Dietary influence on fatty acid composition of blubber fat of seals as determined by biopsy: A multivariate approach

Grahl‐Nielsen, Otto; Mjaavatten, Olav

doi:10.1007/bf01313092

Cited by 48 publications

(26 citation statements)

References 15 publications

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“…Also indicated is the type of tissue analysed for each prey species to extract FAs. blubber is unknown, and whether M. leonina selectively stores specific dietary FAs or actively biosynthesizes other FAs in preparation for the different fasting periods is uncertain (Grahl-Nielsen & Mjaavatten 1991;GrahlNielsen et al 2000;Best et al 2003). Although modification may occur, the difference between the two winter seasons supports the conclusion that the differences observed were caused, to a large extent, by shifts in diet composition.…”

Section: Appendix Amentioning

confidence: 99%

You are what you eat: describing the foraging ecology of southern elephant seals (Mirounga leonina) using blubber fatty acids

Bradshaw

Hindell

Best

et al. 2003

Proc. R. Soc. Lond. B

153

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Understanding the trophodynamics of marine ecosystems requires data on the temporal and spatial variation in predator diet but, particularly for wide-ranging species, these data are often unavailable. The southern elephant seal (Mirounga leonina) consumes large quantities of fish and squid prey in the Southern Ocean relative to other marine mammals; however, how diet varies relative to seasonal and spatial foraging behaviour is unknown. We used fatty acid (FA) signature analysis of 63 blubber cores from adult female M. leonina over three seasons (winter 1999, summer 2000 and winter 2001) to determine diet structure. We detected significant differences between seasons and between the main foraging regions (Antarctic continental shelf versus pelagic). We used the FA profiles from 53 fish, squid and krill species to construct a discriminant function that would classify each seal, from its blubber sample as having a fish-or squid-FA profile. We determined that a higher proportion of M. leonina had fish-dominated diets during the winter and when foraging around the Antarctic continental shelf, and the majority had more squiddominated diets during the summer when foraging pelagically. Thus, we were able to measure the coarsescale diet structure of a major marine predator using FA profiles, and estimate its associated seasonal and temporal variation.

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Section: Appendix Amentioning

confidence: 99%

You are what you eat: describing the foraging ecology of southern elephant seals (Mirounga leonina) using blubber fatty acids

Bradshaw

Hindell

Best

et al. 2003

Proc. R. Soc. Lond. B

153

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“…However, the concept of specific markers or ratios is of limited value to a study dealing with trophic interactions of higher marine predators or large-scale comparisons. Consequently, various statistical multivariate approaches have been proposed (Grahl-Nielsen & Mjaavatten 1991, Smith et al 1997, Mayzaud et al 1999 to account for the covariation of entire profiles of fatty alcohols and/or fatty acids from both potential prey and predator.…”

Section: Use Of Fatty Alcohol and Fatty Acid Patterns In Trophic Studiesmentioning

confidence: 99%

Lipid composition of stomach oil in a procellariiform seabird Puffinus tenuirostris: implications for food web studies

Connan¹,

Mayzaud²,

Boutoute³

et al. 2005

Mar. Ecol. Prog. Ser.

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Some procellariiform seabirds use a dual strategy for provisioning their chicks by alternating between short and long foraging trips (LT). Trophic relationships of adult birds are unknown when they feed for themselves during LT because digestion processes preclude direct prey determination. Since stomach contents collected after LT contain oil of dietary origin, we tested the use of oil lipids as prey trophic markers using the Tasmanian short-tailed shearwater Puffinus tenuirostris as a model seabird. The intra-specific variability of stomach oils was investigated through lipid class composition, and their fatty acid and fatty alcohol profiles. Oils mainly consisted of wax esters (WE) and triacylglycerols (TAG) (49 to 86 and 7 to 41%, respectively). Major fatty acids of TAG were in a decreasing order 18:1n-9, 16:0, 16:1n-7, 14:0, 20:5n-3 and 22:6n-3. The WE-fatty acid profiles were dominated by 18:1n-9 and 16:1n-7 while fatty alcohol profiles were dominated by 16:0. Fatty alcohol and fatty acid patterns were tested as possible descriptors of ingested prey (derived from literature data) through multivariate discriminant analyses. Comparisons of the WE fatty alcohol patterns showed a close association with the alcohol structure of 3 myctophid fish species namely Krefftichthys anderssoni, Gymnoscopelus braueri and Electrona antarctica; these results were corroborated by WE fatty acid analysis. Comparison of TAG fatty acid patterns showed the highest similarity between oils and the digestive gland of the myctophid-eater squid Moroteuthis ingens in association with the myctophid Electrona carlsbergi. Hence, biochemical analysis of both WE and TAG strongly suggested that adult short-tailed shearwaters mainly prey upon Antarctic/subAntarctic myctophids when they feed for themselves, thus emphasizing the role of these oceanic mesopelagic fish in the marine ecosystem of the Southern Ocean.

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“…John and Lund 1996;Iverson et al 1997aIverson et al , 2004. Although the presence of some FAs is directly traceable to a specific source, the universality of the use of FAs as dietary tracers is a point of some contention in the recent scientific literature (e.g., Viga and Grahl-Nielsen 1990;Grahl-Nielsen and Mjaavatten 1991;Hove and Grahl-Nielsen 1991;Smith et al 1997Smith et al , 1999Grahl-Nielsen 1999;Grahl-Nielsen et al 2000).…”

Section: Introductionmentioning

confidence: 99%

“…To achieve the most complete analyses possible, both hard-part remains and FA composition analyses were performed. The analysis of FAs is a rather new technique in the field of marine mammal diet investigation and few studies have attempted to assess the accuracy of this methodology (Grahl-Nielsen and Mjaavatten 1991;Iverson et al 1997a;Kirsch et al 1998). The dual assessment approach in this study allowed for a comparison of the results produced by the two methods.…”

Section: Introductionmentioning

confidence: 99%

Autumn diet of harbour seals (Phoca vitulina) at Prins Karls Forland, Svalbard, assessed via scat and fatty-acid analyses

Andersen¹,

Lydersen²,

Grahl‐Nielsen³

et al. 2004

Can. J. Zool.

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This study used hard-part analyses from scats (n = 117) and stomachs (n = 3) to investigate the diet of high Arctic harbour seals (Phoca vitulina L., 1758) living on Prins Karls Forland, Svalbard, in early autumn. Additionally, it compared the results of fatty-acid analyses of the seals' blubber versus that of potential prey with the findings of the more traditional diet assessment method. Svalbard harbour seals appear to be opportunistic, polyphagous feeders similar to the situation in other parts of their range. Members of the cod-family, and secondarily the sculpin-family, dominated the diet of harbour seals on Svalbard. Small fish comprised most of the diet of the harbour seals; invertebrates appeared to be insignificant. Atlantic cod (Gadus morhua L., 1758) was the most important species in the diet in terms of biomass, whereas polar cod (Boreogadus saida (Lepechin, 1774)) was the most frequently consumed prey. Our comparison between hard-part diet analyses and fatty acids is far from definitive, but it indicates a general influence of the diet on the fatty-acid composition of the inner blubber layer. However, it also suggests systematic selective processes in the incorporation of fatty acids into the blubber. Observed differences between the fatty-acid composition of the different blubber layers and possible differences between sex and age classes warrant further investigation.Résumé : Nous avons analysé les structures dures dans les fèces (n = 117) et les estomacs (n = 3) afin d'étudier le ré-gime alimentaire de phoques veaux marins (Phoca vitulina L., 1758) du haut-arctique vivant à Prins Karls Forland, à Svalbard, au début de l'automne. De plus, nous avons comparé les résultats d'analyses d'acides gras du lard des phoques et de leurs proies potentielles avec les résultats des méthodes plus traditionnelles d'évaluation du régime alimentaire. Les phoques veaux marins de Svalbard semblent être des polyphages opportunistes, comme ailleurs dans leur aire de répartition. Le régime alimentaire des phoques veaux marins de Svalbard est dominé par les poissons de la famille de la morue et secondairement de la famille du chabot. Le régime des phoques comprend surtout des poissons de petite taille; l'importance des invertébrés est insignifiante. La morue franche (Gadus morhua L., 1758) est l'espèce la plus importante en ce qui a trait à la biomasse, alors que le saïda franc (Boreogadus saida (Lepechin, 1774)) est la proie la plus fréquemment consommée. Notre comparaison de l'analyse des structures dures et de l'analyse des acides gras est loin d'être définitive, mais elle montre une influence générale du régime alimentaire sur la composition en acides gras de la couche interne de lard. Elle indique aussi, cependant, l'existence de processus sélectifs systématiques dans l'incorporation des acides gras dans le lard. Les différences observées dans la composition en acides gras des différen-tes couches de lard et les différences possibles entre les sexes et les différentes classeâge requièrent des études supp...

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Dietary influence on fatty acid composition of blubber fat of seals as determined by biopsy: A multivariate approach

Cited by 48 publications

References 15 publications

You are what you eat: describing the foraging ecology of southern elephant seals (Mirounga leonina) using blubber fatty acids

You are what you eat: describing the foraging ecology of southern elephant seals (Mirounga leonina) using blubber fatty acids

Lipid composition of stomach oil in a procellariiform seabird Puffinus tenuirostris: implications for food web studies

Autumn diet of harbour seals (Phoca vitulina) at Prins Karls Forland, Svalbard, assessed via scat and fatty-acid analyses

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