioning

confidence: 99%

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Effects of fasting and nutritional restriction on the isotopic ratios of nitrogen and carbon: a meta‐analysis

Hertz

Trudel

Cox

et al. 2015

Ecology and Evolution

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Many organisms experience fasting in their life time, and this physiological process has the potential to alter stable isotope values of organisms, and confound interpretation of food web studies. However, previous studies on the effects of fasting and starvation on stable isotopes show disparate results, and have never been quantitatively synthesized. We performed a laboratory experiment and meta‐analysis to determine how stable isotopes of δ 15N and δ 13C change with fasting, and we tested whether moderators such as taxa and tissue explain residual variation. We collected literature data from a wide variety of taxa and tissues. We surveyed over 2000 papers, and of these, 26 met our selection criteria, resulting in 51 data points for δ 15N, and 43 data points for δ 13C. We determine that fasting causes an average increase in the isotopic value of organisms of 0.5‰ for δ 15N and that the only significant moderator is tissue type. We find that the overall effect size for δ 13C is not significant, but when the significant moderator of tissue is considered, significant increases in blood and whole organisms are seen with fasting. Our results show that across tissues and taxa, the nutritional status of an organism must be considered when interpreting stable isotope data, as fasting can cause large differences in stable isotope values that would be otherwise attributed to other factors.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of fasting and nutritional restriction on the isotopic ratios of nitrogen and carbon: a meta‐analysis

Hertz

Trudel

Cox

et al. 2015

Ecology and Evolution

View full text Add to dashboard Cite

show abstract

“…Bayesian isotope mixing models [122,139,127]. Using these methods, quantification of link-strengths is extendable to paleontological communities, vastly extending the temporal range over which food-webs can be examined and compared.…”

Section: 33 Predator Dietary Specialization (✏) For Beringianmentioning

confidence: 99%

“…There have been many recent contributions concerning isotope mixing models -some introduce means by which uncertainty is integrated into dietary estimates [122,139,29,73], while others concern geometrical analysis of the mixing space [94,128,127]. We integrate the two approaches, and use the results from mixing models, independent measures of prey availability, and mixing space geometry to improve dietary estimates.…”

Section: Chapter 6 Synthesismentioning

confidence: 99%

“…Because many di↵erent combinations of dietary sources can produce a given set of isotope values under these conditions, quantitative tools are required to parse less likely trophic interactions from those that are more likely to occur. Bayesian mixing models can be used to numerically simulate posterior probability distributions that quantify the range and likelihood of all potential source combinations [163,122,139]. This approach requires prior knowledge of a consumer's diet to be designated, even if that knowledge is specified to be uninformative (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Dedication. Acknowledgments

2011

The Acquisition of German

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xvii Dedication xixAcknowledgments xx . See panel C. for a scenario where one prey is preferred over another. C. A tri-trophic system, where a top-predator consumes a meso-predator, which in turn consumes two prey. The sizes of the nodes denote relative abundance, and the thickness of the arrows denote the magnitude of the biomass flow. The top-predator in the leftmost network is relatively abundant, depressing the meso-predator population, thereby limiting the meso-predator's e↵ect on the two prey populations. The two rightmost networks (boxed) have reduced top-predator populations. In both cases, the meso-predator has greater abundance due to decreased predation pressure. However, in one scenario, both prey are preferred equally, resulting in apparent competition dynamics. In the second scenario, one prey is preferred over another, resulting in an asymmetric cascade. Such preferences could result from specific anatomical constraints of the meso-predator, a scenario explored in Chapter 4. C 1 and C 2 , and 4 prey: r 1 r 4 ) is represented by both pairwise interaction distributions for each link, and a network-level interaction distribution for the system. Link thickness represents the median link-strength, shown with the vertical bar in each pairwise interaction distribution. B-C. Both model food-webs X and Y have link-strengths drawn from the NLID. In model food-web X, the weights are distributed similar to the median weights of the empirical web (i.e. equivalent structure), but they are distributed di↵erently among nodes (i.e. alternative interactions). In model Y , the weight structure is di↵erent than that of the empirical web (i.e. alternative structure), and necessarily, the distribution of weights among nodes di↵ers as well (i.e. alternative interactions). Dotted nodes indicate those with link-strengths that di↵er from the median link-strengths of the empirical food-web. D-F. Given a single niche axis based on a continuous resource trait (e.g. body size) where prey are ranked from r 1 to r 4 , distributions of resource use are shown for the two consumers. Representations of dietary overlap illustrate higher similarity in diet between predators of the empirical system and model X, whereas the consumers in model Y have little dietary overlap, despite sharing the same NLID. 5 A-C. Sensitivity analyses of the Saskatchewan, Amboseli, and Lake Naivasha food-web ensembles, respectively. Similarity values for each cuto↵ (s i ) for Model 2 are on the y-axis, and the x-axis ranges from a lower standard deviation (SD) than the empirical SD to a higher SD (such that the empirical SD is central to the range; stippled vertical line). The colored data points represent the median similarity indices for each cuto↵ value (legend), while the top and bottom whiskers denote the 25 th and 75 th percentiles, respectively. The underlined values mark the standard deviation corresponding to the highest average similarity across cuto↵ values. For all systems, the highest average similarity is close to or exactly matches ...

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An open source Bayesian Monte Carlo isotope mixing model with applications in Earth surface processes

Arendt

Aciego

Hetland

2015

Geochem Geophys Geosyst

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The implementation of isotopic tracers as constraints on source contributions has become increasingly relevant to understanding Earth surface processes. Interpretation of these isotopic tracers has become more accessible with the development of Bayesian Monte Carlo (BMC) mixing models, which allow uncertainty in mixing end-members and provide methodology for systems with multicomponent mixing. and Hawaiian soil data sets that are consistent with the originally published fractional contribution estimates. The advantage of this method is that it quantifies the error induced by variability in the endmember compositions, unrealized by the models previously applied to the above case studies. Results from all three case studies demonstrate the broad applicability of this statistical BMC isotopic mixing model for estimating source contribution fractions in a variety of Earth surface systems.

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Source Partitioning Using Stable Isotopes: Coping with Too Much Variation

Cited by 2,481 publications

References 26 publications

Effects of fasting and nutritional restriction on the isotopic ratios of nitrogen and carbon: a meta‐analysis

Effects of fasting and nutritional restriction on the isotopic ratios of nitrogen and carbon: a meta‐analysis

Dedication. Acknowledgments

An open source Bayesian Monte Carlo isotope mixing model with applications in Earth surface processes

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