Lipid extraction techniques for stable isotope analysis of bird eggs: Chloroform–methanol leads to more enriched 13C values than extraction via petroleum ether

Elliott, Kyle H.; Elliott, John E.

doi:10.1016/j.jembe.2015.09.017

Cited by 21 publications

(16 citation statements)

References 36 publications

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“…Egg samples were analysed in triplicate with precision < 0.05 for both isotopes. Due to the high lipid content of egg samples, δ 13 C values were corrected using the C:N ratio of each sample (Elliott and Elliott, 2016). These analyses were described in more detail in Viñas et al (2020).…”

Section: Discussionmentioning

confidence: 99%

Amino Acid δ15N Can Detect Diet Effects on Pollution Risks for Yellow-Legged Gulls Overlooked by Trophic Position

et al. 2021

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The use of top-consumers as bioindicators of the health of food webs is hampered by uncertainties in their effective use of resources. In this study, the abundance of stable nitrogen isotopes in amino acids from homogenised eggs of the Yellow-legged Gull (Larus michahellis) allowed to identify variations in trophic resource exploitation between geographically adjacent nesting colonies in the Ria de Vigo (NW Spain) that exhibited marked differences in pollutants. Eggs from nests in the Cíes Islands (located in a National Park) showed a large variability in stable carbon and nitrogen isotopes in bulk egg content encompassing that of eggs from Vigo city (a major fishing harbour). However, both colonies differed in the relative concentration and abundance of nitrogen isotopes of lysine, an essential amino acid present in marine prey, but also extensively used in feed stocks for poultry and swine. Notwithstanding the similarity in trophic position for both colonies, gulls from Cíes Islands may have acquired a substantial fraction of lysine from garbage dump sites, while those of the urban colony relied on fish discards. This unexpected conclusion is partly supported by the large variability reported for gull’s diet in this region and calls for detailed estimations of diet when assessing the conservation status and pollution risks of marine ecosystems.

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Section: Discussionmentioning

confidence: 99%

Amino Acid δ15N Can Detect Diet Effects on Pollution Risks for Yellow-Legged Gulls Overlooked by Trophic Position

et al. 2021

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“…Used together, FAs and SIs are complementary since they are proxies of different dietary components. While the FAs are derived from dietary lipids, the δ 15 N values and in this work also the δ 13 C values, analysed by using delipidated samples [69], represent proteins. FA profiling has previously proven to be an effective method to study predator foraging ecology and may even indicate specific prey species [17,18] but the power of the method in such species-level diet determination has also been questioned [70].…”

Section: Discussionmentioning

confidence: 99%

Complementary methods assessing short and long-term prey of a marine top predator ‒ Application to the grey seal-fishery conflict in the Baltic Sea

et al. 2019

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The growing grey seal (Halichoerus grypus) population in the Baltic Sea has created conflicts with local fisheries, comparable to similar emerging problems worldwide. Adequate information on the foraging habits is a requirement for responsible management of the seal population. We investigated the applicability of available dietary assessment methods by comparing morphological analysis and DNA metabarcoding of gut contents (short-term diet; n = 129/125 seals, respectively), and tissue chemical markers i.e. fatty acid (FA) profiles of blubber and stable isotopes (SIs) of liver and muscle (mid- or long-term diet; n = 108 seals for the FA and SI markers). The methods provided complementary information. Short-term methods indicated prey species and revealed dietary differences between age groups and areas but for limited time period. In the central Baltic, herring was the main prey, while in the Gulf of Finland percid and cyprinid species together comprised the largest part of the diet. Perch was also an important prey in the western Baltic Proper. The DNA analysis provided firm identification of many prey species, which were neglected or identified only at species group level by morphological analysis. Liver SIs distinguished spatial foraging patterns and identified potentially migrated individuals, whereas blubber FAs distinguished individuals frequently utilizing certain types of prey. Tissue chemical markers of adult males suggested specialized feeding to certain areas and prey, which suggest that these individuals are especially prone to cause economic losses for fisheries. We recommend combined analyses of gut contents and tissue chemical markers as dietary monitoring methodology of aquatic top predators to support an optimal ecosystem-based management.

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“…) and by the chemical extraction methods (Dobush et al. , Logan and Lutcavage , Elliott and Elliott ). Lipid extraction methods using polar solvents tend to increase the δ 13 C values and decrease CN ratios compared to non‐polar solvents (Logan and Lutcavage ).…”

Section: Introductionmentioning

confidence: 99%

“…The depleted d 13 C ratios result from the isotopic fractionation that occurs during the conversion of pyruvate to acetyl coenzyme A during lipid synthesis (DeNiro and Epstein 1977). The d 13 C values are also influenced by the heterogeneity in lipid content among organisms (Post et al 2007) and tissue types (McConnaughey andMcRoy 1979, Sweeting et al 2006) and by the chemical extraction methods (Dobush et al 1985, Elliott and Elliott 2016. Lipid extraction methods using polar solvents tend to increase the d 13 C values and decrease CN ratios compared to non-polar solvents .…”

Section: Introductionmentioning

confidence: 99%

Influence of lipids on stable isotope ratios in mammal hair: highlighting the importance of validation

2019

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Carbon (δ13C) and nitrogen (δ15N) stable isotope ratios are increasingly used in ecological studies to evaluate diet composition and trophic relationships. However, lipids may influence stable isotope ratios due to the depletion of 13C in adipose tissues relative to proteins and carbohydrates. δ13C values can be corrected by lipid extraction or normalization models. The aims of our study were to evaluate the effects of lipid extraction on stable isotope ratios in a terrestrial mammal, the caribou (Rangifer tarandus caribou), and to propose relevant lipid normalization models that are method‐ and tissue‐specific for δ13C values. We also evaluated whether four δ13C lipid normalization and correction models proposed in the literature were applicable to our study species. Stable isotope ratios were obtained for hair, plasma, and red blood cell samples of 44 caribou in the Gaspésie National Park (Québec, Canada). The effects of lipid extraction on stable isotope ratios were tested using a paired t‐test. A simple linear model was used to correct for the effects of lipid extraction and to assess its performance compared to that of published equations. Lipid content significantly influenced δ13C values in caribou hair. The four lipid normalization equations commonly used in the literature did not accurately predict δ13Clipid‐free values of caribou hair. Based on our results, we recommend controlling systematically for lipids in terrestrial systems and analyzing δ13C (lipid‐free) and δ15N (bulk) from two separate aliquots to reach a greater precision. We also recommend controlling for lipids in hair tissue. If not possible, we recommend using a lipid normalization model that is tissue‐, method‐, and species‐specific or applying a model that has been previously validated for the tissue and species of interest.

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Lipid extraction techniques for stable isotope analysis of bird eggs: Chloroform–methanol leads to more enriched 13C values than extraction via petroleum ether

Cited by 21 publications

References 36 publications

Amino Acid δ15N Can Detect Diet Effects on Pollution Risks for Yellow-Legged Gulls Overlooked by Trophic Position

Amino Acid δ15N Can Detect Diet Effects on Pollution Risks for Yellow-Legged Gulls Overlooked by Trophic Position

Complementary methods assessing short and long-term prey of a marine top predator ‒ Application to the grey seal-fishery conflict in the Baltic Sea

Influence of lipids on stable isotope ratios in mammal hair: highlighting the importance of validation

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