A deep dive into fat: Investigating blubber lipidomic fingerprint of killer whales and humpback whales in northern Norway

P. Bories, A.H. Rikardsen, P. Leonards, A.T. Fisk, S. Tartu, E.F. Vogel, J. Bytingsvik, P. Blévin

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

© 2021 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.In cetaceans, blubber is the primary and largest lipid body reservoir. Our current understanding about lipid stores and uses in cetaceans is still limited, and most studies only focused on a single narrow snapshot of the lipidome. We documented an extended lipidomic fingerprint in two cetacean species present in northern Norway during wintertime. We were able to detect 817 molecular lipid species in blubber of killer whales (Orcinus orca) and humpback whales (Megaptera novaeangliae). The profiles were largely dominated by triradylglycerols in both species and, to a lesser extent, by other constituents including glycerophosphocholines, phosphosphingolipids, glycerophosphoethanolamines, and diradylglycerols. Through a unique combination of traditional statistical approaches, together with a novel bioinformatic tool (LION/web), we showed contrasting fingerprint composition between species. The higher content of triradylglycerols in humpback whales is necessary to fuel their upcoming half a year fasting and energy-demanding migration between feeding and breeding grounds. In adipocytes, we assume that the intense feeding rate of humpback whales prior to migration translates into an important accumulation of triacylglycerol content in lipid droplets. Upstream, the endoplasmic reticulum is operating at full capacity to supply acute lipid storage, consistent with the reported enrichment of glycerophosphocholines in humpback whales, major components of the endoplasmic reticulum. There was also an enrichment of membrane components, which translates into higher sphingolipid content in the lipidome of killer whales, potentially as a structural adaptation for their higher hydrodynamic performance. Finally, the presence of both lipid-enriched and lipid-depleted individuals within the killer whale population in Norway suggests dietary specialization, consistent with significant differences in δ15N and δ13C isotopic ratios in skin between the two groups, with higher values and a wider niche for the lipid-enriched individuals. Results suggest the lipid-depleted killer whales were herring specialists, while the lipid-enriched individuals might feed on both herrings and seals.
Original languageEnglish
Pages (from-to)6716-6729
JournalEcology and Evolution
Volume11
Issue number11
DOIs
Publication statusPublished - 1 Jun 2021

Funding

This work was financed by the Fram Center Flagship Hazardous Substances (WhaleHealth project; PI: Jenny Bytingsvik) and the WhaleFeast project supported by the Regional Research Council No. 282469. This study was approved by the Norwegian Animal Research Authority (FOTS ID 13639 and 14135). We thank Trond Johnsen and Evert Mul for their help collecting the samples in the field and Anders Goksøyr to communicate about LION/web. The authors thank the two reviewers and editor for their comments, which have greatly improved the manuscript.

FundersFunder number
Regional Research Council282469

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