Dietary versus nondietary fatty acid profiles of lake trout ecotypes from Lake Superior and Great Bear Lake: Are fish really what they eat?

• Published in: Canadian journal of fisheries and aquatic sciences Vol. 77; no. 7; pp. 1209 - 1220
• Main Authors: Chavarie, L, Hoffmann, J, Muir, A.M, Krueger, C.C, Bronte, C.R, Howland, K.L, Gallagher, C.P, Sitar, S.P, Hansen, M.J, Vinson, M.R, Baker, L.F, Loseto, L.L, Tonn, W.M, Swanson, H.K
• Format: Journal Article
• Language: English
• Published: 1840 Woodward Drive, Suite 1, Ottawa, ON K2C 0P7 NRC Research Press 01.07.2020; Canadian Science Publishing NRC Research Press
• Subjects: Animal behavior; Associated species; Biochemical analysis; Biological sampling; Biomarkers; Composition; Diet; Ecological niches; Ecotypes; Fatty acid composition; Fatty acids; Feeding habits; Fishes; Food chains; Food webs; Freshwater; Freshwater fishes; Habitat utilization; Habitats; Lakes; Lipids; Methods; Muscles; Niche (Ecology); Niches; Nutritional requirements; Oligotrophic lakes; Salvelinus namaycush; Statistical methods; Tissue; Trophic relationships; Trout; Variation; Arctic Ocean; Canada; Michigan; Lake Superior; Canada, Northwest Territories, Great Bear Lake; USA, Lake Superior
• ISSN: 0706-652X; 1205-7533
• DOI: 10.1139/cjfas-2019-0343

Fatty acids are well-established biomarkers used to characterize trophic ecology, food-web linkages, and the ecological niche of many different taxa. Most often, fatty acids that are examined include only those previously identified as “dietary” or “extended dietary” biomarkers. Fatty acids considered as nondietary biomarkers, however, represent numerous fatty acids that can be extracted. Some studies may include nondietary fatty acids (i.e., combined with dietary fatty acids), but do not specifically assess them, whereas in other studies, these data are discarded. In this study, we explored whether nondietary biomarker fatty acids can provide worthwhile information by assessing their ability to discriminate intraspecific diversity within and between lakes. Nondietary fatty acids used as biomarkers delineated variation among regions, among locations within a lake, and among ecotypes within a species. Physiological differences that arise from differences in energy processing can be adaptive and linked to habitat use by a species’ ecotype and likely explains why nondietary fatty acid biomarkers can be a relevant tool to delineate intraspecific diversity. Little is known about the nondietary-mediated differences in fatty acid composition, but our results showed that nondietary fatty acid biomarkers can be useful tool in identifying variation.