Testing for a change in diet using fatty acid signatures

Stewart, Connie; Iverson, Sara J.; Field, Chris

doi:10.1007/s10651-014-0280-9

Cited by 15 publications

(28 citation statements)

References 23 publications

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“…Our third measure of distance of interest was recently defined in [19] and was based on the chi-square distance measure given in [6] for use in correspondence analysis. According to Jackson [9], correspondence analysis is widely accepted in the ecology community.…”

Section: Measures Of Distance Between Compositionsmentioning

confidence: 99%

“…It should perhaps be mentioned that in [19] a more general definition of the CS distance is provided which includes a power transformation parameter, γ . With this definition and a specific value for γ , the data are power transformed (by γ ) before Equation (4) is used to calculate distance.…”

Section: Downloaded By [University Of Cambridge] At 05:17 11 June 2016mentioning

confidence: 99%

“…We note that Stewart et al [19] examined the type one error and power of multivariate nonparametric tests designed to test for a difference in the compositional FA signatures of the predator themselves which are known to be related to diet. As the authors point out in their paper, however, a difference in FA signatures does not always translate to a difference in diet and using the QFASA diet estimates instead allows for a more direct test.…”

Section: Introductionmentioning

confidence: 99%

“…Working at the FA signature level is somewhat simpler because zeros occur in the data to a much lesser extent and, in practice, are often treated as rounded zeros. Ultimately, we would like to apply the methods in [19] to the diet estimates with a measure of distance determined to be appropriate for compositional data with many essential zeros.…”

Section: Introductionmentioning

confidence: 99%

“…In Section 4, the measures of distance are utilized in a real-life setting involving QFASA diet estimates of grey seals inhabiting the east coast of Canada. We use the multivariate permutation test proposed by Stewart et al [19] for detecting changes in the FA signatures (but applied to the diet estimates) along with our examined measures of distance to determine if there is a difference in the diets of male and female grey seals prior to the breeding season.…”

Section: Introductionmentioning

confidence: 99%

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An approach to measure distance between compositional diet estimates containing essential zeros

Stewart

2016

Journal of Applied Statistics

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For many applications involving compositional data, it is necessary to establish a valid measure of distance, yet when essential zeros are present traditional distance measures are problematic. In quantitative fatty acid signature analysis (QFASA), compositional diet estimates are produced that often contain many zeros. In order to test for a difference in diet between two populations of predators using the QFASA diet estimates, a legitimate measure of distance for use in the test statistic is necessary. Since ecologists using QFASA must first select the potential species of prey in the predator's diet, the chosen measure of distance should be such that the distance between samples does not decrease as the number of species considered increases, a property known in general as subcompositional coherence. In this paper we compare three measures of distance for compositional data capable of handling zeros, but not satisfying some of the well-accepted principles of compositional data analysis. For compositional diet estimates, the most relevant of these is the property of subcompositionally coherence and we show that this property may be approximately satisfied. Based on the results of a simulation study and an application to real-life QFASA diet estimates of grey seals, we recommend the chi-square measure of distance. ARTICLE HISTORY

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Section: Measures Of Distance Between Compositionsmentioning

confidence: 99%

Section: Downloaded By [University Of Cambridge] At 05:17 11 June 2016mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An approach to measure distance between compositional diet estimates containing essential zeros

Stewart

2016

Journal of Applied Statistics

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Poor nutritional quality of primary producers and zooplankton driven by eutrophication is mitigated at upper trophic levels

Taipale

Ventelä

Litmanen

et al. 2022

Ecology and Evolution

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Eutrophication and rising water temperature in freshwaters may increase the total production of a lake while simultaneously reducing the nutritional quality of food web components. We evaluated how cyanobacteria blooms, driven by agricultural eutrophication (in eutrophic Lake Köyliöjärvi) or global warming (in mesotrophic Lake Pyhäjärvi), influence the biomass and structure of phytoplankton, zooplankton, and fish communities. In terms of the nutritional value of food web components, we evaluated changes in the ω‐3 and ω‐6 polyunsaturated fatty acids (PUFA) of phytoplankton and consumers at different trophic levels. Meanwhile, the lakes did not differ in their biomasses of phytoplankton, zooplankton, and fish communities, lake trophic status greatly influenced the community structures. The eutrophic lake, with agricultural eutrophication, had cyanobacteria bloom throughout the summer months whereas cyanobacteria were abundant only occasionally in the mesotrophic lake, mainly in early summer. Phytoplankton community differences at genus level resulted in higher arachidonic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) content of seston in the mesotrophic than in the eutrophic lake. This was also reflected in the EPA and DHA content of herbivorous zooplankton (Daphnia and Bosmina) despite more efficient trophic retention of these biomolecules in a eutrophic lake than in the mesotrophic lake zooplankton. Planktivorous juvenile fish (perch and roach) in a eutrophic lake overcame the lower availability of DHA in their prey by more efficient trophic retention and biosynthesis from the precursors. However, the most efficient trophic retention of DHA was found with benthivorous perch which prey contained only a low amount of DHA. Long‐term cyanobacterial blooming decreased the nutritional quality of piscivorous perch; however, the difference was much less than previously anticipated. Our result shows that long‐term cyanobacteria blooming impacts the structure of plankton and fish communities and lowers the nutritional quality of seston and zooplankton, which, however, is mitigated at upper trophic levels.

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Recycled by leaf inhabitants: Terrestrial bacteria drive the mineralization of organic matter in lake water

Vesamäki,

Rigaud,

Litmanen

et al. 2024

Ecosphere

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Terrestrial organic matter subsidizes aquatic food webs and plays an important role in carbon cycling in lake ecosystems, where it is decomposed mainly by microbes. However, the contribution of terrestrial and aquatic microbiomes on terrestrial carbon cycling and their effects on the biochemical fate of carbon has remained understudied. Therefore, we explored the microbial carbon utilization of three chemically differing leaf species in lake water in microcosms and quantified the biochemical endpoints of leaf carbon in CO2, CH4, and microbial biomass. Additionally, we identified microbial taxa responsible for leaf carbon recycling and studied the role of epiphytic and endophytic leaf microbiomes in microbial community succession in lake water. Microbially utilized leaf carbon was mainly respired (82.7 ± 1.4%), whereas a small proportion (17.1 ± 1.4%) was assimilated into biomass. Carbon from nitrogen‐rich alder leaves was taken up at the fastest rate, whereas birch leaf addition produced the highest concentrations of CH4, suggesting that leaf chemistry affects the decomposition rate and biochemical fate of carbon. In particular, terrestrial bacteria shaped the succession of aquatic bacterial communities. The addition of leaves resulted in the equal contribution of epiphytic and endophytic bacteria in the lake water, whereas epiphytic fungi dominated the fungal community structure. Our results suggest that terrestrial bacteria originating from terrestrial leaves influence the microbiome succession in lake ecosystems and play a key role in linking terrestrial carbon to an aquatic food web and determining the quality of carbon emissions that are released into the atmosphere.

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Testing for a change in diet using fatty acid signatures

Cited by 15 publications

References 23 publications

An approach to measure distance between compositional diet estimates containing essential zeros

An approach to measure distance between compositional diet estimates containing essential zeros

Poor nutritional quality of primary producers and zooplankton driven by eutrophication is mitigated at upper trophic levels

Recycled by leaf inhabitants: Terrestrial bacteria drive the mineralization of organic matter in lake water

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