Estimating stable carbon isotope values of microphytobenthos in the Arctic for application to food web studies

Oxtoby, L. E.; Mathis, Jeremy T.; Juranek, L. W.; Wooller, Matthew J.

doi:10.1007/s00300-015-1800-2

Cited by 14 publications

(7 citation statements)

References 68 publications

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“…Because lipids are not always homogenously distributed within a tissue 9 , lipid content can be an important source of isotopic variability even among multiple samples of a single tissue from one individual 10 . Furthermore, δ 13 C varies among fatty acids 11,12 , thus the δ 13 C of lipids depends on their fatty acid composition and uneven distribution of different types of lipids within a tissue may lead to heterogeneity in δ 13 C.…”

Section: Introductionmentioning

confidence: 99%

Lipid normalization and stable isotope discrimination in Pacific walrus tissues

Clark

Horstmann

Misarti

2019

Sci Rep

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Analysis of stable carbon and nitrogen isotope values (δ 13 C and δ 15 N) of animal tissues can provide important information about diet, physiology, and movements. Interpretation of δ 13 C and δ 15 N values, however, is influenced by factors such as sample lipid content, tissue-specific isotope discrimination, and tissue turnover rates, which are typically species- and tissue-specific. In this study, we generated lipid normalization models for δ 13 C and investigated the effects of chemical lipid extractions on δ 13 C and δ 15 N in Pacific walrus ( Odobenus rosmarus divergens ) muscle, liver, and skin. We also evaluated tissue-specific isotope discrimination in walrus muscle, liver, skin, and bone collagen. Mean δ 13 C lipid-free of skin and bone collagen were similar, as were mean δ 15 N of muscle and liver. All other tissues differed significantly for both isotopes. Differences in δ 13 C lipid-free and δ 15 N among tissues agreed with published estimates of marine mammal tissue-specific isotope discrimination factors, with the exception of skin. The results of this work will allow researchers to gain a clearer understanding of walrus diet and the structure of Arctic food webs, while also making it possible to directly compare the results of contemporary walrus isotope research with those of historic and paleoecological studies.

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Section: Introductionmentioning

confidence: 99%

Lipid normalization and stable isotope discrimination in Pacific walrus tissues

Clark

Horstmann

Misarti

2019

Sci Rep

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“…Other potential sources of primary production in the Arctic are microphytobenthos and under-ice blooms. Microphytobenthos, a diatom dominated community on the sediment surface (Wulff et al 2009), is difficult to characterize for fatty acid and stable isotope composition because separating microphytobenthos from other organic matter sources such as detritus and microbes is very difficult (McTigue and Dunton 2014;Oxtoby et al 2016). Under-ice blooms mostly seem to resemble pelagic phytoplankton communities but are very patchy in occurrence (Arrigo et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Tracing sea ice algae into various benthic feeding types on the Chukchi Sea shelf

et al. 2017

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Climate change in the Arctic is expected to have drastic effects on marine primary production sources by shifting ice-associated primary production to an overall greater contribution from pelagic primary production. This shift could influence the timing, amount, and quality of algal material reaching the benthos. We determined the contribution of sea ice particulate organic matter (iPOM) to benthic-feeding invertebrates by examining concentrations and stable carbon isotope values (expressed as δ13C values) of three FAs prominent in diatoms: 16:4(n-1), 16:1(n-7) and 20:5(n-3). Our underlying assumption was that diatoms make up the majority in sea ice algal communities compared with phytoplankton communities. According to the FA concentrations, subsurface deposit feeders consumed the most iPOM and suspension feeders the least. Conversely, there were little differences in δ13C values of FAs between deposit and suspension feeders, but the higher δ13C values of 16:1(n-7) in omnivores indicated greater consumption of iPOM. We suggest that omnivores accumulate the ice algal FA biomarker from their benthic prey, which in turn may feed on ice algae from a deposited sediment pool. The dissimilar results between FA concentrations and isotope values suggest that the FAs used here may not be sufficiently source-specific and that other unaccounted for production sources, such as bacteria, may also contribute to the FA pool. We propose that FA isotope values are a more indicative biomarker than FA concentrations, but there is a further need for more specific ice algal biomarkers to resolve the question of ice algal contributions to the Arctic benthic food web.

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“…The highest sediment chl a measurements in this study were observed at sampling sites ≤40 m depths, but we did not have the data to estimate the proportion of chl a attributable to pelagic versus benthic algae. It is conceivable that the low δ 13 C values of benthos in the nearshore shelf were partially attributable to the assimilation of benthic microalgal carbon (Oxtoby et al 2016).…”

Section: Influence Of Vertical Water Mass Structurementioning

confidence: 99%