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New insights into the seasonal diet of Antarctic krill using triacylglycerol and phospholipid fatty acids, and sterol composition

Citation

Ericson, JA and Hellessey, N and Nichols, PD and Nicol, S and Kawaguchi, S and Hoem, N and Virtue, P, New insights into the seasonal diet of Antarctic krill using triacylglycerol and phospholipid fatty acids, and sterol composition, Polar Biology, 42, (11) pp. 1985-1996. ISSN 0722-4060 (2019) [Refereed Article]

Copyright Statement

Copyright 2019 Crown

DOI: doi:10.1007/s00300-019-02573-6

Abstract

Fatty acid analysis for estimating dietary sources in marine predators is a powerful tool in food web research. However, questions have been raised about using fatty acids as dietary indicators from whole lipid samples, rather than from separate lipid classes. A drawback of scientific field-based studies is that samples are rarely collected over extended periods, precluding seasonal dietary comparisons. We used fisheries samples obtained over one year to investigate seasonal variations in the fatty acid composition of separated phospholipids and triacylglycerols of Antarctic krill (Euphausia superba). Seasonal variation was observed in fatty acid biomarkers within triacylglycerol and phospholipid fractions of krill. Fatty acids in krill triacylglycerols (thought to best represent recent diet), reflected omnivorous feeding with highest percentages of flagellate biomarkers (18:4n-3) in summer, and diatom biomarkers (16:1n-7c) in autumn, winter and spring. Carnivory biomarkers (∑ 20:1 + 22:1 and 18:1n-9c/18:1n-7c) in krill were higher in autumn. Phospholipid fatty acids were less variable and higher in 20:5n-3 and 22:6n-3, which are essential components of cell membranes. Sterol composition did not yield detailed dietary information, but percentages and quantities of cholesterol, the major krill sterol, were significantly higher in winter and spring compared with summer and autumn. Copepod markers ∑ 20:1 + 22:1 were not strongly associated with the triacylglycerol fraction during some seasons, and neither was 18:4n-3. Krill might mobilise 18:4n-3 from triacylglycerols to phospholipids for conversion to long-chain (≥ C20) polyunsaturated fatty acids, which would have implications for its role as a dietary biomarker. For the first time, we demonstrate the dynamic seasonal relationship between specific biomarkers and krill lipid classes.

Item Details

Item Type:Refereed Article
Keywords:lipids. fatty acids, Antarctic krill, fatty acid biomarkers, inferred diet, phospholipids, sterols, triacylglycerols
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Ecological Physiology
Objective Division:Environment
Objective Group:Climate and Climate Change
Objective Field:Climate and Climate Change not elsewhere classified
UTAS Author:Ericson, JA (Ms Jessica Ericson)
UTAS Author:Hellessey, N (Miss Nicole Hellessey)
UTAS Author:Nichols, PD (Dr Peter Nichols)
UTAS Author:Nicol, S (Dr Stephen Nicol)
UTAS Author:Kawaguchi, S (Dr So Kawaguchi)
UTAS Author:Virtue, P (Associate Professor Patti Virtue)
ID Code:135025
Year Published:2019
Funding Support:Australian Research Council (LP140100412)
Web of Science® Times Cited:1
Deposited By:Ecology and Biodiversity
Deposited On:2019-09-23
Last Modified:2020-01-07
Downloads:0

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