Simultaneous estimation of diet composition and calibration coefficients with fatty acid signature data

Bromaghin, Jeffrey F.; Budge, Suzanne M.; Thiemann, Gregory W.; Rode, Karyn D.

doi:10.1002/ece3.3179

Cited by 35 publications

(19 citation statements)

References 49 publications

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“…An important aspect of such studies is the feeding of mixtures of diets having different FA profiles to better assess performance of QFASA, rather than relying on the modelling exercises that must be applied otherwise. Recently, Bromaghin et al [49] proposed a modelling technique to simultaneously royalsocietypublishing.org/journal/rstb Phil. Trans.…”

Section: Discussionmentioning

confidence: 99%

Dietary fat concentrations influence fatty acid assimilation patterns in Atlantic pollock (Pollachius virens)

Budge

Townsend

Lall

et al. 2020

Phil. Trans. R. Soc. B

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A key aspect in the use of fatty acids (FA) to estimate predator diets using quantitative FA signature analysis (QFASA) is the ability to account for FA assimilation through the use of calibration coefficients (CC). Here, we tested the assumption that CC are independent of dietary fat concentrations by feeding Atlantic pollock ( Pollachius virens ) three formulated diets with very similar FA proportions but different fat concentrations (5–9% of diet) for 20 weeks. CC calculated using FA profiles of diet and triacylglycerols in pollock liver were significantly different for the three diets. To test the robustness of diet estimates to these differences, we used the CC set derived from feeding the diet with the lowest fat concentration, published prey FA profiles and realistic diet estimates of pollock to construct ‘pseudo-predators'. Application of QFASA to each pseudo-predator using the three sets of CC and the same prey FA profiles resulted in diet estimate biases of twofold for major prey items and approximately fivefold for minor prey items. This work illustrates the importance of incorporating diets with fat concentrations that are similar to natural prey when conducting feeding experiments to calculate CC. This article is part of the theme ‘The next horizons for lipids as ‘trophic biomarkers': evidence and significance of consumer modification of dietary fatty acids'.

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Section: Discussionmentioning

confidence: 99%

Dietary fat concentrations influence fatty acid assimilation patterns in Atlantic pollock (Pollachius virens)

Budge

Townsend

Lall

et al. 2020

Phil. Trans. R. Soc. B

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“…We were interested to determine if a model could be established using predators fed prey from one lake and a library of prey fatty acid profiles from another lake. To avoid noise added by traditional QFASA models that incorporate CC, we worked solely with the fatty acid profiles of steelhead trout (Bromaghin, Budge, Thiemann, & Rode, 2017;Galloway et al, 2014;Happel, Stratton, Kolb, et al, 2016).…”

Section: Me Thodsmentioning

confidence: 99%

Fatty acids differentiate consumers despite variation within prey fatty acid profiles

et al. 2019

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Techniques that biochemically trace foraging habits of predators rely on the assumption that intra‐specific variation in prey species is smaller than variation among them. At the same time, these techniques often show that diets can induce drastic changes in the biochemical profiles of prey species, especially across different ecosystems. We tested if intra‐specific variation in fatty acid profiles of prey species added enough noise to confound quantitative fatty acid signature analysis (QFASA) using a controlled feeding experiment. Steelhead trout (Oncorhynchus mykiss) were fed either alewife (Alosa pseudoharengus) or round goby (Neogobius melanostomus) from either Lake Ontario or Cayuga Lake for a period of 8 weeks. Fatty acid profiles were significantly different between prey species and between lake of origin within each species. Differences in fatty acid profiles of steelhead trout strongly reflected prey species differences, whereas differences related to prey origin (lakes) were noted at a much lesser extent. QFASA performed remarkably well given the differences observed between the lakes prey originated from. Our results indicate that QFASA models for steelhead trout are probably not specific to one lake, and could provide estimates for other freshwater systems where alewife and round goby serve as the primary forage.

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“…Lipid storage is affected by the energy acquired from an animal's diet, which is reflected by the fatty acids (FAs) stored in the blubber (Iverson et al, 2004;Budge et al, 2006;Bromaghin et al, 2017). West et al (1979) examined the FA composition of blubber from the sternum of Pacific walruses harvested in the Bering Sea, however samples sizes were limited to two males and two females.…”

Section: Introductionmentioning

confidence: 99%

Variability of Lipids and Fatty Acids in Pacific Walrus Blubber

2021

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The variability of lipid content and fatty acid (FA) composition across blubber depth and body sites are important considerations for condition and diet studies of marine mammals. We investigated lipid and FA variability among inner and outer blubber layers, three body sites, four study years, and lactation status of adult female Pacific walruses (Odobenus rosmarus divergens) using blubber samples collected from subsistence-harvested walruses in spring 2007–2010. Percent lipid content did not differ between the inner and outer blubber layers at the rump, flank, or sternum of walruses. Although FA composition differed between the inner and outer blubber layers, the difference was consistent across body sites, and differences between layers within individual FAs were small (<2%). Lipid content at the sternum of lactating females was 6% higher than non-lactating females, consistent with known variation in body condition among these reproductive classes. Across study years, lipid content varied 18% and individual FAs varied 6%, likely reflecting population-level interannual variability in energy budgets and small differences in diet among years. Consistency in blubber lipid content across blubber depth and body sites and detectable variation in blubber lipid content among reproductive classes and years suggests the potential for lipid content to be a useful indicator of walrus body condition. In addition to information on condition, FA composition of blubber samples could potentially provide insights into changes in walrus diet that may be expected to occur from changes in their access to prey resources resulting from continued sea ice loss.

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Simultaneous estimation of diet composition and calibration coefficients with fatty acid signature data

Cited by 35 publications

References 49 publications

Dietary fat concentrations influence fatty acid assimilation patterns in Atlantic pollock (Pollachius virens)

Dietary fat concentrations influence fatty acid assimilation patterns in Atlantic pollock (Pollachius virens)

Fatty acids differentiate consumers despite variation within prey fatty acid profiles

Variability of Lipids and Fatty Acids in Pacific Walrus Blubber

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