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Polar compounds preclude mathematical lipid correction of carbon stable isotopes in deep-water sharks

Lookup NU author(s): Professor Nick Polunin, Dr Christopher Sweeting, Dr Steve Newman

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This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).


Abstract

© 2017 Elsevier B.V. Lipids affect stable isotope values generated for marine fishes, however these effects remain poorly described for many extant shark taxa, especially deep-sea species. Here, we report the effects of lipid extraction (LE) on δ13C, δ15N, and C:N values of seven deep-sea sharks, generate novel mathematical normalizations for δ13C based on the relationship between bulk and lipid extracted values (δ13CBulk and δ13CLE) and examine whether common normalized correction models provide a robust method for addressing lipid-biasing effects in two species, the Cuban dogfish (Squalus cubensis; n = 20), and Greenland shark (Somniosus microcephalus; n = 24). LE generally resulted in enrichment of 13C and 15N, but produced variable effects on C:N across all species. Novel mathematical normalizations for δ13C were derived from the pooled shark community, and a single species-specific correction was generated for the Cuban dogfish, but could not be determined for the Greenland shark. Four common lipid correction models used for teleosts, failed to accurately predict δ13C values statistically similar to δ13CLE, in both Cuban dogfish and Greenland sharks, likely due to the confounding effects of lipids and urea on C:N. These observations suggest that chemical lipid extraction should be a mandatory procedure prior to interpreting stable isotope data for deep-sea sharks, at least for those species where lipid effects are large.


Publication metadata

Author(s): Shipley ON, Olin JA, Polunin NVC, Sweeting CJ, Newman SP, Brooks EJ, Barker S, Witt MJ, Talwar B, Hussey NE

Publication type: Article

Publication status: Published

Journal: Journal of Experimental Marine Biology and Ecology

Year: 2017

Volume: 494

Pages: 69-74

Print publication date: 01/09/2017

Online publication date: 02/06/2017

Acceptance date: 05/05/2017

ISSN (print): 0022-0981

Publisher: Elsevier BV

URL: https://doi.org/10.1016/j.jembe.2017.05.002

DOI: 10.1016/j.jembe.2017.05.002


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