Stable isotopes and elasmobranchs: tissue types, methods, applications and assumptions

• Published in: Journal of fish biology Vol. 80; no. 5; pp. 1449 - 1484
• Main Authors: Hussey, N. E., MacNeil, M. A., Olin, J. A., McMeans, B. C., Kinney, M. J., Chapman, D. D., Fisk, A. T.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.04.2012
• Subjects: Animal Migration; Animals; Diet; Ecology - methods; Ecosystem; Elasmobranchii; Elasmobranchii - physiology; Isotopes - analysis; lipid extraction; Marine; mixing models; niche width; specialization; Specimen Handling; trophic position; turnover; δ13C; δ15N
• ISSN: 0022-1112; 1095-8649
• DOI: 10.1111/j.1095-8649.2012.03251.x

Stable‐isotope analysis (SIA) can act as a powerful ecological tracer with which to examine diet, trophic position and movement, as well as more complex questions pertaining to community dynamics and feeding strategies or behaviour among aquatic organisms. With major advances in the understanding of the methodological approaches and assumptions of SIA through dedicated experimental work in the broader literature coupled with the inherent difficulty of studying typically large, highly mobile marine predators, SIA is increasingly being used to investigate the ecology of elasmobranchs (sharks, skates and rays). Here, the current state of SIA in elasmobranchs is reviewed, focusing on available tissues for analysis, methodological issues relating to the effects of lipid extraction and urea, the experimental dynamics of isotopic incorporation, diet‐tissue discrimination factors, estimating trophic position, diet and mixing models and individual specialization and niche‐width analyses. These areas are discussed in terms of assumptions made when applying SIA to the study of elasmobranch ecology and the requirement that investigators standardize analytical approaches. Recommendations are made for future SIA experimental work that would improve understanding of stable‐isotope dynamics and advance their application in the study of sharks, skates and rays.